Electrical stimulation and lesions of the medial forebrain bundle of the rat: Changes in voluntary ethanol consumption and brain aldehyde dehydrogenase activity

Abstract

Repeated sessions of electrical stimulation or lesions in the ventral aspect of the medial forebrain bundle (VMFB) region of the brain in rats resulted in a significant increase and a decrease in voluntary ethanol (10% v/v) intake, respectively. Whole brain and midbrain-diencephalon (MB-DE) aldehyde dehydrogenase (ALDH) were measured in different groups of experimental and control animals before, immediately after, and 30 days after the termination of the stimulation regimen, or 8 days and 30 days after the induction of the lesions. By the end of the stimulation regimen, the levels of MB-DE ALDH of the experimental (ethanol-drinking: stimulated) animals were significantly higher than those of control animals (ethanol-drinking: nonstimulated, water-drinking: stimulated, and water-drinking: nonstimulated). A marked decrease in MB-DE ALDH activity was noted in lesioned animals but not in cyanamide-treated or in implanted control animals. Neither the stimulation nor the lesions had any demonstrable effect on whole brain ALDH activity. Cyanamide administration caused a pronounced decrease in ethanol intake and in levels of liver ALDH activity. The increase in MB-DE ALDH activity in the ethanol-drinking, stimulated animals was attributed to the interaction between the VMFB activation and the ethanol drinking, while the reduction in ALDH activity was attributed to the degeneration of biogenic-amine-containing nerve fibers.