Effect of ethanol administration on activities of some lysosomal hydrolases in the mouse

Melatonin and vitamin C ameliorate alcohol-induced oxidative stress and eNOS expression in rat kidney

OBJECTIVES

The aim of this study was to investigate the preventive effects of melatonin and vitamin C as antioxidants on renal injury in chronic alcohol consumption.

MATERIALS AND METHODS

A total of 24 adult male Wistar rats weighing 200-250 g were used in the study. Rats were divided into four equal groups. Group I (control): rats were not fed on alcohol; Group II: rats were fed on alcohol; Group III: rats were fed on alcohol and 40 mg/kg vitamin C; and Group IV: rats were fed on alcohol and 4 mg/kg melatonin.

RESULTS

Light microscopic examination revealed atrophic renal corpuscles, dilatation and congestion of the peritubular vessels, and renal corpuscles with obscure Bowman's space and a few foamy-appearing tubules due to alcohol consumption were observed. Expression of endothelial nitric oxide synthase (eNOS) was localized to glomerulus, distal, and collector tubules. eNOS staining decreased in alcohol treatment group and melatonin and vitamin C encore increased expression pattern of eNOS. Alcohol consumption increased malondialdehyde (MDA) level and superoxide dismutase (SOD) and catalase (CAT) activities significantly in the alcohol consumption groups compared with that in the control group, while in melatonin give group just MDA level was decreased statistically significant and SOD and CAT activities were also decreased numerically compared with the alcohol consumption groups.

CONCLUSIONS

These results indicated that chronic alcohol consumption caused renal damage by increased lipid peroxidation and melatonin and vitamin C administration produced in some degree protection against alcohol-induced damage.

Ethanol inhibitory effect on rat kidney brush border aminopeptidases

BACKGROUND/AIM

Confusing data have been reported about the effect of ethanol or its metabolic products on blood pressure. The pressor agent, angiotensin II (Ang II), is found to be susceptible to degradation by different enzymes known as angiotensinases. We have studied the effects of ethanol and L-NAME, an inhibitor of nitric oxide synthase, consumption on rat serum and kidney ectoenzymes: aminopeptidase N (APN) and aminopeptidase A (APA).

METHODS

Enzymatic activity of both enzymes was determined spectrophotometrically in serum and 10% homogenates of the rat kidney cortex using appropriate chromogenic substrates.

RESULTS

After 2 weeks of treatment with ethanol and L-NAME, blood urea and creatinine levels were significantly increased. The activities of APN (EC 3.4.11.2) and APA (EC 3.4.11.7) were reduced in serum as well as in kidney tissue during this period. L-NAME significantly attenuated activities of both enyzmes. Ethanol and L-NAME given simultaneously did not have an additional effect on the activity of investigated enzymes.

CONCLUSION

Hypertension caused by chronic ethanol treatment as well as L-NAME administration could be associated with the reduction of APN and APA activity. Possible ethanol- and L-NAME-mediated inhibition of angiotensins degrading aminopeptidases could potentiate their effects on blood pressure.

Ethanol-induced alterations of the antioxidant defense system in rat kidney

We report here the effects of chronic ethanol consumption on the antioxidant defense system in rat kidney. Thirty-two male Wistar rats were randomly divided in two identical groups and were treated as follows: control group (water for fluid) and the ethanol-fed group (2 g/kg body weight/24 h). The animals were sacrificed after 10 weeks, and respectively 30 weeks of ethanol consumption, and the renal tissue was isolated and analyzed. Results revealed that kidney alcohol dehydrogenase activities increased significantly after ethanol administration, but the electrophoretic pattern of alcohol dehydrogenase isoforms was unmodified. The SDS polyacrylamidegel electrophoretic study of kidney proteins has revealed the appearance of two new protein bands after long-term ethanol consumption. The kidney reduced glutathione/oxidized glutathione ratio decreased, indicating an oxidative stress response due to ethanol ingestion. The malondialdehyde contents and xanthine oxidase activities were unchanged. The antioxidant enzymatic defense system showed a different response during the two periods of ethanol administration. After 10 weeks, catalase, glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase were activated, while superoxide dismutase, glutathione transferase, and gamma-glutamyltranspeptidase levels were stationary. After 30 weeks, superoxide dismutase and glutathione peroxidase activities were unmodified, but catalase, glutathione transferase, gamma-glutamyltranspeptidase, glutathione reductase, and glucose-6-phosphate dehydrogenase activities were significantly increased. Remarkable changes have been registered after 30 weeks of ethanol administration for glutathione reductase and glucose-6-phosphate dehydrogenase activities, including an increase by 106 and 216' of control values, respectively. These results showed specific changes in rat kidney antioxidant system and glutathione status as a consequence of long-term ethanol administration.

Ethanol modulates neuropeptide-degrading aminopeptidases at synapse level in calcium-dependent conditions

AIMS

To investigate the role of aminopeptidases in the pathways to peptides neurotransmission/neuromodulation ending in the actions of ethanol (EtOH) on the brain.

METHODS

The effects of EtOH on alanyl-, arginyl-, cystyl-, leucyl- and tyrosyl-aminopeptidase activities were studied under basal/resting and K+-stimulated conditions at the synapse level, using mouse frontal cortex synaptosomes and their incubation supernatant in a Ca2+-containing or Ca2+-free medium.

RESULTS

Under basal conditions, synaptosome aminopeptidase activities showed an inhibitory or biphasic response depending on the concentration of EtOH used and the aminopeptidase assayed, whereas supernatant activities showed a more complex response. Under K+-stimulated conditions, EtOH inhibited all synaptosome aminopeptidases assayed in presence of Ca2+. However, in absence of Ca2+, different responses were obtained depending on the concentration of EtOH used. In the supernatant, the highest concentration of EtOH inhibited the K+-stimulated increase on aminopeptidase activities, although the lowest concentration enhanced the release in presence of Ca2+. In absence of it, EtOH blocked the K+-stimulated decrease or increased the activity depending on the concentration of EtOH used.

CONCLUSIONS

The changes on aminopeptidase activities induced by EtOH may reflect the functional status of their corresponding endogenous substrates. EtOH may influence opioid peptides, oxytocin, vasopressin and the brain renin-angiotensin system through their degrading enzymes.