Expression of oestrogen receptor beta (ER beta) in multiple rat tissues visualised by immunohistochemistry

Abstract

Steroid hormones regulate cell function via specific receptors, members of a super family of ligand activated transcription factors, expressed in their target tissues. A second oestrogen receptor (ER beta) has recently been shown by RT-PCR to have a wide tissue distribution distinct from that of oestrogen receptor alpha (ER alpha). We have raised a polyclonal antiserum using a peptide specific for ER beta in order to determine the cellular sites of expression of the receptor. In the adult rat ER beta was localised to cell nuclei in a wide range of tissues including ovary, oviduct, uterus, lung, adrenal, seminal vesicle, bladder, heart, prostate and testis. In the ovary ER beta was present in multiple cell types including granulosa cells in small, medium and large follicles, theca and corpora lutea whereas ER alpha was undetectable in these cell types. In the uterus ER beta and ER alpha were both present in epithelial cells lining the lumen and glands. In the lung ER beta was present in the cells lining the bronchioles and alveoli as well as in smooth muscle. In bladder and seminal vesicle immunostaining was intense in epithelial cells but the receptor was also expressed in nuclei of smooth muscle cells. Cell nuclei of the heart ventricle were immunopositive for ER beta as were most cells of the adult rat adrenal. In the seminiferous epithelium of the testis, nuclei of Sertoli cells were immunopositive but expression was not stage dependent. In conclusion, immunohistochemistry has proved invaluable in visualising specific sites of expression of ER beta in complex tissues including those of the reproductive tract.

Ontogeny of oestrogen receptor alpha in gonads and sex ducts of fetal and newborn mice

“…The quality of the immunohistochemical method used in the present study is believed to be sufficient for evaluating the distribution of ER-α, since the immunostaining is exclusively nuclear and, in both kinds of negative control sections, immunoreaction is absent. Furthermore, when applying the method to the sex organs of newborn male rats, the staining pattern is in accordance with studies in rats in which other ER-α-specific antibodies were used (Fisher et al, 1997;Hess et al, 1997a;Saunders et al, 1997).…”

“…Nevertheless, in both sexes, the germ cells and -at least in the male -their supporting somatic cells never appear ER-α-immunopositive, which is in agreement with observations in postnatal rats (Fisher et al, 1997;Saunders et al, 1997). It is not possible to identify the ER-α-immunopositive somatic cell types in females, but it is important to note that they are not preferentially situated close to the germ cells.…”

“…Furthermore, these studies do not discriminate between ER-α and ER-β. During recent years, reports of immunohistochemical investigations on ER-α and ER-β expression in several tissues of fetal and adult rats, including the gonads and their associated sex ducts, have appeared (Fisher et al, 1997;Hess et al, 1997a;Saunders et al, 1997Saunders et al, , 1998Hiroi et al, 1999). However, none of these studies include a thorough investigation of the expression during sexual differentiation of fetal gonads and sex ducts, the period when such tissue may be susceptible to hormonal exposure.…”

Oestrogen deficiency in men: where are we today?

“…Whether their decreased fertilizing ability is only dependent on the abnormal epididymal function still remains a matter of debate. In fact, oestrogens may have other still unknown actions in normal spermatogenesis, given the wide expression of both ER-a and ER-b in mammals throughout the male reproductive tract (27,135,137,138).…”

Time dependency of uterine effects of naringenin type phytoestrogens in vivo

“…The biological significance of the two ER subtypes still remains unresolved, but may explain the selective and divers effects of estrogens occurring in different target tissues. Whereas ER seems to be the prevalent ER subtype in the female reproductive tract, levels of both ERs are easily detectable in the gonads (Byers et al, 1997;Saunders et al, 1997). The preference of PEs for ER subtypes (Kuiper et al, 1998), leading to a potential organ selectivity of their actions and therefore being a potential naturally occurring selective estrogen receptor modulator (SERM), is of high pharmacological relevance.…”