ORIGINAL PAPER
The role of GABAA receptors in the neural systems of the medial preoptic area in the control of GnRH release during the luteal phase of the oestrous cycle in ewes
 
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The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-110 Jabłonna, Poland
CORRESPONDING AUTHOR
D. Tomaszewska-Zaremba   

The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-110 Jabłonna, Poland
Publication date: 2004-01-14
 
J. Anim. Feed Sci. 2004;13(1):121–132
 
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ABSTRACT
Recent studies from our laboratory suggested that functional interconnection of the GABAergic system with the GnRHergic, β-endorphinergic and catecholaminergic systems in the medial preoptic area (MPOA) plays an important role in the modulation of gonadoliberin (GnRH) release during the follicular phase of the oestrous cycle in ewes. Since the mode of action of γ-aminobutyric acid (GABA) on GnRH neurons is highly dependent on gonadal steroids, we extended our studies to the role of GABAA receptors in the MPOA on the activity of all of the above-mentioned systems during the luteal phase of the oestrous cycle. Stimulation of GABAA receptors by muscimol did not affect either GnRH/LH, β-endorphin release or catecholaminergic activity, expressed by extracellular concentrations of noradrenaline (NE), dopamine (DA) and their metabolites MHPG and DOPAC. Blockade of GABAA receptors decreased β-endorphin release, dopaminergic and noradrenergic activity but did not change GnRH release or LH secretion. It is suggested that progesterone secretion during the luteal phase may desensitize GABAA receptors to further stimulation.
ISSN:1230-1388