Modulation of dopamine receptor supersensitivity by chronic insulin: implication in schizophrenia

Haloperidol-induced increases in the number of dopamine receptors, as measured by [3H]spiperone binding to striatal membranes, do not occur in rats repeatedly treated with insulin in doses eliciting pronounced hypoglycemia. Given alone, however, insulin has no effect on [3H]spiperone binding in normal rats. These findings demonstrate a modulating effect of insulin on brain dopamine receptor sensitization. This effect might be relevant to the mechanism of insulin coma therapy in schizophrenia and is consistent with and supports the dopaminergic hypothesis of this disorder.