Inhibitory actions of amino acids in the preoptic-anterior hypothalamus of the rat.

Extracellular recordings were made from preoptic-anterior hypothalamic neurones with combined recording and iontophoresis electrodes. Short iontophoretic applications of beta-alanine, GABA, glycine and taurine inhibited the discharge of the majority of neurones tested. Bicuculline metho-chloride reversibly and selectively antagonised GABA responses. Strychnine reversibly antagonised beta-alanine, glycine and taurine but not GABA responses. These results suggest the existence of two populations of inhibitory amino acid receptors in the preoptic-anterior hypothalamus. The function of inhibitory amino acids in the rostral hypothalamus was briefly discussed.