Differential distribution of oestrogen receptor-alpha and -beta mRNAs in the female reproductive organ of rats as revealed by in situ hybridization

Abstract

The cellular distribution of two oestrogen receptor (ER) subtypes, ER and ER mRNAs, was studied in the entire female reproductive organ of the rat using in situ hybridization. Expression of ER and ER mRNAs was predominant in the reproductive tract and ovary respectively. ER mRNA had the most pronounced expression in epithelial cells and subepithelial stromal cells from the oviduct to the vagina, while in the ovary it was moderately detected in only the theca folliculi and interstitial glands. The oviduct showed a region-dependent expression of ER mRNA: the isthmus had the most intense signals while the infundibulum revealed a low intensity of expression. Signals for ER mRNA in the ovary were most intense in the granulosa cells of healthy follicles, whereas degenerating follicles lacked any significant expression. Less intense signals for ER mRNA were localized in the theca folliculi and corpus luteum. Detectable levels of ER mRNA were observed in the subepithelial stromal cells from the oviduct to the vagina. This study shows that the two ER subtypes are differentially expressed in cells and compartments of the reproductive organ, suggesting that the mediation of oestrogen action in these tissues may be accomplished through the respective predominant receptor.

Developmental changes of the oestrogen receptor-alpha and -beta mRNAs in the female reproductive organ of the rat--an analysis by in situ hybridization

“…However, oestrogen effects mediated by ER are largely confined to ovarian development and, possibly, to abnormalities which arise when exposed to endocrine disruptors (Newbold et al 1983). The differential distribution patterns of ER and ER mRNAs during development reported here is consistent with data from previous in situ hybridization studies of the adult female rat (Shughrue et al 1998, Mowa & Iwanaga 2000. However, hybridization signals for ER Developmental change of oestrogen receptor mRNAs · C N MOWA and T IWANAGA 365 mRNA during the prenatal period are absent from epithelial cells, unlike in the adult female reproductive tract, and are primarily confined to the stromal cells, except in the oviduct where significant expressions of ER mRNA in the epithelium appeared by as early as foetal day 17.…”

“…Thus, since the epithelia of the foetal uterus, cervix and vagina lacked ER , mesenchymal ER may mediate their proliferation and differentiation. The epithelial expression of ER mRNA in foetuses is in contrast to that of the adult, where epithelia throughout the female reproductive tract expressed intense ER mRNA signals (Mowa & Iwanaga 2000). The biological significance of the precocious appearance of ER only in the oviductal epithelium is not known.…”

“…The in situ hybridization procedure was performed as previously described (Mowa & Iwanaga 2000). Briefly, 20 µm cryostat sections obtained from frozen fresh tissues were mounted on glass slides pre-coated with 3-aminopropyltriethoxysilane, fixed in 4% paraformaldehyde for 10 min, and then acetylated with 0·25% acetic anhydride in 0·1 M triethanolamine-HCl (pH 8·0) for 10 min.…”

“…Ontogenetical studies on ER expression in the rodent reproductive organ have mostly been limited to reports of oestrogen binding assays (Clark & Gorski 1972, Kuiper et al 1997, autoradiography (Cunha et al 1982, Holderegger & Keefer 1986, immunostaining (Greco et al 1991) and RT-PCR (Wu et al 1992, Hou & Gorski 1993, Gorski & Hou 1995. Data on the expression of ER mRNA in specific cell types of female reproductive tissue compartments are largely confined to the adult (Shughrue et al 1998, Mowa & Iwanaga 2000, with minimal postnatal reports (Fishman et al 1996), and, to the best of our knowledge, none for the prenatal period.…”

Effects of Levonorgestrel on Reproductive Hormone Levels and Their Receptor Expression in Mongolian Gerbils (Meriones unguiculatus)

“…ERα is primarily localized in the stromal cells, whereas ERβ is expressed predominantly in the granular cells of developing follicles [10,30,34]. The differential expression of the two ER subtypes in the reproductive organs indicates that the mediation of estrogen action in these tissues may be accomplished through the more dominant receptor [23]. ERβ mRNA expression was down-regulated while ERα mRNA expression did not change significantly after LNG treatment.…”