The role of receptor A g -aminobutyric acid ( GABA ) in the neural control of the release gonadotropin-releasing hormone (GnRH ) from the hypothalamus in sheep anestralnych determined from the extracellular concentration of GnRH , b- endorphin , noradrenaline , dopamine and its metabolites DOPAC and MHPG during perfusion and bicuculliny muscimolu ( agonists and antagonists of the GABAA receptors ) in the kernel funnel ? median eminence (NI / ME ) and the preoptic area ( MPOA ) .