Apart from its obvious biochemical functions, glycine is also an important inhibitory neurotransmitter. Following depolarization, glycine is released from synaptic vesicles, binds to glycine receptors (GlyRs) on postsynaptic membranes thereby causing hyperpolarization of postsynaptic neurons due to the massive influx of Cl- ions. Glycine is then taken up from the synaptic cleft via the glycine transporters GlyT1 and GlyT2.GlyT1 has become a target for the treatment of schizophrenia, although a defect of the protein is not directly associated with the disorder. Inhibiting GlyT1 should lead to the increase in glutamatergic pathways, thereby decreasing psychotic effects in schizophrenic individuals. GlyT2 has been associated with hyperekplexia, a motor disorder characterized by neonatal hypertonia and startle reflex.
