Localization of sensitive sites to taurine, gamma-aminobutyric acid, glycine and beta-alanine in the molecular layer of guinea-pig cerebellar slices.

1 The localization, in the molecular layer of guinea-pig cerebellar slices, of the sites most sensitive to iontophoretically applied taurine, gamma-aminobutyric acid (GABA), glycine and beta-alanine was investigated. 2 The most sensitive sites were located (expressed as the distance from the Purkinje cell body to the pial surface): 0 micrometers, 60 micrometers and 220 micrometers for taurine; 0 micrometers and 180 micrometers for GABA; 80 micrometers and 200 micrometers for glycine, and 80 micrometers, 180 micrometers and 300 micrometers for beta-alanine. 3 The sensitive site (at 0 micrometers) to GABA was considered to represent the basket synapses on the Purkinje cell soma, while the sites (60 to 80 micrometers and 200 to 300 micrometers) for taurine, glycine and beta-alanine were tentatively assigned to the synapses of the stellate neurones on the Purkinje cell dendrites. 4 Inhibitory actions of all four amino acids tested at the most sensitive sites were antagonized by both picrotoxin and strychnine. 5 The possibility that taurine might be the neurotransmitter of the stellate neurones in guinea-pig cerebellum is discussed.