Neuroendocrine and Behavioral Effects of CRH Blockade and Stress in Male Rats

Abstract

Our previous data have shown that restraint (RT), a mild nonpainful stressor, acutely impairs nonsocial and social behavior in male rats. Corticotropin-releasing hormone (CRH) is a regulator of these behavioral responses. To evaluate whether CRH mediates the neuroendocrine and behavioral alterations present 24 h after restraint stress, we administered the CRH antagonist α-helical CRH 9–41 (α-hCRH) intracerebroventricularly to male rats and we compared its effects with those of saline. Twenty-four hours after treatment, nonsocial behaviors were significantly decreased by α-hCRH, this effect being independent of RT. Among social behaviors, only introductory activity showed significant differences as a result of both RT and α-hCRH. The concentrations of ACTH in the plasma and those of β-endorphin in the anterior and neurointermediate lobes of the pituitary were affected by α-hCRH treatment. The effect on ACTH was simply related to the administration of the α-hCRH, while for β-endorphin, significant interactions between α-hCRH and RT were found. On the whole, these results point to the role played by CRH in the control of neuronal mechanisms involved in the stress-induced effects.