Adrenocortical hormone status affects responses to dopamine receptor agonists

The effects of altered adrenocortical hormone status were investigated on hypothermic and behavioural responses elicited following systemically administered apomorphine or LY171555. Hormonal status was modified by surgical adrenalectomy, followed by subsequent replacement therapy with corticosterone, and by chronic corticosterone treatment of intact rats, followed by its withdrawal. The incidence of stereotyped sniffing produced by both apomorphine and LY171555 was increased in the adrenalectomized group and decreased following replacement therapy and in intact rats treated with chronic corticosterone, compared with sham-operated animals and saline-treated controls, respectively. Withdrawal of chronic corticosterone treatment in intact rats reversed the effects of the chronic treatment on dopamine-mediated responses. Similar changes were observed in hypothermic responses to the two dopamine agonists. Striatal D-1 and D-2 dopamine receptor concentration and affinity were unaffected by adrenal hormone modification suggesting that corticosterone may act at a site distal to the dopamine receptor to bring about the observed changes in dopamine-mediated behavioural responsiveness.