Light Alcohol Consumption Linked to β-Endorphin Release
Findings in rodents' midbrain area suggest role in ethanol reward and reinforcement
THURSDAY, March 26 (HealthDay News) -- Alcohol consumption, up to moderate levels, may increase β-endorphin release in the brain and play a role in ethanol reward, according to research published online March 19 in Alcoholism: Clinical and Experimental Research.
Samuel Jarjour, of McGill University in Montreal, Canada, and colleagues gave intraperitoneal injections of saline or alcohol to male Sprague-Dawley rats at a variety of dosages (0.8 to 2.4 grams per kilogram of body weight) while assessing endorphin response at the level of the midbrain, including the ventral tegmental area (VTA), with an in vivo microdialysis technique.
Low to medium doses of ethanol -- 1.2, 1.6 and 2.0 grams -- led to a significant increase in dialysate content of β-endorphin compared to the saline group, but the 2.4-gram dose did not, the authors write.
"The current investigation demonstrated that at the level of midbrain/VTA systemic administration of ethanol mainly altered the release of β-endorphin in a dose-dependent manner with low to medium, but not high, doses of ethanol increasing β-endorphin release. This ethanol induced increase of β-endorphin release in the midbrain/VTA region may play a significant role in the ethanol-induced stimulation of the mesolimbic dopaminergic system and the initiation of the processes of ethanol reward and reinforcement," the authors conclude.