Sleep and orexins in nonmammalian vertebrates.
Although a precise definition of "sleep" has yet to be established, sleep-like behaviors have been observed in all animals studied to date including mammals and nonmammalian vertebrates. Orexins are hypothalamic neuropeptides that are involved in the regulation of many physiological functions, including feeding, thermoregulation, cardiovascular control, as well as the control of the sleep-wakefulness cycle. To date, the knowledge on the functions of orexins in nonmammalian vertebrates is still limited, but the similarity of the structures of orexins and their receptors among vertebrates suggest that they have similar conserved physiological functions. This review describes our current knowledge on sleep in nonmammalian vertebrates (birds, reptiles, amphibians, and fish) and the possible role of orexins in the regulation of their energy homeostasis and arousal states.
Department of Biology, Memorial University of Newfoundland, St John's, Newfoundland, Canada.
Hélène
H
Volkoff
D029845:Amphibian Proteins / Q000737:chemistry / Q000378:metabolism; D000663:Amphibians / Q000378:metabolism*; D000818:Animals; D030161:Avian Proteins / Q000235:genetics / Q000378:metabolism; D001522:Behavior, Animal; D001717:Birds / Q000378:metabolism*; D029941:Fish Proteins / Q000737:chemistry / Q000378:metabolism; D005399:Fishes / Q000378:metabolism*; D007026:Hypothalamic Area, Lateral / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000737:chemistry / Q000378:metabolism*; D064446:Orexin Receptors; D000068797:Orexins; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism; D010802:Phylogeny; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D018013:Receptors, Neuropeptide / Q000378:metabolism*; D012104:Reptiles / Q000378:metabolism*; D030162:Reptilian Proteins / Q000737:chemistry / Q000378:metabolism; D012890:Sleep
D029845:Amphibian Proteins; D030161:Avian Proteins; D029941:Fish Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D030162:Reptilian Proteins