EFFECTS OF BICUCULLINE, γ-AMINOBUTYRIC ACID AND Ca2+ ON THE RELEASE OF 3H-NORADRENALINE AND 14C-γ-AMINOBUTYRIC ACID FROM SLICES OF RAT BRAIN MESODIENCEPHALIC REGION

Publisher Summary The data obtained in various studies have shown that in the presence of C 2+ , bicuculline moderately stimulates K + -evoked release of 3 H-NA whereas significantly inhibited that of 14 C-GABA. This chapter discusses a study to analyze the effects of bicuculline, γ-aminobutyric acid, and Ca 2+ on the release of 3 H-noradrenaline ( 3 H-NA) and 14 C-γ-amino-butyric acid ( 14 C-GABA) from the slices of rat brain mesodiencephalic region. The rate of release of both 3 H-NA and 14 C-GABA was considerably decreased in Ca 2+ -omitted medium, but it was enhanced following the addition of bicuculline. The data indicate that in some cases, bicuculline display an effect that is similar to Ca 2+ . Bearing in mind that 14 C-GABA release was inhibited following joint addition of Ca 2+ and bicuculline, the conclusion may be drawn of a feedback control mechanism of GABA release. It was observed that GABA added in concentration 10 −3 caused 1.5-fold increase of 3 H-NA but in the absence of Ca 2+ , this effect was much more pronounced as compared with Ca 2+ -omitted control.