The role of GABAA receptors in the neural systems of the ventromedial-infundibular region of the hypothalamus in the control of gonadotropin release during the luteal phase in ewes

• Autorzy: Tomaszewska-Zaremba D. , Mateusiak K. , Przekop F.
• Języki publikacji: EN

Abstrakty

EN

To examine the role of GABAA receptor mediating systems in the control of gonadotropin-releasing hormone (GnRH) release from the ventromedial- infundibular region (VEN/NI) in ewes during luteal phase, the extracellular concentrations of GnRH, ß-endorphin, noradrenaline (NE), dopamine (DA), and their metabolites: MHPG and DOPAC were quantified by local stimulation or blockade of GABAA receptors with muscimol or bicuculline, respectively. Stimulation of GABAA receptors in the VEN/NI did not affect GnRH, ß-endorphin release or catecholaminergic system activity. Blockade of GABAA receptors decreased ß-endorphinergic and dopaminergic activity, and lowered the extracellular concentration of MHPG. It did not affect GnRH release or luteinizing hormone (LH) secretion. It is suggested that progesterone-induced GABAergic activity during the luteal phase may desensitize GABAA receptors to muscimol. Lack of changes in GnRH/LH secretion with concomitant depressed ß-endorphinergic activity corroborated the conclusion that ß-endorphin does not inhibit GnRH release from the VEN/NI during the luteal phase. The physiological significance of changes in the catecholaminergic system activity under GABAA receptor blockade in the control of GnRH secretion awaits to be established.

Słowa kluczowe

EN

hypothalamus; neural system; catecholamine; gonadotrophin releasing hormone; ewe; luteal phase; beta-endorphin; ventromedial-infundibular region; gamma-aminobutyric acid

• Wydawca: -
• Czasopismo: Journal of Physiology and Pharmacology
• Rocznik: 2002
• Tom: 53
• Numer: 4,2
• Opis fizyczny: p.835-845,fig.

Twórcy

autor

Tomaszewska-Zaremba D.

• Polish Academy of Sciences, 05-110 Jablonna, Poland

autor

Mateusiak K.

autor

Przekop F.