NITRIC-OXIDE SYNTHASE-CONTAINING NEURONS IN THE HUMAN HYPOTHALAMUS - REDUCED NUMBER OF IMMUNOREACTIVE CELLS IN THE PARAVENTRICULAR NUCLEUS OF DEPRESSIVE PATIENTS AND SCHIZOPHRENICS

The neuroanatomical distribution of nitric oxide synthase-immunoreacti ve neurons was investigated in post moi rem hypothalami of 10 patients suffering from schizophrenia, eight patients with depression and 13 m atched control cases. Neuronal nitric oxide synthase containing nerve cells were detected in several hypothalamic nuclei including the media l preoptic region, the ventromedial, infundibular and suprachiasmatic nuclei and the lateral hypothalamus. The vast majority of hypothalamic nitric oxide synthase-immunoreactive neurons was found to be located in the paraventricular nucleus. Both magno and parvocellular paraventr icular neurons contained the enzyme. A small subset of immunoreactive parvocellular paraventricular neurons co-expresses corticotropin-relea sing hormone. The supraoptic nucleus did not contain nitric oxide synt hase-immunoreactive neurons. Cell counts of paraventricular nitric oxi de synthase-positive neurons in controls, schizophrenics and depressed patients revealed a statistically significant reduction of cell densi ty in the right paraventricular nucleus of depressed patients and schi zophrenics as compared to controls. The total amount of nitric oxide s ynthase-immunoreactive paraventricular neurons was smaller in depressi ve and schizophrenic patients than in normal cases. The putative patho physiologic significance of the reduced expression of paraventricular nitric oxide synthase in depressive patients might be related to the s upposed regulatory function of nitric oxide in the release of corticot ropin-releasing hormone and arginine-vasopressin and/or oxytocin, whic h have been reported to be over-expressed in the so-called endogenous psychoses, especially in depression. (C) 1998 IBRO. Published by Elsev ier Science Ltd.