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

Abstract

Within the hypothalamic paraventricular nucleus (PVN), estrogen receptor (ER) β 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 ERβ 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, ERβ‐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 ERβ‐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 ERβ‐EGFP in neuroendocrine (approximately 70%) and autonomic (approximately 50%) projecting subregions. Ultrastructurally, in soma and dendrites, PVN ERβ‐EGFP colocalized primarily with extranuclear AR (approximately 85% soma) and GPER1 (approximately 70% soma). Aged (12‐ to 24‐month‐old) males had more ERβ‐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.

Estrogen Receptor β Contributes to Both Hypertension and Hypothalamic Plasticity in a Mouse Model of Peri-Menopause

“…Prior anatomic studies demonstrate that ERb is expressed in PVN sympathoexcitatory neurons in both male and female rodents (Bingham et al, 2006;Milner et al, 2010). Interestingly, the density of ERb -labeled cells does not differ in young male and female mice in areas of the PVN populated by spinally projecting PVN neurons (Milner et al, 2010;Oyola et al, 2017;Contoreggi et al, 2021). This suggests that signaling events downstream of ERb may contribute to sex differences in blood pressure regulation and hypertension.…”

“…Thus, dual-label immuno-EM was used to examine the subcellular distribution of the essential NMDAR subunit GluN1 (labeled by SIG) in GFP (labeled by peroxidase) expressing dendrites in the PVN of ERb -GFP reporter mice infused with AngII and cotreated with DPN (N = 3 mice/condition; n = 50 dendrites/mouse). Medio-caudal levels of the PVN, which contain numerous ERb -labeled neurons known to project to the spinal cord (Marques-Lopes et al, 2014;Contoreggi et al, 2021), were selected for analysis (Fig. 3A).…”

“…Estrogen signaling in the hypothalamic paraventricular nucleus (PVN), a key neural component of cardiovascular regulatory circuitry, has been shown to contribute to blood pressure regulation (for review, see Van Kempen et al, 2016). Estrogen receptor b (ERb ) is a predominant estrogen receptor in the PVN (Van Kempen et al, 2016;Contoreggi et al, 2021). In addition to its established transcriptional effects, estrogen acting at ERb is known to modulate fast NMDAR-mediated excitatory signaling (Sellers et al, 2015).…”

Estrogen receptors observed at extranuclear neuronal sites and in glia in the nucleus accumbens core and shell of the female rat: Evidence for localization to catecholaminergic and GABAergic neurons

“…In brains fixed with 4% paraformaldehyde perfusion, immunoreactivity was greatly reduced when the antibody was preadsorbed with 10 mg/ml of purified C‐terminal peptide (Filardo et al., 2000). Furthermore, we performed two additional controls to validate the specificity of the antibody in the hippocampus (Waters et al., 2015) and paraventricular nucleus of the hypothalamus (Contoreggi et al., 2021). The first control was preadsorption experiment.…”

“…Acrolein/paraformaldehyde-fixed sections containing the hippocampus and PVN were processed for peroxidase immunocytochemistry using the two aliquots. In sections incubated with the antibody preadsorbed with the peptide, immunolabeling for GPER1 was completely abolished in the hippocampus (Waters et al, 2015) and PVN (Contoreggi et al, 2021). and was tested for specificity using preabsorption with GABA-bovine serum albumin (BSA), eliminating GABA immunoreactivity (Lauder et al, 1986).…”