Increased response to catecholamines of the cyclic AMP system of rat pineal gland induced by decreased sympathetic activity

Abstract

Norepinephrine added in vitro to cultured rat pineal glands produced a several-fold increase in the concentration of cyclic AMP. Chronically decreasing the sympathetic input to the pineal gland by any one of a variety of procedures, such as superior cervical ganglionectomy, decentralization of these ganglia, or chemical sympathectoomy with 6-hydroxydopamine, results in a several-fold enhancement of this norepinephrine-induced elevation in the levels of cyclic AMP in pineal glands cultured in vitro. The development of the increased sensitivity of the cyclic AMP system can be prevented by administering norepinephrine in vivo during the period of reduced sympathetic input. Ganglionectomy also caused an increase in the isoproterenol-induced elevation of cyclic AMP in pineal glands in vivo. These results support the concept that the increased pharmacologic response to catecholamines in some chronically denervated adrenergic structures may be due to an increase in the catecholamine-sensitive adenylate cyclase system of these structures.