Leptin modulates the expression of its receptors in the hypothalamic-pituitary - Ovarian axis in a differential way
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...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2008 |
| País: | Argentina |
| Institución: | Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales |
| Repositorio: | Biblioteca Digital (UBA-FCEN) |
| Idioma: | inglés |
| OAI Identifier: | paperaa:paper_00220795_v198_n2_p355_DiYorio |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00220795_v198_n2_p355_DiYorio |
| Access Level: | acceso abierto |
| Palabra clave: | gonadorelin leptin leptin receptor progesterone animal experiment animal tissue article female hormone synthesis hypothalamus hypophysis ovarian axis hypothalamus hypophysis system immunohistochemistry nonhuman ovulation priority journal process control protein content protein expression radioimmunoassay rat tissue level Western blotting Animals Blotting, Western Chorionic Gonadotropin Female Gene Expression Gonadotropin-Releasing Hormone Hypothalamus Immunohistochemistry Leptin Ovary Pituitary Gland Rats Rats, Sprague-Dawley Receptors, Leptin |
| Sumario: | 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. © 2008 Society for Endocrinology. |
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