Abstract

Since the isolation of Delta Sleep-Inducing Peptide (DSIP) in 1977, several hundred papers have been published, most of them dealing with proposed central and peripheral actions of the peptide. Using immunochemical and immunocytochemical techniques, DSIP-like material has been localized in the mammalian brain as well as in certain peripheral organs. Interestingly, immunoreactive DSIP has been located to all three levels of the hypothalamic pituitary-adrenal (HPA) axis. These findings may be of importance because DSIP has been shown to affect the activity of this axis. In addition, decreased plasma and cerebrospinal fluid (CSF) levels of immunoreactive DSIP have been found in patients with major depression and reduced CSF concentrations have been described in patients with schizophrenia. Besides being a sleep inducer, DSIP has been used to reduce withdrawal symptoms in alcoholic and opiate addicts and as an analgetic in chronic pain. Whether DSIP is mainly produced in the central nervous system or in peripheral organs is still an open question, however, it seems to passs the blood-brain barrier more easily than many other neuropeptides.