Dopamine receptor-mediated regulation of corticotropin-releasing hormone neurons in the hypothalamic paraventricular nucleus.

ABSTRACT

The present study examined the effects of intraperitoneal administration of selective D1 (SKF 38393) and D2 (quinelorane) dopaminergic receptor agonists on Fos-like immunoreactivity (Fos-LI) and levels of corticotropin-releasing hormone (CRH) mRNA in the paraventricular nucleus of the hypothalamus (PVN) and in the central nucleus of the amygdala (cAMY). Ninety minutes after administration of the D1 agonist SKF 38393, Fos-LI was increased in both the PVN and cAMY. Administration of SCH 39166, a selective D1 antagonist, blocked and attenuated the SKF 38393-induced increase in Fos-LI in the PVN and cAMY, respectively. Similarly, 90 minutes after intraperitoneal injection of the D2 agonist quinelorane, Fos-LI was increased in both PVN and cAMY. Administration of the selective D2 antagonist raclopride prevented the ability of quinelorane to increase Fos-LI in the PVN and cAMY. Both SKF 38393 and quinelorane stimulated the expression of CRH and mRNA in the PVN, but failed to alter its expression in the cAMY. Taken together, these results indicate that stimulation of either D1 and D2 dopaminergic receptors activates CRH neurons in the PVN. Stimulation of either D1 or D2 receptors activates neurons in the cAMY, but these changes do not appear to be occurring in CRH neurons.