Cerebellar Giant Synaptosomes: a Model to Study Basal and Stimulated Release of [3H] gamma-Aminobutyric Acid

Background: neurotransmitter release is an essential link incell communication of the nervous system. many investigationshave focused on gamma amino butyric acid (gaba)ergicneurotransmission, because it has been implicated in thepathophysiology of several central nervous system disorders.to bypass complications related to homo- and heterosynapticmodulation and to avoid indirect interpretations of data, weherein describe a simple approach for direct measurement ofgaba release.material and methods: giant synaptosomes originated fromnerve terminals of rat cerebellum mossy fibers were preparedfor the study. electron micrographs as well as lactate dehydrogenaseassay are used for morphological and biochemical verifications.giant synaptosomes were preloaded with labeled[3h]gaba. spontaneous and stimulated release of eh]gabawas measured using a superfusion apparatus. stimulation wasevoked by increasing exteracellular concentration of k+ ions.results: spontaneous [3h]gaba release had a constant andnearly linear kinetics. eh]gaba outflow evoked by depolarizingsolution containing 15 mm of k+ showed 2-3 fold increasesover the basal release. the same effect was also reproducibleafter several minutes.conclusion: the present findings indicate that this preparationcould be used as a suitable and versatile in vitro model tostudy gaba release from axon terminals under basal andevoked conditions.