Hypocretin-2-saporin lesions of the lateral hypothalamus produce narcoleptic-like sleep behavior in the rat.
Hypocretins (Hcrts) are recently discovered peptides linked to the human sleep disorder narcolepsy. Humans with narcolepsy have decreased numbers of Hcrt neurons and Hcrt-null mice also have narcoleptic symptoms. Hcrt neurons are located only in the lateral hypothalamus (LH) but neither electrolytic nor pharmacological lesions of this or any other brain region have produced narcoleptic-like sleep, suggesting that specific neurons need to be destroyed. Hcrt neurons express the Hcrt receptor, and to facilitate lesioning these neurons, the endogenous ligand hypocretin-2/orexin B (Hcrt2) was conjugated to the ribosome-inactivating protein saporin (SAP). In vitro binding studies indicated specificity of the Hcrt2-SAP because it preferentially bound to Chinese hamster ovary cells containing the Hcrt/orexin receptor 2 (HcrtR2/OX(2)R) or the Hcrt/orexin receptor 1 (HcrtR1/OX(1)R) but not to Kirsten murine sarcoma virus transformed rat kidney epithelial (KNRK) cells stably transfected with the substance P (neurokinin-1) receptor. Administration of the toxin to the LH, in which the receptor is known to be present, eliminated some neurons (Hcrt, melanin-concentrating hormone, and adenosine deaminase-containing neurons) but not others (a-melanocyte-stimulating hormone), indicating specificity of the toxin in vivo. When the toxin was administered to the LH, rats had increased slow-wave sleep, rapid-eye movement (REM) sleep, and sleep-onset REM sleep periods. These behavioral changes were negatively correlated with the loss of Hcrt-containing neurons but not with the loss of adenosine deaminase-immunoreactive neurons. These findings indicate that damage to the LH that also causes a substantial loss of Hcrt neurons is likely to produce the multiple sleep disturbances that occur in narcolepsy.
Gerashchenko
D
D
West Roxbury Veterans Affairs Medical Center and Harvard Medical School, West Roxbury, Massachusetts 02132, USA.
Kohls
M D
MD
Greco
M
M
Waleh
N S
NS
Salin-Pascual
R
R
Kilduff
T S
TS
Lappi
D A
DA
Shiromani
P J
PJ
D000243:Adenosine Deaminase / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002460:Cell Line; D002940:Circadian Rhythm / Q000187:drug effects; D006224:Cricetinae; D006970:Disorders of Excessive Somnolence / Q000139:chemically induced* / Q000503:physiopathology*; D004569:Electroencephalography; D005434:Flow Cytometry; D007031:Hypothalamus / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology*; D000922:Immunotoxins / Q000008:administration & dosage / Q000737:chemistry; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D051379:Mice; D008845:Microinjections; D009699:N-Glycosyl Hydrolases; D009290:Narcolepsy / Q000139:chemically induced / Q000503:physiopathology; D009419:Nerve Tissue Proteins / Q000008:administration & dosage*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009479:Neuropeptides / Q000737:chemistry; D064446:Orexin Receptors; D000068797:Orexins; D010940:Plant Proteins / Q000008:administration & dosage* / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled; D018040:Receptors, Neurokinin-1 / Q000096:biosynthesis / Q000235:genetics; D018013:Receptors, Neuropeptide / Q000096:biosynthesis / Q000235:genetics; D054789:Ribosome Inactivating Proteins, Type 1; D000076985:Saporins; D012890:Sleep / Q000187:drug effects; D014118:Toxins, Biological; D014162:Transfection; D014741:Video Recording
C000596229:HCRT protein, human; C578630:HCRTR1 protein, human; C578625:Hcrtr2 protein, rat; D000922:Immunotoxins; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D010940:Plant Proteins; D043562:Receptors, G-Protein-Coupled; D018040:Receptors, Neurokinin-1; D018013:Receptors, Neuropeptide; D054789:Ribosome Inactivating Proteins, Type 1; D014118:Toxins, Biological; C435665:hypocretin-2-saporin conjugate; D009699:N-Glycosyl Hydrolases; D000076985:Saporins; D000243:Adenosine Deaminase