Regional differences in depolarization-induced release of gamma-hydroxybutyrate from rat brain slices

gamma-Hydroxybutyrate (GHB), an endogenous compound in mammalian brain which possesses important neuroregulatory properties, has been proposed as a neurotransmitter. The present report concerns the heterogeneous regional characteristics of depolarization-induced gamma-[3H]hydroxybutyrate ([3H]GHB) release in rat brain slices. The Ca2+-dependent component of [3H]GHB release in cerebellum and pons-medulla, areas with low concentrations of GHB binding sites, is only about 23% of that in hippocampus, striatum and frontoparietal cortex, all areas rich in binding sites. In addition, veratridine-induced release of [3H]GHB in cerebellum and pons-medulla is only 16% of that measured in hippocampus, striatum and frontoparietal cortex. These findings add support to the suggested neurotransmitter role of GHB in the forebrain and suggest a purely metabolic role for this compound in more posterior regions of brain where both binding sites and Ca2+-dependent release mechanisms are absent.