Identification and developmental changes of aromatase and estrogen receptor expression in prepubertal and pubertal human adrenal tissues

Context: The mechanisms of postnatal adrenal zonation remain unclear. Objective: To provide a clue for a possible role of estrogens in adrenarche, we studied the expression of estrogen receptor (ER)alpha, ER beta, G protein-coupled receptor (GPR) 30, and cP450aromatase (cP450arom) in human adrenal tissue. Design: Human adrenal tissue was collected from three postnatal age groups (Grs): Gr 1, younger than 3 months (n = 12), fetal zone involution; Gr 2, 3 months to 6 yr (n = 17), pre-adrenarche; and Gr 3, older than 6 -20 yr (n = 12), post-adrenarche period. Results: ER beta mRNA in Grs 1 and 3 was higher than in Gr 2 (P < 0.05). By immunohistochemistry and laser capture microdissection followed by RT-PCR, ER beta was expressed in zona reticularis and fetal zone, GPR30 in zona glomerulosa (ZG) and adrenal medulla, while ER alpha mRNA and protein were undetectable. cP450arom mRNA in Gr 3 was higher than in Grs 1 and 2 (P < 0.05), and localized to ZG and adrenal medulla by laser capture microdissection. cP450arom Immunoreactivity was observed in adrenal medulla in the three Grs and in subcapsular ZG of Gr 3. Double-immunofluorescence studies revealed that cP450arom and chromogranin A only colocalize in adrenal medulla of subjects younger than 18 months. In these samples, exon 1. b-derived transcript was 3.5-fold higher, while exon 1. a-, 1. c-, and 1. d-derived transcripts were 3.3-, 1.9-, and 1.7-fold lower, respectively, than in subjects older than 6 yr. Conclusions: Our results suggest that estrogens produced locally in adrenal medulla would play a role in zona reticularis functional differentiation through ER beta. The cP450arom and GPR30 expression in subcapsular ZG, colocalizing with a high-cell proliferation index, previously reported, suggests a local GPR30-dependent estrogen action in proliferation and migration of progenitor adrenal cells.