Estradiol alters ethanol-induced effects on beta-endorphin and met-enkephalin levels in specific brain regions of ovariectomized rats.
The present investigation was conducted to evaluate the effects of estradiol on ethanol-induced alterations of beta-endorphin (beta-EN) and met-enkephalin (ME) levels in specific brain regions of ovariectomized rats. Female Sprague-Dawley rats (100-124 g) adapted to a 12-hour light, 12-hour dark illumination cycle were used in these studies. Animals were ovariectomized under pentobarbital anesthesia. After a recovery period of 14 days, ethanol (3 g/kg as 22.5% solution in saline, i.p.), estradiol (50 micrograms/kg in 0.2 ml of olive oil, s.c. in the dorsal neck region), or a combination of ethanol and estradiol were administered to rats at 11:00 h. Control animals were injected intraperitoneally with 2 ml saline and subcutaneously with 0.2 ml olive oil. Animals were sacrificed by decapitation 2 h later. The brains were immediately removed; the cortex, hippocampus, hypothalamus, and midbrain were dissected and their beta-EN and ME levels were measured by radioimmunoassay. Ethanol administration significantly decreased both beta-EN and ME levels in the hypothalamus. Administration of estradiol alone also resulted in a significant decrease in beta-EN and ME levels in the hypothalamus. Additionally, concurrent administration of ethanol and estradiol showed a decrease in the levels of beta-EN and ME in the hypothalamus. Co-administration of ethanol with estradiol also caused a significant decrease in the levels of beta-EN in midbrain. However, ME levels were increased in the midbrain after concurrent administration of estradiol and ethanol. ME levels also increased in the hippocampus and cortex after co-administration of estrogen and ethanol. These results clearly indicate that estradiol significantly alters ethanol-induced effects on beta-EN and ME levels in specific brain regions of ovariectomized rats. The present findings may in part explain sex differences in alcohol effects.
Carter
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College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee 32307, USA.
Soliman
M R
MR
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D002540:Cerebral Cortex / Q000737:chemistry / Q000187:drug effects; D004347:Drug Interactions; D004744:Enkephalin, Methionine / Q000032:analysis*; D004958:Estradiol / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D006624:Hippocampus / Q000737:chemistry / Q000187:drug effects; D007031:Hypothalamus / Q000737:chemistry / Q000187:drug effects; D008636:Mesencephalon / Q000737:chemistry / Q000187:drug effects; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D001615:beta-Endorphin / Q000032:analysis*
D000431:Ethanol; D004958:Estradiol; D004744:Enkephalin, Methionine; D001615:beta-Endorphin