MULTIHORMONAL RESPONSES TO APOMORPHINE IN MENTAL-ILLNESS

The neuroendocrine responses to subcutaneous (SC) administration of th e dopamine (DA) agonist apomorphine (APO) hydrochloride (0.75 mg) were studied in a large group of subjects: 110 drug-free inpatients with e ither DSM-III-R schizophrenia (SCZ, n = 46), schizoaffective disorder (SAD, n = 14), or major depressive episode (MDE, n = 50), plus 18 hosp italized controls. Compared to a saline test, APO induced a significan t increase of growth hormone (GH), adrenocorticotropin (ACTH), and cor tisol (COR) release and a decrease in prolactin (PRL) secretion. No ch ange in thyrotropin (TSH) levels was observed. In the total sample the extents of ACTH, COR and GH responses were correlated, but in the gro up of 88 subjects who exhibit a normal GH stimulation this correlation disappeared. This discrepancy suggests that APO-induced ACTH and COR stimulation may be mediated by pathways different from those mediating GH stimulation. According to diagnostical categories, we found signif icant lower ACTH and COR stimulation in the schizophrenic group and in patients with SAD, compared with that among controls or depressed pat ients. we found also a significant difference between subgroups of sch izophrenic patients. These results agree with the hypothesis that diff erent aspects of psychosis might involve different subtypes of DA-rece ptors with different localizations and sensitivities.