Acute and chronic ethanol treatment changes endorphin levels in brain and pituitary

Abstract

Acute ethanol administration increased methionine-enkephalin (met-enkephalin) and β-endorphin levels in distinct areas of the rat brain, whereas chronically supplied ethanol caused a depression of met-enkephalin and β-endorphin levels in most of the brain areas investigated. The β-endorphin content of the intermediate/posterior lobe of the pituitary of rats and guinea pigs decreased by 70%. Withdrawal of ethanol resulted in a complete recovery of endorphin levels in brain and pituitary within two weeks. Whether the observed alterations in endorphin concentrations are causally related to the primary mechanisms under-lying alcohol dependence is uncertain, since no obvious signs of physical dependence were observed in treated animals.