EFFECTS OF OMEGA-AMINO ACIDS ON TRITIATED DOPAMINE RELEASE FROM RAT STRIATUM - EVIDENCE FOR A POSSIBLE GLYCINERGIC MECHANISM

The effects of GABA and glycine on the release of tritiated dopamine from prelabelled slices of rat striatum have been compared. Both GABA (>50 μM) and glycine (>200 μM) released tritiated dopamine, but had no effect on the release of radiolabelled 5-hydroxytryptamine and GABA. The GABA antagonist picrotoxin (50 μM) markedly reduced the ability of GABA to release [3H]dopamine, but had no effect on the glycine response. Conversely strychnine (0.5 μM), a specific glycine receptor antagonist at low concentrations, abolished both the GABA and the glycine response on [3H]dopamine release. Two other ω-amino acids, β-alanine and taurine, both at 500 μM, had no effect on [3H]dopamine release from rat striatal slices. In additional experiments, release of radioactivity was demonstrated from neonatal rat spinal cord and striatal slices after prelabelling with [3H]glycine. This release was calcium-dependent. The possibility that glycine may function as a neurotransmitter substance within the striatum is considered, and the hypothesis that GABA may partially exert some of its pharmacological effects through the glycine receptor is discussed. © 1979.