Expression of P-450 aromatase, estrogen receptor α and β, and α-inhibin in the fetal baboon testis after estrogen suppression during the second half of gestation

Abstract

Expression of the molecules that modulate the synthesis and action of estrogen in, or reflect function of, Sertoli cells was determined in the fetal testis of baboons in which estrogen levels were suppressed in the second half of gestation to determine whether this may account for the previously reported alteration in fetal testis germ cell development. P-450 aromatase, estrogen receptor (ER) β, and α-inhibin protein assessed by immunocytochemistry was abundantly expressed in Sertoli cells of the fetal baboon testis, but unaltered in baboons in which estrogen levels were suppressed by letrozole administration. Moreover, P-450 aromatase and ERα and β mRNA levels, assessed by real-time RT-PCR, were similar in germ/Sertoli cells and interstitial cells isolated from the fetal testis of untreated and letrozole-treated baboons. These results indicate that expression of the proteins that modulate the formation and action of estrogen in, and function of, Sertoli cells is not responsible for the changes in germ cell development in the fetal testis of estrogen-deprived baboons.

Fig. 1

Impact of estrogen suppression throughout the second half of primate pregnancy on the numbers of gonocytes, type A pale (Ap) spermatogonia, unidentified cells, and type A dark (Ad) spermatogonia in the fetal testis and proposed impact on spermatogenesis in adulthood (modified from Albrecht et al. [1])

Fig. 2

Serum estradiol (a) and testosterone (T) (b) levels (means ± SE) on day 165 of gestation in male fetuses of baboons untreated (n = 6) or treated daily on days 100–164 of gestation with letrozole (115 μg/kg body weight/day, sc, n = 6). * P < 0.01 (Student’s t test)

Fig. 3

Immunocytochemical localization (brown precipitate) of P-450 aromatase (a), ERβ (b), ERα (c), and α-inhibin (d) in the fetal testis of untreated baboons on day 165 of gestation. e Negative control with omission of α-inhibin primary antibody. GC germ cell nucleus, SC Sertoli cell nucleus, IC interstitial cells. Magnifications: ×400 (a–c, e); ×200 (d)

Fig. 4

Illustration of laser capture microdissection (LCM) of cells from the fetal baboon testis. a Fetal testis section before LCM. b Remaining section after LCM removal of germ and Sertoli cells from within the seminiferous cords. c Remaining section after LCM removal of interstitial cells. d Germ and Sertoli cells on LCM cap. e Interstitial tissue on LCM cap

Fig. 5

P-450 aromatase mRNA/18S rRNA levels (means ± SE) quantified by real-time RT-PCR in germ/Sertoli cells and interstitial cells isolated via LCM from the fetal testis on day 165 of gestation from baboons untreated or treated on days 100–164 of gestation with letrozole as detailed in the legend of Fig. 2

Fig. 6

ERβ and α mRNA/18S rRNA levels quantified by real-time RT-PCR in germ/Sertoli cells and interstitial cells isolated via LCM from the fetal testis of the same baboons in which P-450 aromatase mRNA levels are shown in Fig. 5