INTRACEREBROVENTRICULAR CRF INHIBITS COLD RESTRAINT-INDUCED C-FOS EXPRESSION IN THE DORSAL MOTOR NUCLEUS OF THE VAGUS AND GASTRIC-EROSIONS IN RATS

Acute exposure to cold-restraint induces vagal-dependent gastric erosi ons associated with activation of neurons in the dorsal motor nucleus of the vagus (DMN) in rats. The influence of intracerebroventricular ( i.c.v.) injection of corticotropin-releasing factor (CRF) (10 mu g) on c-fos expression in the brain and gastric erosions induced by 3 h col d-restraint was investigated in conscious rats. In cold-restraint expo sed rats, CRF injected i.c.v. inhibited gastric erosions and the numbe r of Fos positive neurons in the DMN by 93 and 72%, respectively. whil e Fos labelling in the nucleus tractus solitarius (NTS) was as increas ed by 5-fold compared with vehicle group. c-fos expression was also in duced in the central amygdala by i.c.v. CRF, unlike the vehicle-inject ed group exposed to cold-restraint, c-fos expression induced by cold-r estraint in the raphe pallidus (Rpa) and paraventricular nucleus of th e hypothalamus was not altered by i.c.v. CRF. These data indicate that central CRF-induced gastric protection results from the inhibition of DMN neuronal activity enhanced by cold-restraint. CRF action on DMN n eurons may be related to the increase in the NTS and central amygdala inputs leading to inhibition of DMN neurons rather than to the decreas e in the excitatory input from the caudal raphe projections to the DMN .