Dopamine-activated adenylate cyclase of spinal cord: supersensitivity following transection of the cord.

A dopamine-activated adenylate cyclase has been identified in a membrane fraction of rat spinal cord. The concentration of dopamine producing half-maximal activation is about 5 microM and the activation is blocked by haloperidol. Apomorphine also activates the cyclase. Following transection of the cord, adenylate cyclase becomes about 5-10 times more sensitive to dopamine below the transection. The presence of dopamine-activated adenylate cyclase in the cord is consistent with reports of dopamine-containing tracts in spinal cord. This neuronal system may play an essential role in normal spinal mechanisms, in disease associated with dopaminergic neurons, as well as in the side-effects of neuroleptic drugs.