Galanin enhancement of gonadotropin-releasing hormone-stimulated luteinizing hormone secretion in female rats is estrogen dependent
| Autor: | Joseph R. Scheffen, Angela C. Bauer-Dantoin, Vicky Plamann, Joshua A. Desotelle, Cynthia L. Splett |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
endocrine system
medicine.medical_specialty medicine.drug_class Ovariectomy Neuropeptide Galanin Gonadotropin-releasing hormone Gonadotropin-Releasing Hormone Rats Sprague-Dawley Endocrinology Internal medicine medicine Animals GABA Modulators Pentobarbital Progesterone Luteinizing hormone secretion Chemistry digestive oral and skin physiology Estrogens Luteinizing Hormone Rats nervous system Follicular Phase Estrogen Ovariectomized rat Female Gonadotropin Luteinizing hormone hormones hormone substitutes and hormone antagonists |
| Zdroj: | Endocrinology. 144(2) |
| ISSN: | 0013-7227 |
| Popis: | The hypothalamic peptide GnRH is the primary neuroendocrine signal regulating pituitary LH in females. The neuropeptide galanin is cosecreted with GnRH from hypothalamic neurons, and in vitro studies have demonstrated that galanin can act at the level of the pituitary to directly stimulate LH secretion and also augment GnRH-stimulated LH secretion. Several lines of evidence have suggested that the hypophysiotropic effects of galanin are important for the generation of preovulatory LH surges. To determine whether the pituitary actions of galanin are enhanced by the preovulatory steroidal milieu, LH responses to galanin administration (with or without GnRH) were examined in: 1) ovariectomized (OVX); 2) OVX, estrogen (E)-primed; and 3) OVX, E- and progesterone-treated female rats. Results from the study indicate that galanin enhances GnRH-stimulated LH secretion only in the presence of E (in OVX, E-primed, or E- and progesterone-treated rats). Galanin alone does not directly stimulate LH secretion under any of the steroid conditions examined. In the absence of gonadal steroids (OVX rats), galanin inhibits GnRH-stimulated LH secretion. These findings suggest that the primary pituitary effect of galanin is to modulate GnRH-stimulated LH secretion, and that the potentiating effects of galanin occur only in the presence of E. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|