Parallel changes between the percentage of fetal pituitary cells immunoreactive to oestrogen receptor α and the concentration of 17β-oestradiol in fetal and maternal plasma during gestation in sheep

Abstract

The present study was designed to investigate the relationship between fetal sheep pituitary oestrogen receptor (ER) alpha expression and changes in fetal and maternal plasma 17beta-oestradiol (E2) concentrations during gestation. The results revealed that immunoreactivity for ER was located in the nuclei and distributed throughout the fetal pituitary gland during gestation. The percentage of ERalpha-positive cells was approximately 2% of the total cell population in female fetuses at Day 60 of gestation, increased to approximately 7% and 13% of the total cell population at Days 90 and 120 of gestation, respectively, and then declined to approximately 10% at birth. The fetal plasma E2 concentrations were approximately 19 and 71 pg mL(-1) at Days 90 and 120 of gestation, respectively, and decreased to 22 pg mL(-1) after birth. In male fetuses, plasma E2 concentrations and the percentage of ERalpha-positive cells were similar to values in female fetuses throughout gestation, except on Day 120 when the plasma E2 level in female fetuses was significantly higher than in male fetuses. These data demonstrate that changes in the percentage of fetal pituitary ERalpha-positive cells parallel fetal plasma E2 concentrations throughout gestation.

Expression of androgen receptor and its co-localization with estrogen receptor-alpha in the developing pituitary gland of sheep fetus

“…The present results showed that AR-ir cells were observed throughout anterior pituitary at day 60 of gestation, the earliest stage examined. But only a few ER -ir cells were located in a small region at the base of the anterior pituitary and in a band immediately adjacent to the neurointermediate lobe (Sheng et al 1998;Cui et al 2004). This indicates that AR emerges in anterior pituitary before day 60 of gestation, and AR expression in anterior pituitary occurs earlier than ER .…”

“…For AR and ER double staining, ER monoclonal antibody (NCL-ER-LH2, Novocastra, Newcastle upon Tyne, UK) was used, which has been previously utilized to determine the expression of ER in sheep (Sheng et al 1998;Cui et al 2004;Tian et al 2004). AR staining was Wrstly performed as described for AR and pituitary hormone double staining.…”

“…Our recent study results have shown that pituitary ER expression in sheep fetuses is detected in the early stage of the fetal sheep development, and rises to the maximum in the middle stage of gestation, which followed by a decline in late gestation (Sheng et al 1998;Cui et al 2004). This changing pattern of ER expression is paralleled by the changes of plasma E2 and LH containing cells (Sheng et al 1998).…”

“…The expressions of ERs in the developing pituitary gland have been described in many species, such as human (Brandenberger et al 1997), rat (Nishihara et al 2000), chicken (Woods et al 1995;Liu and Cui 2005), and sheep (Sheng et al 1998;Cui et al 2004). Our recent study results have shown that pituitary ER expression in sheep fetuses is detected in the early stage of the fetal sheep development, and rises to the maximum in the middle stage of gestation, which followed by a decline in late gestation (Sheng et al 1998;Cui et al 2004).…”

Ontogeny of estrogen receptor (ER) alpha and its co-localization with pituitary hormones in the pituitary gland of chick embryos

“…The ontogeny and cellular distribution of ER expression in the pituitary gland have been extensively studied in developing mammalian fetuses, such as in rat (Pasqualini et al 1999;Nishihara et al 2000), sheep (Sheng et al 1998;Cui et al 2004), and human (Brandenberger et al 1997). ER expression in these species can be detected at early stages of fetal development, rise to a maximum around the middle of gestation, and then decline at birth (Sheng et al 1998;Cui et al 2004).…”