Effects of neuroleptic drugs on brain somatostatin-like-immunoreactivity.

We previously found a dose-dependent reduction in striatal somatostatin-like immunoreactivity (SLI) following chronic haloperidol therapy. In the present experiments the effect was shown to be specific for the striatum and nucleus accumbens. With pimozide reductions in SLI were seen in the striatum, nucleus accumbens, amygdala, hypothalamus, bed nucleus of the stria terminalis and central grey matter. Other neuroleptics including chlorpromazine and fluphenazine also resulted in reduced concentrations of SLI in the striatum, nucleus accumbens and amygdala. A time course experiment showed that effects were demonstrable by 3 days and maximal at two weeks. The present findings provide further evidence of an interaction between somatostatin and dopaminergic neurons in the striatum.