Localization of estrogen receptors-α and -β and androgen receptor in the human growth plate at different pubertal stages

Abstract

Sex steroids are required for a normal pubertal growth spurt and fusion of the human epiphyseal growth plate. However, the localization of sex steroid receptors in the human pubertal growth plate remains controversial. We have investigated the expression of estrogen receptor (ER) α, ERβ and androgen receptor (AR) in biopsies of proximal tibial growth plates obtained during epiphyseal surgery in 16 boys and eight girls. All pubertal stages were represented (Tanner stages 1-5). ERα, ERβ and AR were visualized with immunohistochemistry and the number of receptor-positive cells was counted using an image analysis system. Percent receptor-positive chondrocytes were assessed in the resting, proliferative and hypertrophic zones and evaluated for sex differences and pubertal trends. Both ERα- and ERβ-positive cells were detected at a greater frequency in the resting and proliferative zones than in the hypertrophic zone (64 ± 2%, 64 ± 2% compared with 38 ± 3% for ERα, and 63 ± 3%, 66 ± 3% compared with 53 ± 3% for ERβ), whereas AR was more abundant in the resting (65 ± 3%) and hypertrophic zones (58 ± 3%) than in the proliferative zone (41 ± 3%). No sex difference in the patterns of expression was detected. For ERα and AR, the percentage of receptor-positive cells was similar at all Tanner pubertal stages, whereas ERβ showed a slight decrease in the proliferative zone during pubertal development (P<0.05). In summary, our findings suggest that ERα, ERβ and AR are expressed in the human growth plate throughout pubertal development, with no difference between the sexes.