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This Article Full Text Full Text (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 Web of Science 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 P Articles by Faletti, A G Search for Related Content PubMed PubMed Citation Articles by Di Yorio, M P Articles by Faletti, A G

¹ Centro de Estudios Farmacológicos y Botánicos (CEFYBO), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Facultad de Medicina, UBA, Paraguay 2155, 16° P, C1121ABG Buenos Aires, Argentina² Dpto. de Química Biológica, Facultad de Ciencias Exactas y Naturales (FCEyN), UBA, Cdad.Universitaria-Pabellón II-4° P, C1428EHA Buenos Aires, Argentina

(Correspondence should be addressed to A G Faletti; Email: agfaletti{at}yahoo.com.ar)

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. The 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 to be 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). 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. LH-releasing hormone secretion increased at 1 ng/ml. In the pituitary, Ob-R increased at 10 or 30 ng/ml of leptin for the long and short isoforms respectively. Leptin also induced an increase in LH release at 30 ng/ml. 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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