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 ER, ER, GPR30 and cP450arom in human adrenal tissue (HAT).

Design: HAT was collected from 3 postnatal age groups: Gr1: < 3 months, n = 12, fetal zone (FeZ) involution; Gr2: 3 months to 6 yr, n = 17, pre-adrenarche; and Gr3: > 6 to 20 yr, n = 12, post-adrenarche period.

Results: ER mRNA in Gr1 and Gr3 was higher than in Gr2, P < 0.05. By Immunohistochemistry and LCM followed by RT-PCR, ER was expressed in ZR and FeZ, GPR30 in ZG and adrenal medulla (AM) while ER mRNA and protein was undetectable.

cP450arom mRNA in Gr3 was higher than in Gr1 and Gr2 (P < 0.05) and localized to ZG and AM by LCM. cP450arom immunoreactivity was observed in AM in the three Grs and in subcapsular ZG of Gr3. Double immunofluorescence studies revealed that cP450arom and chromogranin A only colocalize in AM 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 than in subjects older than 6 yr.

Conclusions: Our results suggest that estrogens, produced locally in AM, would play a role in ZR functional differentiation through ER.

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.