Regulation of ER alpha Protein Expression by 17 beta-Estradiol in Cultured Neurons of Hypothalamic Ventromedial Nucleus

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Malikov, V (Author) Other; Madeira, MD (Author) FMUP

Journal

Title: Neurochemical Research

Vol. 38

Pages: 82-89

ISSN: 0364-3190

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 11 Citations

Scopus - 11 Citations

Scientific classification

FOS: Medical and Health sciences > Basic medicine

Other information

Authenticus ID: P-002-225

DOI: 10.1007/s11064-012-0891-1

Abstract (EN): The activation of the subtype alpha of estrogen receptors (ER alpha) in the hypothalamic ventromedial nucleus (VMNvl) is required to stimulate female sexual receptivity. Moreover, the hormone was found to govern the expression of the receptor. Its removal due to ovariectomy and subsequent substitution suggest that the hormone down-regulates the expression of ER alpha. In contrast, in normally cycling animals the expression of the receptor peaks at proestrus, the phase of highest concentration of 17 beta-estradiol in estrous cycle. Therefore, in this study we examined the influence of the hormone on ER alpha expression in primary dissociated cultures of neurons isolated from the VMNvl of young adult female rats. Measurements of ER alpha immunofluorescence revealed that both supraphysiological and physiological concentrations of 17 beta-estradiol increase the expression of ER alpha. Analyses with selective agonists showed that both nuclear ERs are able to mediate the action of the hormone. However, the activation of ER alpha had a stronger effect on the expression of its own receptor than the activation of ER beta. Simultaneous activation of both receptors attenuated the influence of ER alpha alone. Physiological concentrations of progesterone were found to revoke the effect of 17 beta-estradiol, whereas the expression of ER alpha is up-regulated by progesterone alone. These data indicate that the expression of ER alpha in VMNvl neurons is under the control of both types of nuclear ERs and, in addition, progesterone receptors (PRs). The particular contribution of the receptors is dependent on their level of expression and the hormonal context. In neurons expressing high quantity of ER alpha, ER beta attenuates the overall expression of the receptor, whereas in cells containing mostly ER beta it contributes to the up-regulation of ER alpha synthesis. Simultaneous activation of ERs and PRs reverses the influences of the receptors due to inter-inhibition of their transcriptional activities.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8