Figure 4

UV irradiation stimulated both central and cutaneous HPA axes. Serum levels of (a) CORT and (c) ACTH were measured using ELISA assay. (b) MC2R, STAR, and CYP11B1 mRNA levels in the adrenal glands, and (d) CRH mRNA expression levels in the hypothalamus were measured using RT-qPCR. (e) UCN and POMC expression levels in mouse skin with or without ultraviolet radiation exposure were examined using immunohistochemistry. Scale bars: 50 µm under 400x magnification. (f) The mRNA expression levels of UCN, POMC, MC2R, and CYP11B1 in the skin were analyzed using RT-qPCR. All relative mRNA levels were normalized to those of the endogenous control GAPDH. Graphs show means ± SEM (n = 8mice/group). *P < 0.05, **P < 0.01, and ***P < 0.001 indicate significant differences between groups. ACTH, adrenocorticotropic hormone; CORT, corticosterone; CRH, corticotropin-releasing hormone; CYP11B1, cytochrome P450 family 11 subfamily B member 1; MC2R, melanocortin 2 receptor; POMC, pro-opiomelanocortin; STAR, steroidogenic acute regulatory protein; UCN, urocortin.