Glycine Potentiates the Stimulation of Inositol Phospholipid Hydrolysis by Excitatory Amino Acids in Primary Cultures of Cerebellar Neurons

Glycine potentiates stimulation of inositol phospholipid hydrolysis by glutamate and N‐methyl‐D‐aspartate, but not by quisqualate or carbamylcholine, in primary cultures of cerebellar granule cells. This potentiation occurs in the absence of extracellular Mg²⁺, but is more evident when stimulation of inositol phospholipid hydrolysis by N‐methyl‐D‐aspartate is measured in the presence of 1 mM Mg²⁺. The action of glycine is not antagonized by strychnine. These results suggest that glycine acts as a positive modulator of signal transduction at a specific class of N‐methyl‐D‐aspartate‐sensitive glutamate receptors coupled to inositol phospholipid hydrolysis in cerebellar granule cells.