The role of Na,K-ATPase in human sperm motility

A fourth Na,K-ATPase alpha isoform, which was found to be abundant in testes, was proved to be a catalytical subunit of the enzyme. Recently, it has been shown that the alpha 4 isoform along with alpha 1 is expressed in the midpiece of the flagellum of mature rat sperm and the inhibition of alpha 4 with ouabain led to sperm immotility. In this study, sperm from 135 males with normal semen profile and 50 males with oligoasthenospermia were treated with 10(-5) and 10(-2) M ouabain solutions to inhibit alpha 4, and alpha 4 plus alpha 1 isoforms, respectively. In males with normal semen profile, sperm motility has been demonstrated to decrease with time to almost the same level with both ouabain solutions. In oligoasthenospermic males motility was also found almost completely lost. These observations showed us that the alpha 4 isoform may be held responsible for human sperm motility

Effect of peroxynitrite on glutaredoxin

Glutaredoxin is an important enzyme in thiol homeostasis. As a thioltransferase, it reduces oxidized thiols. It also has dehydroascorbate reductase (DHAR) activity to reduce dehydroascorbate (DHA) to ascorbic acid. Peroxynitrite (ONOO-) is one of the most active elements of oxidative stress that can be formed wherever nitric oxide and superoxide are produced simultaneously. ONOO- is known to react with free thiols easily. To observe the effect of ONOO- on glutaredoxin, rat liver cytosolic fractions were incubated with 0-250 muM ONOO-. Thioltransferase activity was found to be decreased as ONOO- concentration increased. The inhibition was not reversible with dithiothreitol (DTT). In cytosol besides glutaredoxin, another enzyme with DHAR activity is also present. In our study, the cytosolic DHAR activity which consisted both enzymes, was also inhibited by ONOO-, but DTT was able to return the activity almost completely

In vitro effects of peroxynitrite on human spermatozoa

In the present study, the in vitro effects of peroxynitrite on sperm motility, lipid peroxidation and sulfhydryl content were examined. Sperm percentage motility and movement characteristics were assessed by a computer-assisted system. Lipid peroxidation was measured by determining malondialdehyde levels using the thiobarbituric acid (TBA) method. Sperm sulfhydryl content was measured by a spectrophotometric method based on reduction of 5,5'-dithiobis-(2-nitrobenzoic acid) by sulfhydryl groups. Percentage motility, movement characteristics and sulfhydryl content decreased significantly in peroxynitrite-treated samples compared to decomposed peroxynitrite-treated samples. Lipid peroxidation in peroxynitrite-treated samples was significantly higher than in decomposed peroxynitrite-treated samples. These results indicate that peroxynitrite anion may cause sperm dysfunction through lipid peroxidation stimulation and total SH depletion

Betaine or taurine administration prevents fibrosis and lipid peroxidation induced by rat liver by ethanol plus carbon tetrachloride intoxication

The aim of this study was to investigate the effect of betaine or taurine on liver fibrogenesis and lipid peroxidation in rats. Fibrosis was induced by treatment of rats with drinking water containing 5% ethanol and CCl4 (2 x weekly, 0.2 ml/kg, i.p.) for 4 weeks. Ethanol plus CCl4 treatment caused increased lipid peroxidation and disturbed antioxidant system in the liver. Histopathological findings suggested that the development of liver fibrosis was prevented in rats treated with betaine or taurine (1% v/v in drinking water) together with ethanol plus CCl4 for 4 weeks. When hepatic taurine content was depleted with beta-alanine (3% v/v in drinking water), portal-central fibrosis induced by ethanol + CCl4 treatment was observed to proceed cirrhotic structure. Betaine or taurine was also found to decrease serum transaminase activities and hepatic lipid peroxidation without any change in hepatic antioxidant system in rats with hepatic fibrosis. In conclusion, the administration of betaine or taurine prevented the development of liver fibrosis probably associated with decreased oxidative stress

Effect of vitamin C on glutathione and lipid peroxide levels in rats exposed to water-immersion restraint stress

We have investigated the effect of vitamin C (vit C) on malondialdehyde (MDA) and glutathione (GSH) levels in several tissues of rats treated with water-immersion restraint (WIR) stress. Hepatic and intestinal MDA levels increased significantly but GSH content remained unchanged after WIR stress. MDA levels declined following vit C supplementation. On the other hand, MDA and GSH levels were unchanged although ulcerogenic injury was seen in the stomach. Microscopically, this injury was reduced in the rats who received vit C. These results indicate that vit C may have a protective effect in stress-induced lipid peroxidation and gastric ulceration. Med Sci Res 26:595-597 (C) 1998 Lippincott Wiliiams & Wilkins

The effect of carnosine treatment on prooxidant-antioxidant balance in liver, heart and brain tissues of male aged rats

Carnosine (beta-alanyl-l-histidine) is a dipeptide with antioxidant properties. Oxidative damage by free radicals is one of the mechanisms underlying the aging process. This study was done to investigate the effects of carnosine treatment on lipid peroxidation and antioxidant status of liver, heart, brain in male young and aged rats. At the initiation of study, young and aged rats were 5 and 22 months old, respectively. Carnosine (250 mg/kg, daily, i.p.) was administered for 1 month to rats. At the end of this period, malondialdehyde (MDA) and diene conjugate (DC) and protein carbonyl (PC) levels, glutathione (GSH), vitamin E and vitamin C levels and Cu,Zn-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione transferase (GST) activities were determined in tissues of carnosine-treated young and old rats. Liver and heart, but not brain MDA and DC levels increased significantly in aged rats as compared to young rats. Liver PC levels were also significantly elevated. Significant decreases in GSH and vitamin C levels and SOD activities were detected in liver of aged rats, but vitamin E levels and GSH-Px and GST activities remained unchanged. Non-enzymatic and enzymatic antioxidants did not change in heart and brain of aged rats. Carnosine treatment decreased high MDA, DC and PC levels and caused significant increases in vitamin E level and SOD activity in the liver of aged rats. There were no changes in non-enzymatic and enzymatic antioxidants in the heart and brain of carnosine-treated aged rats. In conclusion, carnosine treatment was found to be useful in the decrease of age-related oxidative stress in the liver

Mitochondrial lipid peroxidation and antioxidant system in aged rats

Mitochondria are especially important in cellular senescence since reactive oxygen species (ROS) have been found to be generated constantly as an endogen threat. On the other hand, mitochondrial defence depends mainly on glutathione (GSH), superoxide dismutase (SOD) and glutathione peroxidase (GP(x)). In this study, liver and brain mitochondria of 6- and 22-month-old rats were investigated. Liver mitochondrial malondialdehyde (MDA) levels were found increased, whereas mitochondrial GSH was decreased. SOD activity has been observed elevated, whereas GP(x) was unchanged. However, brain mitochondrial MDA, GSH and SOD and GP(x) activites were found unchanged in old rats. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved