Sex and age influence gonadal steroid hormone receptor distributions relative to estrogen receptor ß-containing neurons in the mouse hypothalamic paraventricular nucleus.

Within the hypothalamic paraventricular nucleus (PVN), estrogen receptor (ER) ß and other gonadal hormone receptors play a role in central cardiovascular processes. However, the influence of sex and age on the cellular and subcellular relationships of ERß with ERα, G-protein ER (GPER1), as well as progestin and androgen receptors (PR and AR) in the PVN is uncertain. In young (2- to 3-month-old) females and males, ERß-enhanced green fluorescent protein (EGFP) containing neurons were approximately four times greater than ERα-labeled and PR-labeled nuclei in the PVN. In subdivisions of the PVN, young females, compared to males, had: (1) more ERß-EGFP neurons in neuroendocrine rostral regions; (2) fewer ERα-labeled nuclei in neuroendocrine and autonomic projecting medial subregions; and (3) more ERα-labeled nuclei in an autonomic projecting caudal region. In contrast, young males, compared to females, had approximately 20 times more AR-labeled nuclei, which often colocalized with ERß-EGFP in neuroendocrine (approximately 70%) and autonomic (approximately 50%) projecting subregions. Ultrastructurally, in soma and dendrites, PVN ERß-EGFP colocalized primarily with extranuclear AR (approximately 85% soma) and GPER1 (approximately 70% soma). Aged (12- to 24-month-old) males had more ERß-EGFP neurons in a rostral neuroendocrine subregion compared to aged females and females with accelerated ovarian failure (AOF) and in a caudal autonomic subregion compared to post-AOF females. Late-aged (18- to 24-month-old) females compared to early-aged (12- to 14-month-old) females and AOF females had fewer AR-labeled nuclei in neuroendrocrine and autonomic projecting subregions. These findings indicate that gonadal steroids may directly and indirectly influence PVN neurons via nuclear and extranuclear gonadal hormone receptors in a sex-specific manner.

The expression of estrogen receptors in rat genioglossus muscle-derived satellite cells and its relationship to intracellular Ca(2+) mobilization.

Genioglossus (GG) is the most important pharyngeal dilator muscle in maintaining upper airway (UA) patency in human; therefore, its dysfunction plays an important role in pathogenesis of sleep-related breathing disorder. Recently, the expression of estrogen receptors (ERs) on mRNA and protein level has been evidenced in GG muscle; however, the cellular localization of two subtypes of ER in GG myoblasts remains unclear. The present study was designed to clarify the expression and cellular distribution of ERs in rat GG muscle-derived satellite cells (MDSCs) and further probe the effect of ERs expression on regulation of intracellular Ca(2+). The immunocytochemistry revealed positive staining for both ERalpha and ERbeta in nuclei and cytoplasm of GG MDSCs. Noticeably, positive signals for ERalpha and ERbeta were comparable in cytoplasm, whereas the positive staining of ERalpha in nuclear was obviously strong than that of ERbeta. More intriguingly, by using Fluo 4-AM as a fluorescent Ca(2+) indicator and 17beta-estradiol (E2) as a stimulant, we observed that the level of intracellular Ca(2+) was not affected by E2 application, which implied that Ca(2+) signaling may not be involved in ER-mediated estrogenic effects on GG MDSCs. Taken together, the present study clearly indicates the differential cellular localization of ERs in rat GG MDSCs; moreover, ER-mediated estrogenic effect in rat GG MDSCs bears no relationship to intracellular Ca(2+) mobilization. In addition, the GG MDSCs express both ERalpha and ERbeta and therefore, provide a suitable and convenient in vitro cell model for investigating the molecular mechanisms of estrogenic effects on rat GG muscle.