No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Oral Administration of L-Citrulline, but not L-Arginine or L-Ornithine, Acts as a Hypothermic Agent in Chicks
Abstract
Some amino acids are important regulators of key metabolic pathways and therefore necessary for several physiological functions. However, little is know about thermoregulatory functions of amino acids. In this study, therefore chicks were either centrally or orally administered with L-citrulline (L-Cit), L-arginine (L-Arg) or L-ornithine (L-Orn) to monitor changes in rectal temperature. In Experiment 1, the amino acids (L-Cit, L-Arg and L-Orn) were administered into the left ventricle of the chicks by intracerebroventicular (i.c.v.) injection at a dose of 1 μmol/10 μl to monitor the effects of these amino acids on rectal temperature during 120 min of the experimental period. In Experiment 2, chicks received the same amino acids by oral administration at a dose of 15 mmol/10 ml/kg body weight. In Experiment 3, chicks received three doses of L-Cit (3.75, 7.5 or 15 mmol/10 ml/kg body weight) by oral administration. I.c.v. injection with any of the amino acids studied did not alter body temperature, but oral administration of L-Cit significantly reduced body temperature. Importantly, the highest does effectively reduced body temperature. These results suggest that peripheral L-Cit has a hypothermic function in chicks, which may be a new candidate to minimize high body temperature in poultry during summer heat stress.
... Previous studies have been reported that oral administration of L-citrulline (L-Cit) decreased body temperature in layer chicks and afforded a degree of thermotolerance [25]. It is well known that the inclusion of synthetic L-Cit in poultry diets has not been approved in some countries, therefore one of alternative way might be the use of natural source of L-Cit from watermelon. ...
... In addition, Poduri, et al. [35] also demontrated that there ware no differences in body temperature when mices were supplemented by WRE. Furthermore, Chowdhury, et al. [25] revealed that intracerebroventricular (i.c.v) of L-Cit failed to affect body temperature in layer chicks. However, the effect of WRE on body temperature differed with other reports. ...
... Nguyen, et al. [30] demontrated that body temperature was significantly decreased when layer chicks were orally administrated with WRE. Additionally, Chowdhury, et al. [25] revealed that oral administration of L-Cit significantly lowered body temperature in layer chicks. The reason for these discrepancies on body temperature in respon to oral administration of WRE or both i.c.v. and oral administration of L-Cit in birds perhaps due to varietas of watermelon, variations in experimental period, differences in doses, breed, strain or species. ...
... (Yamaguchi, Japan). Because L-Cit is difficult to dissolve in water, L-Cit was suspended in 0.25% methyl cellulose solution as described elsewhere (Chowdhury et al., 2015, and these suspensions were stirred vigorously in a vortexer before oral administration. A 0.25% methyl cellulose solution was used as a control. ...
... Following an acclimatization period of 24 h, 8-day-old broiler chicks (average body weight: 182 g) were divided into two groups based on their initial body weight to produce uniform groups. One group (n = 6) of broilers received a single oral administration of L-Cit (15 mmol/10-ml/kg body weight) based on our previous findings in chicks (Chowdhury et al., 2015 using an elastic-plastic needle on a syringe. The control group (n = 6) was administered 0.25% methyl cellulose solution, based on body weight, in the same manner for 60 min. ...
... Previously, we reported that oral administration of L-Cit caused a reduction in rectal temperature in chicks (Chowdhury et al., 2015), and suggested that L-Cit could be a new nutrient to minimize heat stress-induced by incremental body temperature in layer chicks . In the present study, we further confirmed that oral L-Cit reduced the rectal temperature in broiler chicks. ...
Hypothermia is directly linked to metabolism; however, it is still unknown how the overall metabolism is altered by oral administration of hypothermic agent, l-citrulline (l-Cit). The present study aimed to determine the characteristics of liver metabolites of chicks orally administered l-Cit to provide a greater understanding of its metabolism. Capillary electrophoresis–time-of-flight mass spectrometry (CE-TOFMS) and liquid chromatography–time-of-flight mass spectrometry (LC-TOFMS) were conducted on liver samples after oral administration of l-Cit. A total of 361 liver metabolites were identified. Although a small number of samples were used for each group, a principal component analysis and heatmap patterns confirmed that the composition of metabolites could be segregated from each other. Of the 361 compounds detected in the liver, 41 compounds, including amino acids related to the Cit-arginine (Arg) cycle, argininosuccinic acid, Arg, ornithine, and Cit, as well as gamma aminobutyric acid, glycine, histidine, and nicotinamide adenine dinucleotide were abundant in l-Cit-treated livers. In contrast, 24 compounds containing fatty acids, amino acids, and cyclic adenosine monophosphate were lower in the l-Cit group. These data imply that the active Cit-Arg cycle, TCA cycle metabolism, and a low activity in fatty acid metabolism occur in l-Cit-treated broiler chicks.
... Several free amino acids have been found to increase in the blood, brain, and muscle of layer chicks within a short time (15 or 30 min) following exposure to HT at 35 • C (17); however, when layer chicks were exposed to prolonged HT at 35 • C for 48 h, most of these amino acids decreased in the brain and plasma (18). On the basis of these findings, we noticed that citrulline (Cit), which increased in the plasma of layer chicks after short-term heat stress (15 or 30 min at 35 • C) and decreased as a result of long-term heat stress (24 or 48 h at 35 • C), acts hypothermically in chicks when administered to them orally (19,20). In addition, thermal manipulation (TM) during embryogenesis was associated with reduced concentrations of leucine (Leu) in the brain and liver of broiler embryos. ...
... When L-Cit, L-Orn, and L-Arg were administered in the left ventricle of the brain, there was no reduction in body temperature (19); however, orally administered L-Cit, but not L-Arg or L-Orn, did decrease it under control thermoneutral temperature (19). Furthermore, oral L-Cit lowered the body temperature in layer chicks under heat exposure (20). ...
... When L-Cit, L-Orn, and L-Arg were administered in the left ventricle of the brain, there was no reduction in body temperature (19); however, orally administered L-Cit, but not L-Arg or L-Orn, did decrease it under control thermoneutral temperature (19). Furthermore, oral L-Cit lowered the body temperature in layer chicks under heat exposure (20). ...
Increased average air temperatures and more frequent and prolonged periods of high ambient temperature (HT) associated with global warming will increasingly affect worldwide poultry production. It is thus important to understand how HT impacts poultry physiology and to identify novel approaches to facilitate improved adaptation and thereby maximize poultry growth, health and welfare. Amino acids play a role in many physiological functions, including stress responses, and their relative demand and metabolism are altered tissue-specifically during exposure to HT. For instance, HT decreases plasma citrulline (Cit) in chicks and leucine (Leu) in the embryonic brain and liver. The physiological significance of these changes in amino acids may involve protection of the body from heat stress. Thus, numerous studies have focused on evaluating the effects of dietary administration of amino acids. It was found that oral l-Cit lowered body temperature and increased thermotolerance in layer chicks. When l-Leu was injected into fertile broiler eggs to examine the cause of reduction of Leu in embryos exposed to HT, in ovo feeding of l-Leu improved thermotolerance in broiler chicks. In ovo injection of l-Leu was also found to inhibit weight loss in market-age broilers exposed to chronic HT, giving rise to the possibility of developing a novel biotechnology aimed at minimizing the economic losses to poultry producers during summer heat stress. These findings and the significance of amino acid metabolism in chicks and market-age broilers under HT are summarized and discussed in this review.
... Several nutritional strategies have been reported to overcome the adverse effects of heat stress in poultry (Teeter and Belay, 1996;Yahav, 2000;Erwan et al., 2013aErwan et al., , 2014Erwan et al., , 2017Chowdhury et al., 2015). Heat stress reduces laying percentage, egg size, eggshell durability, and body weight gain, as well as increases mortality in layers (Sterling et al., 2003;Lin et al., 2004;Franco-Jimenez and Beck, 2007). ...
... It has been reported that oral administration of Lcitrulline (L-Cit) decreased the body temperature in layer chicks (Chowdhury et al., 2015). However, there are no reports on the function of L-Cit in KUB chicks. ...
... On the day of the experiment, each chick (5 days old) received L-Cit orally (treatment groups) or distilled water (control group) by the plastic needle on small syringe. Based on our recent report on Lor D-Asp and L-Cit in layer chicks (Erwan et al., 2013b(Erwan et al., , 2014Chowdhury et al., 2015), treatment groups received 3.75, 7.5 or 15.0 mmol/ kg body weight as the low, medium and high dose, respectively. The chicks were fed ad libitum diets for 2 h immediately after the treatment. ...
... Additionally, several free amino acids, including L-citrulline (L-Cit), were found to decline in the plasma of heat-exposed chicks . Recently, it has been further found that oral administration of L-Cit can lower the body temperature of chicks (Chowdhury et al., 2015) and impart them with thermotolerance (Chowdhury et al., 2017). However, the use of synthetic L-Cit in poultry rations is still not approved in Japan (Food and Agricultural Materials Inspection Center, Japan, 1953). ...
... (Pansy and Thin, 2011) and low Cit content of 0.002 mmol. In addition, an effective L-Cit dose of 1.03 mmol has been reported to reduce RT in 6-day-old chicks upon acute oral administration (Chowdhury et al., 2015). ...
... Oral administration of 2 ml was selected in accordance with a previous study (Do et al., 2017). Although 2 ml of WRE contained 0.004 mmol of L-Cit, which is lower than the effective L-Cit dose of 1.03 mmol (Chowdhury et al., 2015), administration of pure synthetic L-Cit (Chowdhury et al., 2015) and concomitant administration of Cit with other ingredients in the present study may have different effect on RT. In fact, acute or chronic administration of a medium containing L-Cit-producing live bacteria reduced RT and surface body temperature in chicks even though the L-Cit level was low (Tran et al., 2019). ...
Oral administration of L-citrulline (L-Cit) caused hypothermia, but L-Cit is not recommended in poultry diets in Japan. Watermelon is a natural source of L-Cit. The objective of this study is to examine the effect of watermelon waste, i.e., watermelon rind (WR) on the body temperature and plasma free amino acids of chicks. In Experiment 1, 14-day-old chicks were subjected to acute oral administration of WR extract (WRE) (2ml) under control thermoneutral temperature (CT). In Experiment 2, 15-day-old chicks were orally administered 1.6 ml of either WRE, low-dose L-Cit (7.5mmol/10ml), or high-dose L-Cit (15mmol/10ml) under CT. In both experiments, rectal temperature (RT) and plasma free amino acids were analyzed. In Experiment 3, after dual oral administration of (1.6ml) WRE or L-Cit (15mmol/10ml), 15-day-old chicks were exposed to high ambient temperature (HT; 35 ± 1°C, 2h) to monitor changes in RT. Acute oral administration of WRE significantly reduced RT under CT. The degree of RT reduction by WRE was similar to that by high L-Cit. Moreover, RT was significantly low at HT owing to the oral administration of WRE. However, the reduced RT was difficult to explain by the content of Cit in WRE alone. In conclusion, WRE could be used as a dietary ingredient to reduce body temperature for imparting thermotolerance in chicks.
... Recently, L-citrulline has been revealed as an efficacious nutritional supplement, capable of affording thermotolerance during HS (Table 1). In chicks and broilers, L-citrulline supplementation was reported to elicit hypothermic effects and thermotolerance [23,24,93,134,135]. Chowdhury [134] reports L-citrulline as an HS biomarker AA, since its administration was found to induce hypothermia and more so, the systemic concentration of L-citrulline was severely lowered under HS exposure in chickens [136]. ...
... Dietary supplementation of 1% L-citrulline to broiler chickens subjected to thermoneutral (24°C) or HS (35°C, 60% RH for 5 h) significantly decreased the core body temperature, promoted the antioxidant defenses, and preserved hypothalamic heat shock responses [24]. Orally administered Lcitrulline (10 mL/kg body weight) reduced body temperature effectively, validating its hypothermic role in chicks [93]. Similar experiments using watermelon rinds, an agricultural biowaste rich in L-citrulline have corroborated these findings [94,95]. ...
Heat stress (HS) is an important environmental stress factor affecting poultry production on a global scale. With the rise in ambient temperature and increasing effects of global warming, it becomes pertinent to understand the effects of HS on poultry production and the strategies that can be adopted to mitigate its detrimental impacts on the performance, health, welfare, immunity, and survival of birds. Amino acids (AAs) have been increasingly adopted as nutritional modifiers in animals to ameliorate the adverse effects of HS. They are essential for protein synthesis, growth, maintenance, reproduction, immunity, stress response, and whole-body homeostasis. However, HS tends to adversely affect the availability, transport, absorption, and utilization of these AAs. Studies have investigated the provision of these AAs to poultry during HS conditions, and variable findings have been reported. Taurine, L-theanine, and L-citrulline are non-essential amino acids that are increasingly gaining attention as nutritional supplements in HS animals. Similarly, betaine is an amino acid derivative that possesses favorable biological properties which contributes to its role as a functional additive during HS. Of particular note, taurine is negligible in plants, while betaine, L-theanine, and L-citrulline can be found in selected plants. These nutrients are barely found in feed ingredients, but their supply has been shown to elicit important physiological roles including anti-stress effects, anti-oxidative, anti-inflammatory, gut promoting, and immunomodulatory functions. The present review provides information on the use of these nutritionally and physiologically beneficial nutrients as functional additives to poultry diets during HS conditions. Presently, although several studies have reported on the positive effects of these additives in human and murine studies, however, there is limited information regarding their utilization during heat stress in poultry nutrition. Therefore, this review aims to expound on the functional properties of these nutrients, their potentials for HS alleviation, and to stimulate further researches on their biological roles in poultry nutrition.
... Recently, it has been revealed that nutritional supplementation with L-citrulline (L-CIT) can lower body temperature in chickens (Chowdhury et al., 2015(Chowdhury et al., , 2017Uyanga et al., 2021). L-CIT is a non-essential amino acid and a key metabolite of the urea cycle. ...
... Few studies had reported that there was no significant influence of L-CIT on RT in KUB chicks, laying hens, and pigs (Erwan et al., 2020;Kvidera et al., 2016;Liu et al., 2019;Uyanga et al., 2020), which corresponded to our findings from experiment 2. Contrarily, it was also observed that L-CIT could lower the mean CBT (experiment 1), as well as the RT and mean RT (experiment 3) of broilers. These findings corroborate with the reports on L-CIT-induced hypothermia (Chowdhury et al., 2015(Chowdhury et al., , 2017Uyanga et al., 2021), however, the disparity in findings may be attributed to differences in species, age of birds, ambient temperature, as well as the route of L-CIT administration. ...
Recent studies have revealed the role of L-citrulline (L-CIT) in thermoregulation, but very little is known about the mechanisms involved. In this study, nitric oxide synthase inhibition and endotoxin-induced fever were used to investigate the effects of L-CIT on body temperature and inflammatory responses. In experiment 1, NW-nitro-L-arginine methyl ester (L-NAME, 150 mg/kg BW), was i. p. injected into chicks fed with basal (CON) or L-CIT diets for 14 days. In experiment 2, Lipopolysaccharide (LPS, 2 mg/kg BW) was i. p. injected following 21d feeding with CON or L-CIT diets. In experiment 3, chickens were injected with either L-NAME, LPS, or L-NAME + LPS following 26 days feeding with CON or L-CIT diets. The rectal (RT), ear (ET), and core body temperature (CBT) of chickens were examined. Results showed that L-NAME effectively decreased the RT, ET, CBT, and plasma NO concentration. In contrast, LPS increased NO levels and initiated hyperthermia by increasing RT, ET, CBT, and PGE2 levels. L-CIT diet reduced the mean CBT in experiment 1 and diminished the NO level, PGE2 level, and mean RT in experiment 3. Co-administration of L-CIT + LPS upregulated IL-6 expression, whereas, LPS injection alone induced IL-10, IL-1β, and TLR4 gene expressions. Therefore, this study reveals that L-CIT-induced hypothermia was related to NO inhibition and a decrease in PGE2 concentration. Conversely, LPS induced hyperthermia was associated with an increase in both NO and PGE2 concentrations.
... The ICV injections were administered according to previous reports (Liu et al., 2015;Tachibana et al., 2017). Chicks were implanted with an ICV cannula, and after recovery, the chicks were injected with saline (control) or varying concentrations of L-Cit (1, 2, or 4 mg) injections in a 10-mL volume based on a previous report (Chowdhury et al., 2015). Chicks were fasted during the experiment such that the effect on body temperature could be assessed independently of feed and water intake. ...
... Therefore, these findings from the rectal and head temperature measurements during the ICV experiment affirms that central L-Cit affects body temperature in a dose-responsive manner, such that higher L-Cit concentrations would lower body temperature and vice versa. Previous studies have shown that oral administration of urea cycle amino acids including L-citrulline, L-arginine, and L-ornithine, exhibited significant changes in the rectal temperature of chicks, with L-citrulline strongly initiating hypothermic effects (Chowdhury et al., 2015(Chowdhury et al., , 2017a, suggesting its role as a new candidate for body temperature regulation. However, a single ICV administration (1 mmol/10 mL) of L-citrulline did not elicit any changes in rectal temperature (Chowdhury et al., 2017b). ...
The mechanism that mediates L-citrulline (L-Cit) hypothermia is poorly understood, and the involvement of nitric oxide signaling has not been fully elucidated. Therefore, this study aimed to determine L-Cit's influence on body temperature and to ascertain the central and peripheral mechanisms associated with this response. Chicks responded to intracerebroventricular (ICV) injection of L-Cit with high and low body temperatures (P< 0.05) depending on the dose tested, for both the surface and rectal temperatures. Peripheral (i.p.) L-Cit injection did not affect body temperature responses. Nitric oxide (NO) concentration and NO synthase (NOS) were influenced with varying doses of L-Cit. Hypothalamic NO was increased at 4µg L-Cit whereas, plasma iNOS was elevated at 2µg L-Cit treatment. However, i.p. L-Cit did not change the NO contents, rather it induced higher (P< 0.05) plasma tNOS and iNOS activity, and further upregulated iNOS and nNOS gene expression in the hypothalamus. In addition, ICV L-Cit potentiated a pro- versus anti-inflammatory milieu with the induction of IL-8, IL-10, and TGFβ (P< 0.05), which may be related to the changes in body temperature. Following ICV L-Cit administration, it was observed that L-Cit caused dose variable changes in the ultrastructure of hypothalamic neurons. The lowest dose was associated with a higher number of dead or degenerating neurons, whereas the highest L-Cit dose had fewer neuronal numbers with larger sizes. Therefore, this study shows that central and peripheral L-Cit administration imposes changes in body temperature, nitric oxide production, and inflammatory responses, in a dose-dependent manner.
... Chickens can convert Cit to Arg under the successive actions of argininosuccinate synthetase and argininosuccinate lyase enzymes that occur in the kidney and other extrahepatic tissues (Jahanian 2009;Fernandes and Murakami 2010;Morris 2016). Naturally, Cit can be obtained from watermelon (Citrullus vulgaris, Tedesco et al. 1984;Chowdhury et al. 2015). Thus, supplementation of watermelon rind has been shown to increase plasma Cit level in chicks (Nguyen et al. 2019). ...
... Citrulline supplementation may reduce heat stress by increasing blood NO and subsequent vasodilation (Coleman 2001;Liu et al. 2019). Supplementation of Cit or watermelon rinds has been shown to decrease the rectal temperature in chicks raised under thermal neutral and heat stress conditions (Chowdhury et al. 2015(Chowdhury et al. , 2017Nguyen et al. 2020). ...
Chickens have a high dietary Arg requirement compared to mammalians as they have an incomplete urea cycle and therefore cannot synthesise Arg. Arginine is important for protein synthesis and is also involved in immunity being converted to nitric oxide (NO) at the macrophage level. Nitric oxide is secreted as a free radical during an immune response and is toxic to bacteria, intracellular parasites and also has strong anti-viral and anti-cancer properties. Also, NO serves as a regulating factor for intestinal blood flow, integrity, secretion, and epithelial cell migration. As Arg is a limiting factor for NO synthesis, the increased availability of Arg following dietary supplementation of Arg and/or its metabolites could increase the NO production and subsequent immune status in birds. Such improvements on bird health may become useful for antibiotic growth promoter-free poultry production. The Arg requirement in birds has received special interest due to its large variation in different dietary conditions. Growing evidence suggests that increasing the dietary Arg level and Arg to Lys ratio above currently accepted levels may be necessary to maximise the productive potential of modern broiler strains due to the modulatory effect of Arg on energy and protein metabolism. Also, literature evidence has indicated that crystalline Arg, guanidinoacetic acid (GAA), and citrulline (Cit) can provide Arg activity in chicken diets and are all commercially available. Furthermore, the use of Cit could escape the degradation of enzyme arginase in the intestine and liver resulting in higher Arg levels in the bloodstream and NO production compared to Arg supplementation. The addition of GAA may also provide additional benefits on increasing creatine level and energy metabolism in broiler chickens compared to Arg. This paper will provide new insights into Arg and Arg-sparing effects of GAA and Cit in the broiler diets with a special focus on the supplementation of Arg in reduced protein diets.
... It was observed that plasma citrulline concentration was reduced following exposure to heat stress conditions in chicks [30]. Furthermore, L-Cit has been ascertained to possess hypothermic functions in chickens following its ability to depress rectal temperature under ambient temperatures [31] and in heat-stressed chicks [32]. The utilization of watermelon rinds, as a rich source of citrulline, was shown to reduce rectal temperatures of chicks similarly as citrulline's actions, under ambient and heat stress temperatures [33]. ...
... Al-Saffar and Rose [43] reported that hens were better able to tolerate an increase in diurnal temperatures without marked effects on their productive performance. Our findings differ from Chowdhury et al. [31] who reported that oral administration of L-Cit reduced rectal temperature in chicks. Also, Kvidera et al. [44] showed that citrulline supplementation had a tendency (P = 0.07) to decrease rectal temperature but did not affect the production variables of pigs under thermal stress. ...
Background
L-citrulline (L-Cit), a non-protein amino acid, has been implicated in several physiological functions including anti-inflammatory, anti-oxidative, and hypothermic roles, however, there is a paucity of information with regards to its potential in poultry production.
Methods
This study was designed to investigate the effects of dietary L-Cit supplementation on the production performance, nitric oxide production, and antioxidant status of laying hens during summer period. Hy-Line Brown laying hens ( n = 288, 34 weeks old) were allotted to four treatment, 6 replicates of 12 chickens each. Dietary treatments of control (basal diets), 0.25%, 0.50% and 1.00% L-Cit supplementation were fed to chickens for eight (8) weeks. Production performance, free amino acid profiles, nitric oxide production, and antioxidant properties were measured. Blood samples were collected at the 4 th and 8 th weeks of the experiment.
Results
Air temperature monitoring indicated an average daily minimum and maximum temperatures of 25.02 °C and 31.01 °C respectively. Dietary supplementation with L-Cit did not influence ( P > 0.05) the production performance, and rectal temperature of laying hens. Egg shape index was increased ( P < 0.05) with increasing levels of L-Cit. Serum-free content of arginine, citrulline, ornithine, tryptophan, histidine, GABA, and cystathionine were elevated, but taurine declined with L-Cit diets. Plasma nitric oxide (NO x ) concentration was highest at 1% L-Cit. Likewise, nitric oxide synthase (NOS) activity for total NOS (tNOS) and inducible NOS (iNOS) were upregulated with increasing L-Cit levels, although, tNOS was not affected at the 4 th week. Anti-oxidant enzymes including catalase and superoxide dismutase (SOD) were increased with L-Cit supplementation, however, SOD activity was unchanged at 4 th week, while total anti-oxidant capacity increased at the 8 th week. L-Cit supplementation attenuated the extent of lipid peroxidation, and also inhibited glutathione peroxidase activity.
Conclusion
Dietary L-Cit supplementation modulated systemic arginine metabolism, nitric oxide synthesis, antioxidant defense system, and increased the egg shape index of laying hens during the summer season. 1% L-Cit supplementation proved most effective in potentiating these effects and may be adopted for feed formulation strategies.
... It was observed that plasma citrulline concentration was reduced following exposure to heat stress conditions in chicks [30]. Furthermore, L-Cit has been ascertained to possess hypothermic functions in chickens following its ability to depress rectal temperature under ambient temperatures [31] and in heat-stressed chicks [32]. The utilization of watermelon rinds, as a rich source of citrulline, was shown to reduce rectal temperatures of chicks similarly as citrulline's actions, under ambient and heat stress temperatures [33]. ...
... Al-Saffar and Rose [43] reported that hens were better able to tolerate an increase in diurnal temperatures without marked effects on their productive performance. Our findings differ from Chowdhury et al. [31] who reported that oral administration of L-Cit reduced rectal temperature in chicks. Also, Kvidera et al. [44] showed that citrulline supplementation had a tendency (P = 0.07) to decrease rectal temperature but did not affect the production variables of pigs under thermal stress. ...
Background: L-citrulline (L-Cit), a non-protein amino acid, has been implicated in several physiological functions including anti-inflammatory, anti-oxidative, and hypothermic roles, however, there is a paucity of information with regards to its potential in poultry production. This study was designed to investigate the effects of dietary L-Cit supplementation on the production performance, nitric oxide production, and antioxidant status of laying hens during summer period. Hy-Line Brown laying hens (n=288, 34 weeks old) were allotted to four treatment, 6 replicates of 12 chickens each. Dietary treatments of control (basal diets), 0.25%, 0.50 % and 1.00 % L-Cit supplementation were fed to chickens for eight (8) weeks. Production performance, free amino acid profiles, nitric oxide production, and antioxidant properties were measured. Blood samples were collected at the 4th and 8th weeks of the experiment.
Results: Air temperature monitoring indicated an average daily minimum and maximum temperatures of 25.02 oC and 31.01 oC respectively. Dietary supplementation with L-Cit did not influence (P > 0.05) the production performance, and rectal temperature of laying hens. Egg shape index was increased (P < 0.05) with increasing levels of L-Cit. Serum-free content of arginine, citrulline, ornithine, tryptophan, histidine, GABA, and cystathionine were elevated, but taurine declined with L-Cit diets. Plasma nitric oxide (NOx) concentration was highest at 1% L-Cit. Likewise, nitric oxide synthase (NOS) activity for total NOS (tNOS) and inducible NOS (iNOS) were upregulated with increasing L-Cit levels, although, tNOS was not affected at the 4th week. Anti-oxidant enzymes including catalase and superoxide dismutase (SOD) were increased with L-Cit supplementation, however, SOD activity was unchanged at 4th week, while total anti-oxidant capacity increased at the 8th week. L-Cit supplementation attenuated the extent of lipid peroxidation, and also inhibited glutathione peroxidase activity.
Conclusion: Dietary L-Cit supplementation modulated systemic arginine metabolism, nitric oxide synthesis, antioxidant defense system, and increased the egg shape index of laying hens during the summer season. 1% L-Cit supplementation proved most effective in potentiating these effects and may be adopted for feed formulation strategies.
... Amino acids do not only serve as building blocks for proteins but are also cell signaling molecules and regulators of gene expression and the protein phosphorylation cascade (Wu, 2009). Amino acids play important roles in growth and body temperature regulation (Chowdhury et al., 2015), food intake (Tran et al., 2019), and behavior (Furuse, 2015). Recent studies showed that some free amino acids acting as heat stress biomarkers are also potential bioagents that reduce body temperature under heat stress in chicks (Chowdhury et al., 2015 andHan et al., 2017 and. ...
... Amino acids play important roles in growth and body temperature regulation (Chowdhury et al., 2015), food intake (Tran et al., 2019), and behavior (Furuse, 2015). Recent studies showed that some free amino acids acting as heat stress biomarkers are also potential bioagents that reduce body temperature under heat stress in chicks (Chowdhury et al., 2015 andHan et al., 2017 and. ...
Recently, we found that in ovo feeding of l -leucine ( l -Leu ) afforded thermotolerance, stimulated lipid metabolism and modified amino acid metabolism in male broiler chicks. However, the effects of in ovo feeding of l -Leu on thermoregulation and growth performance until marketing age of broilers are still unknown. In this study, we investigated the effects of in ovo feeding of l -Leu on body weight ( BW ) gain under control thermoneutral temperature or chronic heat stress. We measured changes of body temperature and food intake, organ weight, as well as amino acid metabolism and plasma metabolites under acute and chronic heat stress in broilers. A total of 168 fertilized Chunky broiler eggs were randomly divided into 2 treatment groups in experiments. The eggs were in ovo fed with l -Leu (34.5 µmol/500 µl per egg) or sterile water (500 µl/egg) during incubation. After hatching, male broilers were selected and assigned seven to nine replicates (one bird/replicate) in each group for heat challenge experiments. Broilers (29- or 30-day-old) were exposed to acute heat stress (30 ± 1°C) for 120 min or a chronic heat cyclic and continued heat stress (over 30 ± 1°C; ages, 15 to 44 days). In ovo feeding of l -Leu caused a significant suppression of enhanced body temperature without affecting food intake, plasma triacylglycerol, non-esterified fatty acids, ketone bodies, glucose, lactic acid or thyroid hormones under acute heat stress. Daily body temperature was significantly increased by l -Leu in ovo feeding under chronic heat stress. Interestingly, in ovo feeding of l -Leu caused a significantly higher daily BW gain compared with that of the control group under chronic heat stress. Moreover, some essential amino acids, including Leu and isoleucine, were significantly increased in the liver and decreased in the plasma by l -Leu in ovo feeding under acute heat stress. These results suggested that l -Leu in ovo feeding afforded thermotolerance to broilers under acute heat stress mainly through changing amino acid metabolism until marketing age.
... For instance, L-citrulline (L-Cit) level was reduced in the plasma of heat-exposed chicks . Chowdhury et al. (2015Chowdhury et al. ( , 2017 further showed that oral administration of L-Cit produced hypothermic effects in young chicks. Supplementation of essential amino acids to reduce the negative effects of heat stress and maintain steady production performance has currently attracted the attention of the chicken farming industry. ...
... However, oral administration of an equimolar amount of crystallized L-Cit alone was not able to reduce the body temperature of the chicks. Chowdhury et al. (2015) reported that oral administration of 15 mmol/kg body weight, but not of 3.75 or 7.5 mmol L-Cit /kg body weight, reduced the body temperature of 6-day-old chicks. In the present study, the 7-day-old chicks (average body weight 65 g) were administered L-Cit at a dose of 8.52 mmol/kg body weight/day/2 mL and the 13-day-old chicks (average body weight 125 g) were administered L-Cit at a dose of 4.43 mmol/kg body weight/day/2 mL when calculated based on a basal concentration of 277 mM L-Cit in the medium. ...
Recently, we showed that oral administration of crystallized L-citrulline (L-Cit) caused hypothermia under a control thermoneutral temperature (CT) and provided thermotolerance under high ambient temperature (HT) in chicks. The aim of this study was to clarify whether oral administration of a medium containing L-Cit-producing live bacteria can reduce body temperature in chicks under CT. In Experiment 1, 7-day-old chicks were orally administered either a medium (containing mainly L-Cit-producing live bacteria and 277 mM L-Cit) or an equimolar amount of L-Cit to determine their effects on body temperature (acute treatment). In Experiment 2, chicks were subjected to the same treatment from 7 to 13 days of age (chronic treatment). Rectal and surface body temperatures were recorded daily after 1 h of treatment. Both acute and chronic oral administration of the medium, but not of the equimolar amount of L-Cit, significantly reduced the rectal and surface body temperatures of the chicks. Chronic administration of the medium resulted in consistently low rectal and surface body temperatures during the entire experimental period. In conclusion, acute or chronic administration of the medium containing L-Cit-producing live bacteria, but not of the equimolar amount of L-Cit, reduced the rectal and surface body temperatures of the chicks. Our results suggest that medium containing L-Cit-producing live bacteria can be used as a new feed supplement for lowering the body temperature of chicks.
... Rectal temperature was measured using a digital thermometer with an accuracy of ±0.1 • C (Thermalert TH-5, Physitemp Instruments Inc., USA). The thermistor probe was inserted into the colon (rectum) through the cloaca to a depth of 2 cm as reported previously Chowdhury et al., 2015;Eltahan et al., 2017;Bahry et al., 2017;Nishimura et al., 2022). At the end of 3 h exposure to HT for both acute and chronic heat challenge, all chicks were immediately euthanized for culling by exposure to isoflurane (Mylan Inc., Tokyo, Japan). ...
High ambient temperatures (HT) can increase diencephalic neuropeptide Y (NPY) expression, and central injection of NPY attenuates heat stress responses while inducing an antioxidative state in the chick spleen. However, there is a lack of knowledge about NPY receptor expression, and its regulation by HT, in the chick spleen. In the current study, male chicks were used to measure the expression of NPY receptors in the spleen and other immune organs under acute (30 vs. 40 ± 1℃ for 3 h) or chronic (30 vs. 40 ± 1℃ for 3 h/day for 3 days) exposure to HT and in response to central injection of NPY (47 pmol, 188 pmol, or 1 nmol). We found that NPY-Y4 receptor mRNA was expressed in the spleen, but not in other immune organs studied. Immunofluorescence staining revealed that NPY-Y4 receptors were localized in the splenic pulp. Furthermore, NPY-Y4 receptor mRNA increased in the chick spleen under both acute and chronic exposure to HT. Central NPY at two dose levels (47 and 188 pmol) and a higher dose (1 nmol) did not increase splenic NPY-Y4 receptor mRNA expression or splenic epinephrine under HT (35 ± 1℃), and significantly increased 3-methoxy-4-hydroxyphenylglycol (MHPG) concentrations under HT (40 ± 1℃). In conclusion, increased expression of NPY-Y4 receptor mRNA in the spleen under HT suggests that Y4 receptor may play physiological roles in response to HT in male chicks.
... This provides a theoretical foundation for the dietary addition of glutamic acid to alleviate HS in poultry. Several studies have shown that orally administered L-Cit significantly increases L-Orn levels in the liver and decreases rectal temperature in both layer and broiler chicks exposed to heat (Chowdhury et al., 2015(Chowdhury et al., , 2017(Chowdhury et al., , 2021. However, the underlying mechanisms by which orally administered L-Cit reduces body temperature in chicks remain unclear. ...
... This provides a theoretical foundation for the dietary addition of glutamic acid to alleviate HS in poultry. Several studies have shown that orally administered L-Cit significantly increases L-Orn levels in the liver and decreases rectal temperature in both layer and broiler chicks exposed to heat (Chowdhury et al., 2015(Chowdhury et al., , 2017(Chowdhury et al., , 2021. However, the underlying mechanisms by which orally administered L-Cit reduces body temperature in chicks remain unclear. ...
... However, they did also find the levels of some other amino acids to be significantly reduced. It was further found that body temperature was decreased with orally administered L-Cit, but not L-Arg or L-Orn, under thermoneutral temperature (i.e., control) conditions (CT; Chowdhury et al., 2015). Orally administered L-Cit also lowered the body temperature in layer chicks exposed to heat . ...
With global warming becoming of increasing concern, poultry farms are experiencing a concomitant increase in heat stress. Chickens are very sensitive to high ambient temperature (HT), so the development of novel nutrients that will help deal with the challenge posed by heat stress is vital. We revealed that L-citrulline (L-Cit) can reduce body temperature in chickens. Orally administered L-Cit solution has been found to provide heat tolerance in chickens and to result in reduced food intake. Heat exposure and oral administration of L-Cit led to increased levels of plasma insulin, whereas heat stress led to a decline in plasma thyroxine. Dietary administration of L-Cit was also shown to be effective to reduce heat stress in broiler chickens. Moreover, L-Cit was found to be metabolized in the liver within 1 h of its administration, and in L-Cit-treated broiler chicks, the Cit-Arginine cycle and the Krebs cycle were found to be active. L-Cit has not yet been approved for inclusion in the poultry diet, so it is important to find alternative sources of L-Cit. Taken together, these findings suggest that L-Cit may serve as an important novel nutrient with the ability to produce heat tolerance in chickens under HT.
... Rectal temperature was measured using a digital thermometer with an accuracy of ± 0.1 • C (Thermalert TH-5, Physitemp Instruments Inc.). The thermistor probe was inserted into the colon (rectum) through the cloaca to a depth of 2 cm as reported previously [2,25,32,38]. Spleen and liver samples were collected in parallel with the brain sampling mentioned above. Blood was centrifuged at 10,000×g for 4 min at 4 • C to collect plasma. ...
Previously it was found that mRNA expression of neuropeptide Y (NPY) was increased in the chicken brain under heat stress. NPY has also been reported as an anti-stress factor to regulate brain functions in heat exposed chicks. However, to the best of our knowledge, there is no report on the action of central NPY in the immune organs under heat stress. The aim of this study was to examine whether central injection of NPY can regulate heat stress response in the spleen and liver. After intracerebroventricular (ICV) injection of NPY, chicks were exposed to control thermoneutral temperature (CT: 30 ± 1°C) or high ambient temperature (HT: 35 ± 1°C) chambers for 60 min. Central injection of NPY caused lowering in rectal temperature under CT, but not under HT. Moreover, ICV injection of NPY caused a significant lower mRNA expression of heat-shock protein-70 and higher expression of glutathione synthase in the spleen, but not liver. Furthermore, plasma uric acid concentrations were significantly increased by the ICV injection of NPY in chicks under HT. These results indicate that brain NPY may contribute to attenuate the intracellular heat stress response and enhance antioxidative status in the immune organ, spleen in chicks.
... There are several reports showing that amino acids are also important in the regulation of body temperature Chowdhury et al., 2015Chowdhury et al., , 2017Han et al., 2017;Elhussiny et al., 2021). Brain monoamines can regulate different behaviors including thermoregulation (Denbow et al., 1981). ...
High ambient temperatures (HT) in summer are becoming more severe due to global warming, leading to severe adverse effects on poultry production. Recently, we have reported that oral administration of L-citrulline (L-Cit) can minimize hyperthermia in chickens under HT. However, whether oral L-Cit can enter the brain, the center for thermoregulation, has not been studied. We investigated the effects of oral administration of L-Cit on free amino acids and monoamines in the diencephalon region of the brain of heat-exposed broilers. Broilers were treated with L-Cit (40 mmol/20 ml/bird), then moved to a chamber at HT (30 ± 1°C) or to a thermoneutral temperature (CT: 22 ± 1°C) chamber for 2 h. Control groups were given methyl cellulose solution and placed in the CT or HT chambers. After 2 h of exposure to HT, there were increased brain concentrations of Cit in comparison with concentrations in broilers exposed to CT, whereas brain ornithine (Orn) concentrations were decreased, and arginine (Arg) concentrations were not changed. Interestingly, oral administration of L-Cit increased brain concentration of Cit, Arg, and Orn under both CT and HT. Tryptophan and its metabolite, serotonin (5-HT) concentrations were lower in the brain under HT than under CT. HT did not change brain concentrations of tyrosine, but dopamine (DA, a metabolite of tyrosine) concentrations decreased, and methoxyhydroxyphenylglycol (MHPG, a metabolite of DA) concentrations increased in comparison with CT. Oral administration of L-Cit decreased brain concentrations of both tryptophan and tyrosine under CT and HT without changing 5-HT; however, DA levels declined under HT. Moreover, MHPG concentrations increased. In conclusion, these results suggest that metabolism of amino acids and metabolism of DA can be enhanced in the brain by oral administration of L-Cit. Metabolic changes in the brain in response to oral administration of L-Cit may influence the thermoregulatory center in the brain, leading to a reduction in body temperature and conferring thermotolerance in heat-exposed broiler chickens.
... The vocalizations were counted using a digital hand tally counter, and the behaviors were analyzed by a researcher blind to treatment. A digital thermometer with a precision of ±0.1 • C (Thermalert TH-5, Physitemp Instruments Inc., Clifton, NJ, USA) was used to measure the rectal temperature at 0 and 10 min post-injection by inserting the thermistor probe into the rectum via the cloaca to a depth of approximately 2 cm, as we reported [32,67]. The chicks were anesthetized 10 min post-ICV injection with isoflurane (Mylan Pharmaceutical Co., Ltd., Tokyo, Japan) before the collection of blood samples from the jugular vein. ...
The objective of this study was to determine the effects of centrally administered taurine on rectal temperature, behavioral responses and brain amino acid metabolism under isolation stress and the presence of co-injected corticotropin-releasing factor (CRF). Neonatal chicks were centrally injected with saline, 2.1 pmol of CRF, 2.5 μmol of taurine or both taurine and CRF. The results showed that CRF-induced hyperthermia was attenuated by co-injection with taurine. Taurine, alone or with CRF, significantly decreased the number of distress vocalizations and the time spent in active wakefulness, as well as increased the time spent in the sleeping posture, compared with the saline- and CRF-injected chicks. An amino acid chromatographic analysis revealed that diencephalic leucine, isoleucine, tyrosine, glutamate, asparagine, alanine, β-alanine, cystathionine and 3-methylhistidine were decreased in response to taurine alone or in combination with CRF. Central taurine, alone and when co-administered with CRF, decreased isoleucine, phenylalanine, tyrosine and cysteine, but increased glycine concentrations in the brainstem, compared with saline and CRF groups. The results collectively indicate that central taurine attenuated CRF-induced hyperthermia and stress behaviors in neonatal chicks, and the mechanism likely involves the repartitioning of amino acids to different metabolic pathways. In particular, brain leucine, isoleucine, cysteine, glutamate and glycine may be mobilized to cope with acute stressors.
... Some free amino acids are recognized as biomarkers of heat stress, since they are significantly affected by heat stress [3,4]. These free amino acids play critical roles in thermoregulation, as well as in reducing body temperature in chicks under heat stress [5][6][7][8][9]. ...
... Amino acids play a vital role in regulating body temperature in chicks Chowdhury et al., 2015;Han et al., 2017). It has been reported that heat stress increases brain NPY levels in chicks . ...
The aim of this study was to examine the central action of taurine on body temperature and food intake in neonatal chicks under control thermoneutral temperature (CT) and high ambient temperature (HT). Intracerebroventricular injection of taurine caused dose-dependent hypothermia and reduced food intake under CT. The mRNA expression of the GABAA receptors, GABAAR-α1 and GABAAR-γ, but not that of GABABR, significantly decreased in the diencephalon after central injection of taurine. Subsequently, we found that picrotoxin, a GABAAR antagonist, attenuated taurine-induced hypothermia. Central taurine significantly decreased the brain concentrations of 3-methoxy-4-hydroxyphenylglycol, a major metabolite of norepinephrine; however, the concentrations of serotonin, dopamine, and the epinephrine metabolites, 3,4-hydroxyindoleacetic acid and homovanillic acid, were unchanged. Although hypothermia was not observed under HT after central injection of taurine, plasma glucose and uric acid levels were higher, and plasma sodium and calcium levels were lower, than those in chicks under CT. In conclusion, brain taurine may play a role in regulating body temperature and food intake in chicks through GABAAR. The changes in plasma metabolites under heat stress suggest that brain taurine may play an important role in maintaining homeostasis in chicks.
... injection and the data were adopted as the measurements at 0 min, followed by measurements at 30 and 60 min after the treatments. Rectal temperature was measured using a digital thermometer with an accuracy of ± 0.1°C (Thermalert TH-5, Physitemp Instruments Inc., USA); the thermistor probe was inserted into the colon (rectum) through the cloaca to a depth of 2 cm as reported previously Chowdhury et al., 2015;Eltahan et al., 2017). At the end of the experiment, the chicks were euthanized following anesthesia by isoflurane (Mylan Inc., Tokyo, Japan) in order to collect blood and brain samples. ...
Oral administration of sucralose has been reported to stimulate food intake through inducing hypothalamic neuropeptide Y (NPY) in mice and fruit flies. However, the underlying mechanisms of action of sucralose in hypothermia and NPY and monoamine regulation remain unknown. The aim of the present study was to investigate central effects of sucralose on body temperature, NPY, and monoamine regulation, as well as its peripheral effects, in chicks. In Experiment 1, 5-day-old chicks were centrally injected with 1 μmol of sucralose, other sweeteners (erythritol and glucose), or saline. In Experiment 2, chicks were centrally injected with 0.2, 0.4, and 1.6 μmol of sucralose or saline. In Experiment 3, chicks were centrally injected with 0.8 μmol of sucralose or saline, with a co-injection of 100 μg fusaric acid (FA), an inhibitor of dopamine-β-hydroxylase, to examine the role dopamine in sucralose induced hypothermia. In Experiment 4, 7–16-day-old chicks were orally administered with 75, 150, and 300 mg/2 ml distilled water or sucralose, daily. We observed that the central injection of sucralose, but not other sweeteners, decreased body temperature (P < .05) in chicks; however, the oral injection did not influence body temperature, food intake, and body weight gain. Central sucralose administration decreased dopamine and serotonin and stimulated dopamine turnover rate in the hypothalamus significantly (P < .05). Notably, sucralose co-injection with FA impeded sucralose-induced hypothermia. Sucralose decreases body temperature potentially via central monoaminergic pathways in the hypothalamus.
... It was observed that plasma citrulline concentrations were reduced following exposure to heat stress conditions in chicks (43). Furthermore, L-Cit has been ascertained to possess hypothermic functions in chickens following its ability to depress rectal temperature under ambient temperatures (44) and in heat stressed chicks (45). The utilization of watermelon rinds, as a rich source of L-Cit was shown to reduce rectal temperatures of chicks in a similar fashion as L-Cit administration both at control and heat stress temperatures (46). ...
Background
L-Citrulline (L-Cit), a non-protein amino acid, has been implicated in several physiological functions including anti-inflammatory, anti-oxidative, and hypothermic roles, however, there is paucity of information with regards to its potential in poultry production. This study was designed to investigate the effects of dietary L-Cit supplementation on the production performance, nitric oxide production and anti-oxidant status of laying hens during summer periods. Hy-line laying hens (n = 288, 34 weeks old) were allotted to four treatment with 6 replicates of 12 chickens each. Dietary treatments of control (basal diets), 0.25%, 0.50% and 1.00% L-Cit supplementation were fed to chickens for eight (8) weeks. Production performance, egg quality characteristics, nitric oxide production and antioxidant properties were measured. Blood samples were collected at 4th and 8th weeks of experiment.
Results
Air temperature monitoring indicated average minimum and maximum recordings of 25.02 ⁰C and 31.01 ⁰C respectively. Dietary supplementation with L-Cit did not significantly (P > 0.05) influence the production performance, plasma biochemistry and rectal temperatures of laying hens. Egg shape index was increased with L-Cit diet, similarly, albumen heights and Haugh units also tended (P < 0.10) to improve with higher L-Cit supplementation. Plasma nitric oxide (NOx) concentration was observed to increase with highest contents at 1% L-Cit supplementation. Likewise, nitric oxide synthase (NOS) enzyme activity for both total NOS (tNOS) and inducible NOS (iNOS) were upregulated with increasing L-Cit levels, although, tNOS was not affected at week 4. Anti-oxidant enzymes including catalase and superoxide dismutase (SOD) were increased with L-Cit supplementation, however, SOD activity was unchanged at week 4. Total anti-oxidant capacity increased with L-Cit groups at week 8. L-Cit supplementation attenuated the extent of lipid peroxidation measured by malondialdehyde levels, and also inhibited glutathione peroxidase activity.
Conclusion
Dietary L-Cit supplementation enhanced nitric oxide synthesis, promoted antioxidant defense systems, and tended to improve internal egg quality traits of laying hens during summer season. 1% L-Cit supplementation proved most effective in enhancing both nitric oxide production and anti-oxidant defenses.
... Uni et al. [19] demonstrated that late-term (16-18 day of incubation) In ovo injection of supplemented solutions containing carbohydrates led to a 5-6% increase in body weight of the newborn chicks and this difference continued till the last day of the examined period of that study (25 days of age). Moreover, Chowdhury et al. [20] reported that AA plays critical roles in the growth and controlling body temperature. ...
Sulfur amino acids are typically the first-limiting amino acids (AA) used in protein metabolism in poultry. Therefore, we hypothesized that their utilization in the pre-hatch period would affect embryonic development, IGF-I and TLR4 gene expression, antioxidant status, serum biochemical profile, and jejunum histomorphometry of newly hatched Ross broiler chicks incubated under heat stress conditions. A total of 150 fertile broiler eggs were subjected to heat stress (39.6 °C for 6 h/d) from d10 until d18 and injected at d 17.5 of incubation with methionine and cysteine (Met-Cys) at a dose of 5.90 mg l-methionine plus 3.40 mg l-cysteine. The effects of Met-Cys administration were examined and compared with the control (Non-injected group) and 0.75% NaCl injected group. The results showed that no significant differences among all groups in serum protein profiles (total protein, albumin, globulin, and albumin/globulin ratio) and creatine kinase were observed. The level of heat shock protein-90 was decreased with Met-Cys In ovo injection. The In ovo injection of Met-Cys also improved the values of total antioxidants capacity and glutathione in examined tissues. At the same time, an increase in fold change mRNA abundance of IGF-I and TLR4 was observed after Met-Cys injection in tested tissues. Finally, an increase of 29% in villus area was found after Met-Cys injection compared to the control group. In conclusion, the In ovo injection of Met-Cys resulted in improved embryonic development, IGF-I and TLR4 gene expression, antioxidant status and jejunum histomorphometry of newly hatched broiler chicks exposed to heat stress during incubation.
... However, NPY did not show any effect that might modulate their levels. Amino acids have some roles in reducing body temperature in chicks Chowdhury et al. 2015Chowdhury et al. , 2017. In rabbits, i.c.v. ...
Exposure of chicks to a high ambient temperature (HT) has previously been shown to increase neuropeptide Y (NPY) mRNA expression in the brain. Furthermore , it was found that NPY has anti-stress functions in heat-exposed fasted chicks. The aim of the study was to reveal the role of central administration of NPY on thermotolerance ability and the induction of heat-shock protein (HSP) and NPY sub-receptors (NPYSRs) in fasted chicks with the contribution of plasma metabolite changes. Six-or seven-day-old chicks were centrally injected with 0 or 375 pmol of NPY and exposed to either HT (35 AE 1°C) or control thermoneutral temperature (CT: 30 AE 1°C) for 60 min while fasted. NPY reduced body temperature under both CT and HT. NPY enhanced the brain mRNA expression of HSP-70 and-90, as well as of NPYSRs-Y5,-Y6, and-Y7, but not-Y1,-Y2, and-Y4, under CT and HT. A coinjection of an NPYSR-Y5 antagonist (CGP71683) and NPY (375 pmol) attenuated the NPY-induced hypothermia. Furthermore, central NPY decreased plasma glucose and triacylglycerol under CT and HT and kept plasma corticosterone and epinephrine lower under HT. NPY increased plasma taurine and anserine concentrations. In conclusion, brain NPYSR-Y5 partially afforded protective thermotolerance in heat-exposed fasted chicks. The NPY-mediated reduction in plasma glucose and stress hormone levels and the increase in free amino acids in plasma further suggest that NPY might potentially play a role in minimizing heat stress in fasted chicks.
... Tian and a (2015), using 1HNMR and LC-MC approaches, showed that proline, arginine, ornithine and citruline among the most reliable plasma metabolomic biomarkers in lactating dairy cows [44]. Additionally, proline and glutamate can be precursors of citrulline biosynthesis, which has important hypothermic function, as shown in chicken [45]. Indeed, citrulline has been shown to increase endogenous nitric oxide production that can promote heat dissipation from skin [46]. ...
The negative impact of heat stress (HS) on the production performances in pig faming is of particular concern. Novel diagnostic methods are needed to predict the robustness of pigs to HS. Our study aimed to assess the reliability of blood metabolome to predict the sensitivity to chronic HS of 10 F1 (Large White × Creole) sire families (SF) reared in temperate (TEMP) and in tropical (TROP) regions (n = 56±5 offsprings/region/SF). Live body weight (BW) and rectal temperature (RT) were recorded at 23 weeks of age. Average daily feed intake (AFDI) and average daily gain were calculated from weeks 11 to 23 of age, together with feed conversion ratio. Plasma blood metabolome profiles were obtained by Nuclear Magnetic Resonance spectroscopy (1HNMR) from blood samples collected at week 23 in TEMP. The sensitivity to hot climatic conditions of each SF was estimated by computing a composite index of sensitivity (Isens) derived from a linear combination of t statistics applied to familial BW, ADFI and RT in TEMP and TROP climates. A model of prediction of sensitivity was established with sparse Partial Least Square Discriminant Analysis (sPLS-DA) between the two most robust SF (n = 102) and the two most sensitive ones (n = 121) using individual metabolomic profiles measured in TEMP. The sPLS-DA selected 29 buckets that enabled 78% of prediction accuracy by cross-validation. On the basis of this training, we predicted the proportion of sensitive pigs within the 6 remaining families (n = 337). This proportion was defined as the predicted membership of families to the sensitive category. The positive correlation between this proportion and Isens (r = 0.97, P < 0.01) suggests that plasma metabolome can be used to predict the sensitivity of pigs to hot climate.
... A signifi cant (P<0.005) interaction was found between HT and time, which indicates that the difference in rectal temperature increased with the progress It was interesting to reveal that the L-Cit, which was a hypothermic agent in young chicks 47) , did also 49) . Developing embryos (n = 8-10) were randomly selected from each group and euthanized by cervical dislocation at ED 14 and 19. ...
... Long-term exposure to high ambient temperature (HT: 35 °C, 48 h) has been found to significantly reduce some free amino acid concentrations in the brain and plasma of chicks ( Chowdhury et al., 2014). Among those amino acids reduced in plasma, it was found that L-citrulline (L-Cit), when supplemented, caused hypothermia in chicks ( Chowdhury et al., 2015), which ultimately afforded thermotolerance ( Chowdhury et al., 2017). Thermal manipulation (TM) is a technique in which the fertilized eggs are incubated (i.e. during embryogenesis) at a higher temperature than usual. ...
Thermal manipulation declined embryonic brain and liver concentrations of leucine (Leu). L-Leu in ovo injection afforded thermotolerance in male broiler chicks. This study aimed to examine the role of in ovo injection of L-Leu in metabolic functions, and differences between male and female broiler chicks in thermotolerance. L-Leu injection was performed in ovo on embryonic day (ED) 7 to reveal its role in metabolic activity in embryos and in post-hatch male and female broiler chicks under heat stress. To examine the metabolic activity of embryos, oxygen (O2) consumption, carbon dioxide (CO2) production, heat production and plasma metabolites were analyzed. Rectal temperature, food intake and plasma metabolites were also analyzed in heat-exposed (35 ± 1°C for 180min) male and female broiler chicks. It was found that O2 consumption, heat production, and plasma triacylglycerol (TG) and non-esterified fatty acid (NEFA) concentrations in ED 14 embryos were significantly increased by in ovo injection of L-Leu in comparison with the controls. Plasma glucose concentration was significantly increased in both male and female chicks under heat stress, but in ovo injection of L-Leu attenuated the increase in male chicks. In contrast, plasma TG, NEFA, and ketone body concentrations were significantly higher in male chicks injected in ovo with L-Leu, but not in similarly injected female chicks, compared with control chicks, all under heat stress. Rectal temperature and food intake were significantly lower in male, but not female, chicks under heat stress injected in ovo with L-Leu. In conclusion, in ovo L-Leu administration enhanced the prenatal metabolic rate and lipid metabolisms, which possibly appeared as sex-dependent fashion to facilitate thermotolerance in males. A reduction in heat production through lowered food intake in heat-exposed male, but not female chicks injected in ovo with L-Leu may help to afford thermotolerance in male broiler chicks under heat stress.
... (Thermalert TH-5, Physitemp Instruments Inc., USA) by inserting the thermistor probe into the colon (rectum) through the cloaca to a depth of 2 cm as reported previously ( Chowdhury et al., 2015;Ito et al., 2015;Yang et al., 2016;Han et al., 2017Do et al., in press). At the end of the experiment, blood was collected from the ju- gular vein into a heparinized Eppendorf tube to measure NOx (NO 2 + NO 3 ), an index of NO production. ...
Recently we demonstrated that L-citrulline (L-Cit) causes hypothermia in chicks. However, the question of how L-Cit mediates hypothermia remained elusive. Thus, the objective of this study was to examine some possible factors in the process of L-Cit-mediated hypothermia and to confirm whether L-Cit can also afford thermotolerance in young chicks. Chicks were subjected to oral administration of L-Cit along with intraperitoneal injection of a nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine methyl ester HCl (L-NAME), to examine the involvement of NO in the process of hypothermia. Food intake and plasma metabolites were also analyzed after oral administration of L-Cit in chicks. To examine thermotolerance, chicks were orally administered with a single dose of L-Cit (15 mmol/10 ml/kg body weight) or the same dose twice within a short interval of 1 h (dual oral administration) before the exposure to high ambient temperature (35 ± 1 °C) for 180 min. Although the rectal temperature was reduced following administration of L-Cit, L-NAME caused a greater reduction. L-NAME reduced total NO2 and NO3 (NOx) in plasma, which confirmed its inhibitory effect on NO. A single oral administration of L-Cit mediated a persistent state of hypothermia for the 300 min of the study without affecting food intake. It was further found that plasma glucose was significantly lower in L-Cit-treated chicks. Dual oral administration of L-Cit, but not a single oral administration, afforded thermotolerance without a significant change in plasma NOx in chicks. In conclusion, our results suggest that L-Cit-mediated hypothermia and thermotolerance may not be involved in NO production. L-Cit-mediated thermotolerance further suggests that L-Cit may serve as an important nutritional supplement that could help in coping with summer heat.
... Amino acids are also important in regulating body temperature Chowdhury et al., 2015) and food intake (Izumi et al., 2004). It was reported that anorexia increased brain and plasma tryptophan concentrations and brain serotoninergic activity in rats (Kuzer et al., 1988;Meguid et al., 2000). ...
Recently, we demonstrated that brain neuropeptide Y (NPY) mRNA expression was increased in heat exposed chicks. However, the functions of brain NPY during heat stress are unknown. This study was conducted to investigate whether centrally administered NPY affects food intake, rectal temperature, monoamines, stress hormones and plasma metabolites in chicks under high ambient temperatures (HT). Five or six-day-old chicks were centrally injected with 0, 188 or 375 pmol of NPY and exposed to either HT (35 ± 1 °C) or a control thermoneutral temperature (CT; 30 ± 1 °C) for 3 h whilst fed or fasted. NPY increased food intake under both CT and HT. NPY reduced rectal temperature 1 and 2 h after central administration under CT, but not under HT. Interestingly, NPY decreased brain serotonin and norepinephrine concentrations in fed chicks, but increased concentrations of brain dopamine and its metabolites in fasted and fed chicks, respectively. Plasma epinephrine was decreased by NPY in fed chicks, but plasma concentrations of norepinephrine and epinephrine were increased significantly by NPY in fasted-heat exposed chicks. Furthermore, NPY significantly reduced plasma corticosterone concentrations in fasted chicks. Plasma glucose and triacylglycerol were increased by NPY in fed chicks, but triacylglycerol declined in fasted NPY-injected chicks. In conclusion, brain NPY may attenuate the reduction of food intake during heat stress and the increased brain NPY might be a potential regulator of the monoamines and corticosterone to modulate stress response in heat-exposed chicks.
... Amino acids play important roles in growth and could also play critical roles in controlling body temperature Chowdhury et al., 2015), food intake Erwan et al., 2013;Tran et al., 2016) and behavior (Kabuki et al., 2011;Erwan et al., 2013;Ikeda et al., 2014;Tran et al., 2015). Several free amino acids were significantly increased in the blood, brain and muscle of chicks within 15 or 30 min of exposure to high ambient temperature (HT; 35°C; Ito et al., 2014); however, most of those free amino acids declined in the brain and plasma when chicks were exposed to HT (35°C) for a long timethat is, for either 24 or 48 h . ...
Thermal manipulation (TM) of incubation temperature causes metabolic alterations and contributes to improving thermotolerance in chicks post hatching. However, there has been no report on amino acid metabolism during TM and the part it plays in thermotolerance. In this study, we therefore first analyzed free amino acid concentrations in the embryonic brain and liver during TM (38.6 °C, 6 h/d during embryonic day (ED) 10 to ED 18). It was found that leucine (Leu), phenylalanine and lysine were significantly decreased in the embryonic brain and liver. We then chose l-Leu and other branched-chain amino acids (l-isoleucine (l-Ileu) and l-valine (l-Val)) for in ovo injection on ED 7 to reveal their roles in thermoregulation, growth, food intake and thermotolerance in chicks. It was found that in ovo injection of l-Leu, but not of l-Ileu or l-Val, caused a significant decline in body temperature at hatching and increased food intake and body weight gain in broiler chicks. Interestingly, in ovo injection of l-Leu resulted in the acquisition of thermotolerance under high ambient temperature (35 ± 1 °C for 180 min) in comparison with the control thermoneutral temperature (28 ± 1 °C for 180 min). These results indicate that the free amino acid concentrations during embryogenesis were altered by TM. l-Leu administration in eggs caused a reduction in body temperature at hatching, and afforded thermotolerance in heat-exposed young chicks, further suggesting that l-Leu may be one of the key metabolic factors involved in controlling body temperature in embryos, as well as in producing thermotolerance after hatching.
Brain amino acid metabolism has been reported to regulate body temperature, feeding behavior and stress response. Central injection of taurine induced hypothermic and anorexigenic effects in chicks. However, it is still unknown how the amino acid metabolism is influenced by the central injection of taurine. Therefore, the objective of this study was to investigate the changes in brain and plasma free amino acids following central injection of taurine. Five-day-old male Julia layer chicks (n = 10) were subjected to intracerebroventricular (ICV) injection with saline or taurine (5 µmol/10 µL). Central taurine increased tryptophan concentrations in the diencephalon, and decreased tyrosine in the diencephalon, brainstem, cerebellum, telencephalon and plasma at 30 min post-injection. Taurine was increased in all the brain parts after ICV taurine. Although histidine and cystathionine concentrations were increased in the diencephalon and brainstem, several amino acids such as isoleucine, arginine, methionine, phenylalanine, glutamic acid, asparagine, proline, and alanine were reduced following central injection of taurine. All amino acid concentrations were decreased in the plasma after ICV taurine. In conclusion, central taurine quickly changes free amino acid concentrations in the brain and plasma, which may have a role in thermoregulation, food intake and stress response in chicks.
The objective of this study was to evaluate the effect of in ovo feeding cysteine, lysine or their combinations on the perinatal and post-hatch physiological responses of broiler embryos exposed to heat stress during incubation. A total of two thousand fertile eggs of broiler breeders (Ross 308) flock (at 38 weeks of age) were used for this study. In the first 10 days, the eggs were incubated using the conventional protocol of relative humidity and temperature of 55% and 37.8°C respectively. From day ten onward, the temperature was increased to 39.6°C for 6 h per day. On day 17.5, 1,500 eggs with the evidence of living embryos were randomly selected and assigned to 6 treatments having five replicates of 50 eggs each. The treatments were: un-injected eggs (UI), eggs injected with only 0.5 ml distilled water (DW), 3.5 mg/egg cysteine (CY), 2mg/egg lysine (LY), 3.4 mg cysteine+2 mg lysine (CLH) and 1.7 mg cysteine+1 mg lysine (CLL). On day 21, the hatchability, anatomical characteristics, chick quality and the antioxidant status of the chicks were evaluated. During the post-hatch phase, data were collected on the haematology, biochemical parameters, growth performance and intestinal morphology of the birds. The results revealed that the hatchability of CY chicks was higher (p < 0.05) than in the other treatments, while the lowest values were recorded in CLH. The hatching muscle of the chicks of CLL was similar to those of CY but higher (p < 0.05) than the others. The MDA of DW and UI chickens was similar and higher than birds in the other treatment groups. The serum SOD of CLL birds was comparable to that of CY but higher than the values recorded in the other treatments. The final weights of CLL chickens were similar to those of LY but significantly higher (p < 0.05) than those of the other treatments. The duodenal villus heights of the birds of CLL were higher than those of the other treatment groups, whereas the villus height of the birds of CLH was higher than those of UI, DW and CY. Overall, in ovo feeding of cysteine alone improved the hatchability of thermally-challenged broiler embryos. In contrast, a low-dose mixture of cysteine plus lysine improved the post-hatch growth performance.
Brain monoamines are reported to regulate body temperature and food intake. The objective of this study was to investigate the mechanism of brain monoamine metabolism in taurine-induced hypothermia and appetite suppression. In Experiment 1, 5-day-old male Julia layer chicks (n = 10) were subjected to intracerebroventricular (ICV) injection with saline or taurine (5 μmol/10 μL). In Experiment 2, the chicks were ICV injected with saline, taurine, fusaric acid (dopamine-β-hydroxylase inhibitor: 558 nmol), or taurine with fusaric acid. In Experiment 3, the chicks were ICV injected with saline, taurine, para-chlorophenylalanine (PCPA, tryptophan hydroxylase inhibitor: 400 nmol), or taurine with PCPA. In Experiment 4, the chicks were ICV injected with saline, taurine, clorgyline (monoamine oxidase inhibitor: 81 nmol), or taurine with clorgyline. Central taurine lowered rectal temperature at 30 min post-injection and increased norepinephrine in the brainstem and its metabolite 3-methoxy-4-hydroxyphenylglycol in both the diencephalon and brainstem. Similarly, taurine treatment induced increases in serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid in the diencephalon. Fusaric acid completely and PCPA partially, but not clorgyline, attenuated taurine-induced hypothermia. The anorexigenic effect of taurine was partially attenuated by PCPA, but not fusaric acid nor clorgyline. In conclusion, central taurine activates dopamine-β-hydroxylase and tryptophan hydroxylase to produce norepinephrine and 5-HT, and then induces hypothermia, but 5-HT alone may be linked with taurine-induced anorexia in chicks.
We examined the effects of oral administration of L-citrulline (L-Cit) on plasma met�abolic hormones and biochemical profile in broilers. Food intake, water intake, and body temperature were also analyzed. After dual oral administration (20 mmol/
head/administration) of L-Cit, broilers were exposed to a high ambient temperature
(HT; 30 � 1�C) chamber for 120 min. Oral administration of L-Cit reduced (p < .001) rectal temperature in broilers. Food intake was increased (p < .05) by heat stress, but it was reduced (p < .05) by L-Cit. Plasma levels of 3,5,30-triiodothyronine, which initially increased (p < .0001) due to heat stress, were reduced (p < .01) by oral administration of L-Cit. Plasma insulin levels were increased by heat exposure (p < .01) and oral L-Cit (p < .05). Heat stress caused a decline (p < .05) in plasma thyroxine. Plasma lactic acid (p < .05) and non-esterified fatty acids (p < .01) were increased in L-Cit-treated heat-exposed broilers. In conclusion, our results suggest that oral L-Cit can modulate plasma concentrations of major metabolic hormones and reduces food intake in broilers.
Heat stress (HS) threatens the worldwide dairy industry by decreasing animal production performance and health. Holstein cows and dairy buffaloes are the most important dairy animals, but their differences in the metabolic mechanism of thermotolerance remains elusive. In this study, we used serum metabolomics to evaluate the differences in thermotolerance between Holstein cows and crossbred dairy buffaloes under chronic heat stress (HS) and thermal-neutral conditions. In response to HS, the body temperatures and respiratory rates were increased more for Holstein cows than for dairy buffaloes (38.78 vs. 38.24 °C, p < 0.001; 43.6 vs. 32.5 breaths/min, p < 0.001). HS greatly affected serum metabolites associated with amino acids, fatty acids and bile acids. Enriched metabolic pathways of these serum metabolites are closely related to HS. We demonstrated that buffaloes adapt to HS by adopting a metabolism of branched-chain amino acids, ketogenic amino acids and gluconeogenesis, but Holstein cows decrease the effect of HS with citrulline and proline metabolism. Both physiological parameters and serum metabolic profiles indicate that dairy buffaloes are more thermotolerant than Holstein cows, providing it is feasible to vigorously develop buffalo dairy industry in tropical and subtropical regions.
Objective:
Heat stress poses an increasing threat for poultry production. Some amino acids have been found to play critical roles in affording thermotolerance. Recently, it was found that in ovo administration of L-leucine (L-Leu) altered amino acid metabolism and afforded thermotolerance in heat-exposed broiler chicks.
Methods:
In this study, two doses (35 and 70 μmol/egg) of L-Leu were administered in ovo on embryonic day 7 to determine their effect on rectal temperature (RT), body weight (BW) and thyroid hormones at hatching. Changes in RT, BW and thermotolerance in post-hatched chicks were also analyzed.
Results:
It was found that in ovo administration of L-Leu dose-dependently reduced RT and plasma thyroxine (T4) level just after hatching. In post-hatched neonatal broiler chicks, however, the higher dose of L-Leu administered in ovo significantly increased RT without affecting BW gain. In chicks that had been exposed to heat stress, the RT was significantly lowered by in ovo administration of L-Leu (high dose) in comparison with the control chicks under the same high ambient temperature (HT: 35 ± 1°C, 120 min).
Conclusion:
In ovo administration of L-Leu in a high dose contributed to an increased daily body temperature and afforded thermotolerance under HT in neonatal broiler chicks.
Recently, we found that in ovo feeding of L-leucine (L-Leu) stimulated the metabolism of lipids and afforded thermotolerance in male Chunky broiler chicks. In this study, we investigated the effects of feeding L-Leu in ovo on the metabolism of amino acids and on the cellular stress response mainly in the central and peripheral tissues in neonatal male broiler chicks and partly in embryonic tissues. Chicks (9 d old) were exposed to high ambient temperature (HT: 35 ± 1°C) or control thermoneutral temperature (CT: 28 ± 1°C) for 180 min. The ambient temperatures were based on our recent reports and the recommendation of the Chunky broiler manual in which 28°C has been suggested as a normal ambient temperature for 5 to 9-d-old broiler chicks. In ovo feeding of L-Leu caused a significant (P < 0.05) decline in diencephalic arginine concentrations but it increased the diencephalic and plasma lysine concentrations when compared with the control chicks under HT. Notably, in ovo feeding of L-Leu significantly (P < 0.05) attenuated the increment of hepatic arginine compared with the control chicks under HT. Interestingly, in ovo feeding of L-Leu significantly (P < 0.05) attenuated the diencephalic gene expression of heat-shock protein (HSP) −70 and −90 in heat-exposed chicks. The gene expressions of mammalian target of rapamycin (mTOR) and its downstream genes (ribosomal protein S6 kinase (S6K1) and eukaryotic initiation factor 4E binding protein 1 (4E-BP1)) in the central and peripheral tissues were not influenced in the chicks under heat stress. We found that the gene expressions of mTOR, S6K1, and 4E-BP1 were significantly (P < 0.05) stimulated only in the embryonic breast muscle, and not in the other embryonic tissues, by in ovo feeding of L-Leu. In conclusion, in ovo feeding of L-Leu caused a change in the metabolism of amino acids in response to heat stress in broiler chicks. Attenuated gene expressions of HSP-70 and −90 under heat stress further suggests that in ovo feeding of L-Leu may afford thermotolerance in broilers.
Heat stress is an increasing concern in poultry industry as it can cause a rise in the body temperature of chickens. Recently, we reported that L-citrulline (L-Cit) is a potential hypothermic agent that could improve thermotolerance in chicks. However, synthetic L-Cit has not yet been approved for inclusion in animal diets. L-Cit was first isolated from watermelon. Watermelon rind (WR), an agricultural waste product, contains more L-Cit than the flesh of the fruit. In the current study, the chemical composition and L-Cit content of WR dried powder (WRP) were determined. WRP was mixed with water at a ratio of 4:5 (wt/wt) to make WRP mash, and then mixed with a commercial starter diet to prepare a 9% WRP mash diet. The WRP mash diet was fed to 3- to 15-day-old chicks and daily food intake, body weight, and changes in rectal temperature were measured. At the end of the experiment, blood was collected from the chicks to analyze plasma L-Cit and other free amino acids. The chemical analysis of WRP revealed a variety of components including 19.1% crude protein. L-Cit was the most abundant free amino acid in WRP (3.18mg/g). Chronic supplementation of the WRP mash diet significantly increased compensatory food intake, plasma L-Cit, L-ornithine, and L-tyrosine in chicks. WRP mash diet did not affect the body temperature of the chicks. In conclusion, WRP mash diet supplementation increased plasma L-Cit concentration in chicks. The increase in plasma L-Cit concentrations suggest that WR could be used as a natural source of L-Cit in chicks to ameliorate the adverse effects of heat stress.
With global warming, heat stress is becoming a pressing concern worldwide. In chickens, heat stress reduces food intake and growth, and increases body temperature and stress responses. Although it is believed that young chicks do not experience heat stress as they need a higher ambient temperature to survive, our series of studies in young chicks showed that they are sensitive to heat stress. This review summarizes current knowledge on amino acid metabolisms during heat stress, with special emphasis on the hypothermic functions of L-citrulline (L-Cit) and L-leucine (L-Leu), and the functions of neuropeptide Y (NPY) in terms of body temperature and heat stress regulation in chicks. Amino acid metabolism is severely affected by heat stress. For example, prolonged heat stress reduces plasma L-Cit in chicks and L-Leu in the brain and liver of embryos. L-Cit and L-Leu supplementation affords thermotolerance in young chicks. NPY expression is increased in the brains of heat-exposed chicks. NPY has a hypothermic action under control thermoneutral temperature and heat stress in chicks. The NPY-sub-receptor Y5 is a partial mediator of the hypothermic action of NPY. Further, NPY stimulates brain dopamine concentrations and acts as an anti-stress agent in heat-exposed fasted, but not fed chicks. In conclusion, young chicks can serve as a model animal for the study of heat stress in chickens. L-Cit, L-Leu, and NPY were identified as biomarkers of heat stress, with the potential to afford thermotolerance in chicks.
L-Aspartate (L-Asp), D-aspartate (D-Asp) or their chemical conjugates plays important physiological roles in regulating food intake, plasma metabolites and thermoregulation in animals. However, there are very few studies available in layers and no reports have been found in broilers. Broilers are very important commercial birds for meat production, so effects of L- or D-Asp in broilers would provide new physiological insight of this strain. Therefore, the purpose of this study was to determine the effect of oral administration of L- or D-Asp on feed intake, rectal temperature and some plasma metabolites in broiler chicks. Broiler chicks (5 days old) were orally administered with different doses (0, 3.75, 7.5 and 15mmol/kg body weight) of L- or D-Asp. At 120 min after administration of L- or D-Asp, the blood was immediately collected through the jugular vein. The rectal temperature of chicks was measured at 30, 60 and 120 min after administration using a digital thermometer with an accuracy of ± 0.1°C, by inserting the thermistor probe in the rectum to a depth of 2cm. A repeated-measures two-way ANOVA was applied for the analysis of feed intake and rectal temperature. Plasma metabolites were statistically analyzed by one-way ANOVA and regression equations. The study showed that oral administration of both L- and D-Asp did not alter feed intake. However, D-Asp, but not L-Asp, dose-dependently decreased the rectal temperature in chicks. It was also found that D-Asp increased plasma glucose and decreased triacylglycerol concentrations. The changes in plasma metabolites further indicate that D-Asp treatment modulates the energy metabolism in broiler chicks. In conclusion, D-Asp may be a beneficial nutrient not only for layers but also for broilers, since orally administered D-Asp lowered rectal temperature without reducing feed intake.
Heat stress is known to impair performance and to induce oxidative stress in poultry. The aim of the present study was to compare the effects of dietary supplementation of dl-methionine (dl-M) or the synthetic analog 2-hydroxy-4-methylthiobutanoic acid (dl-HMTBA) on broiler growth performance, plasma hormone levels, and some oxidative stress-related parameters under conditions of chronic exposure to high temperatures (HT). From 2 to 6 wk of age, male broiler chickens were reared under either a constant temperature of 32°C until 6 wk of age or a normal temperature scheme (gradual decrease to 18°C at 5 wk of age). Chicks in both the normal and HT treatments were provided with a commercial grower diet supplemented with either 1.0 or 1.2 g/kg of dl-M or 1.0 or 1.2 g/kg of dl-HMTBA. Because there were no effects of supplement dose, data were pooled over both doses within each temperature treatment. The chronic HT treatment impaired feed intake and BW gain, but these negative effects were less pronounced when the chickens received dl-HMTBA. Exposure to HT was also associated with decreased (P < 0.001) plasma thyroid hormones and increased (P < 0.0001) plasma corticosterone levels. At 4 wk of age, and irrespective of the supplemental source, chickens subjected to HT were characterized by significantly lower plasma TBA-reactive substance levels. In contrast, at 6 wk of age, plasma TBA-reactive substance levels were significantly increased by HT, but this effect was observed only for the chickens receiving dl-M and not for those receiving dl-HMTBA. High temperatures induced a significant increase in hepatic total glutathione (GSH) and oxidized GSH levels, regardless of the supplemental source. However, the hepatic ratios of reduced GSH to total GSH and reduced GSH to oxidized GSH were highest in chickens supplemented with dl-HMTBA. In conclusion, dl-HMTBA supplementation partially prevented the growth-depressing effects of chronic heat exposure compared with dl-M supplementation. It can be inferred that dl-HMTBA is more efficient in alleviating HT-induced oxidative damage because of a more favorable reduced GSH-to-total GSH ratio.
Oral L-citrulline is efficiently converted to L-arginine, the precursor for endothelial nitric oxide (NO) synthesis. Oral L-arginine supplementation reduces brachial blood pressure (BP). We evaluated the effects of watermelon supplementation on aortic BP and arterial function in individuals with prehypertension.
Heart rate (HR), brachial systolic BP (bSBP), brachial pulse pressure (bPP), aortic SBP (aSBP), aortic PP (aPP), augmentation index (AIx), AIx adjusted for HR of 75 beats/min (AIx@75), amplitude of the first (P1) and second (P2) systolic peaks, reflection time (Tr), and carotid-femoral pulse wave velocity (PWV) were evaluated in the supine position in nine subjects (four men/five women, age 54 ± 3 years) with prehypertension (134/77 ± 5/3 mm Hg). Subjects were randomly assigned to 6 weeks of watermelon supplementation (L-citrulline/L arginine, 2.7 g/1.3 g/day) or placebo followed by a 4-week washout period and then crossover.
There was a significant treatment effect (change in the value of watermelon minus placebo from baseline to 6 weeks) on bPP (-8 ± 3 mm Hg, P < 0.05), aSBP (-7 ± 2 mm Hg, P < 0.05), aPP (-6 ± 2 mm Hg, P < 0.01), AIx (-6 ± 3%, P < 0.05), AIx@75 (-4 ± 2%, P < 0.05), and P2 (-2 ± 1 mm Hg, P < 0.05). There was no significant treatment effect (P > 0.05) on bSBP, brachial diastolic BP (DBP), aortic DBP, Tr, P1, HR, and carotid-femoral PWV.
This pilot study shows that watermelon supplementation improves aortic hemodynamics through a decrease in the amplitude of the reflected wave in individuals with prehypertension.
Chicks were conditioned by exposure to heat stress (36 +/- 1 C; to 80% RH) for 24 h at the age of 5, or 5 and 7 d. During conditioning, weight gain was depressed. Due to accelerated growth during the postconditioning period, a complete compensation for lost weight gain was achieved by the group conditioned at 5 d, but only a partial compensation was obtained in the group conditioned at both 5 and 7 d. At the age of 42 d, challenge with acute heat stress (35 +/- 1 C; 20 to 30% RH) resulted in a large increase in cloacal temperature of the controls and a more moderate increase in the conditioned chickens. Mortality during the thermal challenge was significantly higher in the control than that of the previously exposed (conditioned) groups. Conditioning at an early age resulted in hemodynamic changes (significant decrease in heart weight and hematocrit) and reduced plasma triiodothyronine (T3) concentration. The results suggest that reduced T3 and hemodynamic changes may be part of the mechanism associated with improved thermotolerance by early age temperature conditioning.
Four trials of identical experimental design were conducted to determine the effects of temperature, dietary Lys level, and dietary Arg:Lys ratios on performance and carcass yield of male broilers. Birds of a commercial strain were grown from 21 to 42 d of age in wire-floored finishing batteries placed in environmental chambers. The chambers were programmed to provide either a constant thermoneutral temperature (21.1 C), a constant cold temperature (15.5 C), or a cycling hot diurnal temperature (25.5 to 33.3 C). Within each environment there was a factorial arrangement of three Lys levels (1.0, 1.1, and 1.2%) with four Arg:Lys ratios (1.1:1, 1.2:1, 1.3:1, and 1.4:1). Environmental temperature significantly influenced virtually every characteristic examined. Hot cyclic temperatures reduced weight gain, feed intake, and breast meat yield, and increased feed conversion, dressing percentage, leg quarter yield, and abdominal fat content. The cold environment promoted increased feed intake and mortality. Ascites and cardiomyopathy were the leading causes of death under cold exposure and thermoneutral conditions, whereas complications arising from heat exposure were the main cause of death under hot cyclic conditions. Levels of Lys affected leg quarter yield and abdominal fat content over all environments but increased breast meat yield only under cold conditions. Increasing Arg:Lys ratios improved feed conversion and dressing percentage and reduced abdominal fat content; it could not be determined whether these responses were consistent with Arg per se or were due to a nonspecific N response. As increasing Lys levels or Arg:Lys ratios did not improve weight gain, increase breast meat yield, or attenuate adverse effects due to heat or cold exposure, it is concluded that the levels of Lys and Arg suggested for 21 to 42 d by the NRC are adequate for birds of this age under the environmental conditions encountered.
Citrulline (Cit, C6H13N3O3), which is a ubiquitous amino acid in mammals, is strongly related to arginine. Citrulline metabolism in mammals is divided into two fields: free citrulline and citrullinated proteins. Free citrulline metabolism involves three key enzymes: NO synthase (NOS) and ornithine carbamoyltransferase (OCT) which produce citrulline, and argininosuccinate synthetase (ASS) that converts it into argininosuccinate. The tissue distribution of these enzymes distinguishes three "orthogonal" metabolic pathways for citrulline. Firstly, in the liver, citrulline is locally synthesized by OCT and metabolized by ASS for urea production. Secondly, in most of the tissues producing NO, citrulline is recycled into arginine via ASS to increase arginine availability for NO production. Thirdly, citrulline is synthesized in the gut from glutamine (with OCT), released into the blood and converted back into arginine in the kidneys (by ASS); in this pathway, circulating citrulline is in fact a masked form of arginine to avoid liver captation. Each of these pathways has related pathologies and, even more interestingly, citrulline could potentially be used to monitor or treat some of these pathologies. Citrulline has long been administered in the treatment of inherited urea cycle disorders, and recent studies suggest that citrulline may be used to control the production of NO. Recently, citrulline was demonstrated as a potentially useful marker of short bowel function in a wide range of pathologies. One of the most promising research directions deals with the administration of citrulline as a more efficient alternative to arginine, especially against underlying splanchnic sequestration of amino acids. Protein citrullination results from post-translational modification of arginine; that occurs mainly in keratinization-related proteins and myelins, and insufficiencies in this citrullination occur in some auto-immune diseases such as rheumatoid arthritis, psoriasis or multiple sclerosis.
1. An experiment was conducted to analyse the changes in free amino acid concentrations in the blood, brain and muscle of chicks in response to 15 or 30 min exposure to high ambient temperature (HT).
2. Food intake and body weight were not affected, while rectal temperature was significantly increased by short-term HT exposure.
3. Several free amino acid concentrations increased in the blood, brain and muscle even with short-term HT, whereas levels of a few amino acids declined significantly. As well as the nonessential amino acids, essential amino acids also significantly increased with exposure to HT.
4. 3-Methylhistidine, a marker of proteolysis, significantly declined in the muscle of HT chicks, implying a reduction of protein breakdown under HT.
5. These results indicate that alteration of protein metabolism may occur in chicks even with short-term heat exposure.
Birds reduce their food intake by the exposure to high ambient temperature (HT) which ultimately affects their productivity. However, physiological and behavioral responses of young chicks of different ages to HT have not yet been investigated. In this study, we examined the effects of HT (40℃, 4-h) in 3-, 5-, 7-, 14-and 21-d old chicks. There were no significant differences in food intake between heat exposed and control chicks up to 7-d old, while clear suppressions of food intake were observed in 14-and 21-d old heat exposed chicks. Body weights were not affected in all age groups; however, rectal temperature was significantly increased in almost all ages. We examined blood metabolites of 7-, 14-and 21-d old chicks and found that plasma glucose concentration gradually increased in 14-to 21-d old heat exposed chicks. Conversely, triacylglycerol age-dependently decreased during exposure to HT. No significant changes were detected in plasma total protein, uric acid and calcium investigated in 7-, 14-and 21-d old heat exposed chicks compared to control groups. However, plasma glutamic-oxalacetic transaminase showed a significant interaction between HT and age, implying that liver and/or heart was damaged by HT with aging. These results indicate that HT (40℃; 4-h) suppresses food intake in young chicks of 14-or 21-d old age which reflects in some of their plasma metabolic concentrations.
Aims:
L-Aspartate (L-Asp) and D-aspartate (D-Asp) are physiologically important amino acids in mammals and birds. However, the functions of these amino acids have not yet been fully understood. In this study, we therefore examined the effects of L-Asp and D-Asp in terms of regulating body temperature, plasma metabolites and catecholamines in chicks.
Main methods:
Chicks were first orally administered with different doses (0, 3.75, 7.5 and 15 mmol/kg body weight) of L- or D-Asp to monitor the effects of these amino acids on rectal temperature during 120 min of the experimental period.
Key findings:
Oral administration of D-Asp, but not of L-Asp, linearly decreased the rectal temperature in chicks. Importantly, orally administered D-Asp led to a significant reduction in body temperature in chicks even under high ambient temperature (HT) conditions. However, centrally administered D-Asp did not significantly influence the body temperature in chicks. As for plasma metabolites and catecholamines, orally administered D-Asp led to decreased triacylglycerol and uric acid concentrations and increased glucose and chlorine concentrations but did not alter plasma catecholamines.
Significance:
These results suggest that oral administration of D-Asp may play a potent role in reducing body temperature under both normal and HT conditions. The alteration of plasma metabolites further indicates that D-Asp may contribute to the regulation of metabolic activity in chicks.
Intracerebroventricular (i.c.v.) injection of L- and D-aspartate (L- and D-Asp) has been shown to have a sedative effect with and without a hypnotic effect, respectively, in neonatal chicks experiencing isolation stress. However, the mechanisms of the different stress-attenuating functions of L- and D-Asp have not yet been fully clarified. In the present study, we investigated the involvement of the N-methyl-D-aspartate (NMDA) receptor in order to reveal the receptor-mediated function of L- and D-Asp. To reveal whether L-and D-Asp act through the NMDA receptor, (+)-MK-801, which is an antagonist of NMDA receptors, was used in the current study. In Experiment 1, the chicks were injected i.c.v. with either saline, (+)-MK-801, L-Asp or L-Asp plus (+)-MK-801. The sedative and hypnotic effects induced by L-Asp were blocked by co-administration with (+)-MK-801. In Experiment 2, the chicks were injected i.c.v. with either saline, (+)-MK-801, D-Asp or D-Asp plus (+)-MK-801. Importantly, the sedative effects induced by D-Asp were shifted to hypnotic effects by co-administration with (+)-MK-801. Taken together, L-Asp could induce sedative and hypnotic effects for stress behaviors through the NMDA receptor, but the attenuation of stress behaviors by D-Asp might be via simultaneous involvement of other receptors besides the NMDA receptor in this process. These differences may explain the different functional mechanisms of L- and D-Asp in the central nervous system.
High ambient temperatures (HT) reduce food intake and body weight in young chickens, and HT can cause increased expression of hypothalamic neuropeptides. The mechanisms by which HT act, and the effects of HT on cellular homeostasis in the brain, are however not well understood. In the current study lipid peroxidation and amino acid metabolism were measured in the brains of 14 d old chicks exposed to HT (35 °C for 24 or 48 h) or to control thermoneutral temperature (CT; 30 °C). Malondialdehyde (MDA) was measured in the brain to determine the degree of oxidative damage. HT increased body temperature and reduced food intake and body weight gain. HT also increased diencephalic oxidative damage after 48 h, and altered some free amino acid concentrations in the diencephalon. Diencephalic MDA concentrations were increased by HT and time, with the effect of HT more prominent with increasing time. HT altered cystathionine, serine, tyrosine and isoleucine concentrations. Cystathionine was lower in HT birds compared with CT birds at 24 h, whilst serine, tyrosine and isoleucine were higher at 48 h in HT birds. An increase in oxidative damage and alterations in amino acid concentrations in the diencephalon may contribute to the physiological, behavioral and thermoregulatory responses of heat-exposed chicks.
1. An experiment was conducted to evaluate the effects of dietary glutamine (Gln, 0 and 5 g/kg) and gamma-aminobutyric acid (GABA, 0 and 100 mg/kg) on raw breast meat colour, pH, composition and water-holding characteristic of broilers under cyclic heat stress (HS). 2. A total of 360 21-d-old Arbor Acres male chicks were randomly assigned to 5 treatment groups (6 replicates of 12 birds per cage). The positive control (PC) broilers were kept in a thermoneutral chamber (22-24°C) and fed on the basal diet. The other 4 groups were kept in a cyclic HS chamber (30-34°C) for 9 h (from 09:00 to 18:00). 3. A significant increase was observed in breast meat lightness at 28, 35 and 42 d; and pH values at 28, 35 and 42 d; while a significant decrease was observed in breast meat cooking loss (CL) and contents of moisture, crude protein (CP), crude fat (CF) and crude ash (CA) due to HS. 4. The supplementation with 0·5 g Gln/kg decreased lightness at 28, 35 and 42 d; while increasing redness at 28 d, yellowness at 35 d, contents of CP, CF and CA, thawing loss (TL) and drip loss (DL). The addition of 100 mg GABA/kg decreased lightness at 28 and 35 d, pH value at 28, 35 and 42 d, and TL; while increasing redness at 28 d, 35 and 42 d, contents of moisture, CP and CF. 5. The lightness, redness, and pH value; contents of moisture, CP, CF and CA; and TL, DL and CL of breast meat of broilers fed with the mixture of Gln and GABA under cyclic HS were similar to those of the broilers in the PC group. 6. Significant interactions were found between Gln and GABA for yellowness at 28 and 35 d; pH at 28, 35 and 42 d; moisture content, CP content, water-holding capacity and TL. 7. These results demonstrated that dietary Gln and GABA offer a potential nutritional strategy to prevent cyclic HS-related depression in broiler meat chemical composition and quality.
Intracerebroventricular (i.c.v.) administration of L-aspartate (L-Asp) attenuates stress responses in neonatal chicks, but the mechanism has not been clarified. In the present study, three behavioral experiments were carried out under socially isolated stressful conditions exacerbated by the use of corticotrophin-releasing factor (CRF). In Experiment 1, i.c.v. injection of L-Asp attenuated behavioral stress responses (distress vocalization and active wakefulness) in a dose-dependent manner. Furthermore, L-Asp increased time spent standing/sitting motionless with eyes open and sitting motionless with head dropped (sleeping posture) in comparison with the group receiving CRF alone. In Experiment 2, i.c.v. injection of D-Asp dose-dependently decreased the number of distress vocalizations and the amount of time spent in active wakefulness. D-Asp increased the time spent standing/sitting motionless with eyes open compared with the group receiving CRF alone. In Experiment 3, we directly compared the effect of L-Asp with that of D-Asp. Both L- and D-Asp induced sedative effects under an acutely stressful condition. However, L-Asp, but not D-Asp, increased the time spent in a sleeping posture. These results indicate that both L- and D-Asp, when present in the brain, could induce a sedative effect, while the mechanism for hypnosis in neonatal chicks may be different for L-Asp in comparison with D-Asp.
The regulation of food intake in chickens (Gallus gallus domesticus) represents a complex homeostatic mechanism involving multiple levels of control, and regulation during high ambient temperatures (HT) is poorly understood. In this study, we examined hypothalamic mRNA expression of gonadotropin-inhibitory hormone (GnIH) to understand the effect of HT on an orexigenic neuropeptide. We examined the effects of HT (35 °C ambient temperature for 1, 24 or 48 h) on 14-day old chicks. HT significantly increased rectal temperature and suppressed food intake, and also influenced plasma metabolites. The expression of GnIH precursor mRNA in the diencephalon was significantly increased in chicks at 24-and 48 h of HT when food intake was suppressed significantly, whilst no change was observed for GnIH precursor mRNA and food intake at 1h of HT. In situ hybridization and immunocytochemistry further revealed the cellular localization of chicken GnIH precursor mRNA and its peptide in the paraventricular nucleus (PVN) in the chick hypothalamus. We examined plasma metabolites in chicks exposed to HT for 1 or 48 h and found that triacylglycerol concentration was significantly higher in HT than control chicks at 1h. Total protein, uric acid and calcium were significantly lower in HT chicks than control chicks at 48h. These results indicate that not only a reduction in food intake and alteration in plasma metabolites but also the PVN-specific expression of GnIH, an orexigenic agent, may be induced by HT. The reduced food intake at the same time as GnIH expression was increased during HT suggests that HT-induced GnIH expression may oppose HT-induced feeding suppression, rather than promote it. We suggest that the increased GnIH expression could be a consequence of the reduced food intake, and would not be a direct response to HT.
Intracerebral injection of C14-labeled L-proline resulted in its distribution in periventricular tissue (including septum, hippocampus, and hypothalamus) in neonatal chicks decapitated 1 min after injection. Delay of decapitation for 3, 9 or 45 min resulted only in an increased spread of label into the fourth ventricle. A simple, effective chick head-holder is also described.
1.1. Studies in respiratory physiology and acid-base balance of panting birds exposed to high Ta s show that flying as well as nonflying birds can use the respiratory system simultaneously for gas exchange and evaporative cooling.2.2. The present study proves that well acclimated hand-reared birds can effectively regulate a normal CO2 level and acid-base status in arterial blood, when exposed to extremely high temperatures (50–60°C).3.3. In many birds practising simple or “flush out” anting, the dead space can be reduced to a volume which is estimated to be approx 15% the volume of the respiratory tract.4.4. These two modes of ventilation, shallow and high-rate, restricted to the nonrespiratory surfaces, may ensure the avoidance of CO2-washout and limit lung ventilation to the volumes needed for oxygen consumption.5.5. This view supports earlier theories, suggesting the existence of physiological shunt mechanisms which operate during thermal panting in birds.
Endothelium-derived relaxing factor (EDRF) is a labile humoral agent which mediates the action of some vasodilators. Nitrovasodilators, which may act by releasing nitric oxide (NO), mimic the effect of EDRF and it has recently been suggested by Furchgott that EDRF may be NO. We have examined this suggestion by studying the release of EDRF and NO from endothelial cells in culture. No was determined as the chemiluminescent product of its reaction with ozone. The biological activity of EDRF and of NO was measured by bioassay. The relaxation of the bioassay tissues induced by EDRF was indistinguishable from that induced by NO. Both substances were equally unstable. Bradykinin caused concentration-dependent release of NO from the cells in amounts sufficient to account for the biological activity of EDRF. The relaxations induced by EDRF and NO were inhibited by haemoglobin and enhanced by superoxide dismutase to a similar degree. Thus NO released from endothelial cells is indistinguishable from EDRF in terms of biological activity, stability, and susceptibility to an inhibitor and to a potentiator. We suggest that EDRF and NO are identical.
High environmental temperature has detrimental effects on the gastrointestinal tract of poultry. An experiment was conducted to determine the effect of acute heat stress on endogenous amino acid (EAA) flow in broiler chickens. A total of 90, day-old broiler chicks were housed in battery cages in an environmentally controlled chamber. Chicks were fed a nitrogen-free diet on day 42 following either no heat exposure (no-heat) or 2 weeks exposure to 35 ± 1 °C for 3 h from days 28 to 42 (2-week heat) or 1 week exposure to 35 ± 1 °C for 3 h from days 35 to 42 (1 week heat). The most abundant amino acid in the ileal flow was glutamic acid, followed by aspartic acid, serine and threonine in non-heat stressed group. The EAA flow in 1-week heat and 2-week heat birds were significantly (p < 0.05) higher than those under no heat exposure (14682, 11161 and 9597 mg/kg of dry matter intake respectively). Moreover, the EAA flow of 2-week heat group was less than 1-week heat group by approximately 36%. These observations suggest that the effect of heat stress on EAA flow is mostly quantitative; however, heat stress may also alter the content of EAA flow qualitatively.
To the Editor.—
Currently accepted dietary management of citrullinemia and other urea cycle disorders includes protein restriction, sodium benzoate, and dietary supplements of keto acids or essential amino acids with postblock intermediates such as arginine in citrullinemia and arginino-succinic aciduria. When a child survives the neonatal period on such a regimen and solid foods are introduced into the diet, there is at least one fruit that should be avoided, Citrullus Vulgaris, commonly known as watermelon.
Quantitation of free amino acids extracted from 1 g wet weight of watermelon fruit yielded the following (in mmoles per gram wet weight): Phenylalanine, 1.25; histidine, 0.24; tryptophan, 0.35; lysine, 0.82; ornithine, 0.32; arginine, 11.36; aspartic acid, 0.97; threonine, 0.74; serine, 1.05; glutamine, 3.86; glutamic acid, 1.38; citrulline, 23.68; alanine, 1.15; valine, 0.17; isoleucine, 1.24; leucine, 0.24.
Previous work has demonstrated a continuous release of citrulline from the small intestine into the circulation. To evaluate the physiologic significance of this process, we have now measured citrulline uptake and release by isolated, perfused livers and, through surgical means and arteriovenous difference measurements, by various organs of the rat in vivo. Intestinally derived citrulline, an end product of glutamine nitrogen metabolism, passes through the liver without appreciable uptake. No significant extraintestinal source of circulating citrulline was found. Contrary to earlier suggestions, the liver releases no citrulline normally, but only when supplied with unphysiological high levels of ornithine and ammonia. Renal citrulline uptake was equivalent to approximately 83% the rate of intestinal release; kidneys, in turn, released arginine equivalent to approximately 75% of the citrulline taken up. Acute experiments in which the intestine, intestine plus liver, or kidneys were excluded from the circulation indicate that additional organs may also participate in citrulline exchange, at least when the circulating citrulline level is abnormal. The intestinal-renal pathway seems to account for a large though still unmeasured portion of the citrulline turnover in the circulation.
Nitric oxide (NO) is produced by three distinct isoforms of nitric oxide synthases in the central nervous system. Here, the roles of nitric oxide in the central nervous system are reviewed under physiological and pathophysiological conditions. Under physiological conditions, NO plays a role in the regulation of cerebral blood flow and autoregulation, blood flow-metabolism coupling, neurotransmission, memory formation, modulation of neuroendocrine functions, and behavioral activity. Impairment of the NO-mediated cerebrovascular vasodilatation occurs during ischemia-reperfusion, diabetes, hypertension, subararchnoid hemorrhage, and various forms of shock. Enhancement of NO production in the brain occurs during stoke, seizures, and acute and chronic inflammatory and neurodegenerative disorders. The alterations of the expression of the various isoforms of nitric oxide synthases under the above conditions are discussed. Moreover, the molecular mechanisms of NO and peroxynitrite induced cellular injury are delineated. Finally, the current strategies available for selective pharmacological manipulation of individual nitric oxide synthase isoforms are discussed.
1. The effects of varying the dietary arginine:lysine (Arg:Lys) ratio for broiler chickens at thermoneutral and high temperatures was studied in a series of 5 experiments which measured intestinal epithelial transport or evaluated growth and food efficiency with practical diets or diets supplemented with L-arginine free base. 2. The growth studies showed that increasing the Arg:Lys ratio at high temperatures produced consistent improvements in food conversion without any loss in growth. 3. Increasing dietary sodium chloride concentration reduced the Arg:Lys ratio necessary for optimum food conversion. 4. Food conversion responses were improved whether L-arginine free base was used as a dietary supplement in place of an inert filler or practical diets with differing ingredients were used to vary the Arg:Lys ratio. 5. In the presence of an equimolar concentration of lysine the uptake of arginine by the intestinal epithelium of heat-stressed broilers was reduced significantly compared with that of broilers at thermoneutral temperatures. 6. The results indicate that the ideal amino acid balance for broilers varies with ambient temperature.
1. Recently, 2 novel neuropeptides were discovered, both derived from the same precursor by proteolytic processing, which bind and activate 2 closely related orphan G protein-coupled receptors, Named orexin-A and -B (Sakurai et al., 1998). Both stimulate food intake when administered centrally to rats. 2. Our aim was to elucidate whether central injection of mammalian orexin-A or -B stimulates food intake in the chick. 3. Under conditions of free access to food, orexin-A did not alter the food intake of chicks, but cumulative food intake was significantly suppressed by orexin-B. 4. The orexin-B was then administered to chicks deprived of food for 3 h to confirm its suppressive effect. No significant effect of orexin-B on food intake was detected. 5. Central injection of orexin-B did not modify food intake when appetite was stimulated by fasting. 6. Neither of these orexins appears to stimulate feeding in chicks.
Ornithine transcarbamylase, argininosuccinate synthetase, argininosuccinate cleavage enzyme, and arginase, but not carbamyl phosphate synthetase, have been found in the chick kidney in moderate amounts. None of these, except traces of arginase, have been found in chick liver. Relatively small amounts of the cleavage enzyme have also been found in pancreas, spleen, and intestinal tract. The distribution of these enzymes is consistent with the ability of the chick to utilize citrulline in the diet in place of arginine and the inability to utilize ornithine in place of arginine. The significance of the findings is discussed in relation to arginine and nitrogen metabolism in the growing chick and in the developing embryo.
The effects L-arginine (0.15-0.60 micromol), a nitric oxide precursor, and SIN-1 (3-morpholino-sydnonimine; linsidomine) (0.05-0.2 micromol), a nitric oxide donor, on spontaneous sleep were studied in adult rats implanted for chronic sleep recordings. L-arginine or SIN-1 given intracerebroventricularly during the light phase of the light-dark cycle induced no significant changes in sleep variables. On the other hand, administration of L-arginine or SIN-1 during the dark phase significantly increased slow wave sleep and reduced waking during the first 4 h of the recording period. The time spent in rapid-eye-movement sleep (REMS) was not significantly modified. The increase of slow wave sleep and/or reduction of waking was already evident during the first 2 h of recording. On the other hand, values of these variables were not different from control values during post-injection hours 5 and 6. Our findings confirm the role of nitric oxide, generated from L-arginine or released from SIN-1, in the regulation of sleep variables in the rat.
The present study investigated whether centrally administered phosphatidylserine (PS) could modify the behavior of chicks under isolation-induced stress. Isolation stress-induced vocalization and spontaneous activity for 10 min, which were attenuated by intracerebroventricular (i.c.v.) injection of PS. The effect of PS was compared with other phospholipids or L-serine, a constituent of PS. Phosphatidylcholine (PC) had no effect on these behavior, but phosphatidylethanolamine (PE) significantly increased vocalizations and spontaneous activity compared with PS. L-Serine similarly decreased isolation-induced vocalizations and spontaneous activity. To clarify the mechanism by which central PS attenuates isolation-induced stress behavior, the contribution of the acetylcholine (ACh) receptor (AChR) was also investigated. PS was co-injected i.c.v. with the muscarinic AChR (M-AChR) antagonist scopolamine or the nicotinic AChR (N-AChR) antagonist hexamethonium. The suppression of vocalizations and spontaneous activity by PS was partially attenuated by scopolamine, but not hexamethonium. These findings indicate that isolation-induced stress behavior are attenuated by PS, acting partially through the M-AChR.
Watermelon (Citrullus vulgaris Schrad.) is a natural and rich source of the non-essential amino acid citrulline. Citrulline is used in the nitric oxide system in humans and has potential antioxidant and vasodilatation roles. A method using gas chromatography-mass spectrometry (GC-MS) was developed to separate citrulline from glutamic acid, which co-elute when analyzed by high performance liquid chromatography. Watermelons were analyzed by GC-MS to determine the citrulline content among varieties, types, flesh colors, and tissues. Citrulline content ranged from 3.9 to 28.5 mg/g dry weight (dwt) and was similar between seeded and seedless types (16.6 and 20.3 mg/g dwt, respectively). Red flesh watermelons had slightly less citrulline than the yellow or orange flesh watermelons (7.4, 28.5 and 14.2 mg/g dwt, respectively). Rind contained more citrulline than flesh on a dry weight basis (24.7 and 16.7 mg/g dwt, respectively) but a little less on a fresh weight (fwt) basis (1.3 and 1.9 mg/g fwt, respectively). These results indicate that watermelon rind, an underutilized agricultural waste, offers a source of natural citrulline.
Oral L-arginine supplementation has been used in several studies to improve endothelium-dependent, nitric oxide (NO)-mediated vasodilation. L-Arginine treatment is hampered by extensive presystemic elimination due to intestinal arginase activity. In contrast, L-citrulline is readily absorbed and at least in part converted to L-arginine. The aim of our study was to assess this metabolic conversion and its subsequent pharmacodynamic effects.
In a double-blind, randomized, placebo-controlled cross-over study, 20 healthy volunteers received six different dosing regimes of placebo, citrulline, and arginine. Pharmacokinetic parameters (C(max), T(max), C(min), AUC) were calculated after 1 week of oral supplementation. The ratio of plasma L-arginine over asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide synthase (arginine/ADMA ratio), urinary cyclic guanosine monophosphate (cGMP) and nitrate excretion rates, and flow-mediated vasodilation (FMD) was measured to assess pharmacodynamic effects.
L-Citrulline dose-dependently increased AUC and C(max) of plasma L-arginine concentration more effectively than L-arginine (P < 0.01). The highest dose of citrulline (3 g bid) increased the C(min) of plasma L-arginine and improved the L-arginine/ADMA ratio from 186 +/- 8 (baseline) to 278 +/- 14 [P < 0.01, 95% confidence interval (CI) 66, 121]. Moreover, urinary nitrate and cGMP were increased from 92 +/- 10 to 125 +/- 15 micromol mmol(-1) creatinine (P = 0.01, 95% CI 8, 58) and from 38 +/- 3.3 to 50 +/- 6.7 nmol mmol(-1) creatinine (P = 0.04, 95% CI 0.4, 24), respectively. No treatment improved FMD over baseline. However, pooled analysis of all FMD data revealed a correlation between the increase of arginine/ADMA ratio and improvement of FMD.
Our data show for the first time that oral L-citrulline supplementation raises plasma L-arginine concentration and augments NO-dependent signalling in a dose-dependent manner.
Recently, we observed that central administration of L-arginine attenuated stress responses in neonatal chicks, but the contribution of nitric oxide (NO) to this response was minimal. The sedative and hypnotic effects of L-arginine may be due to L-arginine itself and/or its metabolites, excluding NO. To clarify the mechanism, the effect of intracerebroventricular (i.c.v.) injection of L-arginine metabolites on behavior under social separation stress was investigated. The i.c.v. injection of agmatine, a guanidino metabolite of L-arginine, had no effect during a 10 min behavioral test. In contrast, the i.c.v. injection of L-ornithine clearly attenuated the stress response in a dose-dependent manner, and induced sleep-like behavior. The L-ornithine concentration in the telencephalon and diencephalon increased following the i.c.v. injection of L-arginine. In addition, several free amino acids including L-alanine, glycine, L-proline and L-glutamic acid concentrations increased in the telencephalon. In conclusion, it appears that L-ornithine, produced by arginase from L-arginine in the brain, plays an important role in the sedative and hypnotic effects of L-arginine observed during a stress response. In addition, several other amino acids having a sedative effect might partly participate in the sedative and hypnotic effects of L-arginine.
Oral administration of D-aspartate, but not Laspartate , depresses rectal temperature and alters plasma metabolites in chicks Effects of watermelon supplementation on aortic blood pressure and wave reflection in individuals with prehypertension: a pilot study
- E Erwan
- Vs Chowdhury
- M Nagasawa
- R Goda
- T Otsuka
- S Yasuo
- M Furuse
- A Figueroa
- Ma Sanchez-Gozalez
- Pm Perkins-Veazie
- Bh Arjmandi
Erwan E, Chowdhury VS, Nagasawa M, Goda R, Otsuka T, Yasuo S
and Furuse M. Oral administration of D-aspartate, but not Laspartate, depresses rectal temperature and alters plasma metabolites in chicks. Life Sciences, 109: 65-71. 2014b.
Figueroa A, Sanchez-Gozalez MA, Perkins-Veazie PM and
Arjmandi BH. Effects of watermelon supplementation on aortic
blood pressure and wave reflection in individuals with prehypertension: a pilot study. American Journal of Hypertension,
8: 1-5. 2010.
Hypothermic Action of L-Citrulline in Chicks
- Chowdhury
Chowdhury et al.: Hypothermic Action of L-Citrulline in Chicks
Energy generation in Mitochondria and chloroplast
- B Alberts
- D Bray
- K Hopkins
- A Johnson
- J Lewis
- M Raff
- K Roberts
Alberts B, Bray D, Hopkins K, Johnson A, Lewis J, Raff M, Roberts K, and Walter P.
Energy generation in Mitochondria and chloroplast. In: Essential Cell Biology. 4th
ed. Garland Science, Taylor and Francis Group Press. USA. 2014.