Evidence for a role of endogenous cold, ether, immobilization, and tr: (ACTH secretion/immunoneutralization/neural mediation)

The role of corticotropin-releasing factor (CRF) in four model stresses (cold, ether, immobilization, and trauma) was examined in the guinea pig by using passive im- munoneutralization with anti-CRF antiserum. Plasma cortico- tropin levels were measured at various times after exposure to stress, and groups treated with CRF antiserum were com- pared with those treated with normal rabbit serum. Of the four stresses tested, ether had the most pronounced effect on corticotropin secretion. Treatment with anti-CRF inhibited most of the ether-induced corticotropin secretory response, the difference between the normal serum- and the anti-CRF anti- serum-treated groups being significant at 5 and 10 min (P < 0.01). Corticotropin responses to cold stress in the two groups differed at the 0.05 level of significance at 10 and 20 min. After administration of trauma (leg fracture), a statistically signifi- cant difference (P < 0.01) between the two groups also was evident, albeit only at 20 min. During immobilization, cortico- tropin levels differed significantly from control only in the normal serum-treated group but not in the anti-CRF-treated group. These findings show that CRF antiserum was effective in reducing corticotropin levels, indicating that CRF has an important role in mediating corticotropin response to stress. The fact that neutralization was incomplete might be due to an inability of the antiserum to sufficiently neutralize the endoge- nous CRF or, more likely, reflects the contribution of addi- tional mediators, notably catecholamines and vasopressin, of corticotropin release upon stress.