No abstract

Chronic alcohol administration leads to hepatic membrane alterations which, at least in part, are due to lipid peroxidation and may contribute to the toxicity of ethanol at the level of the hepatocyte. Because changes in testicular function also occur after chronic administration of ethanol to rats, we evaluated testicular mitochondria for evidence of alcohol-associated peroxidation injury which might contribute to the gonadal injury that occurs with prolonged use of the drug. Lipid peroxidation was assessed through measurement of diene conjugates, polyenoic fatty acid composition, malonaldehyde formation, and testicular reduced glutathione levels. Compared to isocalorically matched dextrimaltose-fed controls (ISO), rats fed alcohol (ETOH) for 50 days had a decreased content of polyenoic acids and a compensatory increase in saturated fatty acids [ETOH, 50.69 +/- 0.65% (by wt); ISO, 52.93 +/- 0.72 (mean +/- SE); P less than 0.01]. This decrease in polyunsaturated fatty acid content was accompanied by an increase in diene conjugates in testicular mitochondria (ETOH, 0.455 +/- 0.053 OD units at 233 nm/mg lipid; ISO, 0.382 +/- 0.045; P less than 0.05). An increase in malonaldehyde formation also was observed in the alcohol-fed rats compared to the control level (ETOH, 21.39 +/- 1.67 nmol/mg protein; ISO, 17.50 +/- 1.39; P less than 0.05) as well as a decrease in glutathione content (ETOH, 1218 +/- 89 micrograms GSH/testes; ISO, 1638 +/- 89; P less than 0.05). Taken together, these findings support the concept that lipid peroxidation may be an important mechanism responsible, at least in part, for the toxic effect of ethanol on the testes.

No abstract

Phytoestrogenic substances have previously been isolated and identified in two alcoholic beverages: bourbon and beer. To delineate the relative potencies of the estrogenic substances of plant origin thus far identified in these commonly consumed alcoholic beverages, we evaluated the ability of biochanin A, beta-sitosterol, genistein, and daidzein to bind to cytosolic estrogen receptor binding sites. The in vitro studies demonstrated that each of the contained substances was capable of effectively competing for cytosolic estrogen receptor binding sites of rat liver and uterus. Further, the two phytoestrogenic constituents of bourbon, beta-sitosterol and biochanin A, were less potent than those present in beer. Given the high concentration of beta-sitosterol in bourbon, we chose to evaluate the estrogenicity of beta-sitosterol in vivo using ovariectomized rats. beta-sitosterol was administered either daily or intermittently at 3 doses, based on amounts previously determined to be present in bourbon. The in vivo studies demonstrated that beta-sitosterol is capable of producing a weak estrogenic effect only at the lowest dose (6.2 micrograms/dl) administered intermittently. These responses suggest that beta-sitosterol may be weakly estrogenic at low doses, but is unable to maintain such an effect at higher doses.

Oxygen free radical (OFR) formation and lipid peroxidation (LP) were measured in freshly isolated perfused rat hepatocytes during 2-h reoxygenation after 2.5 h of anoxia. Superoxide anions and hydrogen peroxide (H2O2) were detected by enhanced chemiluminescence. LP and cell damage were assessed by measuring malondialdehyde (MDA) and lactic dehydrogenase (LDH) release, respectively. During anoxia, the chemiluminescence decreased to background levels and MDA remained constant, whereas LDH release increased progressively to 168 +/- 22 mU/min in 2.5 h. During reoxygenation after a 2.5-h period of anoxia, superoxide formation increased rapidly to 125 +/- 16 nA and then it declined progressively toward the control level. At the same time, H2O2 production exhibited a biphasic pattern with an initial peak reaching 78 +/- 16 nA at 15.5 +/- 1 min, followed by a slower increase to 92 +/- 14 nA during the 2nd h. LDH release increased from 168 +/- 22 to 286 +/- 32 mU/min in the first 30 min of reoxygenation and then declined toward the control rate during the 2nd h. MDA release increased continuously from 1.16 +/- 0.18 to 7.75 +/- 0.74 pmol/min. OFR generation occurred 15-30 min before the peak rise in LDH. Moreover, after shorter periods of anoxia (1-2 h), hepatocytes produced measurable amount of OFR but without a significant increase in LDH release. These results demonstrate that 1) isolated liver parenchymal cells generate measurable amounts of superoxide anions and of H2O2 during reoxygenation after 1-2.5 h of anoxia, 2) lipid peroxidation follows the formation of OFR, and 3) reoxygenation injury is correlated to OFR generation but not to lipid peroxidation.