A high dose of long term treatment with deprenyl loses its effect on antioxidant enzyme activities as well as on survivals of Fischer-344 rats

Glyceraldehyde-3-phosphate Dehydrogenase is a Multifaceted Therapeutic Target

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a glycolytic enzyme whose role in cell metabolism and homeostasis is well defined, while its function in pathologic processes needs further elucidation. Depending on the cell context, GAPDH may bind a number of physiologically important proteins, control their function and correspondingly affect the cell’s fate. These interprotein interactions and post-translational modifications of GAPDH mediate its cytotoxic or cytoprotective functions in the manner of a Janus-like molecule. In this review, we discuss the functional features of the enzyme in cellular physiology and its possible involvement in human pathologies. In the last part of the article, we describe drugs that can be employed to modulate this enzyme’s function in some pathologic states.

What really declines with age? The Hayflick Lecture for 2006 35th American Aging Association

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.

The Necessity of Having a Proper Dose of (-)Deprenyl (D) to Prolong the Life Spans of Rats Explains Discrepancies among Different Studies in the Past

(-)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.

Dose-dependency of Life Span Prolongation of F344/DuCrj Rats Injected with (−)deprenyl

The effect of (-)deprenyl (D) on prolonging survival has previously been reported in different species of animals. In rats, three studies reported a positive effect, while one study reported a shortening of life spans. In the present study, we attempted to clarify past discrepancies in the results based on the speculation that there exists a certain effective dose range for this effect of the drug. F344/DuCrj rats of both sexes began to receive subcutaneous (s.c.) injections of D at the age of 18 months at a dose of 0.25 mg/kg/injection (inj.), 3 times a week. Control animals were given a vehicle (a saline solution). Average life spans of animals (days) were significantly increased in both male (895 +/- 109.7, n=30; 967.8 +/- 88.6, n=30, control vs. D treated, P<0.01, t-test) and female (924.7 +/- 132.2, n=38; 987.1 +/- 133.4, n=39, P<0.05) rats by 8.1% and 6.7%, respectively. We have previously reported that a dose of 0.5mg/kg/inj. (s.c.) significantly increased the life span of male F344 rats, while a dose of 1.0 mg/kg/inj. somewhat shortened the life span, although the difference was not statistically significant. The results of the present study coupled with our previous reports clearly indicate that a proper dose of D within a certain dose range can significantly increase the life span of animals of both sexes, but that a greater dose becomes less effective and may actually adversely affect the life span of rats. The presence of this effective dose range of D may explain discrepancies in the effect of D on life spans of animals previously reported.

Effect of I-deprenyl and gliclazide on oxidant stress/antioxidant status and dna damage in a diabetic rat model

BACKGROUND

This study investigates the possible effect of monoamine oxidase inhibitor (MAOI), selegyline (l-deprenyl), in combination with oral antidiabetic-gliclazide (OAD), in preventing oxidative stress in streptozotocin-induced diabetes model in male Swiss Albino rats by measuring oxidant stress/ DNA damage and antioxidant levels.

METHODS

Diabetic rats were divided into four groups (n = 10) as (1) diabetic untreated (DM), (2) deprenyl treated (DM + D), (3) gliclazide treated (DM + O), and (4) gliclazide and deprenyl treated (DM + O + D). Controls were divided into two groups (n = 8) (1) untreated (C), and (2) deprenyl treated (C + D). Gliclazide 5 mg/kg and/or MAOI 0.25 mg/kg daily were given orally by gavage for 4 weeks. At the end of the 12th week, catalase and superoxide dismutase (SOD) levels in erythrocyte lysates (EL); total antioxidant status (TAS), 8-hydroxy-deoxyguanosine (8-OHdG), malondialdehyde (MDA), and vitamin A and E levels in plasma, MDA, and MAO in liver homogenates were determined.

RESULTS

Diabetic rats showed a decrease in EL-SOD, plasma TAS, and vitamin E, and an increase in plasma 8-OHdG, plasma, and liver MDA levels (p < 0.05). Gliclazide and/or deprenyl decreased 8OHdG levels and increased antioxidant levels and survival when compared with untreated diabetic rats (p < 0.05). The lowest 8-OHdG levels were determined in the DM +O + D group.

CONCLUSIONS

The combined treatment of deprenyl and gliclazide may contribute to the control of the physiopathological mechanisms underlying both the process of aging and type 2 diabetes by reducing oxidant stress and DNA damage, improving antioxidant status, and increasing survival, and may have implications for further clinical studies.

Selegiline attenuates cardiac oxidative stress and apoptosis in heart failure: association with improvement of cardiac function

We have shown recently that selegiline exerts a cardiac neuroprotective effect in chronic heart failure. Since selegiline has an antioxidant antiapoptotic effect, we proposed to determine whether selegiline attenuates cardiac oxidative stress and myocyte apoptosis in chronic heart failure by modulating Bcl-2 and Bax protein expression, and whether the effects are associated with the improvement of cardiac function. Rabbits with rapid cardiac pacing (360 beats/min) and sham operation without pacing were randomized to receive oral selegiline (1 mg/day) or placebo for 8 weeks. Echocardiography was used to measure left ventricular fractional shortening. After 8 weeks of treatment, animals were studied for arterial norepinephrine and left ventricular systolic function (fractional shortening and dP/dt), and were then sacrificed for measuring the stable oxidative product of myocardial mitochondrial DNA (mtDNA) 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), myocyte apoptosis by monoclonal antibody to single stranded DNA, and Bcl-2 and Bax protein expression by Western blot and immunohistochemistry. Rapid cardiac pacing increased plasma norepinephrine, cardiac oxidative stress and myocyte apoptosis, reduced Bcl-2 and the Bcl-2 to Bax ratio. These changes were associated with decreased left ventricular fractional shortening and dP/dt. Selegiline treatment in chronic heart failure animals reduced plasma norepinephrine, cardiac oxidative stress and myocyte apoptosis, prevented the changes of Bcl-2 and Bcl-2 to Bax ratio, and improved left ventricular fractional shortening and dP/dt. The findings suggest that the reduction by selegiline of myocyte apoptosis is related to the decrease of cardiac oxidative stress and the modulation of apoptotic and antiapoptotic proteins. The antioxidant antiapoptotic effects of selegiline are potentially beneficial in the improvement of cardiac function in chronic heart failure.

Effects of short- and long-term (--)-deprenyl administration on mRNA for copper, zinc- and manganese-superoxide dismutase and glutathione peroxidase in rat brain

The effect of short-term (3 weeks, 2 mg/kg day) and long-term (12 and 20 months, 0.5 mg/kg day) administration of (-)-deprenyl on the mRNA expression of three neuroprotective enzymes in subdivisions of rat basal ganglia was investigated. In situ hybridisation histochemistry with oligodeoxynucleotide probes was used to measure levels of copper, zinc superoxide dismutase (Cu,Zn-SOD), manganese superoxide dismutase (Mn-SOD), and glutathione peroxidase (GPX) mRNA. The 3-week administration of (-)-deprenyl caused a significant increase in Cu,Zn-SOD mRNA in the nucleus accumbens (NA) (P<0.05), striatum (CP) (P<0.01), and globus pallidus (GP) (P<0.05), but had no effect on Mn-SOD or GPX mRNA levels throughout basal ganglia. In rats which received (-)-deprenyl for 12 months, there was a significant increase in Mn-SOD mRNA in the NA, CP, GP, and substantia nigra (SN) (all P<0.05); there were no changes in either Cu,Zn-SOD or GPX mRNA. Except for the significant increase in Cu,Zn-SOD mRNA in SN pars compacta (SC) (P<0.05), by 20 months there were almost no differences between (-)-deprenyl-treated and age-matched control animals that had received equivalent injections of saline. We conclude that (-)-deprenyl administration can induce mRNA expression for both forms of SOD, but the effects are variable and not sustained over 20 months.

Why (--)deprenyl prolongs survivals of experimental animals: increase of anti-oxidant enzymes in brain and other body tissues as well as mobilization of various humoral factors may lead to systemic anti-aging effects

(--)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.

Do antioxidant strategies work against aging and age-associated disorders? Propargylamines: a possible antioxidant strategy

The free radical theory of aging was initially proposed by Harman 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, 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. (-)Deprenyl has also been shown to increase superoxide dismutase (SOD) and catalase (CAT) activities selectively in brain dopaminergic tissues. 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 extrabrain catecholaminergic systems such as the heart and kidneys as well. 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, we might be able to advance the elucidation of mechanism(s) of aging based on the free radical theory of aging.