Neuroendocrine and behavioral effects of CRH blockade and stress in male rats

Our previous data have shown that restraint (RT), a mild nonpainful stresso r, acutely impairs nonsocial and social behavior in male rats. Corticotropi n-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 ct -helical CRH9-41, (alpha-hCRH) intracerebroventricularly to male rats and w e compared its effects with those of saline. Twenty-four hours after treatm ent, nonsocial behaviors were significantly decreased by alpha-hCRH, this e ffect being independent of RT. Among social behaviors, only introductory ac tivity showed significant differences as a result of both RT and alpha-hCRH . The concentrations of ACTH in the plasma and those of beta-endorphin in t he anterior and neurointermediate lobes of the pituitary were affected by a lpha-hCRH treatment. The effect on ACTH was simply related to the administr ation of the alpha-hCRH, while for beta-endorphin, significant interactions between alpha-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 t he stress-induced effects. (C) 1999 Elsevier Science Inc.