High delta sleep-inducing peptide-like immunoreactivity in plasma in suicidal patients with major depressive disorder

Background: Delta sleep-inducing peptide (DSIP) supposedly involves the hypothalamus-pituitary-adrenal (HPA) axis. Previous studies have shown deviated plasma DSIP-like immunoreactivity (DSIP-LI) levels, as well as abnormal DSIP-LIW responses to corticotropin-releasing hormone in patients with major depressive disorder (MDD). This study was performed to investigate plasma-DSIP-LI and its association with the dexamethasone suppression test (DST) in suicide attempters. Methods: Plasma-DSIP and serum cortisol were measured before and after dexamethasone intake in 34 suicide attempters and in healthy age-and sex-matched controls. Results: We Sound significantly elevated DSIP-LI levels in MDD patients (p < .005), and a significant correlation between predexamethasone cortisol and predexamethasone DSIP-LI levels in healthy controls, Postdexamethasone DSIP-LI levels increased in subjects with low predexamethasone DSIP-LI levels, whereas they decreased in subjects with high predexamethasone DSIP-LI levels. Conclusions: Results give some support to the theory of glucocorticoid involvement in the regulation of DSIP, and suggest altered DSIP-LI levels in suicidal MDD patients. (C) 1998 Society of Biological Psychiatry.