Involvement of GABA in the Neuroendocrinology of Reproduction

Abstract

Pulsatile LHRH secretion from hypothalamic neurons is a prerequisite for proper pituitary LH and FSH release (Knobil, 1980). As will be shown in other chapters in this volume, pulsatile LHRH secretion is the result of synchronous, phasic activation of LHRH neurons. This pulsatility can be disrupted by noradrenergic antagonists and this mechanism involves most probably α-adrenoceptors (Kaufmann et al., 1985). Furthermore, the amino acid neuro-transmitter γ-aminobutyric acid (GABA) can also disrupt pulsatile LHRH secretion (Lamberts et al., 1982; Fuchs et al., 1984). GABA was recently shown to be the neurotransmitter of many estrogen-receptive preoptic/anterior hypothalamic (MPO/AH) neurons (Flügge et al., 1986). The majority of LHRH neurons in the rat are also located in this area. In previous publications, it was shown that both positive as well as negative feedback effects of estrogens on LH secretion involve among other structures also the MPO/AH area (Mansky et al., 1982; Fuchs et al., 1984).