Biological Psychiatry Original Paper Neuropsychobiology 1998;37:142–145 Platelet 5-HT and Plasma Cortisol Concentrations after Dexamethasone Suppression Test in Patients with Different Time Course of Schizophrenia Miro Jakovljevic ´ a, c Dorotea Mück-S ˇ eler b, c Nela Pivac b, c Z ˇ eljka Crnc ˇevic ´ d a University Psychiatric Clinic, Clinical Hospital Center, b Laboratory for Molecular Neuropharmacology, ‘Rudjer Bos ˇkovic ´’ Institute, and c Croatian Institute for Brain Research, Zagreb, d Department of Endocrinology, Clinical Hospital Center, Rijeka, Croatia OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO Key Words Time course of schizophrenia Plasma cortisol Dexamethasone suppression test Platelet serotonin OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO Abstract Platelet 5-HT and plasma cortisol concentrations were determined in 59 schizophrenic patients with different time course of illness before and after dexamethasone suppression test (DST). An abnormal DST (nonsuppression) was observed in 51% of patients. In these patients basal cortisol and platelet 5-HT concentrations were higher than in patients with normal DST. After DST, plasma cortisol levels were higher in nonsuppressors with intermittent and intermittent-chronic time course, whereas platelet 5-HT concentrations were increased in nonsuppressors with intermittent-chronic time course. The results suggest that schizophrenic patients have dysregulated hypothalamic- pituitary-adrenal axis as shown by a high rate of DST nonsuppression, and that nonsuppressors showed hypercortisolemia and hyperserotonemia inde- pendent of the time course of schizophrenia. No significant association between DST and time course of the illness was found. OOOOOOOOOOOOOOOOOOOOOO Introduction There is increasing evidence that serotonin (5-hy- droxytryptamine, 5-HT) is involved in the pathophysiolo- gy of schizophrenia [1]. However the significance of its involvement remains to be elucidated [2, 3]. The neuroen- docrine changes, like elevated plasma cortisol levels [4–6], and abnormal response to dexamethasone suppression test (DST) [7], observed in some schizophrenic patients suggest a dysregulation of the hypothalamic-pituitary- adrenal (HPA) axis in this disease. 5-HT has been re- ported to exert a stimulatory effect on the HPA axis [8, 9], which in turn regulates the central 5-HT system [8, 9]. The blood platelet can be considered as a good model for studying the central serotoninergic synaptosomes [10, 11]. In the previous report, we have found an increased platelet 5-HT concentration in schizophrenic patients, es- pecially in those with chronic time course of disease [12]. The aims of the present study were to (a) investigate the function of the HPA axis after DST in schizophrenic patients with different time course of disease, and (b) eluci- date if there is a connection between platelet 5-HT concen- trations and HPA axis activity in schizophrenic patients. Method The population studied comprised 59 male schizophrenic pa- tients (mean age 30.2 B 6.5 years). Clinical diagnosis of schizophre- nia was made according to DSM-III-R criteria [13]. They were subdi- vided according to the time course of the illness into three subgroups: (a) with chronic (14 patients; mean age 32.3 B 7.5 years); (b) inter- mittent-chronic (29 patients; 29.8 B 7.1 years), and (c) intermittent ABC Fax + 41 61 306 12 34 E-Mail karger@karger.ch www.karger.com © 1998 S. Karger AG, Basel 0302–282X/98/0373–0142$15.00/0 This article is also accessible online at: http://BioMedNet.com/karger Nela Pivac, DVM, PhD Laboratory for Molecular Neuropharmacology ‘Rudjer Bos ˇkovic ´ ’ Institute HR–10000 Zagreb (Croatia) Tel. +385 1 456 1111/1321, Fax +385 1 468 0084, E-Mail npivac@rudjer.irb.hr