Corticotrophin and corticosterone secretory patterns following acute neurogenic stress, in intact and in variously hypothalamic deafferented male rats.

Adult male rats, intact (N) or bearing complete (CHD), anterior (AHD), or posterior (PHD) hypothalamic deafferentations, were acutely exposed to either visual or audiogenic stimulation. At 2, 4, 10 or 30 min following the onset of stress exposure the animals were decapitated and trunk blood was collected for ACTH (RIA) and corticosterone (CS, CBG) determinations. Basal serum concentrations of both hormones were elevated in CHD and AHD, but not in PHD animals as compared to N animals. In N rats, exposure to both stresses resulted in elevated serum ACTH and CS concentrations, with the ACTH response to audiogenic but not visual stimulation being biphasic. In CHD animals, serum ACTH concentrations decreased, and those of CS were unchanged following stress exposure. While audiogenic stimulation caused elevation in serum levels of both hormones in AHD rats, the normal ACTH and CS response to visual stimulation were completely abolished by anterior hypothalamic deafferentation. In PHD animals, no ACTH response to either of the stress exposures was apparent; in spite of this, partial CS responses were elicited. These data thus describe the temporal aspects of the ACTH and CS secretory responses to different neurogenic stresses, and provide insight into the neural pathways mediating these responses.