Application of the glycine labelling method to the cerebellum, hippocampus and spinal cord

3H-glycine was applied to the cat cerebellar cortex under resting conditions and during inferior olive stimulation which activated the climbing fiber system on a restricted area. Electric recording was made. The autoradiograms showed, that under resting condition labelled glycine was incorporated mainly in granule, Golgi and basket cells and only a few Purkinje and stellate cells were active. Also cerebellar glomeruli remained without labelling. On climbing fiber stimulation Purkinje cells became activated singly and grouped, also Golgi and stellate cells increased in number. Granule cells were totally inhibited. 3H-glycine, when applied to the rat hippocampus, the dentate gyrus, CA1 and CA4 fields showed labelling at low frequency stimulation. When 400 Hz high frequency stimulation periods were interposed, long-term potentiation ensued. The overall labelling of each hippocampal region was intensified significantly, indicating that glycine incorporation may be a sign not only of excitation but also of long-term potentiation. 3H-glycine was applied to frog spinal cord during rest and dorsal root stimulation. Interneurons and motor neurons excited by the afferent fibers showed intensive glycine uptake. It is concluded that the glycine labelling method is suitable for detecting neural excitation in the structures dealt with in this paper.