HETEROGENEOUS NEUROCHEMICAL RESPONSES TO DIFFERENT STRESSORS - A TESTOF SELYES DOCTRINE OF NONSPECIFICITY

Selye defined stress as the nonspecific response of the body to any de mand. Stressors elicit both pituitary-adrenocortical and sympathoadren omedullary responses. One can test Selye's concept by comparing magnit udes of responses at different stress intensities and assuming that th e magnitudes vary with stress intensity, with the prediction that, at different stress intensities, ratios of increments neuroendocrine resp onses should be the same. We measured arterial plasma ACTH, norepineph rine, and epinephrine in conscious rats after hemorrhage, intravenous insulin, subctaneous formaldehyde solution, cold, or immobilization. R elative to ACTH increments, cold evoked large norepinephrine responses , insulin large epinephrine responses, and hemorrhage small norepineph rine and epinephrine responses, whereas immobilization elicited large increases in levels of all three compounds. The ACTH response to 25% h emorrhage exceeded five times that to 10%, and the epinephrine respons e to 25% hemorrhage was two times that to 10%. The ACTH response to 4% formaldehyde solution was two times that to 1%, and the epinephrine r esponse to 4% formaldehyde solution exceeded four times that to 1%. Th ese results are inconsistent with Selye's doctrine of nonspecificity a nd the existence of a unitary ''stress syndrome,'' and they are more c onsistent with the concept that each stressor has its own central neur ochemical and peripheral neuroendocrine ''signature.''