Postsynaptic supersensitivity in schizophrenia

In the context of the dopamine hypothesis of schizophrenia, the authors examined postsynaptic dopamine (DA) receptor sensitivity in schizophrenic patients by means of a neuroendocrine strategy using the DA receptor agonist apomorphine and growth hormone (GH) release as the measurable postsynaptic event. The activity of platelet adenylate cyclase, an enzyme intimately associated with catecholamine receptor activity, was also studied following stimulation by prostaglandin E₁ (PGE₁). Patients diagnosed as having acute schizophrenia had significantly higher GH responses and adenylate cyclase activity than normal control subjects and patients diagnosed as having chronic schizophrenia. Chronic schizophrenic patients with and without tardive dyskinesia showed GH responses slightly lower than but not significantly different from those of control groups.