Chronic corticosterone administration in rats: Behavioral and biochemical evidence of increased central dopaminergic activity

Abstract Chronic corticosteroid treatment in humans is frequently complicated by behavioral changes. The present study suggests that chronic steroid administration in rats has distinct neurochemical consequences which are behaviorally relevant. Ten male Sprague-Dawley rats received 7 daily injections of corticosterone, following which they exhibited increased caudate homovanillic acid as well as an attenuated decline in vertical and ambulatory movement (functional measures of dopamine activity) compared to placebo-treated rats. A subgroup of steroid-treated rats which was more behaviorally responsive to ccrticosterone also showed increased caudate 5-hdroxyindole acetic and decread prefrontal cortex dopamine and serotonin. These results are discussed in relation to the known behavioral side effects of chronic corticosteroid administration in man and the psychiatric manifestations of naturally occuring states of hypercortisolemia.