Ovarian steroids increase veratridine-induced release of amino acid neurotransmitters in preoptic area synaptosomes.

In vivo treatment of ovariectomized rats with estradiol benzoate plus progesterone, but not with either steroid alone, produced a large increase in veratridine-induced release of radiolabeled glutamate and newly synthesized GABA from preoptic area synaptosomes in vitro. Neither basal nor KCl-evoked release of amino acids was altered. Thus gonadal steroids appear to be involved in the control of amino acid neurotransmitter release in a brain region of importance for regulation of female reproductive physiology and behavior.