Central cyclic-AMP-linked noradrenergic receptors: new findings on properties as related to the actions of stress.

Central noradrenergic receptors that control cyclic AMP formation in the brain may be involved in the process of adaptation to stress and in the clinical actions of antidepressant drugs. The present paper reviews recent findings on the properties and susceptibility to stress of these receptors. Two types of adrenergic receptors are known to mediate the central cAMP response, beta and alpha receptors. It has been found that chronic stress causes a selective desensitization of the alpha receptors (alpha-1 subtype) producing a partial reduction of the overall cAMP response to catecholamines. This desensitization occurs in the cerebral cortex, hypothalamus and possibly other areas of the forebrain. The physiological factor responsible for the effect appears to be an elevated corticosterone secretion. The behavioral function of the stress-induced desensitization may be to reduce behavioral inhibition and facilitate the recovery of behavioral function during adaptation to stress.