“…In humans, levels of MEnk in blood were decreased in chronic alcoholics in two of three studies (Govini et al 1983(Govini et al , 1987Vescovi et al, 1992). In rodents and dogs, levels in the brain and blood are altered by acute and chronic administration of ethanol (Gianoulakis, 1989;Hong et al, 1981;Medbak et al, 1989;Ng et al, 1996;Schulz et al, 1980;Seizinger et al, 1983). Treatment with enkephalins, their analogs, or blockers of their enzymatic degradation can decrease ethanol drinking or prevent alcohol withdrawal seizures (Ho and Rossi, 1982;Sandi et al, 1990;Schwartz et al, 1981), and antagonists specific for the ␦-receptor suppress drinking (Krishnan-Sarin et al, 1995).…”