Effect of physical exercise on changes in activities of creatine kinase, cytochrome c oxidase and ATP levels caused by ovariectomy.

The reduction in the secretion of ovarian hormones, principally estrogen, is a consequence of menopause. Estrogens act primarily as female sex hormones, but also exert effects on different physiological systems including the central nervous system. The treatment normally used to reduce the symptoms of menopause is the hormone therapy, which seems to be effective in treating symptoms, but it may be responsible for adverse effects. Based on this, there is an increasing demand for alternative therapies that minimize signs and symptoms of menopause. In the present study we investigated the effect of ovariectomy and/or physical exercise on the activities of energy metabolism enzymes, such as creatine kinase (cytosolic and mitochondrial fractions), pyruvate kinase, succinate dehydrogenase, complex II, cytochrome c oxidase, as well as on ATP levels in the hippocampus of adult rats. Adult female Wistar rats with 90 days of age were subjected to ovariectomy (an animal model widely used to mimic the postmenopausal changes). Thirty days after the procedure, the rats were submitted to the exercise protocol, which was performed three times a week for 30 days. Twelve hours after the last training session, the rats were decapitated for subsequent biochemical analyzes. Results showed that ovariectomy did not affect the activities of pyruvate kinase, succinate dehydrogenase and complex II, but decreased the activities of creatine kinase (cytosolic and mitochondrial fractions) and cytochrome c oxidase. ATP levels were also reduced. Exercise did not produce the expected results since it was only able to partially reverse the activity of creatine kinase cytosolic fraction. The results of this study suggest that estrogen deficiency, which occurs as a result of ovariectomy, affects generation systems and energy homeostasis, reducing ATP levels in hippocampus of adult female rats.

Maternal depression model: long-lasting effects on the mother following separation from pups.

This study was carried out to ascertain the effects of maternal separation (3 h per day) of mothers from their pups in the neonatal period in rats, which has been suggested to induce a depressive-like state, would have long lasting effects on different parameters including hippocampal Na(+), K(+)-ATPase activity, NO production, free radical production and antioxidant enzymes activities in dams. Fourty-eight Wistar rats were divided into 3 groups: control, brief separation (10 min) and long separation (3 h). The neonatal interventions were done on postpartum days 1-10. At 35 days post-partum the dams were killed and the hippocampal Na(+), K(+)-ATPase activity were measured, as well as the activity of the antioxidant enzymes catalase, glutathione peroxidase, superoxide dismutase, free radicals production, and the production of nitric oxide. Hippocampal Na(+), K(+)-ATPase activity was decreased in the brief separated group and in dams subjected to 3 h separation from their pups. A reduction in nitric oxide levels in the hippocampus in dams of the long separated group was also observed. It is concluded that the withdrawal of pups from their mothers make the mothers more susceptible to the development of neurochemical alterations that could be related to depressive features.

Ovariectomy alters energy metabolism in rat striatum: effect of supplementation with soy diet rich in isoflavones.

In the present study we investigated the effect of ovariectomy on some parameters of energy metabolism, namely Na(+),K(+)-ATPase and pyruvate kinase activities, as well as the mitochondrial respiratory chain enzymes activities succinate dehydrogenase, complex II and cytochrome c oxidase in rat striatum. The influence of soy diet rich in isoflavones on the effects elicited by ovariectomy on enzyme activities was also evaluated. Female adult Wistar rats were assigned to one of the following groups: sham (submitted to surgery without removal of the ovaries) and ovariectomized. Seven days after surgery animals were fed for 30 days on a special diet with soy protein or a standard diet with casein (control). Rats were sacrificed after treatment and the striatum was dissected. Results showed that rats subjected to ovariectomy presented a significant increase in Na(+),K(+)-ATPase, succinate dehydrogenase and complex II activities. Treatment with isoflavones-rich soy diet was able to reverse the increase of Na(+),K(+)-ATPase activity, but was not effective in reversing the changes caused by ovariectomy on succinate dehydrogenase and complex II activities. Since ovariectomy mimics postmenopausal changes, our findings suggest that dysfunction of brain energy metabolism may be related to neurological symptoms observed in some postmenopausal women.

Proline impairs energy metabolism in cerebral cortex of young rats.

In the present study we investigated the effect of acute hyperprolinemia on some parameters of energy metabolism, including the activities of succinate dehydrogenase and cytocrome c oxidase and (14)CO(2) production from glucose and acetate in cerebral cortex of young rats. Lipid peroxidation determined by the levels of thiobarbituric acid-reactive substances, as well as the influence of the antioxidants alpha-tocopherol plus ascorbic acid on the effects elicited by Pro on enzyme activities and on the lipid peroxidation were also evaluated. Wistar rats of 12 and 29 days of life received one subcutaneous injection of saline or proline (12.8 or 18.2 micromol/g body weight, respectively) and were sacrificed 1 h later. In another set of experiments, 5- and 22-day-old rats were pretreated for a week with daily intraperitoneal administration of alpha-tocopherol (40 mg/kg) plus ascorbic acid (100 mg/kg) or saline. Twelve hours after the last injection, rats received one injection of proline or saline and were sacrificed 1 h later. Results showed that acute administration of proline significantly reduced cytochrome c oxidase activity and increased succinate dehydrogenase activity and (14)CO(2) production in cerebral cortex, suggesting that Pro might disrupt energy metabolism in brain of young rats. In addition, proline administration increased the thiobarbituric acid-reactive substances levels, which were prevented by antioxidants. These findings suggest that mitochondrial dysfunction and oxidative stress may be important contributors to the neurological dysfunction observed in some hyperprolinemic patients and that treatment with antioxidants may be beneficial in this pathology.

Homocysteine induces oxidative stress, inflammatory infiltration, fibrosis and reduces glycogen/glycoprotein content in liver of rats.

Hyperhomocysteinemia has been related to various diseases, including homocystinuria, neurodegenerative and hepatic diseases. In the present study we initially investigated the effect of chronic homocysteine administration on some parameters of oxidative stress, named total radical-trapping antioxidant potential, total antioxidant reactivity, catalase activity, chemiluminescence, thiobarbituric acid-reactive substances, and total thiol content in liver of rats. We also performed histological analysis, evaluating steatosis, inflammatory infiltration, fibrosis, and glycogen/glycoprotein content in liver tissue sections from hyperhomocysteinemic rats. Finally, we evaluated the activities of aminotransferases in liver and plasma of hyperhomocysteinemic rats. Wistar rats received daily subcutaneous injection of Hcy from their 6th to their 28th day of life. Twelve hours after the last injection the rats were sacrificed, liver and plasma were collected. Hyperhomocysteinemia decreased antioxidant defenses and total thiol content, and increased lipid peroxidation in liver of rats, characterizing a reliable oxidative stress. Histological analysis indicated the presence of inflammatory infiltrate, fibrosis and reduced content of glycogen/glycoprotein in liver tissue sections from hyperhomocysteinemic rats. Aminotransferases activities were not altered by homocysteine. Our data showed a consistent profile of liver injury elicited by homocysteine, which could contribute to explain, at least in part, the mechanisms involved in human liver diseases associated to hyperhomocysteinemia.

Chronic hyperhomocysteinemia alters antioxidant defenses and increases DNA damage in brain and blood of rats: protective effect of folic acid.

We have previously demonstrated that acute hyperhomocysteinemia induces oxidative stress in rat brain. In the present study, we initially investigated the effect of chronic hyperhomocysteinemia on some parameters of oxidative damage, namely total radical-trapping antioxidant potential and activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase), as well as on DNA damage in parietal cortex and blood of rats. We also evaluated the effect of folic acid on biochemical alterations elicited by hyperhomocysteinemia. Wistar rats received daily subcutaneous injection of Hcy (0.3-0.6 micromol/g body weight), and/or folic acid (0.011 micromol/g body weight) from their 6th to their 28th day of life. Twelve hours after the last injection the rats were sacrificed, parietal cortex and total blood was collected. Results showed that chronic homocysteine administration increased DNA damage, evaluated by comet assay, and disrupted antioxidant defenses (enzymatic and non-enzymatic) in parietal cortex and blood/plasma. Folic acid concurrent administration prevented homocysteine effects, possibly by its antioxidant and DNA stability maintenance properties. If confirmed in human beings, our results could propose that the supplementation of folic acid can be used as an adjuvant therapy in disorders that accumulate homocysteine.