Water-avoidance stress-induced c-fos expression in the rat brain and stimulation of fecal output: role of corticotropin-releasing factor.
Immunohistochemical detection of the immediate-early gene c-fos was used to determine the pattern of neuronal activity in the rat brain after exposure to water-avoidance stress known to stimulate fecal output in rats. Avoidance to water for 1 h by standing on a small platform increases pellet output and induces numerous Fos-positive cells in the parvocellular part of the paraventricular nucleus of the hypothalamus (PVN), locus coeruleus (LC) and, to a lesser extent, in the bed nucleus of the stria terminalis, lateral septum, dorsal raphe nucleus and A5 and A1 noradrenergic neurons. The corticotropin-releasing factor (CRF) antagonist, alpha-helical CRF9-41 (50 micrograms i.c.v.) reduced water-avoidance stress-induced c-fos expression mainly in the PVN and the LC (44 and 60%, respectively) and decreased by 60% the stimulated fecal output. These data indicate that water-avoidance stress activates PVN and LC neurons through CRF pathways which contribute to the stimulation of colonic motor function.
VA Wadsworth Medical Center, Department of Medicine, Los Angeles, CA 90073.
B
B
Bonaz
Y
Y
Taché
D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D001921:Brain / Q000378:metabolism*; D003346:Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000502:physiology*; D003672:Defecation / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000378:metabolism*; D014867:Water
D016760:Proto-Oncogene Proteins c-fos; D014867:Water; D003346:Corticotropin-Releasing Hormone