Takako Yamamoto

Enhancing effect of rasagiline on superoxide dismutase and catalase activities in the dopaminergic system in the rat

Rasagiline [N-propargyl-l(R)-aminoindan] is a selective irreversible MAO-B inhibitor as is (-)deprenyl. The effect of the drug on antioxidant enzyme activities on dopaminergic tissue was examined in male F-344 rats (8.5-months-old). Two experimental groups were infused subcutaneously with rasagiline saline solutions by means of osmotic minipumps implanted subcutaneously in the back of the rats. Control animals were also similarly implanted with saline filled mini-pumps. Three-and-one-half weeks later, animals were sacrificed and selected tissue samples removed from brain, kidney and heart. Two doses of rasagiline (0.5 mg/kg/day, 1.0 mg/kg/day, both for 3.5 weeks) significantly increased catalase activities about 2-fold in substantia nigra and striatum but not in hippocampus. Interestingly, in both renal cortex and medulla. catalase (CAT) activities were significantly increased. Both Mn- and Cu,Zn-superoxide dismutase (SOD) activities were increased 2 to 4 fold in substantia nigra, striatum and renal cortex and heart. Several groups, including our own have reported an extension of survival of deprenyl-treated animals of different species. Although the mechanism(s) of the life extension by deprenyl remains unresolved, it would be interesting to investigate the effect of rasagiline on the survival of animals, since deprenyl also was shown to increase antioxidant enzyme activities in brain dopaminergic regions.

Selective nitration of mitochondrial complex I by peroxynitrite: involvement in mitochondria dysfunction and cell death of dopaminergic SH-SY5Y cells

Summary. 3-Nitrotyrosine (3-NT) is a specific marker of protein nitration by peroxynitrite (ONOO−) produced from nitric oxide and superoxide. Increase in 3-NT containing protein (3-NT protein) was reported in brains from patients with some neurodegenerative disorders and aging. In this paper, intracellular localization of 3-NT protein was examined in dopaminergic SH-SY5Y cells using the selective antibody against protein-bound 3-NT. 3-NT protein was detected in plasma membrane/nucleus and mitochondria fractions, and interestingly in polypeptide composition of mitochondrial complex I. ONOO−-generating SIN-1 induced apoptotic cell death with concomitant increase in 3-NT protein and reduction in mitochondrial ATP synthesis. In addition, an inhibitor of proteasomes, carbobenzoxy-L-isoleucyl-γ-t-butyl-L-glutamyl-L-alanyl-L-leucinal, enhanced the effects of ONOO−. These results suggest that ONOO− may induce mitochondrial dysfunction and cell death in neurons through nitration of mitochondrial complex I subunits.

Mechanism underlying anti-apoptotic activity of a (−)deprenyl-related propargylamine, rasagiline

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 (DeltaPsim), followed by caspase 3 activation. Rasagiline prevented the loss of DeltaPsim, 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 Parkinsons disease.

Effects of Pre-exercise Listening to Slow and Fast Rhythm Music on Supramaximal Cycle Performance and Selected Metabolic Variables

We examined the effect of listening to two different types of music (with slow and fast rhythm), prior to supramaximal cycle exercise, on performance, heart rate, the concentration of lactate and ammonia in blood, and the concentration of catecholamines in plasma. Six male students participated in this study. After listening to slow rhythm or fast rhythm music for 20 min, the subjects performed supramaximal exercise for 45 s using a cycle ergometer. Listening to slow and fast rhythm music prior to supramaximal exercise did not significantly affect the mean power output. The plasma norepinephrine concentration immediately before the end of listening to slow rhythm music was significantly lower than before listening (p < 0.05). The plasma epinephrine concentration immediately before the end of listening to fast rhythm music was significantly higher than before listening (p < 0.05). The type of music had no effect on blood lactate and ammonia levels or on plasma catecholamine levels following exercise. In conclusion, listening to slow rhythm music decreases the plasma norepinephrine level, and listening to fast rhythm music increases the plasma epinephrine level. The type of music has no impact on power output during exercise.

Effect of gender differences and voluntary exercise on antioxidant capacity in rats

The effects of gender difference and voluntary exercise on antioxidant capacity in rats were evaluated. The subjects were divided into two groups, physically active and sedentary. In the sedentary group, the level of hydroxyl radical in the liver was higher (P<0.001) in male rats than in female rats, however, in the physically active group, the level in male rats was lower (P<0.05) than in female rats. The levels of reduced glutathione (GSH) in physically active males and females were higher compared to those in the sedentary group. The physically active group also showed an increase in antioxidant enzymes, such as glutathione peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase activities. The level of liver GSH was higher in physically active females than in physically active males. For both groups, GPx and GR activities in females were significantly higher than in males. These results indicate that female rats have an intrinsically higher antioxidant capacity, which resulted in increased levels of GSH via the glutathione redox cycle and gamma-glutamyl cycle enzymes. The adaptation to altered antioxidant capacity, induced by physical activity, appeared to be affected by gender differences.

Pharmacological interventions in aging and age-associated disorders: potentials of propargylamines for human use.

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 drugs 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 Parkinsons disease was given to monkeys, SOD and CAT activities were increased in striatum of these monkeys, which suggests potential for the drugs 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.

Do Antioxidant Strategies Work against Aging and Age‐associated Disorders?

Abstract: The free radical theory of aging was initially proposed by Harman 1 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.

Relation between voluntary physical activity and oxidant/antioxidant status in rats.

The relationship between voluntary distance running and antioxidant capacity was studied in rats after three weeks voluntary running. Hydroxyl radical level, reduced glutathione level, activities of glutathione reductase and superoxide dismutase were measured in plasma, liver, brain, soleus and gastrocnemius white muscle. Hydroxyl radical level of liver negatively correlated with the running distance (r=-0.616, P<0.001). The reduced glutathione levels of liver and brain increased depending on the running distance and the correlation was confirmed between them in liver (r=0.638, P<0.01) and brain (r=0.766, P<0.001). The hydroxyl radical level in liver positively correlated with the activities of glutathione reductase (r=0.464, P<0.05) and superoxide dismutase (r=0.549, P<0.05). A significant positive correlation was detected between the hydroxyl radical level and superoxide dismutase activity in brain (r=0.488, P<0.05). These results demonstrate that physical activity correlates well with glutathione level and anti-oxidant enzyme activities in liver, suggesting a close relation between physical activity and induction of antioxidant systems.

Effect of Hypoxia on Norepinephrine of Various Tissues in Rats

Abstract Objective.—To determine the effects of hypoxia and hypoxic exercise (HE) on the norepinephrine levels of various tissues in rats. Methods.—Male Wistar rats were randomly assigned to 3 groups: an HE group (n = 6), a hypoxic-sedentary (HS) group (n = 6), and a normoxic-sedentary (NS) group (n = 6). The HE rats had access, ad lib, to an exercise wheel for 8 weeks. HE and HS rats were maintained in a normobaric hypoxic chamber with an Fio2 of 16%. Norepinephrine levels were measured and compared in liver, heart, diaphragm, soleus, and gastrocnemius tissues from the 3 groups. Results.—Liver norepinephrine levels in the HE and HS groups were significantly lower than the levels in the NS group (P < .05). No significant difference was found in liver norepinephrine levels between the HE and the HS groups. The heart norepinephrine levels in the NS group were significantly lower than the levels in the HE (P < .01) and HS groups (P < .01). In contrast, no significant differences were found in the norepinephrine levels for the diaphragm and soleus muscle among the 3 groups. The norepinephrine levels in the gastrocnemius white muscles were significantly higher in the HS group than in the HE (P < .05) and NS groups (P < .01). P < .01 represents a significant difference at the level of 1%. Conclusions.—This study demonstrated that hypoxia and HE both elicit a decreased sympathetic response in the liver tissue of male Wistar rats but cause an increased response in heart tissue. These results suggest that the sympathetic responses to long-term hypoxia and HE training are different in various rat tissues.

Effect of varying light intensity on maximal power production and selected metabolic variables.

This study was designed to examine the effect of exposure to two levels of light intensity (bright; 5000 lux, dim; 50 lux) prior to supramaximal cycle exercise on performance and metabolic alterations. The exercise was performed after bright and dim light exposure for 90 minutes. Ten male long-distance runners volunteered to take part in the study. They performed 45-sec supramaximal exercise using a cycle ergometer in a 500-lux. Mean power output was measured during the exercise. Lactate and ammonia in the blood and epinephrine and norepinephrine concentrations in plasma were measured at rest immediately after bright and dim light exposures and after the exercise. Bright and dim light exposure priors to exercise did not significantly affect the power output during the exercise. Blood glucose concentration immediately after exercise and plasma epinephrine during the resting period were significantly lower after bright light exposure compared with dim light exposure (p < 0.05). No significant difference was found in blood lactate, ammonia, or plasma norepinephrine levels after exercise following bright and dim light exposures. This study demonstrated that bright light stimulation prior to supramaximal exercise decreases glucose and epinephrine levels, but is not related to physical performance.