The secretion of steroid hormones from the adrenal cortex as well as cathecolamines from the adrenal medulla is stimulated by stress. In this study, we studied the effect of capsaicin-induced stress on the expression of the immediate-early genes (IEGs) NGFI-A, -B, -C, egr-2, -3 and Nurr1 in the rat adrenal gland using in situ hybridization. All of these IEGs except egr-2 were rapidly induced in the adrenal cortex and medulla. The temporal patterns of the IEG induction in medulla varied significantly. NGFI-A was induced in medulla within 15 min after stress, NGFI-B, egr-3 and Nurr1 were induced by 30 min, whereas NGFI-C was induced by 2 h. Surprisingly, only NGFI-B and Nurr1 were induced in the glucocorticoid secreting regions of zonae reticularis and fasciculata of the cortex, starting 15 min after the stress. All of the inducible IEGs were induced in the aldosterone secreting zona glomerulosa 15–30 min after the capsaicin injection. NGFI-A, NGFI-B and Nurr1 expression persisted for 6 h. Since the IEGs studied had major differences in their temporospatial induction pattern, they are likely to be induced by distinct stress-elicited factors and have separate target genes and roles in stress-induced glucocorticoid and catecholamine secretion.
