Correlation between 3H-haloperidol binding in the striatum and brain amine metabolism in the rat after treatment with neuroleptics.

Rats were pretreated with haloperidol, clothiapine, loxapine, chlorpromazine, thioridazine, NT 104-252, clozapine or perlapine. The animals were decapitated at various times after drug administration, the striata removed and homogenized in tris buffer containing pargyline, ascorbic acid, EGTA and various salts. After centrifugation the homogenates were incubated with ³H-haloperidol, and total and unspecifically bound ³H-haloperidol were measured. Excellent correlations were found between inhibition of specific ³H-haloperidol binding and increases in the striatal concentration of DOPAC induced by the neuroleptics, confirming that DA-receptor blockade provokes an increase in DA-metabolism. No correlation, however, was found with neutoleptic-induced changes in the concentrations of MOPEG-SO₄ in the brain stem or of 5-HIAA in the cortex, re-affirming that inhibition of specific ³H-haloperidol binding is due to drug effects on DA-receptors only.