Effect of hippocampal lesions produced by intracerebroventricular kainic acid on alcohol drinking in the rat

Abstract

An alcohol self-selection test was first given to adult male rats of either the Sprague-Dawley or Long-Evans strain in which the concentrations available with water were increased from 3% to 30% over an eight-day period. Subsequently, the animals were anesthetized and, using stereotaxic procedures, a 1.2 or 2.4 nmole dose of kainic acid was infused bilaterally into the cerebral ventricle (ICV) over a 30-sec interval and in a total volume of 10 μl. When the same alcohol self-selection test was repeated two weeks post-operatively, alcohol intake was significantly suppressed in terms of both g/kg intake per day as well as proportion of alcohol to water selected. Alcohol intake of the control rats infused with the CSF carrier vehicle was unchanged. When a much longer interval of 7–10 min was used to infuse the 2.4 nmole dose of kainic acid ICV, the intake of alcohol of this group also was not significantly changed. Post-mortem histological analysis of forebrain tissue of the kainic acid infused rats confirmed cytological damage to the hippocampus, particularly in cell fields CA3 and CA4, which has been reported previously. Since the hippocampus has been implicated recently in the mechanisms underlying alcohol drinking, our results suggest that a pathological lesion of this limbic-forebrain structure could influence the degree to which alcohol is self-administered in a free-choice situation.