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This Article Accepted manuscript (PDF) All Versions of this Article: JOE-07-0622v1 198/2/355    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Di Yorio, M. Articles by Faletti, A. Search for Related Content PubMed PubMed Citation Articles by Di Yorio, M. Articles by Faletti, A.

M Di Yorio, Centro de Estudios Farmacologicos y Botanicos (CEFYBO) - CONICET, Cdad Aut de Buenos Aires, Argentina
M Bilbao, Centro de Estudios Farmacologicos y Botanicos (CEFYBO) - CONICET, Cdad Aut de Buenos Aires, Argentina
M Pustovrh, Centro de Estudios Farmacologicos y Botanicos (CEFYBO) - CONICET, Cdad Aut de Buenos Aires, Argentina
J Prestifilippo, Centro de Estudios Farmacologicos y Botanicos (CEFYBO) - CONICET, Cdad Aut de Buenos Aires, Argentina
A Faletti, Centro de Estudios Farmacologicos y Botanicos (CEFYBO) - CONICET, Cdad Aut de Buenos Aires, Argentina

Correspondence: Alicia Faletti, Email: agfaletti{at}yahoo.com.ar

Abstract

To investigate the expression of leptin receptors (Ob-R) in the rat hypothalamus-pituitary-ovarian axis, immature rats were treated with eCG/hCG and Ob-R expression was evaluated by Western blot analysis. Ob-R expression increased 24 h after eCG administration in all the tissues assayed. In the hypothalamus, these levels immediately decreased to those obtained without treatment. In the pituitary, the Ob-R expression continued elevated 48 h after eCG administration, whereas the hCG injection did not modify these levels. Similar results were obtained with the ovarian long isoform. To assess the effect of leptin on its receptors, Ob-R was assessed in hypothalamus, pituitary and ovarian explants cultured in the presence or absence of leptin (0.3-500 ng.ml-1). In the hypothalamus, we found a biphasic effect: the Ob-R expression was either reduced or increased at low or high concentrations of leptin, respectively. Luteinizing hormone-releasing hormone secretion increased at 1 ng.ml-1. In the pituitary, Ob-R increased at 10 or 30 ng.ml-1 of leptin, for the long and short isoforms, respectively. Leptin also induced an increase in luteinizing hormone release at 30 ng.ml-1. In the ovarian culture, the presence of leptin produced an increase in Ob-R expression at different ranges of concentrations and a dose-dependent biphasic effect on the progesterone production. In conclusion, all these results clearly suggest that leptin is able to modulate the expression of its own receptors in the reproductive axis in a differential way. Moreover, the positive or negative effect that leptin exerts on the ovulatory process may be dependent on this regulation.

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