title: Homeostatic response to sleep/rest deprivation by constant water flow in larval zebrafish in both dark and light conditions.
abstract: Sleep-or sleep-like states-have been reported in adult and larval zebrafish using behavioural criteria. These reversible quiescent periods, displaying circadian rhythmicity, have been used in pharmacological, genetic and neuroanatomical studies of sleep-wake regulation. However, one of the important criteria for sleep, namely sleep homeostasis, has not been demonstrated unequivocally. To study rest homeostasis in zebrafish larvae, we rest-deprived 1-week-old larvae with a novel, ecologically relevant method: flow of water. Stereotyped startle responses to sensory stimuli were recorded after the rest deprivation to study arousal threshold using a high-speed camera, providing an appropriate time resolution to detect species-specific behavioural responses occurring in a millisecond time-scale. Rest-deprived larvae exhibited fewer startle responses than control larvae during the remaining dark phase and the beginning of the light phase, which can be interpreted as a sign of rest homeostasis-often used as equivalent of sleep homeostasis. To address sleep homeostasis further, we probed the adenosinergic system, which in mammals regulates sleep homeostasis. The adenosine A1 receptor agonist, cyclohexyladenosine, administered during the light period, decreased startle responses and increased immobility bouts, while the adenosine antagonist, caffeine, administered during the dark period, decreased immobility bouts. These results suggest that the regulation of sleep homeostasis in zebrafish larvae consists of the same elements as that of other species.
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Vilma
authors.initials: V
authors.lastname: Aho
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Maija
authors.initials: M
authors.lastname: Vainikka
authors.affiliation: Neuroscience Center and Department of Anatomy, University of Helsinki, Helsinki, Finland.
authors.forename: Henri A J
authors.initials: HAJ
authors.lastname: Puttonen
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Heidi M K
authors.initials: HMK
authors.lastname: Ikonen
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Tiia
authors.initials: T
authors.lastname: Salminen
authors.affiliation: Neuroscience Center and Department of Anatomy, University of Helsinki, Helsinki, Finland.
authors.forename: Pertti
authors.initials: P
authors.lastname: Panula
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Tarja
authors.initials: T
authors.lastname: Porkka-Heiskanen
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Henna-Kaisa
authors.initials: HK
authors.lastname: Wigren
mesh_terms: D000241:Adenosine / Q000037:antagonists & inhibitors; D000818:Animals; D001143:Arousal / Q000502:physiology / Q000528:radiation effects; D002110:Caffeine / Q000494:pharmacology; D002940:Circadian Rhythm / Q000502:physiology / Q000528:radiation effects; D003624:Darkness; D006706:Homeostasis / Q000502:physiology* / Q000528:radiation effects; D007814:Larva / Q000502:physiology / Q000528:radiation effects; D008027:Light; D023421:Models, Animal; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D043682:Receptor, Adenosine A1 / Q000378:metabolism; D013216:Reflex, Startle / Q000502:physiology / Q000528:radiation effects; D012146:Rest / Q000502:physiology; D012890:Sleep / Q000502:physiology* / Q000528:radiation effects*; D012892:Sleep Deprivation / Q000503:physiopathology*; D014851:Wakefulness / Q000502:physiology / Q000528:radiation effects; D014872:Water Movements; D015027:Zebrafish / Q000254:growth & development* / Q000502:physiology*
chemical_list: D043682:Receptor, Adenosine A1; D002110:Caffeine; C028544:cyclohexylalanine; D010649:Phenylalanine; D000241:Adenosine
keywords: 
  Danio rerio
  ; cyclohexyladenosine; escape response; sleep deprivation; sleep homeostasis