The immediate-early genes c-fos and c-jun are differentially expressed in the rat adrenal gland after capsaicin treatment.

In situ hybridization histochemistry was used to study the expression of c-fos and c-jun mRNA in the rat adrenal gland of untreated and capsaicin treated rats. In untreated animals, very low levels of c-fos mRNA were present both in zona fasciculata and reticulata of the adrenal cortex, with no detectable labelling in the zona glomerulosa or adrenal medulla. In contrast, the levels of c-jun mRNA were high in the cortical layers fasciculata and reticulata, again without labelling in the zona glomerulosa or adrenal medulla. After capsaicin (25 mg/kg, s.c.), a rapid increase in both c-fos and c-jun mRNA levels was observed in adrenal medulla. Capsaicin also induced an increase in c-fos mRNA levels in all 3 cortical layers, especially in the zona glomerulosa, whereas only small changes in c-jun mRNA levels were seen in zona fasciculata and reticulata. The present results indicate that c-fos and c-jun mRNA levels are both increased in the adrenal gland after capsaicin treatment, although the time course, magnitude and regional distribution of these increases differed for the two mRNAs.