Cerebral glutamate, neuroleptic drugs and schizophrenia: increase of cerebrospinal fluid glutamate levels and decrease of striate body glutamate levels following sulpiride treatment in rats.

Chronic (12 days) administration of sulpiride (50 mg/kg, i.p.) in rats resulted in a significant (12%) increase in the glutamate contents of cerebrospinal fluid. Sulpiride had no effect on the GABA content of the brain areas investigated (frontal cortex, striatum, hippocampus and substantia nigra). Sulpiride is a neuroleptic drug which is believed to block especially the non-adenylate cyclase dopaminergic receptors which are supposed to be inhibitory axoaxonic receptors on glutamatergic corticostriatal terminals. The results are compatible with the hypothesis that glutamatergic hypofunction might be the primary defect in schizophrenia rather than hyperactivity of the dopamine synapses.