5-HT, HPA function impaired in depressed and schizophrenic patients
September 29, 2004
Depression and schizophrenia are characterized by disturbed serotonin (5-HT) transmission and dysregulated hypothalamic-pituitary-adrenal axis (HPA) activity, say investigators after finding altered serotonin and cortisol levels in both groups of patients.
Dorotea Muck-Seler and colleagues hypothesized that "if the interaction between 5-HT and HPA systems was impaired in depression and schizophrenia, then the association between platelet 5-HT, plasma cortisol, and plasma prolactin values would differ among healthy, depressed, and schizophrenic women."
The researchers therefore determined the concentrations of these variables in 20 schizophrenic, 25 depressed, and 25 mentally healthy women who had not taken medications for at least 7 days before blood samples were taken.
They found that platelet 5-HT concentration was significantly higher in schizophrenic patients (1.57 nmol/mg of protein) than in controls (1.24 nmol/mg), while levels were significantly lower in depressed patients (0.93 nmol/mg) than in the other two groups.
Plasma cortisol levels were significantly increased in both depressed and schizophrenic patients, compared with controls, at 496 nmol/l, 533 nmol/l, and 389 nmol/l, respectively.
Values for prolactin levels, however, were comparable for the three groups.
These findings remained after taking into account age and menopausal status.
Muck-Seler et al note that a significant correlation existed between platelet 5-HT and plasma cortisol and prolactin levels in controls, whereas there was no significant relationship seen for either schizophrenia or depressed patients.
"Our data... indicate that depression and schizophrenia are characterized by disturbed 5-HT transmission at the hypothalamic or pituitary level, or by excessive activity of the HPA axis, that leads to elevated cortisol levels, and consequently to alterations of central and peripheral 5-HT systems," the researchers report in the journal Psychiatry Research.
Psych Res 2004; 127: 217-226