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ABSTRACT: The effect of feeding of two different antioxidants, tetrahydrocurcumin (TC) and green tea polyphenols (PPs) on the survival of male C57BL/6 mice was examined. Mice that started to receive diets containing TC (0.2%) at the age of 13 months had significantly longer average life spans (days, mean +/- SD) than control mice (797.6 +/- 151.2 vs.882 +/- 154.6, both n = 50, controls vs. TC treated, plus 11.7%, P < 0.01). The 10% longest survival was also significantly greater in TC-treated mice (plus 6.5%, P < 0.01). In contrast, in mice that started to receive TC in their 19th month of life, no significant difference from the control mice was found for either the average life span or the 10% longest survival. In mice that received water containing PPs (80 mg/l), the average life span was also significantly longer than in the control mice (801 +/- 121.5 vs. 852.7 +/- 88.2, plus 6.4%, P < 0.05), although the 10% longest survival was not significantly different from that in the control mice (P > 0.05). The body weights of the TC (but not PP) fed mice, were slightly (2-4%) but significantly (P < 0.05) lower than the values for the corresponding ages in the control mice in the first six months of treatment. Thereafter, the difference in average body weight between the control and the TC-fed animals was totally lost. Although an additional contribution of an unintended slight decrease in food intake due to TC feeding (suspected due to the difference in body weight) is not excluded, we suggest that the feeding of nutritional antioxidants such as TC and PPs may have the potential to beneficially modify the life spans of animals.
Biogerontology 11/2007; 8(5):567-73. · 3.34 Impact Factor
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ABSTRACT: Objective: Age-related changes in endogenous antioxidant enzyme activities have been widely discussed in relation to mechanisms of organismic aging. However, some discrepancies in this regard can be seen in the published work. The present study aimed to clarify past discrepancies using BN/Bi rats in which no study has been reported in the past.Methods: Antioxidant enzyme activities such as superoxide dismutase (SOD) and catalase (CAT) were compared in several brain regions and the liver between young (8–9 months) and old (27–29 months) BN/BiRijHsd rats of both sexes.Results: CAT activities in brain regions were quite comparable between young and old rats of both sexes. SOD activity changes with age also were not remarkable, with the exception of significantly lower Mn-SOD activities in substantia nigra and hippocampus of old male rats and significantly higher activities of Cu/Zn-SOD in substantia nigra of old female rats in comparison with respective values in young rats. CAT activities in the liver tended to be lower in old male rats, while in females the opposite was observed. SOD activities in the liver stayed essentially unchanged with age in males, while in females total as well as Cu/Zn-SOD activities were more than twofold higher in old animals.Conclusion: These data coupled with previously reported results, indicate that no generalization can be made in terms of age-related changes in antioxidant enzyme activities. These differences emphasize the need of “public observations” in any attempt to generate a theory for mechanisms of aging based on antioxidant enzyme activity changes with age.
Geriatrics & Gerontology International 09/2007; 7(3):279 - 284.
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Kenichi Kitani
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ABSTRACT: In order to understand the basic mechanisms underlying the organismic aging process, considerable efforts have been devoted in the last half-century to biochemical (enzyme activity) alterations in specific tissues and organs of various organisms associated with aging. When a decline in enzyme activities with age has been found in a study, especially for key enzymes such as antioxidant enzymes, the results have often been interpreted as a cause for the aging of the entire body. Retrospectively, however, these changes turned out to be so variable--depending on species, strains and sexes of animals--that the interpretation of these results in general terms of aging became invalid. Further, unlike the prediction for the whole human body, many enzyme activities in a vital organ, such as the liver, remained unchanged, as long as the old subjects remained healthy. However, enzyme activities in old animals and humans are often more susceptible to morbidities and frailties, which themselves are often accompanied by infections and malnutrition. Despite the rather stable enzyme functions in the liver with age, a distinct and progressive decline in the lateral diffusion coefficient of proteins of hepatocyte plasma membranes has been demonstrated by fluorescence recovery after photobleaching (FRAP), which was implicated as the cause for the decline of hepatocyte functions such as ouabain (and taurocholate) hepatic uptake and their eventual biliary excretion. Since a similar decline in protein diffusion coefficients was observed in brain and muscle cells, it is likely that these changes are occurring in common with many cell types of the body, thus causing a delay in transmembrane transport of endogenous and exogenous substances whose transports are mediated by membrane proteins. In attempts to prolong the life spans of animals other than by calorie restriction, but instead using deprenyl or tetrahydrocurcumin, works by the author and coworkers are introduced and discussed. Despite limited success along these lines thus far, further attempts are encouraged, primarily to understand the mechanisms underlying organismic aging processes and to find a practical way to prolong the health span of the elderly.
Age 04/2007; 29(1):1-14. · 6.28 Impact Factor
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Annals of the New York Academy of Sciences 12/2006; 786(1):391 - 409. · 3.15 Impact Factor
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ABSTRACT: (-)Deprenyl (D) has been shown to be effective in prolonging life span in experimental animals, although, there are some discrepancies in its effect on the life span the even within the same species (rats). The present study aims to clarify the reason for these discrepancies. Male F344/DuCrj rats began receiving subcutaneous (s.c.) injections of D at the age of 18 months. Doses used were 0.25, 0.50, and 1.0 mg/kg/injection (inj.), three times a week. Average life spans of animals were significantly longer in male rats given 0.25 and 0.5 mg/kg/inj.; however, rats given a 1.0 mg/kg dose began dying earlier than control rats, leading to an inverse U-shaped dose-efficacy relationship, a hormesis. Old (27-month-old) rats given different doses of D for 1 month showed a typical hormetic response for antioxidant enzyme activities, indicating a significant increase in superoxide dismutase (SOD) and catalase (CAT) activities in brain dopaminergic regions with four lower doses (0.25 to 2 mg/kg/inj., 3 times a week), but a significantly negative response with the highest dose (4 mg/kg/inj.). Our results clearly indicate that a proper dose of D within a certain dose range can significantly increase the life span of rats, but that a greater dose becomes less effective and may actually adversely affect the life span of rats. A similar hormetic response for its effect on antioxidant enzyme activities and the parallel between the two different effects of D suggest a possible causal relationship between these two effects of D. The presence of this effective dose range of D may explain previously reported discrepancies in the effect of D on the life span of animals.
Annals of the New York Academy of Sciences 06/2006; 1067:375-82. · 3.15 Impact Factor
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ABSTRACT: The free radical theory of aging was initially proposed by Harman1 half a century ago primarily to explain biological aging processes. Although administration of so-called antioxidant chemicals, which have been tested in the past for several decades, turned out to be mostly ineffective in prolonging the life spans of animals,2,3 the same theory of age-associated diseases appears to be increasingly supported in the last two decades. Despite these difficulties, the success in extending life span of 4 different animal species (mice, rats, hamsters, and dogs) with (−)deprenyl (including a study of our group) indicates that there might exist another type of antioxidant strategy in addition to a simple administration of antioxidant chemicals (for review, see Refs. 4,5). (−)Deprenyl has also been shown to increase superoxide dismutase (SOD) and catalase (CAT) activities selectively in brain dopaminergic tissues.4,5 Interestingly, we have recently shown that another propargylamine, rasagiline not only increases antioxidant enzyme activities (CAT and SOD) in brain dopaminergic regions as (−)deprenyl does, but also increases CAT and SOD activities in extra-brain catecholaminergic systems such as the heart and kidneys as well.6 These recent observations coupled with previous observations on the life span of animals with (−)deprenyl suggest that pharmacological modulation of endogenous antioxidant enzyme activities could be one potential antioxidant strategy against aging and age-associated disorders. If the causal relationship between the two effects of (−)deprenyl exists as we hypothesized,4,5,7 we might be able to advance the elucidation of mechanism(s) of aging based on the free radical theory of aging.
Annals of the New York Academy of Sciences 01/2006; 928(1):248 - 260. · 3.15 Impact Factor
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ABSTRACT: Past studies including our own have confirmed that chronic administration of deprenyl can prolong life spans of at least four different animal species. Pretreatment with the drug for several weeks increases activities of superoxide dismutase (SOD) and catalase (CAT) in selective brain regions. An up-regulation of antioxidant enzyme activities can also be induced in organs such as the heart, kidney, spleen, and adrenal gland, and all are accompanied by an increase in mRNA levels for SODs in these organs. The effect of deprenyl on enzyme activities has a dose-effect relationship of a typical inverted U shape. A similar inverted U shape also has emerged for the drug's effect on survival of animals. An apparent parallelism observed between these two effects of the drug seems to support our contention that the up-regulation of antioxidant enzymes is at least partially responsible for the life-prolonging effect on animals. Further, when a clinically applied dose of the drug for patients with Parkinson's disease was given to monkeys, SOD and CAT activities were increased in striatum of these monkeys, which suggests potential for the drug's applicability to humans. The drug was also found to increase concentrations of cytokines such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the above rat organs. Together with past reports demonstrating that deprenyl increases natural killer (NK) cell functions and interferon-γ, and prevents the occurrence of malignant tumors in rodents and dogs, the mobilization of these humoral factors may therefore be included as possible mechanisms of action of deprenyl for its diverse antiaging and life-prolonging effects. The potentials of propargylamines, (−)deprenyl in particular, for human use as antiaging drugs remain worthy of exploration in the future.
Annals of the New York Academy of Sciences 01/2006; 959(1):295 - 307. · 3.15 Impact Factor
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ABSTRACT: So-called antioxidant strategies have not been shown convincingly to be effective in increasing life spans of animals. Thus, the general consensus of experimental gerontology in the last century was that the only reproducible means of prolonging survivals of animals is the calorie restriction paradigm. As a challenge against this dogma, we attempted to examine the effect of two potent antioxidants, one tetrahydrocurcumin (a biotransformed metabolite of curcumin contained in turmeric of Indian curry) and the other green tea polyphenols.
Annals of the New York Academy of Sciences 07/2004; 1019:424-6. · 3.15 Impact Factor
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ABSTRACT: Female C57BL mice of six different ages (from 6 to 26 months) were given a protein free-diet (PFD) for 1 week and then given a normal diet (ND). Mice were examined for enzyme activities of glutathione S-transferase (GST) in the hepatic cytosol fraction using l-chloro-2, 4-dinitrobenzene (CDNB) as substrate. Enzyme activities were very close among the six different age groups when examined for basal levels as well as after 1 week of PFD. However, a remarkable age difference became manifest when animals were examined 2 days after the start of ND refeeding following 1 week of PFD. In young animals (6, 8 months), activities became much higher than their respective basal levels while in old animals (24, 26 months) enzyme levels remained significantly lower than their basal levels on day 2 of ND refeeding. A significant negative linear correlation between enzyme activities (Y axis) and animal age (X axis) was demonstrated only on day 2 or 3 of ND refeeding, while in control animals or animals given 1 week of PFD diet, no significant correlation could be found between enzyme activities and animal age. We conclude that liver cytosolic GST activity is a function of animal age only after a dietary manipulation such as a PFD and ND refeeding, while basal GST activities remain stable throughout the observation period of animal age.
Mechanisms of Ageing and Development 12/2002; 123(12):1617-23. · 3.44 Impact Factor
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ABSTRACT: Potential of sanguiin H-6, a component of Sanguisorbae Radix, to protect against oxidative damage in renal mitochondria and apoptosis mediated by peroxynitrite (ONOO(-)) was examined using a model in which rats were injected with lipopolysaccharide (LPS) and then subjected to renal ischemia followed reperfusion (LPS plus ischemia-reperfusion). Ischemia-reperfusion was achieved by occluding bilateral renal artery for 60 min and then releasing for 350 min. At 50 min after ischemia started, LPS was injected intravenously. LPS plus ischemia-reperfusion induced a large amount of 3-nitrotyrosine, an oxidative product of protein that is produced via ONOO(-) nitration, which was not detectable in normal group. Oxidative damage of mitochondria was indicated by an accumulated thiobarbituric acid (TBA)-reactive substance, glutathione (GSH) depletion and glutathione peroxidase (GSH-Px) inactivation in the mitochondria. Treatment of rats with sanguiin H-6 (10 mg/kg body weight/day) for 30 days prior to LPS plus ischemia-reperfusion attenuated the oxidative damage in the mitochondria. The amount of TBA-reactive substance was decreased and the GSH levels significantly increased as compared with that in control group. However, its effect on GSH-Px activity was much weaker. Apoptosis induced by LPS plus ischemia-reperfusion was detected by fluorescence staining, TdT-mediated dUTP-biotin nick end labeling and electrophoretic analysis. Sanguiin H-6 appeared to inhibit apoptosis, and this was associated with the suppression of caspase-3 activity. These beneficial effects of sanguiin H-6 against oxidative damage in mitochondria and apoptosis contributed to the improvement in renal function by reversing the elevated levels of blood urea nitrogen and creatinine caused by ONOO(-).
Nephron 10/2002; 92(1):133-41. · 13.26 Impact Factor
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ABSTRACT: This study investigated the effects of green tea polyphenol on the serum antioxidative activity and cholesterol levels of cholesterol-fed rats and compared them with those of probucol, an antioxidant hypocholesterolemic agent. To evaluate the antioxidative activity, the susceptibility to oxidative modification of low-density lipoprotein (LDL) isolated from the serum of cholesterol-fed rats was measured, as was the serum antioxidative activity using the spontaneous autoxidation system of brain homogenate. Administration of green tea polyphenol effectively inhibited LDL oxidation and elevated serum antioxidative activity to the same degree as probucol. However, higher amounts of polyphenol than probucol needed to be administered to reduce the total, free, and LDL cholesterol levels. Furthermore, green tea polyphenol increased the levels of high-density lipoprotein (HDL) cholesterol, leading to dose-dependent improvement of the atherogenic index, an effect that was not seen with probucol. Thus, green tea polyphenol may exert an antiatherosclerotic action by virtue of its antioxidant properties and by increasing HDL cholesterol levels.
Journal of Agricultural and Food Chemistry 07/2002; 50(12):3549-52. · 2.82 Impact Factor
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Kenichi Kitani
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ABSTRACT: The National Institute for Longevity Sciences (NILS) of Japan opened on July 7, 1995, 15 years after the Science Council of Japan recommended the establishment of the National Center for Aging and Geriatric Illnesses (the provisional name for NILS) in 1980. During the first four years of operation, 8 separate research departments, containing 21 laboratories, were established. NILS has both research departments for biomedical sciences, such as dementia research, molecular genetics, and geriatric research, and also departments of gerontechnology and the care of the elderly, which engage in research directed toward the comprehensive improvement of the health and well- being of the elderly. On July 9, 1995, the day of the opening ceremonies, NILS employed only three staff members, including the director general. At the end of fiscal year 2000 (March 31, 2001), the institute comprised a staff of more than 200 people, including 30 senior science staff and about 50 junior scientists. The Japanese government has recently decided to expand NILS to double its present size by the end of fiscal year 2004 (March 2005).
Annals of the New York Academy of Sciences 05/2002; 959:517-25. · 3.15 Impact Factor
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ABSTRACT: Past studies including our own have confirmed that chronic administration of deprenyl can prolong life spans of at least four different animal species. Pretreatment with the drug for several weeks increases activities of superoxide dismutase (SOD) and catalase (CAT) in selective brain regions. An up-regulation of antioxidant enzyme activities can also be induced in organs such as the heart, kidney, spleen, and adrenal gland, and all are accompanied by an increase in mRNA levels for SODs in these organs. The effect of deprenyl on enzyme activities has a dose-effect relationship of a typical inverted U shape. A similar inverted U shape also has emerged for the drug's effect on survival of animals. An apparent parallelism observed between these two effects of the drug seems to support our contention that the up-regulation of antioxidant enzymes is at least partially responsible for the life-prolonging effect on animals. Further, when a clinically applied dose of the drug for patients with Parkinson's disease was given to monkeys, SOD and CAT activities were increased in striatum of these monkeys, which suggests potential for the drug's applicability to humans. The drug was also found to increase concentrations of cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) in the above rat organs. Together with past reports demonstrating that deprenyl increases natural killer (NK) cell functions and interferon-gamma, and prevents the occurrence of malignant tumors in rodents and dogs, the mobilization of these humoral factors may therefore be included as possible mechanisms of action of deprenyl for its diverse antiaging and life-prolonging effects. The potentials of propargylamines, (-)deprenyl in particular, for human use as antiaging drugs remain worthy of exploration in the future.
Annals of the New York Academy of Sciences 05/2002; 959:295-307. · 3.15 Impact Factor
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ABSTRACT: (--)Deprenyl, a monoamine oxidase B (MAO B) inhibitor is known to upregulate activities of anti-oxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) in brain dopaminergic regions. The drug is also the sole chemical which has been repeatedly shown to increase life spans of several animal species including rats, mice, hamsters and dogs. Further, the drug was recently found to enhance anti-oxidant enzyme activities not only in brain dopaminergic regions but also in extra-brain tissues such as the heart, kidneys, adrenal glands and the spleen. We and others have also observed mobilization of many humoral factors (interferone (INF)-gamma, tumor necrosis factor (TNF)-alpha, interleukine (IL)-1beta,2,6, trophic factors, etc.) and enhancement of natural killer (NK) cell functions by (-)deprenyl administration. An apparent extension of life spans of experimental animals reported in the past may be better explained by these new observations that (-)deprenyl upregulate SOD and CAT activities not only in the brain but also in extra-brain vital organs and involve anti-tumorigenic as well as immunomodulatory effect as well. These combined drug effects may lead to the protection of the homeostatic regulations of the neuro-immuno-endocrine axis of an organism against aging.
Mechanisms of Ageing and Development 05/2002; 123(8):1087-100. · 3.44 Impact Factor
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ABSTRACT: The present study was conducted to evaluate the effect of sanguiin H-6, a component of Sanguisorbae Radix, on the production of nitric oxide (NO), using macrophages activated by lipopolysaccharide (LPS). Sanguiin H-6 inhibited nitrite production, taken as an index for NO, in a concentration-dependent fashion. This compound decreased inducible NO synthase (iNOS) activity, with the inhibitory effect at a concentration of 25 microM being equal to that of the known iNOS inhibitor aminoguanidine at 50 microM. However, unlike aminoguanidine, sanguiin H-6 was associated with improved cell viability. Reverse transcription-polymerase chain reaction analysis revealed that the expression of iNOS mRNA in activated macrophages was suppressed by sanguiin H-6 in a concentration-dependent manner. In addition, sanguiin H-6 even at a low concentration showed a clear scavenging effect on the NO generated from sodium nitroprusside (an NO donor). These findings indicate that not only does sanguiin H-6 act directly as an NO scavenger, but it also inhibits NO production in LPS-activated macrophages by the concomitant inhibition of iNOS mRNA induction and enzyme activity.
Biochemical Pharmacology 04/2002; 63(5):853-8. · 4.70 Impact Factor
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ABSTRACT: A potent inhibitor of type B monoamine oxidase, (−)deprenyl, is known to protect or rescue dying neurons, independent of inhibition of the enzyme activity. After long term administration to rodents, a propargylamine structurally related to (−)deprenyl, (R)(+)-N-propargyl-1-aminoindan (rasagiline) increased the activities of anti-oxidative enzymes, superoxide dismutase and catalase. Rasagiline protected in vitro dopamine cells from apoptosis induced by oxidative stress or neurotoxins. The mechanism of the anti-apoptotic effect was studied by in vitro experiments using human dopaminergic neuroblastoma, SH-SY5Y cells. Peroxynitrite-generating N-morpholino sydonimine (SIN-1) induced apoptosis in SH-SY5Y cells via disruption of mitochondrial membrane potential (ΔΨm), followed by caspase 3 activation. Rasagiline prevented the loss of ΔΨm, the initial step to apoptosis, and also following caspase 3-activation and DNA fragmentation. The results suggest that rasagiline may interact with the specific molecule in the mitochondria and suppress the death signal transduction. By the anti-apoptotic function, rasagiline may rescue or protect declining neurons in aging and neurodegenerative disorders, such as Parkinson’s disease.
Mechanisms of Ageing and Development 08/2000; · 3.44 Impact Factor
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ABSTRACT: Hepatic biotransformation and the effect on bile flow of 7-ketolithocholic acid (7-oxo-3α-hydroxy-5β-cholan-24-oic acid),
in comparison to ursodeoxycholic acid, were examined in rats under conditions of continuous infusion of solutions of sodium
salts of these bile acids (1.2μmol/min/100 g body wt) for 2 hr. Both bile salts elevated the bile flow rate as well as the
bile bicarbonate concentration to a similar degree. The minor difference observed was a transient (10–20 min) and subtle drop
of bile flow during the first hour in rats given 7-ketolithocholate. In ursodeoxycholate infused rats, the major bile salt
in the bile was its taurine conjugate, although excretion of tauroursodeoxycholate dropped considerably during the second
hour. In 7-ketolithocholate infused rats, the major bile salt in the bile was again, its taurine conjugate, but ursodeoxycholate
and chenodeoxycholate and their conjugates were also excreted. In contrast to ursodeoxycholate infused rats, the drop in excretion
of taurine conjugates and the increase of glycine conjugates in rats infused with 7-ketolithocholate were more rapid. In rats
infused with 7-ketolithocholate, excretion of ursodeoxycholate and its conjugates was significantly higher than the corresponding
values for chenodeoxycholate, suggesting that 7-ketolithocholate is reduced predominatly to the 7β-epimer in this species.
However, the concentration of ursodeoxycholate and its conjugates excreted into the bile in rats infused with 7-ketolithocholate
was only 10% of that of rats infused with ursodeoxycholate, yet the magnitude of choleresis and the rise in bile bicarbonate
concentration were similar in both experiments. Therefore, it is suggested that the bicarbonate-rich bile, induced by 7-ketolithocholate
infusion, is caused mainly by 7-ketolithocholate rather than by its metabolite, ursodeoxycholate.
Lipids 09/1989; 24(10):859-865. · 2.13 Impact Factor
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ABSTRACT: The biliary excretion of intravenously injected ouabain and the diffusion constant of the lateral mobility of hepatocyte plasma membrane proteins were examined in control (saline-treated) and spironolactone-treated Wistar male rats of different ages (4, 14 to 15 and 24 months old). The biliary excretion of ouabain progressively decreased with age in control rats, the first 10-min biliary recovery in 24-month-old animals being one-third that of the youngest rats (4-month-old). The oral administration of spironolactone for 4 days (10 mg per 100 gm body weight on the first day and 20 mg per 100 gm body weight for the successive 3 days) caused a marked increase in the biliary recovery of ouabain in all age groups. Similarly, the average lateral diffusion constant of hepatocyte plasma membrane proteins as measured by fluorescence recovery after photobleaching showed a linear decrease with age, as was previously observed with F-344 rats of both sexes. Markedly and significantly (30 to 40%) higher diffusion constants were observed in rats pretreated with spironolactone for all three age groups, compared with the respective control values of corresponding ages. The parallelism between ouabain excretion and protein diffusion (i.e., a decrease with age and an increase with spironolactone pretreatment) suggests that the lateral mobility of proteins in the hepatocyte plasma membrane is a candidate mechanism for regulating ouabain excretion through the liver into the bile, most probably by regulating the hepatic uptake process for ouabain.
Hepatology 12/1987; 8(1):125 - 131. · 11.66 Impact Factor
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ABSTRACT: Leupeptin, a thiol protease inhibitor, has previously been shown to cause a dense accumulation of substances resembling age pigment and called ceroid-lipofuscin, in brain cells of young rats [1]. Thus far, however, attempts to produce age pigments in hepatocytes of normal young rats with protease inhibitor(s) have not been successful. The present study provides the first demonstration that leupeptin induces lipofuscin-like substances in normal young rat hepatocytes. Male Fischer-344 rats (age 4–6 weeks) were continuously infused with leupeptin or saline i.p. for 2 weeks by an osmotic minipump (dosage, 1–50 mg/100 g per day). Liver tissues were then examined by light, fluorescence and electron microscopy. Both hepatocytes and non-parenchymal cells of livers treated with leupeptin, but not saline, showed a dense accumulation of pigments which stained deeply with toluidine blue, were PAS-positive and were brightly autofluorescent. After UV excitation the pigments had an emission spectrum with a broad peak at 480–540 nm extending to 650 nm resembling the spectrum of age pigment from livers of normal aged rats. Electron microscopic examination revealed numerous lipofuscin-like deposits with heterogeneous morphology in the cytoplasm of both hepatocytes and non-parenchymal cells; lipid and myelin-like bodies were also present in hepatocytes. The results indicate that the perturbation of proteolytic activity in liver by leupeptin causes an accumulation of substances which by several criteria resemble lipofuscin. These results thus provide further support for the ‘Protease Inhibitor Model of Lipofuscin Formation’ [2] as well as a potential experimental model for studying hepatocellular aging processes.
Mechanisms of Ageing and Development.
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ABSTRACT: Female Fischer-344 rats of different ages (8 and 25 months old) were fed a protein-free diet (PFD) for 7 days and refed a normal diet (ND) (23% protein) thereafter. Rats were killed immediately after the PFD was stopped (day 0) and at different time intervals during refeeding of a ND. Four subunits (1,2,3 and 4) and activities of glutathione S-transferases (GSTs) toward five different substrates, [styrene oxide (STOX), 1,2-dichloro-4-nitrobenzene (DCNB), 1-chloro-2,4-dinitro benzene (CDNB), sulfobromophthalein (BSP) and benzalacetone (PBO)] were determined.There were no significant differences between young and old rats in the liver enzyme activities before the PFD. The PFD caused significant decreases in activities for three substrates (DCNB, BSP and STOX) in both age groups, with no significant differences between young and old rats at day 0. During recovery from the PFD, activities for the three substrates exceeded basal levels in young rats but at different time intervals (STOX, day 2; BSP, day 5; DCNB, day 9), while enzyme values in old rats tended to return slowly to basal values with no “overshoot.” Concentrations of subunits 3 and 4 in young rat livers that were depressed by the PFD did not recover until day 9 of the ND, while subunits 2 and especially 1 increased during the ND refeeding, overshoting the basal levels. In contrast, in old rat livers the only change was a reduction of subunit 1 by the PFD and its gradual recovery during ND refeeding. These results demonstrate that our previous observation of overshooting of enzyme activities in mice is reproducible in rats but with certain substrate specificities. Furthermore, changes in subunit concentrations caused by aging and a PFD are more complex than what was predicted from changes in enzyme activities of GSTs.
Mechanisms of Ageing and Development.
