Oxytocin, But Not Oxytocin Receptor, is Regulated by Oestrogen Receptor β in the Female Mouse Hypothalamus

Abstract

In the female rat, oestrogen receptor (ER) β is colocalized with both oxytocin‐ and vasopressin‐producing neurones in the paraventricular nucleus of the hypothalamus (PVN). In this study, we demonstrate that the same pattern of colocalization between ERβ and oxytocin exists in the female mouse. Because this nucleus contains only a negligible quantity of ERα, it is likely that the oestrogen‐dependent regulation of oxytocin and vasopressin synthesis in the PVN is mediated by ERβ. Thus, we compared the effect of ovarian hormones on oxytocin and vasopressin mRNA expression in the PVN of wild‐type (WT) and ERβ knockout (βERKO) mice. We also compared the effects of ovarian hormones on oxytocin receptor (OTR) expression in the medial amygdala (MeA) and ventromedial nucleus of the hypothalamus (VMN) in female WT and βERKO mice. Ovariectomized mice underwent long‐term treatment with oestradiol or oil. Progesterone was given concurrently on the final 7 days of treatment, and all mice were killed 48 h after the final progesterone injection. In the PVN, hormone treatment increased oxytocin mRNA expression in WT but not βERKO females. These results suggest that ERβ is necessary for the regulation of the expression of oxytocin in the PVN. Hormone treatment had no effect on vasopressin mRNA expression in the PVN, but significantly increased OTR binding in both the VMN and the MeA in both genotypes. Collectively, our data show region and peptide specific regulation by ERα and ERβ in the mouse hypothalamus.

Telencephalic binding sites for oxytocin and social organization: A comparative study of eusocial naked mole‐rats and solitary cape mole‐rats

“…These two African mole-rat species display extreme differences in social organization and reproductive strategy. Our objective was to identify species-specific rather than statedependent distribution patterns for OTR binding and oxytocin-containing processes; consequently, because estrogen has been shown to enhance OTR expression at certain central sites in other species (Insel et al, 1993;Kremarik et al, 1995;Broad et al, 1999;Patisaul et al, 2003;Bealer et al, 2006), we restricted the present study to animals with low or undetectable levels of urinary estrogen: adult female mole-rats, which were either subordinate, hypogonadal naked mole-rats or Cape mole-rats during the nonreproductive season (Bennett and Jarvis, 1988;Westlin et al, 1994). Given that species-typical degrees of allomaternal behavior have been shown to be positively correlated with the density of OTR binding in the nucleus accumbens (Olazabal and Young, 2006b) and that naked mole-rats of both sexes are highly alloparental (Jarvis, 1981;Lacey and Sherman, 1991), a parallel, but limited, study was also undertaken on OTR binding in the nucleus accumbens in subordinate, hypogonadal, male naked mole-rats.…”

The distributions of the duplicate oestrogen receptors ER-βa and ER-βb in the forebrain of the Atlantic croaker (Micropogonias undulatus): evidence for subfunctionalization after gene duplication

“…These neurohypophyseal hormones are involved in modulating reproductive behaviours in vertebrates (Moore 1992). Oestrogen treatment alters AVP and OT mRNA levels in the PVN of mice but has no effect in ER-b knockout mice (Nomura et al 2002;Patisaul et al 2003). It is likely that some of the cells expressing ER-bb in croaker are also AVT or OT neurons.…”

Attachment, aggression and affiliation: The role of oxytocin in female social behavior

“…Estrogen receptor β is expressed in hypothalamic neurons that synthesise OT and estrogen receptor α is needed for the synthesis of OT receptors in the amygdala (Patisaul, Scordalakes, Young & Rissman, 2003). Gonadal steroids play a "permissive" role in modulating central and peripheral OT synthesis and OT receptor proliferation, density and affinity.…”