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Zinc protection from fluoride-induced testicular injury in the bank vole (Clethrionomys glareolus)

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Abstract

Previous work has shown that a high fluoride intake in rodents leads to histopathological changes in the germinal epithelium of testes that is associated with zinc deficiency. The purpose of this study was to determine whether supplemental dietary Zn would protect against testicular toxicity induced by fluoride in a small rodent, the bank vole. The 4-month exposure period to fluoride (200 microg/ml of drinking water) induced histopathological changes (hemorrhage in interstitium, necrosis and apoptosis in seminiferous tubule epithelium) which were accompanied by decreased testicular zinc concentration and increased lipid peroxidation. Supplemental dietary zinc (110-120 microg/g) together with fluoride treatment resulted in complete reversal of the fluoride-mediated effects. However, supplemented dietary Zn did not affect the accumulation of fluoride in the testes and bone. These data suggest that a zinc-enriched diet protects seminiferous tubules against fluoride toxicity by preventing the fluoride-induced testicular zinc deprivation.

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... Moreover, fluoride exposure has been associated with reduced zinc concentrations in testicular tissue (Krasowska et al. 2004;Radovanović et al. 2022). Zinc also serves as an essential cofactor involved in sex hormone synthesis and is critical for sexual maturation (Shao et al. 2023). ...
... Some studies have revealed that zinc can counteract apoptosis, cell cycle changes, and oxidative stress induced by excessive fluoride (Xu et al. 2014). Additionally, supplemental dietary zinc can ameliorate fluoride-induced testicular lipid peroxidation and abnormal sex steroid hormone levels (Krasowska et al. 2004). These findings emphasize the necessity of considering the effects of both fluoride exposure and zinc deficiency on human reproductive health. ...
... A recent animal study has demonstrated that fluoride exposure can cause a decrease in zinc concentration, testicular lipid peroxidation, histopathological changes, and increased incidence of testicular apoptosis, ultimately damaging reproductive function. However, it has been reported that dietary zinc supplementation can alleviate the detrimental effects of fluoride (Krasowska et al. 2004). Zinc, as an antioxidant, can help resist oxidative stress and inflammatory reactions (Jarosz et al. 2017). ...
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Excessive fluoride exposure can disturb the balance of sex hormones. Zinc is essential for sex hormone synthesis and spermatogenesis. But it is not clear how zinc affects the relationship of fluoride exposure with abnormal sex steroid hormones. Here, a total of 1008 pubertal males from the National Health and Nutrition Examination Survey (NHANES) in two cycles (2013–2014, 2015–2016) were enrolled. The concentrations of water fluoride and plasma fluoride and the levels of serum testosterone, estradiol, and sex hormone binding globulin (SHBG) were measured. Two 24-h dietary recall interviews were conducted to assess the dietary zinc intake. The relationships of fluoride exposure and zinc intake with sex hormones were examined using linear regression and logistic regression models, while the generalized additive model was used to evaluate their non-linear relationship. Our findings revealed that for every two-fold increase in plasma fluoride concentration, testosterone levels decreased by 7.27% (95% CI − 11.49%, − 2.86%) and estradiol levels decreased by 8.73% (95% CI − 13.61%, − 3.57%). There was also significant non-linear association observed between zinc intake and SHBG levels. Being in the first tertile of plasma fluoride had a 60% lower risk of high SHBG (OR = 0.40, 95% CI 0.18, 0.89) compared with being in the second tertile. When compared to the first tertile, being in the second tertile of zinc intake was associated with a 63% (OR = 0.37, 95% CI 0.14, 0.98) lower risk of high SHBG. Furthermore, we observed an interactive effect between the plasma fluoride and zinc intake on estradiol and SHBG, as well as the risk of high SHBG (P-interaction < 0.10). These findings suggest that fluoride exposure and zinc intake can affect sex steroid hormone levels and the risk of high SHBG. Notably, zinc intake may alleviate the increased risk of high SHBG and the abnormal changes of estradiol and SHBG caused by higher fluoride exposure.
... Animal studies have shown the effect of fluoride on metabolism & morphology of spermatozoa. High fluoride intake can lead to Zn deficiency in the testes and male re-production system 9,10 leading to a reduction in testosterone levels that is critically necessary for testicular development 9,11 . High fluoride content is also reported to increase oxidative stress in the testes affecting spermatozoa 9,11,12 . ...
... High fluoride intake can lead to Zn deficiency in the testes and male re-production system 9,10 leading to a reduction in testosterone levels that is critically necessary for testicular development 9,11 . High fluoride content is also reported to increase oxidative stress in the testes affecting spermatozoa 9,11,12 . ...
... Zn plays a key role in spermatogenesis [18][19][20][21][22][23] and reverses fluoride toxicity 9,10 . Also vitamin E has been proved for the reversal of fluoride toxicity in mice 7 . ...
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Infertility is a major problem of the day amongst men and women and marked by no pregnancy even after one year of unprotected intercourse. Almost 30% of infertility has been related with male factors-low sperm concentration, motility, viability and morphology. Factors like pollution, drugs, stress, life style changes, toxicants and insufficient nutrition have harmful effects on spermatogenesis and reproductive health. Fluorine is one such potent toxicant to which humans are exposed and the problem of fluorosis was known for long in India, especially in Andhra Pradesh. It was reported in several studies that fluorine interferes with the structural and functional integrity of the male reproductive system resulting in male factor infertility. The present research has been undertaken to evaluate the efficacy of Avena sativa as a nutrient and food supplement to lower the fluoride induced infertility in male rats as, A. sativa has a wide range of chemical and mineral constituents. In this study, fluorine at a dose of 0.01 g/kg body weight, administered through oral route induced infertility by causing damage to histoarchitecture of the testis and decreased the levels of serum testosterone, FSH, and LH. Treatment with hydroalcholic extract of A. sativa resulted in decreased damage to the reproductive organs and lesser impact on sperm parameters-sperm count, viability, morphology, motility etc. The results were analyzed through one way ANNOVA using graph pad prism 5 software. Form the present study it is concluded that oats has the ability to decrease the toxic effect of fluorine.
... The reproductive toxicity is of great concern to the public, as clearly demonstrated by epidemiological studies that environmental exposure to fluoride was associated with male infertility and low birth rates of people living in the area of endemic fluorosis [5,6]. However, increased evidences demonstrated that fluoride exposure also affected the soft tissues including testes [7] . Epidemiological data have also indicated that fluoride may adversely affect the reproductive systems of men living in endemic areas of fluorosis [8] . ...
... The mechanism of inhibition of these enzymes was principally due to the over production of ROS by Fl which leads to the degradation of plasma FSH and LH. These two gonadotrophins are the prime regulators for hydroxysteroidogenic enzymes and testosterone synthesis in testes [7]. An increase in Fl induced oxidative stress causes ROS-induced damage to macromolecules such as DNA, protein, and key enzymes involved in testicular steroidogenesis and spermatogenesis in germ cells. ...
... The activities of H 2 O 2 scavenging enzymes CAT and GPx were also decreased significantly in the testes of Fl intoxicated rats. The turn down activity of these enzyme levels may be explained by the fact that excessive superoxide anions may inactivate SOD thus, resulting in an inactivation of the H 2 O 2 scavenging enzymes [7] . EGCG was reported to scavenge superoxide radicals and hydrogen peroxide [21] . ...
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Objective: To explore the ameliorative potential of Epigallocatechin gallate (EGCG) by evaluating markers of oxidative stress, apoptosis, and inflammation and antioxidant competence in Fl intoxicated rats. Methods: The animals were divided in to four groups that is control, EGCG alone, NaF, and EGCG with NaF. Group III animal were exposed to Fl as sodium Fluoride (NaF) (25 mg/kg BW) for 4 weeks. After the completion of the treatment, the testis tissues has been removed and used for the experimental observations. Results: Pre-administration of EGCG to Fl intoxicated rats showed a significant normalization in the levels of steroidogenic enzymes, testosterone, sperm functions, oxidative stress markers and antioxidant status. The altered levels of proinflammatory cytokines and apoptotic markers were also relapsed in close proximity to control. In addition, EGCG significantly improved antioxidant status and reduced the oxidative stress and pathological changes in testes. The mRNA and protein analysis also substantiated that EGCG pre-treatment markedly enhanced the expression of Nrf2 and its target genes HO-1, NQO1 and γGCS and suppressed the expression of Keap1 in testis. Conclusion: Altogether, our findings supports that EGCG attenuates Fl toxicity in testis through Nrf2 activation.
... Also the spermatogonia in some seminiferous tubules were detached from the basement membrane. Previous work has shown that a high fluoride intake in rodents leads to histopathological changes in the germinal epithelium of testes (hemorrhage in interstitium, necrosis and apoptosis in seminiferous tubule epithelium) which were accompanied by decreased testicular zinc concentration and increased lipid peroxidation (Krasowska and Wlostowski, 1996 ;Krasowska et al., 2004). In addition, Shashi (1990) observed deficient maturation and differentiation of the spermatocytes, an increase in the amount of interstitial tissue and arrested spermatogenesis while the seminiferous tubules became necrotic in the testes of experimental animals following subcutaneous administration of different doses of sodium fluoride. ...
... In addition, Shashi (1990) observed deficient maturation and differentiation of the spermatocytes, an increase in the amount of interstitial tissue and arrested spermatogenesis while the seminiferous tubules became necrotic in the testes of experimental animals following subcutaneous administration of different doses of sodium fluoride. The current results are in accordance with many studies indicating that fluoride toxicity can be associated with deleterious effects on the testis structure, which could be related to oxidative damage due to peroxidation of membrane lipids ) Kumara and Susheela, 1995 ;Shivashankara et al., 2002 ;Krasowska et al., 2004). ...
... The mechanism of inhibition of these enzymes was principally due to the over production of ROS by Fl which leads to the degradation of plasma FSH and LH. These two gonadotrophins are the prime regulators for hydroxysteroidogenic enzymes and testosterone synthesis in testes [46]. An increase in Fl induced oxidative stress causes ROS-induced damage to macromolecules such as DNA, protein, and key enzymes involved in testicular steroidogenesis and spermatogenesis in germ cells. ...
... The decreased level of these non-enzymatic antioxidants upon Fl intoxication is in accordance with the results in which testicular lipid peroxides were increased along with the decreased antioxidants in rats intoxicated with Fl [9]. The depleted levels of GSH, vitamin C and E were significantly restored in EGCG [46]. EGCG was reported to scavenge superoxide radicals and hydrogen peroxide [21]. ...
Article
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Objective:To explore the ameliorative potential of Epigallocatechin gallate (EGCG) byevaluating markers of oxidative stress, apoptosis, and inflammation and antioxidantcompetence in Fl intoxicated rats.Methods:The animals were divided in to four groups that is control, EGCG alone, NaF,and EGCG with NaF. Group III animal were exposed to Fl as sodium Fluoride (NaF)(25 mg/kg BW) for 4 weeks. After the completion of the treatment, the testis tissues hasbeen removed and used for the experimental observations.Results:Pre-administration of EGCG to Fl intoxicated rats showed a significantnormalization in the levels of steroidogenic enzymes, testosterone, sperm functions,oxidative stress markers and antioxidant status. The altered levels of proinflammatorycytokines and apoptotic markers were also relapsed in close proximity to control. Inaddition, EGCG significantly improved antioxidant status and reduced the oxidativestress and pathological changes in testes. The mRNA and protein analysis also sub-stantiated that EGCG pre-treatment markedly enhanced the expression of Nrf2 and itstarget genes HO-1, NQO1 andgGCS and suppressed the expression of Keap1 in testis.Conclusion:Altogether, ourfindings supports that EGCG attenuates Fl toxicity in testisthrough Nrf2 activation
... NaF exposure has been shown to exert a dose-dependent detrimental effect on sperm quality, resulting in decreased sperm count, density, viability, motility, and increased rates of sperm deformity [36,50,63,74,76,78,117,118,[143][144][145][146][147] (Table 3 and Fig. 5). These effects are partly attributed to NaF's ability to lower zinc levels in the testes, subsequently reducing angiotensin-converting enzyme activity, which ultimately disrupts normal sperm production [148,149]. Sperm morphology is a critical parameter that influences fertilization success. The toxic effects of NaF lead to an increased prevalence of abnormal spermatozoa, characterized by various head and tail defects [50,63,150] (Fig. 5). ...
Article
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Fluoride (F), as a natural element found in a wide range of sources such as water and certain foods, has been proven to be beneficial in preventing dental caries, but concerns have been raised regarding its potential deleterious effects on overall health. Sodium fluoride (NaF), another form of F, has the ability to accumulate in reproductive organs and interfere with hormonal regulation and oxidative stress pathways, contributing to reproductive toxicity. While the exact mechanisms of F-induced reproductive toxicity are not fully understood, this review aims to elucidate the mechanisms involved in testicular and ovarian injury. In males, F exposure at different doses has been associated with reduced testis weight, reduced sperm quality in terms of count, motility, and viability, as well as abnormal sperm morphology and disruption of seminiferous tubules by altering hormone levels (especially testosterone), impairing spermatogenesis, and inducing oxidative stress and zinc deficiency. Similarly, administration of F can impact female reproductive health by affecting ovarian function, hormone levels, oocyte quality, and the regularity of the estrous cycle. However, the impact of F exposure on LH, FSH, and GnRH levels is controversial between males and females. In both males and females, F exerts its adverse effects by triggering apoptosis, autophagy, inflammation, mitochondrial dysfunction, reduction in ATP synthesis, and modulation of important genes involved in steroidogenesis. Furthermore, genetic susceptibility and individual variations in F metabolism may contribute to different responses to fluoride exposure.
... In male animals the consequences include diminished activity of the steroidogenic enzymes, reduced serum testosterone levels, decreased sperm count and motility, testicular damages, structural defects in spermatozoa along with oxidative stress. [15][16][17][18][19][20][21] In female Sprague-Dawley rats, administration of sodium fluoride in drinking water notably reduces in the number of viable fetuses and increases in the resorption rate were observed. 22 Fluoride induced free radical toxicity was also reported in mice ovary. ...
Article
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Epididymis is a complex tubular structure of male reproductive system where spermatozoa undergo maturation and gain the fertilizing ability. Epididymal pseudostratified columnar epithelium with different cell types play imperative role by their secretory properties and enrich the luminal microenvironment necessary for achieving spermatozoal motility. During epididymal transit several secretory proteins like P26h, SPAG11, HSPD1 and many others are deposited on spermatozoal surface. At the same time spermatozoal proteins are also modified in this intraluminal milieu, which include cyritestin, fertilin, CE9 and others. Natural and anthropogenic activities disclose various environmental pollutants which affect different physiological systems of animals and human being. Likewise, reproductive system is also being affected. Fluoride causes structural alterations of caput and cauda segments of epididymis. Redox homeostasis and functional integrity are also altered due to diminished activities of SOD1, GR, Crisp2, Lrp2 and other important proteins. On the contrary arsenic affects mostly on cauda segment. Redox imbalance and functional amendment in epididymis have been observed with arsenic revelation as evidenced by altered genomic appearance of SOD, GST, catalase, Ddx3Y, VEGF and VEGFR2. This review is dealt with structure-function interplay in normal epididymal spermatozoal maturation along with subsequent complications developed under fluoride and arsenic toxicities.
... It has been widely reported in the male reproductive systems that spermatogenesis was formed in testes and regulated by the hormone testosterone, cytokines and gene and protein expressions 17,18 . Meanwhile, our previous studies and many hazard identification studies also revealed that high doses of fluoride in animals affect potentially sensitive reproductive-tract targets and pathways, such as the reduction of antioxidant defenses, the enhancement of oxidative stress, and changes in the testicular cell cycle [19][20][21][22] . Overall, a number of studies have indicated fluoride exposure disrupts testicular development, but most of them focused on pathological observation and a limited number of genes so that up to now the specific molecular mechanisms of fluoride-induced spermatogenesis dysfunction were not clear. ...
Article
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We sequenced RNA transcripts from the testicles of healthy male mice, divided into a control group with distilled water and two experimental groups with 50 and 100 mg/l NaF in drinking water for 56 days. Bowtie/Tophat were used to align 50-bp paired-end reads into transcripts, Cufflinks to measure the relative abundance of each transcript and IPA to analyze RNA-Sequencing data. In the 100 mg/l NaF-treated group, four pathways related to IL-17, TGF-β and other cellular growth factor pathways were overexpressed. The mRNA expression of IL-17RA, IL-17RC, MAP2K1, MAP2K2, MAP2K3 and MAPKAPK2, monitored by qRT-PCR, increased remarkably in the 100 mg/L NaF group and coincided with the result of RNA-Sequencing. Fluoride exposure could disrupt spermatogenesis and testicles in male mice by influencing many signaling pathways and genes, which work on the immune signal transduction and cellular metabolism. The high expression of the IL-17 signal pathway was a response to the invasion of the testicular immune system due to extracellular fluoride. The PI3-kinase/AKT, MAPKs and the cytokines in TGF-β family were contributed to control the IL-17 pathway activation and maintain the immune privilege and spermatogenesis. All the findings provided new ideas for further molecular researches of fluorosis on the reproduction and immune response mechanism.
... Vitamines E prevents the organism from the activity of free oxidative radicals ,Stawiarska-Pieta et al., (2007) reported that antioxidants have a beneficial influence upon oxidation-reduction equilibrium. Different studies confirmed that administration of antioxidants to animals intoxicated with sodium fluoride inhibits the alterations observed in exposure to fluorides, which clearly shows their preventive action on brain, Chinoy & Patel (2000) and testis, Krasowska et al., (2004). ...
Article
Excessive fluoride ingestion has been identified as a risk factor for fluorosis and oxidative stress. The present study was aimed to evaluate vitamin E in combination with methionine and L- carnosine as a potential natural antioxidant to mitigate the effects of sodium fluoride on hematological indices, DNA damage, pancreatic digestive enzyme activities and histological structure of pancreas through light, electron microscopic and immunohistochemical studies. Thirty-six of adult male albino rats were divided into six groups (6 rats in each group). Oral administration of sodium fluoride caused a statistical significant decrease in RBC, HCT, MCV, RDW, MCH, MCHC and PLT and increase in WBC, lymphocytes and granulocytes The levels of the these parameters were significantly reversed in the groups pretreated with vitamin E in combination with methionine and L- carnosine prior to NaF. Animals treated with NaF showed significant decrease in pancreatic digestive enzyme activities and protein levels as compared to the control group, while significant increase in animals treated with vitamin E in combination with methionine and L- carnosine prior to NaF. Also, NaF resulted in a significant decrease in serum total protein, albumin and blood glucose levels, while pretreated with vitamin E in combination with methionine and L- carnosine prior to NaF resulted in a significant increase in these parameters. Plasma malondialdehyde levels were significantly increased and the activities of erythrocyte superoxide dismutase were significantly decreased in the NaF treated group. However, vitamin E in combination with methionine and L- carnosine prior to NaF reduced the process of lipid peroxidation and increased the activity of SOD. NaF reduced DNA, RNA contents of the liver and significant increase DNA damage in liver and the frequencies of micro nucleated polychromatic erythrocytes (MN-PCE) in bone marrow. But, concurrent administration of NaF and vit. E in combination with methionine and L- carnosine for 35 days caused significant amelioration in all parameters was studied. Histologically, multiple vacuoles of variable size were observed in the cytoplasm of pancreatic acinar cells together with inflammatory cells infiltration in the stroma of pancreas of Na F treated group. Pancreas of animals treated with vit. E in combination with methionine and L- carnosine prior to NaF displayed amelioration in toxic effects of NaF. Intensive positive immunoreactivity for caspase- 3 was observed in the cytoplasm of most pancreatic acinar cells of NaF treated group which was of significant value. On the other hand the cytoplasmic acinar cells of vit. E in combination with methionine prior to NaF treated group and L-carnosine prior to NaF treated groups showed apparent reduction of caspase-3 immunoreactivity which were also of significant values. Dilatation and globular- shaped rER, intra-cisternal granules, few or even absence of zymogen granules and irregular shaped, pyknotic and heterochromatic nuclei were observed ultrastructurally in the cytoplasm of pancreatic acinar cells of NaF treated group. Ultrathin sections of serous cells of vit. E in combination with methionine prior to NaF treated group and L-carnosine prior to NaF treated group showed preservation of acinar cytoplasmic contents. These results indicate that sodium fluoride can inhibit pancreatic digestive enzyme activities and cause histological and immunohistochemical changes, which may lead to a series of biochemical and pathological abnormalities and concurrent administration of NaF and vit.E in combination with methionine and L- carnosine for 35 days to these animals alleviated the adverse effects of fluoride.
... Thus, hystopathological action of fluoran is in increasing of apoptosis through fluor-induced depletion of zinc in testicles of rodent embryos. Introduction of additional Zn-containing ration allows to protect seminiferous tubules (Krasowska et al., 2004) by decrease of fluorine toxicity. ...
Article
This review brings together and analyzes the problem of zinc effects on the body through apoptosis, also affecting the latest data in the study of process itself apoptosis. Also, the possibility of using zinc and its derivatives and its complexes in cancer treatment are discussed. The review also focuses on the biochemical problems that lead to various diseases occurring in conditions of excess or deficiency of intracellular zinc. Review includes more than 300 references and contains research over the past ~ 15 years, focusing on the latest data.
... The reproductive toxicity is of great concern to the public, as clearly demonstrated by epidemiological studies that environmental exposure to fluoride was associated with male infertility and low birth rates of people living in the area of endemic fluorosis [5,6]. However, increased evidences demonstrated that fluoride exposure also affected the soft tissues including testes [7]. Epidemiological data have also indicated that fluoride may adversely affect the reproductive systems of men living in endemic areas of fluorosis [8]. ...
Article
Full-text available
Objective: To explore the ameliorative potential of epigallocatechin gallate (EGCG) by evaluating markers of oxidative stress, apoptosis, and inflammation and antioxidant competence in Fl intoxicated rats. Methods: The animals were divided in to four groups that is control, EGCG alone, NaF, and EGCG with NaF. Group III animal were exposed to Fl as sodium Fluoride (NaF) (25 mg/kg BW) for 4 weeks. After the completion of the treatment, the testis tissues has been removed and used for the experimental observations. Results: Pre-administration of EGCG to Fl intoxicated rats showed a significant normalization in the levels of steroidogenic enzymes, testosterone, sperm functions, oxidative stress markers and antioxidant status. The altered levels of proinflammatory cytokines and apoptotic markers were also relapsed in close proximity to control. In addition, EGCG significantly improved antioxidant status and reduced the oxidative stress and pathological changes in testes. The mRNA and protein analysis also substantiated that EGCG pre-treatment markedly enhanced the expression of Nrf2 and its target genes HO-1, NQO1 and 毭GCS and suppressed the expression of Keap1 in testis. Conclusion: Altogether, our findings supports that EGCG attenuates Fl toxicity in testis through Nrf2 activation.
... 17 Because of their free radical scavenging ability, antioxidants have an important role in ameliorating F toxicity. [12][13][14][15][16]41 As seen in the experiments here, the free radical scavenging effect of tamarind pulp is authenticated by the decreased MDA content in the liver and by the increased levels of polyphenols (34.02±2.11 nM/ mL) and flavonoids (35.51±5.61 ...
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: To evaluate the protective effect of tamarind pulp against fluoride (F)-induced oxidative stress in the liver, adult female Wistar rats were treated daily for 45 days with sodium fluoride (300 ppm NaF = 136.7 ppm fluoride ion) in drinking water, alone or in combination with tamarind pulp (20 mg/kg bw by oral intubation). Malondialdehyde (MDA), antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and ascorbic acid level in the liver, and levels of calcium and F, plus activities of aspartate transaminase (AST) and alanine transaminase (ALT) in serum were determined 24 hr after the last treatment. In the NaF-treated animals, a significant increase in MDA content and a concomitant decrease in antioxidant enzyme activities of SOD, CAT, GSH-Px, and the ascorbic acid level in liver and increased activities of AST and ALT, and increased calcium and F concentrations in serum were observed. Administration of tamarind pulp together with NaF produced significant amelioration in all parameters studied, indicating that tamarind pulp is able to prevent free radical induced oxidative stress by F, attributable to its antioxidant property. It is concluded that tamarind pulp may be useful to prevent the oxidative damage caused by consumption of excessive amounts of F.
... sylvaticus) on the water with 40 or 80 mg F/l for 84 days resulted in the premature animal death, whereas teeth of survived animals had significant morphological alterations and damages [64]. The maintenance of female voles M. agrestis on diet with high fluoride concentration led to a reduction in the number of offsprings, a decrease in the size and weight of offsprings, a rise of newborn lethality; in males of C. glareolus, high fluoride doses led to a damage of testicular tissue-epithelium hemorrhage, necrosis and apoptosis of epithelium [65,66]. ...
Article
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The presented review summarizes literature data on pathways of the inorganic fluoride intake into the plant, animal, and human organisms, on its metabolism, distribution, and accumulation in the organism, forms of fluoride in biological tissues, toxic effects of fluoride on physiological and reproductive functions of living organisms of various phylogenetic groups, as well as clinical symptoms of deficient and excessive fluoride intake into the human organism.
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Previous studies have indicated that fluoride (F) can affect testicular toxicity in humans and rodents. However, the mechanism underlying F-induced testicular toxicity is not well understood. This study was conducted to evaluate the sperm quality, testicular histomorphology and inflammatory response in mice followed F exposure. Healthy male mice were randomly divided into four groups with sodium fluoride (NaF) at 0, 25, 50, 100 mg/L in the drinking water for 180 days. At the end of the exposure, significantly increased percentage of spermatozoa abnormality was found in mice exposed to 50 and 100 mg/L NaF. Disorganized spermatogenic cells, vacuoles in seminiferous tubules and loss and shedding of sperm cells were also observed in the NaF treated group. In addition, chronic F exposure increased testicular interleukin-17(IL-17), interleukin-17 receptor C (IL-17RC), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in transcriptional levels, as well as IL-17 and TNF-α levels in translational levels. Interestingly, we observed that F treated group elevated testicular inducible nitric oxide synthase (iNOS) mRNA level and nitric oxide (NO) concentration. Taken together, these results indicated that testicular inflammatory response could contribute to chronic F exposure induced testicular toxicity in mice.
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Sir Samuel Wilks well described ulcerative colitis in 1859 but Crohn's Disease was named after Burrill B. Crohn, an American physician in 1884. Although the efforts for exploring the mechanisms by which these diseases developed were intensified over the last sixty years, where tens of thousands of articles discussing this topic were published, the outcome was trivial. It was only concluded that smoking has protective effects in subjects with ulcerative colitis but aggressive effects in subjects with Crohn's disease but no reason was provided. Similarly, several hypotheses were supposed for explaining such mechanism (s) but none of them stood against the stream of raised concerns. Different prevalence and incidences of Crohn's disease and ulcerative colitis in different countries across the globe are well- recognized. Higher incidences of these diseases occur in the Western side of the globe, rather than its Eastern side, which suggests the role of lifestyle in the induction, promotion and/or development of inflammatory bowel disease. If this is true, what is this role? This chapter is aimed at exploring this possibility.
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Objective: To study the effect of fluorine on expression of B-cell lymphorria/leukemia-2 (Bcl-2) and, Bcl-associated x (Bax) protein in rat testis, and to reveal the mechanism of impaired male reproduction caused by endemic fluorosis of coal burning. Methods: Forty male SD rats were randomly divided into 4 groups according to body weight with the method of random digits table: control group, low, moderate and high fluorosis groups. Low, moderate and high fluoride groups were fed, with fluorinated food (20.0, 40.0, 60.0 mg/kg), and control group was fed conventional fat chow (fluorinated 1.3 mg/kg). After 120 and 180 days, the rats were sacrificed. Dental fluorosis was determined by observation and urinary fluoride was detected by fluorine ion-selective electrode. The apoptotic index of spermatogenic cell was measured by terminal deoxynucleotidyl transferase-mediated dUTP. nick end labeling (TUNEL). The expression of Bcl-2 and Bax were measured by immuohistochemistry. Results: At 120 and 180 days, low, moderate and high fluorosis groups were suffered from different degrees of dental fluorosis, the teeth of the control group was normal/At 120: and 180 days, the content of urinary fluoride was increased in turn in the control group, low, moderate and high fluorosis group [(1.69 ± 0.03), (3.56 ± 0.10), (12.09 ± 0.38), (23.55 ± 0.33) mg/L; (1.71. ± 0.09), (4.07 ± 0.25), (16.23 ± 0.28), (8.44 ± 0.50)mg/L; all P < 0.05]. Urinary fluoride of low, moderate and high fluorosis groups at 180 days was higher than that of each corresponding groups at 120 days (all P < 0.05). At 120 and 180 days, the apoptotic indexes were increased in turn in the control group, low, moderate and high fluorosis groups [(0.46 ± 0.11)%, (8.83 ± 1.64%), (17.24 ±3.96)%, (44.21 ±7.85)%; (0.54 ± 0.11)%, (10.41 ± 2.70)%, (22.23 ± 3.96)%, (49162 ± 4.77)%; all P < 0.05]. At 180 days, the apoptotic indexes of low, moderate and high fluorosis groups were higher than those of each corresponding groups at 120 days (all P < 0.05). At 120 and 180 days, the expression of Bcl-2 were descended in turn in the control, low, moderate and high fluorosis groups (0.183 ±0.007, 0.165 ± 0.007, 0.152 ± 0.003, 0143 ± 0.007, 0.184 ± 0:006, 0.159 ± 0.011, 0.151 ± 0.005, 0.135 ± 0.005, all P < 0.05). The expression of Bax of moderate and high fluoride groups (0.194 ± 0.018, 0.209 ± 0.012) were significantly higher than that of the control and low fluorosis group (0.145 ± 0.007, 0.161 ± 0.012) at 120 days (all P < 0.05). The expression of Bax were increased in turn in the control, low, moderate and high fluorosis groups (0.145 ± 0.009, 0.185 ± 0.013, 0.207 ± 0.011, 0.230 ± 0.014, all P < 0.05). At 120 days, the Bcl-2/Bax ratios were descended in turn in the control, low, moderate and high fluorosis groups (1.264 ± 0.044, 1.028 ± 0.096, 0.788 ± 0.060, 0.688 ± 0.064, all P < 0.05). At 180 days, the Bcl-2/Bax ratio of control, low, moderate fluorosis groups (1.277 ± 0.100, 0.865 ± 0.066, 0.731 ± 0.045) was significantly higher than that of high fluorosis group (0.592 ± 0.031, all P < 0.05), and that of control group was significant higher than that of moderate fluorosis group (P < 0.05). Conclusions: Endemic fluorosis of coal burning may leads to increased apoptotic index of rats' spermatogenic cell, increased Bax expression and decreased Bcl-2/Bax ratio. The mechanism of impaired male reproduction is possibly caused by regulation of the related apoptosis gene in the testis.
Article
Long-term excessive fluoride intake is known to be toxic and can damage a variety of organs and tissues in the human body. However, the molecular mechanisms underlying fluoride-induced male reproductive toxicity are not well understood. In this study, we used a rat model to simulate the situations of human exposure and aimed to evaluate the roles of endoplasmic reticulum (ER) stress and inflammatory response in fluoride-induced testicular injury. Sprague-Dawley rats were administered with sodium fluoride (NaF) at 25, 50 and 100 mg/L via drinking water from pre-pregnancy to gestation, birth and finally to post-puberty. And then the testes of male offspring were studied at 8 weeks of age. Our results demonstrated that fluoride treatment increased MDA accumulation, decreased SOD activity, and enhanced germ cell apoptosis. In addition, fluoride elevated mRNA and protein levels of Glucose-regulated protein 78 (GRP78), inositol requiring ER-to-nucleus signal kinase 1 (IRE1), C/EBP homologous protein (CHOP), indicating activation of ER stress signaling. Furthermore, fluoride also induced testicular inflammation, as manifested by genes up-regulation of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), in a nuclear factor-κB (NF-κB)-dependent manner. These were associated with marked histopathological lesions including injury of spermatogonia, decrease of spermatocytes and absence of elongated spermatids, as well as severe ultrastructural abnormalities in testes. Taken together, our results provide compelling evidence that ER stress and inflammation would be novel and significant mechanisms responsible for fluoride-induced disturbance of spermatogenesis and germ cell loss in addition to oxidative stress.
Article
High fluoride intake may affect biological systems by increasing free radicals, which may enhance lipid peroxidation levels of the tissues, thus leading to oxidative damage. Caffeic acid phenethyl ester (CAPE), a component of honeybee propolis, protects tissues from reactive oxygen species mediated oxidative stress in ischemia-reperfusion and toxic injuries. Several studies suggest that supplementation with anti-oxidant can influence fluoride induced tissue damage. The aims of this study was to investigate the possible role of malondialdehyde (MDA) levels and activity of superoxide dismutase (SOD) and catalase (CAT), in the pathogenesis of fluoride-induced endometrial damage and to demonstrate the effect of CAPE, the potent antioxidant, in decreasing the toxicity. Twenty-four adult female rats were randomly divided into three experimental groups, as follows: control group, fluoride-treated group (F), and fluoride plus CAPE-treated group (F+CAPE). Fluoride was given orally as 30mg/L NaF solution in spring water daily for 45 days. CAPE was co-administered intraperitoneally (i.p.) with a dose of 10μM/(kgday) for 46 days. Extensive formation of DNA strand breaks, the typical biochemical feature of apoptosis, was detected with the use of the terminal deoxynucleotidyl transferase (TdT)-mediated d UTP-biotin nick and labeling (TUNEL) method. The activities of antioxidant enzymes such as SOD and CAT as well as the concentration of MDA, as an indicator of lipid peroxidation, were measured to evaluate oxidative stress in homogenates of the endometrium. Fluoride administration increased MDA levels (p<0.05), decreased SOD (p<0.05) and CAT (p<0.05) activities. CAPE co-administration with fluoride treatments caused significantly decreased MDA levels (p<0.05), increased SOD (p<0.05) and CAT (p<0.05) activities in endometrial tissue when compared with F alone. Diffuse apoptosis in glandular epithelium and stromal cells was found by TUNEL method in endometrial tissues of rats treated with fluoride. The severity of these lesions was reduced by administration of CAPE. In conclusion, our study demonstrated that MDA may play an important role in the pathogenesis of fluoride-induced oxidative endometrial damage. CAPE may have protective aspects in this process by its antioxidant and anti-inflammatory effect.
Article
Epidemiological studies provide strong evidence to confirm the correlation between cigarette smoking and inflammatory bowel diseases. This relationship is proved to be positive in Crohn's disease and negative in ulcerative colitis. What in smoking alters the course of inflammatory bowel diseases is still a mystery. Different smoking parts have different and may be opponent actions. Smoking has dual effects. Some of its activities are, sometimes, constructive as they are working in an antagonistic manner to the mechanism of the disease, such as reducing rectal blood flow and accordingly less recruitments of inflammatory mediators to the area of inflammation, enhancement of mucosal production, and consequently, strengthening the membranes, and inhibition of pro-inflammatory mediators' liberation and activity in subjects with ulcerative colitis. Yet the outcome of smoking actions may be affected by the existence of other cofactors. Odd factors, such as shortage of zinc in subjects with Crohn's disease, may facilitate liberation of pro-inflammatory mediators and their activities and accordingly exacerbates symptoms.
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p> Background and Objectives There has so far been controversy among researches about the effect of unilateral blunt testis trauma on structure and function of contra lateral testis. This study was designed to evaluate the effect of unilateral blunt testicular trauma after a time span of spermatogenesis (40 days) on the number of round and elongated spermatic cells, spermatogonia, primary spermatocyte, sertoli and leydig cells of contra-lateral testis as well as to assess the protective effect of zinc on unilateral blunt testicular trauma. Methods In this experimental study 30 pre-pubertal male Wistar rats (age 7 weeks) were divided into three equal groups (n=10). Group 1(control) underwent a sham operation of the left testis under general anesthesia. Rats in group II and group III (with blunt testicular trauma) were subjected to left blunt testicular trauma to rupture the tunica albuginea. In group III just after the trauma, 30 mg/kg zinc sulfate were given intra-peritoneally followed by admission of Zn for 40 days at a dose of 500 parts per million (ppm) /day orally. Later on, all rats were sacrificed and their right testes were removed and after histological processing and staining by H & E method the samples were evaluated by counting round and elongated spermatid cells, spermatogonia, primary spermatocyte, sertoli and leydig cells and also by cell structures study. Data were analyzed using ANOVA, Tukey and Duncan's tests and pvalue of <0.05 was considered as statistically significant. Results There were no significant differences in the number of round and elongated spermatid, spermatogonia, sertoli and leydig cells of testis of the three groups(P>0.05). Histological changes in sertoli and leydig cell were seen. Therefore, the protective effect of zinc was not significant on germ cell proliferation and structure. Conclusion The results suggest that unilateral blunt testis trauma after time course of 40 days has no effect on germ cell layers and leydig and sertoli cells proliferation. This study suggests long term evaluation of testes after blunt trauma with use of electron microscope. </p
Article
Fluoride is a strong, hard anion and cumulative toxic agent. The effect of fluoride intoxication on lipid peroxidation in endometrial tissue and the protective effects of combinations of vitamins E and C in rats were studied. Additionally, the apoptotic changes in endometrial tissue were examined. Experimental groups were as follows: control group; a group treated with 100 mg/l fluoride (F group); and a group treated with 100 mg/l fluoride plus vitamins E and C (F+Vit group). The F and F+Vit groups were treated orally with fluoride for 30 days. Vitamins E and C were injected simultaneously at doses of 50 mg/kg day i.m. and 20 mg/kg day body weight i.p. Extensive formation of DNA strand breaks, the typical biochemical feature of apoptosis, was detected with the use of the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick and labeling (TUNEL) method. Malondialdehyde (MDA) levels were determined in uterine tissue of rats. Fluoride caused a significant increase in MDA levels (an important marker of lipid peroxidation) in the fluoride group compared with the controls (p<0.05). Vitamins E and C significantly reduced the fluoride-induced lipid peroxidation in the F+Vit group compared with the F group (p<0.05). Diffuse apoptosis in glandular epithelium and stromal cells was found in endometrial tissues of F treated rats by TUNEL method. The severity of these lesions was reduced by the administration of vitamins. From these results, it can be concluded that subchronic fluoride administration causes endometrial apoptosis, and lipid peroxidation may be a molecular mechanism involved in fluoride-induced toxicity. Furthermore, treatment with a combination of vitamins E and C reduced endometrial apoptosis caused by fluoride.
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The effect of fluoride intoxication on lipid peroxidation and antioxidant systems in the blood, brain, and liver of rats was studied. Twelve one-month-old albino rats were administered 100-ppm fluoride (as NaF) in their drinking water for four months. In the red blood cells the levels of malondialdehyde (MDA) and glutathione (GSH) increased, along with the activity of glutathione peroxidase (GSH-Px), but the activity of superoxide dismutase (SOD) decreased. In the plasma the level of ascorbic acid increased while that of uric acid decreased. In the brain and liver, MDA and GSH levels increased, as did the activities of GSH-Px and glutathione S-transferase (GST). The level of ascorbic acid increased in the brain, but it decreased in the liver. These results suggest that fluoride enhances lipid peroxidation in the red blood cells, brain and liver of rats and causes increased or decreased enzyme activity associated with free radical metabolism.
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To investigate the effects of zinc deficiency on oxidative damage to testes proteins, lipids and DNA, weanling male rats were allowed free access to low (0.5 microgram Zn/g) or adequate (25 micrograms Zn/g) zinc diets for 14 d. A third group was restricted intake of the adequate Zn diet to the amount consumed by the low Zn diet-fed group. Compared with ad libitum-fed controls, testes from rats fed the low zinc diet had lower glutamine synthetase activity, lower Fe(2+)-stimulated 2-thiobarbituric acid-reactive substances (TBARS) production, higher protein carbonyl concentrations (P < 0.05), and higher 8-oxo-2'-deoxyguanosine levels (P = 0.06). Glutamine synthetase activity in testes of the food-restricted controls was between the values for the ad libitum controls and zinc-deficient animals. Protein carbonyls were higher in the restricted controls compared with the ad libitum controls, whereas stimulated TBARS production was lower (P < 0.05). Levels of 8-oxo-2'-deoxyguanosine were lower in testes DNA of the restricted controls than in the zinc-deficient group (P < 0.05). Testes iron concentrations were higher in the zinc-deficient and restricted control rats than in ad libitum controls (P < 0.05). The oxidative damage observed may have occurred as a consequence of increased reactive oxygen species generation secondary to tissue iron accumulation and/or reductions in zinc-dependent antioxidant processes.
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Many small, nontropical mammals stop breeding during winter. Chronic exposure of males to short days (<12.5 h light/day) causes the testes to atrophy and both steroidogenesis and gametogenesis to decrease. Male white-footed mice (Peromyscus leucopus) exposed to inhibitory short day lengths provide a natural animal model to study the cellular mechanisms regulating testicular regression. In the present study, the possible role of apoptosis was assessed during naturally occurring, short day-induced gonadal regression in white-footed mice by in situ terminal transferase-mediated end labeling (TUNEL), quantitative DNA 3'-end-labeling autoradiography (laddering) of DNA fragments, and quantification of Fas protein expression, an early initiator of apoptosis. Sexually mature male mice were exposed to short (8 h of light, 16 h of darkness) or long (16 h of light, 8 h of darkness) day lengths for 2, 4, 6, 8, or 10 weeks; gonads were then removed and processed for detection of apoptotic activity. In common with previous studies, the first significant reduction in relative testis mass was observed at week 10 of short day exposure. A 2- to 3-fold increase in apoptotic (TUNEL-positive) germ cells per seminiferous tubule was observed in the testes of mice exposed to short days for 4, 6, 8, or 10 weeks compared with the testes of long day animals. The extent of 3'-end labeling of low mol wt DNA increased with 4-8 weeks of short day exposure. Western blot analysis revealed an up-regulation of the Fas protein in the testes of short day males at 4, 8, and 10 weeks. Fas staining was primarily localized to spermatocytes and spermatids. Plasma testosterone concentrations decreased in short compared with long day animals after 6, 8, or 10 weeks. The increase in TUNEL positive-labeled germ cells, testicular DNA fragmentation, and up-regulation of the Fas protein before short day reductions of testis mass and function suggest that apoptosis is important for the mediation of photoperiod-induced testicular regression in white-footed mice.
Article
The present study assesses the effect of sodium fluoride administration on kidneys of mice. One hundred adult male Albino mice were fed 10 ppm (Group A), 500 ppm (Group B), and 1000 ppm (Group C) of sodium fluoride for 3 months. Some of the animals from each group were sacrificed at the end of one, two and three months. The kidneys were removed and stained with hematoxylin and eosin. The most consistent changes in the kidneys were cloudy swelling of the tubular cells. In the higher dosage group (B and C), sacrificed at the end of three months, we found marked necrosis of tubular cells, atrophy of the glomeruli, and areas of interstitial infiltration of round cells. It is concluded that kidneys are adversely affected by prolonged use of sodium fluoride.
Article
The study was designed in order to assess the relationship between infertility and histological structure of testes following administration of varying doses of sodium fluoride. One hundred adult male albino mice were fed 10 ppm (Group A), 500 ppm (Group B) and 1000 ppm (Group C) of sodium fluoride in drinking water. The Group A animals were sacrificed at the end of one month, Group B after two and Group C after three months. The testes were removed and, after being processed in the usual manner, they were stained with hematoxylin and eosin. In Groups B and C, the higher dosage groups, there was a lack of maturation and differentiation of spermatocytes. In animals sacrificed at the end of three months, spermatogenesis had stopped and the seminiferous tubules had become necrotic. A definite relationship between fluorosis and damage to the testes has, therefore, been established by this study.
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1. Clethrionomys glareolus fed on a diet containing krill meal assimilated excessive amounts of fluoride.2. Excess of fluoride caused disturbances in the reproduction of these animals: reduction of the number of litters, higher mortality of offspring and degenerative changes in seminiferous tubules.3. The disturbances in the reproduction occurred still more distinctly in the successive generation.4. Among the bank vole offspring which received the diet with the greater amount of krill meal, both in the parent generation and in the generation F1, a changed sex ratio was found, which was evidenced by a significantly higher number of males.
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Routine separation of fluoride from large numbers of biological samples (soft and hard tissues) is achieved by microdiffusion from perchloric acid and absorption by sodium hydroxide on filter paper in disposable polypropylene vials. Spectrophotometry with a modified lanthanum/alizarin complexone reagent allows rapid determination of fluoride. Up to 80 samples can be processed per day. Recoveries are in the range 88–102%. Results obtained by spectrophotometry and with the fluoride-sensitive electrode agree within 3–10% for various samples of krill and shrimp products.
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The effect of zinc on reproductive function was studied in rats fed with a zinc-deficient diet and control rats fed with a standard diet.Serum testosterone (T) levels were measured before and after the injection of HCG (human chorionic gonadotropin). Serum gonadotrophin levels were measured before and after the injection of GnRH (gonadotropin releasing hormone). In addition, structural parameters were studied and morphometric techniques were used to study the seminiferous tubules. The findings were used to investigate the possible relationship between biochemical and morphometric changes. Body weight (BW) gain, zinc content of testes and weight of the testes, seminal vesicle, and prostate were significantly lower in zinc-deficient rats compared with controls. Serum zinc concentrations and alkaline phosphatase activity were decreased in zinc-deficient rats compared with controls. Serum basal and stimulated FSH concentrations were similar in the two groups. Serum LH response to GnRH was higher in zinc-deficient rats. Serum basal T was lower in zinc deficient animals, but the response of T to HCG was similar in the two groups. The basal and luminal diameters, perimeter, and surface area of the seminiferous tubules as well as tubule volume, wall thickness, and cross-section area decreased in zinc-deficient animals in comparison with controls. Concentrations of zinc were significantly correlated with structural parameters and serum T levels. The changes in T levels correlated positively with the structural parameters and morphological findings.
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The reaction of lipid peroxides in animal tissues with thiobarbituric acid was dependent on pH of the reaction mixture as was the case for linoleic acid hydroperoxide. The optimum pH was found to be 3.5. Taking this fact into consideration, a standard procedure for the assay of lipid peroxide level in animal tissues by their reaction with thiobarbituric acid was developed as follows. Ten percent ( tissue homogenate was mixed with sodium dodecyl sulfate, acetate buffer (pH 3.5), and aqueous solution of thiobarbituric acid. After heating at 95°C for 60 min, the red pigment produced was extracted with n-butanol-pyridine mixture and estimated by the absorbance at 532nm. As an external standard, tetramethoxy-propane was used, and lipid peroxide level was expressed in terms of nmol malondialdehyde. Using this method, the liped peroxide level in the liver of rats suffering from carbon tetrachloride intoxication was investigated. The results were in good agreement with previously reported data obtained by measuring diene content.
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The dose-dependent release of alanine aminotransferase and aspartate aminotransferase into plasma 24 hr following various doses of CCl4 (ip) was markedly lower in rats pretreated for 3 days with zinc chloride (150 μmol/kg/day) than in control rats. Although this dose of zinc produced a 34% decrease in hepatic concentration of cytochrome P-450 and a 50% decrease in binding of 14C derived from 14CCl4 to hepatic microsomal protein and lipid in vitro, prior treatment with a single injection of zinc (250 μmol/kg) resulted in protection against CCl4 toxicity without changing P-450 concentrations or 14C binding. Administration of a single dose (250 μmol/kg) of zinc or pretreatment on 3 consecutive days with 150 μmol/kg zinc produced a 700 or 1900% increase in hepatic concentration of metallothionein (MT), respectively. Following administration of 14CCl4 to zinc-treated rats, radioactivity was present in the same elution volume as MT following gel filtration (G-75) of liver cytosol. This suggests that MT may protect against CCl4-induced liver damage by sequestering reactive metabolites of CCl4.
Article
1. Male Wistar rats were exposed to fluoride (F) at concentrations of 100- and 200 ppm in their drinking water for 6- and 16 weeks. 2. The high F intake caused several-fold increase in the F concentrations in the testes and bone as compared with control rats, both after the 6- and 16 wk exposure; the bone F, but not testicular F, appeared to increase with dose and time. 3. F exposure (100- and 200 ppm) decreased significantly the concentrations of zinc (Zn) in the testes, plasma, liver and kidneys particularly in the 16 wk groups; in the bone Zn tended to increase, however. 4. The iron concentrations of the testes and plasma were not affected by F, whereas those of the liver, kidneys and bone appeared to increase under the influence of F. 5. The concentrations of copper and manganese in the testes, liver and kidneys were not changed by F exposure. 6. Fifty percent of the 100- and 200 ppm F rats after 16 weeks exhibited histopathologic changes in the germinal epithelium of the testes, which resembled those in Zn-deficient rats. 7. The data suggest that a deprivation of testicular Zn due to a high F intake may be directly responsible for the injury of testicular tubules.
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Mice of the Balb'c strain were administered bromobenzene (BB) or acetaminophen (AA) i.p., in single doses of 400 and 300 mg/kg, respectively. In the blood activity of SGOT and SGPT as well as SDH was determined. In the liver the level of metallothionein (MT), malondialdehyde (MDA) and glutathione (GSH) was measured. The level of MT as well as GSH (determined as non-protein SH groups) showed a significant increase following administration of zinc alone. Joint action of zinc and either BB or AA resulted in a decrease of GSH which was less pronounced than expected for each of the xenobiotics alone. The protective effect of zinc reflected in the reduction of the increase of SGPT and SGOT activity was apparent shortly (4 h) after administration of AA. A day after injection of AA alone the activity of enzymes was lower and the rate of decline followed the sequence SGPT greater than SGOT greater than SDH. For BB, both the toxic effect and the protective influence of zinc were apparent 24 h following administration. At 4 h in a group receiving BB alone no changes of the indicatory enzymes in blood were noted.
Article
Mild and severe chronic fluorosis were produced in Wistar rats by feeding them with water containing 10 ppm and 30 ppm fluoride respectively for eight months. There were some different changes in the eighteen blood biochemical indices between mild and severe chronic fluorosis. GSH-px, K+, Ca2+, p2-, Apr and cAMP from these blood biochemical indices were chosen to set up a diagnostic function discriminant of mild and severe chronic fluorosis by the computer.
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The effects of ethanol and/or zinc sulphate on liver glutathione and glutathione transferase activity were studied in mice. Ethanol suppressed glutathione transferase activity and had no significant effect on glutathione levels in the organ. Zinc sulphate administration dose-dependently increased glutathione transferase activity but did not affect hepatic glutathione content. Furthermore, the depressive action of ethanol on glutathione transferase activity was prevented by zinc sulphate pretreatment. It is suggested that zinc sulphate can reactivate glutathione transferase which in turn increases the excretion of the active metabolites produced by ethanol, through conjugation with glutathione in the liver. This action of zinc may alleviate the hepatic toxicity of ethanol in mice.
Article
Deposition of fluoride (F) in the skeleton is a major factor in the metabolic regulation of F. The progressive increase in bone F levels with age suggests that F is rather firmly sequestered once it is deposited in bone. We have examined the extent to which F is resorbed and redeposited during bone turnover in growing rats. The skeleton was first preloaded with F by intake of water containing a high level of F (50 mg F/L) and simultaneously labeled with [3H]tetracycline (3H-TC) to provide a measure of subsequent bone turnover. Rats were then changed to a very low F intake, and bone F loss was compared with 3H-TC loss in animals undergoing normal bone turnover or turnover accelerated by a low calcium (Ca) intake. Approximately 60% of F mobilized during bone resorption was redeposited in the skeleton (humerus and vertebrae). The redeposition of F showed a positive correlation with mineral deposition. Thus the retention of F in the skeleton of growing rats results predominantly from redeposition of resorbed F rather than passive retention associated with low bone turnover.
Article
Young, growing mice were fed diets containing six different levels of added fluoride; only the two highest (1500 and 2000 ppm) had any effect on either growth or mortality. A dietary level of 1500 ppm fluoride was required to cause a statistically significant growth reduction. When a dietary level of 2000 ppm was fed, 100% mortality occurred. No alteration was found in the apparent digestion of either energy, fat or protein due to fluoride feeding. Examination of numerous bones showed citric acid levels to be lowered, while tibia bone fluoride concentrations were elevated. The tibia fluoride concentrations in mice fed either 1000 or 1500 ppm of added fluoride were 45 times those of the control mice. Liver homogenates were analyzed for enzyme activities, and both cytochrome oxidase and isocitric dehydrogenase activities were lowered by both the 1000 and 1500 ppm levels of fluoride. The cytochrome oxidase activity of heart tissue was reduced only with 1500 ppm fluoride in the diet.
Article
Female mice were fed a low fluoride diet (0.1 to 0.3 ppm fluoride) plus drinking water containing 0, 50, 100 or 200 ppm fluoride as sodium fluoride. Toxic effects of fluoride were evidenced by retarded growth and impaired reproduction in mice with intakes of 100 and 200 ppm fluoride, and the higher level resulted in a high mortality rate (50% deaths in 5 wk). Mice with a low fluoride intake developed signs of fluorine deficiency, with a progressive development of infertility in 2 successive generations. Growth rate and litter size were not affected by the low fluoride intake, but the percentage of mice producing litters was lower, and the age at delivery of the first litter was greater than in mice receiving 50 ppm fluoride.
Article
Pretreatment with Zn is known to produce tolerance to several toxic effects of Cd. This study was designed to determine if zinc pretreatment decreased Cd-induced lethality and hepatotoxicity. Rats given 4.0 mg Cd/kg, iv, died within 10 to 20 hr while there was no mortality in rats pretreated with Zn (12 mg Zn/kg, sc, 48 and 24 hr prior to Cd challenge). Ten hr after Cd, plasma aspartate aminotransferase and sorbitol dehydrogenase activities were markedly elevated and extensive histopathologic lesions of the liver were evident in control rats while such injury was not evident in Zn-pretreated rats. To examine the mechanism of this tolerance, distribution of Cd to 14 organs and the subcellular distribution in 6 organs (liver, kidneys, intestines, heart, spleen, and testes) was determined in control and Zn-pretreated rats. Two hours after challenge (3.5 mg Cd/kg, iv, 7 microCi 109Cd/mg Cd), the distribution of Cd to the liver markedly increased after Zn pretreatment without concomitant decreases in other tissues. Zn pretreatment resulted in distribution of more Cd to hepatic cytosol and less associated with endoplasmic reticulum. Gel filtration chromatography indicated that most cytosolic Cd was bound to metallothionein. These data suggest that Zn pretreatment reduces Cd-induced hepatotoxicity which prevents the lethal effects of Cd possibly by altering the hepatic subcellular distribution of Cd.
Article
These studies concern histológica! changes in the testes of pre- and postpubertal zinc-deficient and repleted rats. Three experiments involved a total of 69 rats. In experiment 1, 12 weanling rats were fed a zinc-deficient (0.5 ppm) diet, ad libitum; 11 were fed a zinc-sufficient (100 ppm) diet and pair-fed to the zinc-deficient group; and 10 were fed the zinc-sufficient diet, ad libitum. After 26 days of being fed the different diets, one testis with the epididymis was surgically removed (hemicastrated) from each animal for histológica!examination. The rats fed the zinc-deficient diet were then fed the zinc-sufficient diet, ad libitum, for 30 or 41 days. Pair-feeding between the zinc-sufficient group and the zinc-deficient-repleted group was continued. The results indicated that 26 days of zinc depletion caused general immaturity of the testis and varied degrees of degeneration of the germinal epithelium compared to controls. After the zinc repletion period of 30 or 41 days, the remaining testis, epididymis, and sperm count were normal in all previously deficient animals. In experiment 2, 10 weanling rats were fed a marginally zinc-deficient diet (4 ppm) for 90 days and after hemicas- tration showed degenerative changes in the testes. All animals were then fed a zinc- sufficient (100 ppm) diet, with two animals killed every 15 days during a period of 75 additional days. The degenerative changes were not completely reversed during the 75- day repletion period, and only 4 out of 10 testes showed definite improvement. In experiment 3, 26 weanling rats were fed a zinc-adequate diet (15 ppm) for 42 days at which time 3 were killed to assure adequacy of the diet for maintenance of the testes and to confirm sexual maturity. When 12 of these postpubertal animals were fed the deficient diet for up to 68 days, a wide range of testicular damage occurred. Forty-two days of zinc repletion of the remaining 11 postpubertal rats, did not reverse the damage. In toto, the experiments suggest that a prepubertà ! short-term zinc deficiency resulted in degenerative changes that were repaired by repletion. In contrast, the degenerative changes of the testes of postpubertal zinc-deficient rats were not reversible to any sig nificant extent. J. Nutr. 112: 1019-1028, 1982.
Article
The influence of Zn on the acute hepatotoxicity of pyrrolizidine alkaloids (PAs) was determined in male rats. Zinc, 72 mumol/kg as ZnCl2, was administered ip for 3 consecutive days, followed 16 h after the last dose by a single ip injection of purified mixed PAs (80, 120, or 160 mg/kg) obtained from tansy ragwort (Senecio jacobaea). Hepatotoxicity of the PAs was assessed by measuring the activities of plasma glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) and by histological examination of the liver. There was a dose-dependent increase in plasma GOT and GTP 24 h after PA administration, whereas no significant increase of these enzymes was seen after administering Zn alone. The 7-fold increase in plasma GOT and 12-fold increase in GPT after PA (120 mg/kg) were reduced to 2.4- and 2.1-fold, respectively, by Zn pretreatment. The PA-induced liver necrosis was either reduced in severity or abolished by Zn when the PA dose was 80 or 120 mg/kg. These results suggest a protective effect of Zn against PA hepatotoxicity. The protective effect was associated with a marked increase in liver metallothionein and a significant decrease in hepatic cytochrome P-450 content, aminopyrine N-demethylase activity, and in vitro microsomal conversion of the PAs to pyrroles. Liver nonprotein sulfhydryls were unchanged. The possible role of metallothionein in the sequestration of pyrrole metabolites merits further investigation.
Article
A review of fluoride toxicity showed decreased fertility in most animal species studied. The current study was to see whether fluoride would also affect human birth rates. A U.S. database of drinking water systems was used to identify index counties with water systems reporting fluoride levels of at least 3 ppm. These and adjacent counties were grouped in 30 regions spread over 9 states. For each county, two conceptionally different exposure measures were defined, and the annual total fertility rate (TFR) for women in the age range 10-49 yr was calculated for the period 1970-1988. For each region separately, the annual TFR was regressed on the fluoride measure and sociodemographic covariables. Most regions showed an association of decreasing TFR with increasing fluoride levels. Meta-analysis of the region-specific results confirmed that the combined result was a negative TFR/fluoride association with a consensus combined p value of .0002-.0004, depending on the analytical scenario. There is no evidence that this outcome resulted from selection bias, inaccurate data, or improper analytical methods. However, the study is one that used population means rather than data on individual women. Whether or not the fluoride effect on the fertility rate found at the county level also applies to individual women remains to be investigated.
Article
The effect of zinc on the destruction of vascular endothelial cell monolayer caused by cadmium was investigated using bovine aortic endothelial cells in a culture system. It was histologically revealed that cadmium-induced de-endothelialized area formation was markedly prevented by zinc. Zinc prevented cadmium-induced detachment of [3H]thymidine-labeled endothelial cells from the monolayer. Although cadmium increased the activity of lactate dehydrogenase in the medium, a marker of nonspecific cell damage, zinc markedly suppressed it. On the other hand, zinc significantly prevented cadmium-induced decrease in the incorporation of [3H]thymidine into the acid-insoluble fraction of the growing cells. From these results, it was suggested that impairment of the endothelial cell monolayer caused by cadmium is protected by zinc; this protection was postulated to be due to both a reduction of the cell detachment caused by cadmium-induced nonspecific cell damage and a decrease in cadmium inhibition of the cell proliferation which would help the repair of de-endothelialized areas.
Article
F- is not mutagenic in standard bacterial systems, but produces chromosome aberrations and gene mutations in cultured mammalian cells. Although there is disagreement in the literature concerning the ability of F- to induce chromosome aberrations in cultured human and rodent cells, the weight of the evidence leads to the conclusion that F- exposure results in increased chromosome aberrations in these test systems. NaF induced primarily chromatid gaps and chromatid breaks, indicating that the rodent cells are responsive in the G2 stage of the cell cycle. In contrast, studies with synchronized human cells indicated that the S phase was the most sensitive. If F- does have a cell cycle-specific effect, it could be expected that differences in the cell treatment and harvest protocols could lead to conflicting results for the induction of chromosome aberrations. Gene mutations were produced in cultured rodent and human cells in the majority of the studies. Unfortunately, a number of the in vitro and in vivo cytogenetic studies are of questionable utility because of the protocols used, the quality of the responses reported, or the interpretations of the data. The conflicting results in the in vivo cytogenetic studies are difficult to reconcile. There are reports of increased chromosome aberrations in rat bone marrow and testes, but other studies, using similar protocols and dose ranges, have reported no induced chromosome damage. Although some of the studies were performed at toxic levels of F-, other studies, including those that showed positive results, were at F- concentrations (1-5 ppm) equivalent to human exposure levels. In the majority of studies that were reported to be positive, there were high background frequencies, or the investigators reported categories of nuclear or chromosome damage that are difficult to interpret. Interestingly, many of the positive results were obtained when anaphase cells were scored, whereas similar treatment protocols in other laboratories yielded negative results when metaphase cells were the only cell type examined. It is difficult, without additional data, to determine the reasons for finding chromosome breaks in anaphase, but not metaphase, cells. Other reports have presented insufficient information to allow adequate evaluations. Therefore, at this time, the question of whether F- produces chromosome damage in vivo should be considered unresolved.
Article
The potential of sodium fluoride to affect spermatogenesis in the rat was assessed by intratesticular injection. Experimental rats' left testis was injected with sodium fluoride (50, 175 and 250 ppm) in vehicle (0.9% physiological saline); control testes were injected with vehicle. The right testis served as a non-injected control. Testicular tissues collected 'at' and 'distal to' the injection site and from the non-injected control testes were evaluated microscopically 24 hr and 1, 2 and 3 wk post-injection. Testicular tissues obtained at and distal to the injection site in all fluoride-injected groups resembled tissues collected from corresponding areas in the controls. Seminiferous tubule damage observed in both the vehicle-injected control testes and the fluoride-injected testes but not in the non-injected testes was attributed to injection trauma. Polymorphonuclear leucocyte infiltration was observed 24 hr post injection only at the injection site in the vehicle- and fluoride-injected groups. Leydig cells were unaffected. Leucocyte infiltration with seminiferous tubule damage was not considered to be a fluoride treatment-related effect because it was observed in both vehicle- and fluoride-injected testes. The results demonstrate that the rat is not adversely affected by direct exposure to fluoride at levels 200 times greater than those under normal conditions.
Article
Recent work has shown that a high fluoride (F) intake in rodents leads to histopathologic changes in the germinal epithelium of testes and to zinc deficiency in the testis and several other organs. The purpose of the present study was to determine whether an elecvation of testicular zinc concentration during fluoride exposure could protect the testes of bank vole from damage. The elevation of testicular zinc was achieved by exposing the bank voles to a long photoperiod (16 hr light/8 hr dark). The zinc concentration in the testes of bank voles kept under the long photoperiod was 38% higher than that in animals exposed to a moderate photoperiod (12 hr light/12 hr dark). Fluoride exposure (200 micrograms F/ml drinking water) during 4 months decreased additionally (p < 0.05) zinc concentration in the testes of bank voles kept under the moderate photoperiod. The same animals also exhibited histopathologic changes in the germinal epithelium. By contrast, these disturbances were not observed in animals maintained in the long photoperiod. This experiment suggests that an increase in testicular zinc due to a long photoperiod prevents seminiferous tubules from a damage induced by fluoride in bank voles. The protective effects of zinc (or a long photoperiod) did not appear to be related to a decrease in testicular fluoride accumulation or lipid peroxidation.
Article
The importance of photoperiod and ambient temperature on the accumulation of cadmium in the liver and kidneys of bank voles was determined in the present study. Males and females, aged 1 month, were given 3.0 micrograms Cd ml-1 drinking water and divided into four groups according to photoperiod (16 h light/8 h dark and 8 h light/16 h dark) and ambient temperature (20 or 5 degrees C); liver and kidneys were removed for cadmium as well as copper, iron and zinc analyses at the end of 6 weeks. Bank voles exposed to 5 degrees C in both photoperiods consumed approximately 30% less water containing cadmium than those kept at 20 degrees C. However, the total accumulation of cadmium in the liver and kidneys of males and females exposed to the low temperatures was 4.3-4.8 and 2.2-3.3 times less than that in animals maintained at room temperature in the long and short photoperiod, respectively. Simultaneously, the low temperature brought about an increase in the copper concentrations in the liver (12-43%) and kidneys (47-78%), giving rise to an inverse correlation between the cadmium accumulation and the tissue copper concentration. In contrast to cadmium and copper, the concentrations of iron and zinc were affected primarily by photoperiod. These findings indicate that ambient temperature is an important determinant of cadmium retention in the bank vole. It appears that low temperature decreases tissue cadmium accumulation not only by reducing cadmium intake but also through changes in copper metabolism.
Article
Male Wistar rats were fed a Zn-deficient diet (1.2 mg/kg of Zn) for 28 days. Testes were then studied by light and electron microscopy. Zn deficiency induced necroses of precursors of germ cells leading to tubular atrophy and affected differentiation of spermatids. This was expressed by the occurrence of 2-4 axoneme-dense fibre-mitochondria complexes in one spermatid. Moreover, outer dense fibres, which normally contain 90% of sperm Zn, were "uncoiled" and flattened. The multiplication of the axoneme-dense fibre-mitochondria complexes induced by Zn deficiency might have been produced by an increase of Fe in spermatids and an increased formation of oxygen free radicals.
Article
The cell viability, lipid peroxidation (LPO) and hydrogen peroxide (H(2)O(2)) generation were measured in cultured primary astrocytes, from metallothionein (MT)-I isoform overexpressing transgenic (MT-I*), MT-I/MT-II null and control mice after exposure to tert-butylhydroperoxide (tBH). Astrocytes from MT-I* mice have high basal levels of both MT-I mRNA and MT protein, whereas there is only MT-III isoform in astrocytes from MT-I/MT-II null mice. The results showed that (1) cultured astrocytes from MT-I* mice were most resistant to the cytotoxicity of tBH and those from MT-I/MT-II null mice were most sensitive to the cytotoxicity of tBH; (2) LPO after exposure to tBH were increased in all cells, but the levels were the highest in astrocytes from MT-I/MT-II null mice, while those in MT-I* mice were the lowest; (3) the levels of H(2)O(2) in cultured astrocytes from MT-I* mice were the lowest, while those in astrocytes from MT-I/MT-II null mice were the highest. These results support the hypothesis that MT can scavenge free radicals and protect astrocytes from oxidative stress.
Article
Zinc deficient rats were prepared to investigate histopathological changes in thymus, testis, skin, esophagus, kidney and liver and the relationship between these changes and apoptosis. Seven-week-old male SD rats were given a Zn deficient diet (0% Zn diet) or a standard diet (0.02% Zn diet). The above-mentioned organs were excised 1, 2, 3, 4, 5, 10, 13, and 34 weeks after initiating diet administration. Then, these organs were examined morphologically, and apoptotic changes were analyzed by either the TdT- mediated dUTP - biotin nick end labeling (TUNEL) or electrophoresis. Significant morphological changes were seen only in rats on the 0% Zn diet. After 4 weeks, atrophy of the thymus was seen. After 5 weeks, oligospemia was observed, and after 10 weeks, testicular atrophy accompanied by the loss of sperm cells and spermatocytes was confirmed. In addition, after 10 weeks, thickening of epithelia was seen in the skin and esophagus of rats on the 0% diet. During the observation period, no marked morphological changes were observed in the liver or kidney. In the thymus and testis of rats on the 0% Zn diet, prior to detecting any morphological changes, increases in apoptosis were confirmed at 1 and 3 weeks after initiating diet administration, respectively. In the kidney and liver, TUNEL positive cells appeared after 13 and 34 weeks, respectively. These observations suggest that the functional and morphological changes in the thymus and testis of rats on the 0% Zn diet are caused by increased apoptosis, and that even when the supply of Zn is terminated for only a short period of time, immunocytes and germ cells can not survive or regenerate sufficiently. Again, the fact that even in the liver and kidney, apoptosis was observed when administration of the 0% Zn diet was prolonged suggests that the appearance of apoptosis is dependent on the amount of Zn in tissues. In addition, the fact that increases in apoptosis were confirmed in the skin of rats on the 0% Zn diet, but not in the esophagus of these rats suggests that apoptosis does not directly cause thickening of stratified squamous epithelium in Zn deficient rats.
Article
Previous studies using metallothionein (MT)-overexpressing transgenic mice have demonstrated that MT protects the liver from oxidative injury induced by alcohol. The mechanism of action of MT is unknown. Because MT primarily binds to zinc under physiological conditions and releases zinc under oxidative stress and zinc is an antioxidant element, it is likely that zinc mediates the protective action of MT. The present study was undertaken to determine the distinct role of zinc in hepatic protection from alcoholic injury. MT I/II-knockout (MT-KO) mice along with their wild-type controls were treated with three gastric doses of ethanol at 5 g/kg at 12-hour intervals. Zinc sulfate was injected intraperitoneally in a dosage of 5 mg/kg/day for 3 days before ethanol treatment. MT concentrations in MT-KO mice were very low and zinc concentrations in MT-KO mice were lower than in wild-type mice. Zinc treatment significantly elevated hepatic MT concentrations only in wild-type mice and increased zinc concentrations in both MT-KO and wild-type mice. Ethanol treatment caused degenerative morphological changes and necrotic appearance in the livers of MT-KO mice. Microvesicular steatosis was the only ethanol-induced change in the liver of wild-type mice. Ethanol treatment decreased hepatic glutathione concentrations and increased hepatic lipid peroxidation, and the concentrations of lipid peroxide products in the wild-type mice were lower than in the MT-KO mice. All of these alcohol-induced toxic responses were significantly suppressed by zinc treatment in both MT-KO and wild-type mouse livers. These results demonstrate that zinc, independent of MT, plays an important role in protection from alcoholic liver injury. However, MT is required to maintain high levels of zinc in the liver, suggesting that the protective action of MT in the liver is likely mediated by zinc.
Article
Dietary zinc deficiency produced by feeding a zinc-poor diet (0.5 μg. zinc per g.) to weanling rats for 8 weeks caused marked retardation in body growth, depressed growth and development of testes, epididymes, accessory sex organs, and pituitary glands, and in many cases severe atrophy of testicular germinal epithelium. The zinc concentration of dorsolateral prostates, testes, epididymes, and bone was reduced in zinc-deficient rats compared with controls receiving the zinc-poor diet plus 100 μg. zinc daily. Restricted feeding of the zinc-supplemented diet to produce body weights comparable to those in zinc-deficient rats caused a reduction in pituitary gland and accessory sex organ size which was similar to that observed in zinc-deficient rats. Testis growth and development were normal in the restricted controls and did not differ from controls fed ad libitum. The zinc concentration of dorsolateral prostates was reduced in restricted controls but exceeded that in the zinc-deficient rats. All the observed changes produced by zinc deficiency except the testicular atrophy were reversed when zinc was replaced in the diet. If testicular atrophy had occurred, neither testis nor epididymis regained normal size, function, or zinc concentration.
Zinc protection against bromobenzene induced hepatotoxicity in the rat Testis damage by zinc deficiency in rats
  • D A Mcmillan
  • R C Schnell
  • H J Merker
  • T Günther
McMillan, D.A., Schnell, R.C., 1984. Zinc protection against bromobenzene induced hepatotoxicity in the rat. Toxicologist 4, 451. Merker, H.J., Günther, T., 1997. Testis damage by zinc deficiency in rats. J. Trace Elem. Med. Biol. 11, 19–22.
The influence of inorganic fluorine compounds on functional condition of the hypophysistestis system
  • V I Tokar
  • O N Savchenko
Tokar, V.I., Savchenko, O.N., 1977. The influence of inorganic fluorine compounds on functional condition of the hypophysistestis system. Probl. Endokrinol. 23, 104-107.
Zinc protection against bromobenzene induced hepatotoxicity in the rat
  • D A Mcmillan
  • R C Schnell
McMillan, D.A., Schnell, R.C., 1984. Zinc protection against bromobenzene induced hepatotoxicity in the rat. Toxicologist 4, 451.