A role of central alpha-1 adrenergic mechanism in shaking stress-induced ACTH and noradrenaline secretion.

The role of alpha-1 adrenergic mechanism in the shaking stress-induced adrenocorticotropic hormone (ACTH), and plasma noradrenaline secretion and pressor response were investigated using conscious rats. We also studied whether or not central corticotropin releasing hormone (CRH) is involved in the shaking stress-induced ACTH secretion. The shaking stress caused significant elevations of plasma ACTH, noradrenaline, and systolic blood pressure. Intra-third ventricular administration of alpha-1 adrenergic blocker, bunazosin, inhibited the shaking stress-induced ACTH secretion, but did not alter stress-induced noradrenaline secretion and pressor response. Furthermore, intra-third ventricular administration of CRH antagonist, alpha-helical CRH, significantly attenuated stress-induced ACTH secretion. These results indicate that alpha-1 adrenergic pathway and CRH at least partly mediate the shaking stress-induced ACTH secretion.