The effect of adrenalectomy on stress-induced c-fos mRNA expression in the rat brain.
Previously, we determined the pattern of stress-induced c-fos mRNA expression throughout the brain in order to gain further insight into the identification of the neural circuits mediating stress-induced regulation of the hypothalamic-pituitary-adrenal axis. In the present study, we determined if rapid effects of increased glucocorticoid levels after stress contribute to changes in c-fos mRNA expression. To this end, stress-induced c-fos expression was characterized in adrenalectomized (ADX) or adrenalectomized and corticosterone replaced (ADX/B) male rats. Animals were sacrificed 30 min post-onset of a 10 min swim stress, and in situ hybridization histochemistry was used to detect c-fos mRNA throughout the brain. The pattern of c-fos induction in the ADX and ADX/B animals was similar to that observed in the sham operated animals. Additionally, densitometric measurements were made to quantify the c-fos response in the paraventricular nucleus of the hypothalamus and the CA1/2 region of the hippocampus. We found that ADX did not alter the magnitude of the c-fos response to stress in these areas, but there was a slight dampening of the response in ADX/B animals. In sum, these results suggest that the pattern of c-fos expression observed 30 min post-stress is independent of stress-induced increases in circulating glucocorticoid concentrations.
Helmreich
D L
DL
Mental Health Research Institute, University of Michigan, Ann Arbor 48109-0720, USA.
Cullinan
W E
WE
Watson
S J
SJ
D000208:Acute Disease; D000311:Adrenal Glands / Q000502:physiology*; D000315:Adrenalectomy; D000818:Animals; D001921:Brain / Q000378:metabolism*; D005938:Glucocorticoids / Q000097:blood; D017403:In Situ Hybridization; D008297:Male; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000378:metabolism*
D005938:Glucocorticoids; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger