Colocalization of Progesterone Receptors and Thyroid Hormone Receptors Alpha in the Ovine Diencephalon: No Effect of Estradiol

Abstract

Progesterone and thyroid hormones are key hormones in the control of reproduction in the ewe since both have been shown to inhibit GnRH secretion. GnRH neurons do not express progesterone receptors (PR) but half of them contain thyroid hormone receptors α (THRα), two nuclear receptors potentially able to act on gene transcription. PR and THRα distributions overlap in most regions of the ovine preoptic area (POA) and hypothalamus. To determine whether progesterone and thyroid hormones may also have common neuronal targets for the control of GnRH cell activity, we searched for coexpression of PR with THRα within neurons of the POA and hypothalamus of ovariectomized ewes treated with estradiol plus progesterone or with progesterone alone. Double-labeled cells were found throughout the medial POA, the periventricular part of the paraventricular nucleus (PVNpe), the arcuate nucleus (ARC) and the ventrolateral ventromedial nucleus (VMNvl). Colocalization ratios were not statistically different between steroid treatment groups. 84% of PR-immunoreactive cells in VMNvl, 90% in POA and ARC and 95% in PVNpe contain THRα. More than two-thirds of THRα-immunoreactive cells contain PR in each area examined. This study provides evidence that progesterone and thyroid hormones may act within the same cells to modulate physiological functions such as reproduction.

The Content of Thyroid Hormone Receptor α in Ewe Kisspeptin Neurones is not Season‐Dependent

“…A two-way ANOVA statistical analysis was performed using Prism, version 5 (GraphPad Software Inc.) to compare percentages of variation of Kiss tissular content related with controls for different incubation times and doses. neurones matched that previously described in the ewe hypothalamus (26,36) (Fig. 1).…”

Effect of estradiol and progesterone on thyroid gland in pigs: A histochemical, stereological, and ultrastructural study

“…Recent molecular studies suggest that the possible mechanism of estrogen-thyroid hormone interaction is mediated by cross-talk of estrogen and thyroid receptors and their respective ligands (Fujimoto et al, 2004). In addition, Dufourny and Skinner (2003) had demonstrated that Pr receptors and thyroid hormone receptors a (TH R-a) were coexpressed within the cells of ovine brain, and hypothesized that these hormones may act sinergisticaly to modulate different physiological functions, such as reproduction.…”

Progesterone exerts neuroprotective effects after brain injury

“…Sex hormones are known to influence neuronal differentiation during fetal development. In adults, progesterone affects neuronal function by modulating gene transcription and cellular activity through classical intracellular receptors abundant in the CNS (Auger and De Vries, 2002;Blaustein, 2003;Coughlan et al, 2005;Dufourny and Skinner, 2003;Ghoumari et al, 2005;Gruber and Huber, 2003;Labombarda et al, 2003;Lonstein and Blaustein, 2004;Mani, 2006;Ozawa, 2005;Pierson et al, 2005). Progesterone, or its metabolite allopregnanolone, binds to a variety of intracellular receptors, including GABAA (Lambert et al, 2003;Pierson et al, 2005;Smith and Gong, 2005), the Sigma receptor (Baulieu, 1998;Maurice et al, 2001;Monnet and Maurice, 2006), 25-Dx (Meffre et al, 2005), and potentially others.…”