CSF hypocretin-1 levels in schizophrenics and controls: relationship to sleep architecture.
Hypocretins/orexins are newly identified peptides of hypothalamic origin. Hypocretin deficiency is involved in the sleep disorder narcolepsy, suggesting the importance of hypocretin neurotransmission for the regulation of sleep. Hypocretin is known to excite midbrain dopaminergic neurons and to induce hyperactivity and stereotypy in animals. Altered hypocretin neurotransmission might therefore be involved in schizophrenia, since an involvement of dopaminergic mechanisms and an association with sleep disturbance are well demonstrated in patients with schizophrenia. Hypocretin is also known to affect the hypothalamic-pituitary-adrenal axis by stimulating the release of corticotropin releasing hormone (CRH). In the current study, we measured CSF hypocretin levels in 12 controls and 13 patients with chronic schizophrenia associated with moderate sleep disturbance, such as longer sleep onset latency, decreased total sleep time and decreased sleep efficacy. No difference in CSF hypocretin levels between schizophrenia and control subjects was found. CSF hypocretin levels were positively correlated with CSF CRH levels in the patient, control and combined subject populations, but the correlation did not reach statistical significance in any population. The hypocretin levels in schizophrenic patients were, however, positively and significantly correlated with sleep latency, one of the most consistent sleep abnormalities seen in schizophrenia. This correlation was not significant in controls, and no other significant correlation between CSF hypocretin levels and any measure of sleep architecture in either patients or controls was observed. Further studies of whether CNS hypocretin neurotransmission is involved in sleep and neuroendocrine abnormalities seen in patients with schizophrenia and other psychiatric conditions are warranted.
Nishino
Seiji
S
Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA 94305, USA. nishino@leland.stanford.edu
Ripley
Beth
B
Mignot
Emmanuel
E
Benson
Kathleen L
KL
Zarcone
Vincent P
VP
D000328:Adult; D002352:Carrier Proteins / Q000134:cerebrospinal fluid*; D002908:Chronic Disease; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D009479:Neuropeptides / Q000134:cerebrospinal fluid*; D000068797:Orexins; D010913:Pituitary-Adrenal System / Q000503:physiopathology; D017286:Polysomnography; D011569:Psychiatric Status Rating Scales; D011930:Reaction Time / Q000502:physiology; D012559:Schizophrenia / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology
D002352:Carrier Proteins; C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins