Effect of thermal inactivation and ATP on age related changes in hepatic glutamate dehydrogenase activity of male garden lizard

The total glutamate dehydrogenase (GDH) activity of the liver of the male garden lizard did not change during maturation (young to middle-aged) but showed a decline in later phase of the life span (middle-aged to old). On the other hand, the heat stable GDH activity increase during maturation and declined thereafter. The degree of thermal inactivation of the total GDH activity at 45 degrees +/- 1 degree C was not age-dependent. ATP stimulation of total GDH activity was about three times higher in old than in middle-aged lizards.     

Effect of two inhibitors on succinic dehydrogenase activity in cerebral hemispheres of male garden lizards of three different age groups

Age changes in the specific activity of cerebral succinic dehydrogenase (SDH) and the effect of two inhibitors (malonate and p-chlorophenoxy acetic acid) on enzyme activity were traced in a short-lived species of reptile, Calotes versicolor, the garden lizard. The enzyme activity reached a peak level in middle-aged lizards followed by a decline in old counterparts. The enzyme inhibitions by both the inhibitors were significantly higher in old than in middle-aged and young lizards suggesting a change in specificity of SDH molecules during ageing.     

Effect of age and cold shock on the SDH activity of brain mitochondria and carbohydrate contents of brain of male garden lizard

The SDH activity of brain mitochondria reached a peak level when the lizards were 1 year old and then declined. Blood glucose level and the carbohydrate contents glucose and glycogen) exhibited a trend of rise with advancing age.Short term cold shock induced a significant rise in mitochondrial SDH activity in old lizards but only marginally in young and middle-aged. While the degree of decline in glucose and glycogen contents of brain of old following cold shock was significantly higher than that of young, the fall in blood glucose level followed a reverse trend.     

Age-related responses of hepatic glucose uptake to starvation and cold stress in male garden lizards

The hepatic glucose uptake of male garden lizards did not change during maturation but showed a decline between middle-aged and old age groups. The decline in glucose uptake following starvation and cold stress was age-dependent, the young and middle-aged lizards being more responsive than the old counterparts.     

Some biochemical changes in the ageing heart of the male garden lizard

The SDH activity of cardiac muscle homogenates reached a peak level in the middle-aged lizards followed by a decline in the old. The inhibition of enzyme activity by oxaloacetate, a competitive inhibitor, declined with advancing age. Both salt and acid solubilities of cardiac muscle collagen declined with advancing age of the lizard. An age-related accumulation of total collagen was evident per organ basis but a reverse trend prevailed on the basis of relative value. Quantitative estimations revealed a loss of DNA in ageing heart; per organ basis the DNA content increased till the lizards were middle-aged showing no further change thereafter. On the other hand the RNA content and the RNA/DNA ratio of cardiac muscle declined between young and middle-aged followed by a rise in the old lizards. The protein content increased with rise in fresh weight of heart during ageing.     

Age-related changes in glucose uptake of cerebral hemisphere slices of male garden lizards in response to starvation stress

In the male garden lizard, the glucose uptake of cerebral hemisphere slices did not change during maturation (young to middle-aged) but declined during ageing (middle-aged to old). Short-term starvation (3 days) did not cause a significant change in glucose uptake of cerebral hemisphere of young lizards but led to an increase in the parameter in both the middle-aged and old.     

Age-related differences in the response of hepatic oxygen consumption to thermal stress in the male garden lizard

The main aim of the present study is to compare the thermal adaptation capacity of young, middle-aged and old lizards with respect to hepatic oxygen consumption. Cold exposure (1 h at 0-4 degrees C) caused a decline in endogenous oxygen consumption in young but did not evoke significant changes in middle-aged and old lizards. On the other hand, with 5 mM succinate the rate of respiration increased marginally only in cold-exposed old lizards. This suggests that the metabolic response to cold is age-dependent in these lizards. Exposure of homogenates at 40 +/- 1 degree C for 15 min led to a rise in the hepatic oxygen consumption of young but not in that of either middle-aged or old lizards. There were no changes in the rate of oxygen consumption upon exposure for a similar period at 45 +/- 1 degree C of liver homogenates from lizards of three different age groups. However, exposure at 51 +/- 1 degree C resulted in a higher degree of decline in the rate of hepatic oxygen consumption in middle-aged and old than in young lizards. Thus, the young lizards appear to be better-adapted to hyperthermic stress than the middle-aged and old.     

Effect of malonate and p-chlorophenoxy acetic acid on hepatic succinic dehydrogenase activity of ageing lizards

The degree of inhibition of hepatic succinic dehydrogenase activity by malonate, a competitive inhibitor, did not differ between young and middle-aged lizards. On the other hand, the same parameter increased significantly between middle-aged and old lizards. The percent inhibition of enzyme activity by p-chlorophenoxy acetic acid was also age-dependent, being higher in middle-aged and old than in young lizards.     

Age-related changes in catalase activity and its inhibition by manganese (II) chloride in the brain of two species of poikilothermic vertebrates

Two species of poikilothermic vertebrates, a teleost fish (Channa punctatus) and the garden lizard (Calotes versicolor) were used to study the effect of age on brain catalase (CT) activity and its inhibition by manganese (II) chloride (MnCl(2)). While in fish the CT activity of brain remained unchanged throughout the lifespan, the enzyme activity decreased during maturation and then showed an increase during aging in the garden lizard. MnCl(2) at a concentration of 333 muM in incubating medium significantly inhibited the CT activity of the brain of both fishes and lizards of all the three age groups (young, middle-aged and old), the degree of inhibition showing a trend of increase with advancing age. However, statistical significance was observed when fishes of the young age group were compared either with those of middle-aged or old counterparts, and between young versus old and middle-aged versus old lizards. Increased susceptibility to Mn(2+) during aging suggests changes in regulation of CT.     

Changes in catalase activity and its thermolability in liver and kidneys of ageing male garden lizard.

Catalase activity in liver and kidneys of male garden lizards remained unchanged during maturation, but showed an increase during ageing. Instead of inactivating catalase, thermal treatment at 60 +/- 1 degree C caused a marginal increase in enzyme activity in the liver of middle-aged and kidneys of young lizards with no significant effect in old counterparts. Increase in basal enzyme activity during ageing and the maintenance of resistance against thermal inactivation of the enzyme throughout the life-span support the contention that catalase molecules in lizard tissues are not altered as a function of age, a deviation from the predictions of Orgel's error catastrophe hypothesis.     

Effect of age on thermal inactivation of glucose-6-phosphate dehydrogenase in liver and kidney of the male garden lizard.

A comparison between middle-aged and old lizards revealed no significant age change in glucose-6-phosphate dehydrogenase activity of liver and kidney. Thermal inactivation at 51 +/- 1 degree C induced a significantly higher degree of decline in enzyme activity of tissues of old than that of middle-aged lizards. The increase in thermolability of enzyme in liver and kidney of ageing lizards suggests an accumulation of altered enzyme molecules.     

Age-related changes in the response of hepatic succinic dehydrogenase activity to thyroxine and thiourea in lizards

Intraperitoneal injection of thyroxine (T4; 1 microgram/g body weight on alternate days, seven doses) to male garden lizards of three different age groups caused a stimulation of hepatic succinic dehydrogenase activity, the degree of response being higher in the old (63%) than in middle-aged (39%) and young (31%). Percent inhibition of enzyme activity following thiourea treatment (0.05 mg/g body weight on alternate days, three doses) was higher in middle-aged lizards (24%) than in young (10%) and old (12%) ones.     

Age-related effect of aluminium on the catalase activities of the brains of two species of poikilothermic vertebrates

BACKGROUND: Although aluminium (Al) has been implicated in various neuropathological states with aging due to its involvement in neurotoxicity, the exact role of the metal ion is still unclear. OBJECTIVE: The aim of the present study is to ascertain whether the antioxidant enzymes of the brain protecting from oxidative damages which accumulate with aging are regulated by Al in an age-dependent manner. METHOD: The inhibitory effect of Al on the catalase activity of brain homogenates of two species of poikilothermic vertebrates was studied in vitro using a spectrophotometric method. RESULTS: At a final concentration of 666 microM, the metal ion inhibited the enzyme activity of the brain in both species. In fish brain the degree of inhibition was not age-dependent. On the other hand, the rate of inhibition increased between young and middle-aged lizards followed by a decline in the old counterparts. CONCLUSION: Al inhibits catalase activity but this effect may not be a major contributing factor in the aging of the brain in the two species capable of maintaining their antioxidant capacity until old age.     

Effects of age and manganese (II) chloride on peroxidase activity of brain and liver of the teleost, Channa punctatus.

Fish provide enormous spectrum of longevity and thus present the possibility of multiple mechanisms of senescence. Oxidative stress as a causative agent of senescence and the protective role of antioxidant enzymes were tested in the teleost, Channa punctatus taking peroxidase (POD) (EC 1.1 1.1.7) as the representative enzyme. The activity of POD in brain and liver declined during maturation phase (young vs middle-aged). During senescence phase (middle-aged to old) the enzyme activity increased in liver but remained stabilized in brain. The degree of increase in peroxidase activity following in vitro MnCl2 treatment was always higher in liver than in brain. The rate of MnCl2 induced increase in POD activity of both tissues showed an increasing trend with age. However statistical significance was observed only in brain during senescence phase. No significant loss of enzyme activity in both the tissues and greater degree of increase by MnCl2 in brain suggest that antioxidant capacity is not impaired in old murrels.     

Lactate dehydrogenase, succinate dehydrogenase and nucleotide tetrazolium reductase histochemical activities in the mesentric arteries and arterioles of young and old rats

Age-related changes of the metabolic characteristics of large, medium and small brances of the rat superior mesenteric artery were investigated in young (4 month) and old (25 month) male Wistar rats, using enzyme histochemical techniques. The following enzymatic activities were examined: lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH); NADPH(2)-tetrazolium reductase (NADPHD) and NADH(2)-tetrazolium reductase (NADHD). The intensity of enzymatic reactions within the tunica media of the large, medium and small branches and within the tunica intima of the large and medium branches of the artery was assessed microphotometrically. In young rats the reactivity of enzymes investigated is similar in both the tunica media and the intima with the exception of SDH which reacts stronger in the media than in the intima. LDH and NADHD displayed the most intense reaction whereas SDH reaction was less intense. In old rats LDH and NADPHD reactivity decreased, SDH reactivity increased in the intima of large and medium branches; and SDH increased in the media of large branches. The possibility is discussed that an impaired endothelial function may represent one of the most consistent phenomena of aging of the superior mesenteric artery.     

Lactic dehydrogenase activity in lung lymph during hemorrhagic shock, resuscitation and recovery

Lactic dehydrogenase activity was determined in lung lymph before, during and after hemorrhagic shock to determine if this insult produced pulmonary cellular damage. Lung lymph flow and lymph protein content, reliable indices of fluids filtration rate and microvascular protein permeability were also monitored. The experiment was performed in unanesthetized sheep with a chronic lung lymph fistula. Lymph flow, lymph LDH and protein content did not change during the period of shock. Lymph flow increased significantly during resuscitation but lymph LDH and protein content decreased in relation to plasma values indicating the sieving effect of the microvascular membrane for protein to be intact. The increased flow was most likely caused by an increase in microvascular hydrostatic pressure. Plasma LDH was significantly increased during the 72 hour recovery period with lymph flow, lymph protein and lymph LDH being normal. We therefore found that hemorrhagic shock produced a systemic cellular injury reflected in an increased plasma LDH activity. No pulmonary cellular damage was noted.     

Age-related changes in brain and spinal cord lipids of the male garden lizard

The lipid composition (cholesterol, phospholipid triglyceride and fatty acids) of brain and spinal cord of the male garden lizard was traced during maturation and ageing. The total brain cholesterol content of both the tissues showed a significant rise during maturation, remaining almost constant thereafter. The free cholesterol content of the brain increased between middle and old age and that of the spinal cord increased during maturation. The esterified cholesterol content of the brain increased during maturation, the same parameter being not age-dependent in the spinal cord. While in the brain the phospholipid content increased during maturation followed by a decrease in old age, it showed a reverse trend in the spinal cord. The level of triglyceride in the brain declined during maturation followed by an increase in old age with no appreciable age change in the spinal cord. A comparison between young and old age-groups revealed a decrease in fatty acid content of the brain. A similar trend of decline was observed during maturation in the spinal cord. The pattern of age changes in the lipid profile of nervous tissue of the lizard, a non-mammalian vertebrate, almost conform to the pattern observed in a majority of mammals.     

Effect of thyroxine (T4) and thiourea on the hepatic oxygen consumption of male garden lizards of three different age groups

Administration of T4 (1 microgram/g body-weight on alternate days) to male garden lizards of three different age groups (young, middle-aged and old) for a period of 2 weeks caused a significant rise in the hepatic oxygen consumption, the degree of response increasing with advancing age. On the other hand, when treated in vitro (5 micrograms T4 in the medium) the stimulation of hepatic oxygen consumption was observed only in lizards of the young age group. Oral administration of thiourea (0.05 mg/g body-weight on alternate days, three doses) led to a decrease in hepatic oxygen uptake, the degree of inhibition being higher in young (30%) and old (28%) than in middle-aged lizards (12%).     

Effect of paradoxical sleep deprivation on oxidative stress parameters in brain regions of adult and old rats

The present study examined the effects of paradoxical sleep (PS) deprivation on the oxidative stress parameters: lipid peroxidation, superoxide dismutase, glutathione peroxidase, and glutathione in brain regions: cerebral cortex, striatum, hippocampus, thalamus, hypothalamus, and brain stem of adult (8 months) and old (24 months) rats. PS deprivation (96 h) was performed by the classical flower pot technique. PS deprivation did not affect oxidative stress parameters in the striatum of both age groups; and the activity of glutathione peroxidase was not affected in any of the studied brain regions in both age groups. PS deprivation decreased the levels of glutathione only in the hippocampus, thalamus and hypothalamus; the magnitude of decrease was higher in the old than in the adult age group. PS deprivation increased the superoxide dismutase activity in the cerebral cortex and brain stem but reduced it in the hippocampus, thalamus and hypothalamus in both age groups. Increases in the activity were greater in adult animals than in old ones; the decline in the activity was greater in the hippocampus of old animals than in that of the adult ones. Lipid peroxidation was reduced by PS deprivation in the cerebral cortex and brain stem but was elevated in the hypothalamus and thalamus: the magnitude of alteration in the cerebral cortex, brain stem, hippocampus and hypothalamus was higher in adult animals than in old ones. The results showed that oxidative stress was not uniformly affected in all the brain regions. The cerebral cortex and brain stem showed a fall in oxidative stress after PS deprivation; the fall was greater in the adult than in the old animals. However, the oxidative stress was elevated in the hippocampus, thalamus and hypothalamus, and old animals were more severely affected than the adult ones.     

Disorders of myocardial metabolism in sudden coronary death in the presence of coronary atherosclerosis: findings of quantitative histoenzymologic studies

The activity of human myocardial enzymes in sudden coronary death (SCD) was quantitatively histochemically examined. The activity of succinate dehydrogenase (SDH), lactate dehydrogenase (LDH), beta-oxybutyrate dehydrogenase (beta-OBDH), alpha-glycerolphosphate dehydrogenase (alpha-GPDH), NAD-diaphorase (NAD-ase), and glucose-6-phosphate dehydrogenase (G-6-PDH) was measured on prompt autopsies (up to 3 hours of death onset). beta-OBDH and LDH showed an increase in activity in the myocardium from the subjects who had suddenly died from coronary heart disease without evident changes in the heart. In SCD in the presence of small cardiosclerosis, the activity of the enzymes characterizing the major processes of energy generation was also enhanced, which was caused by moderately severe myocardial hypertrophy. In the myocardium from the subjects who had died from coronary heart disease in the presence of large postinfarction cardiosclerosis, the activity of the enzymes was directly related to the degree of myocardial hypertrophy and the signs of chronic heart failure. As myocardial hypertrophy progressed, the enzymatic activity rose, but there were signs of chronic heart failure, it fell. The findings suggest that the changes in myocardial enzymatic activity in SCD are heterogeneous and associated with the type of prior abnormalities in the cardiovascular system.