title: Comparative effects of melatonin, zolpidem and diazepam on sleep, body temperature, blood pressure and heart rate measured by radiotelemetry in Wistar rats.
abstract: BACKGROUND
  The role of melatonin (MLT) in mediating the sleep-wake cycle has been previously suspected of indicating that this substance could be a candidate for a new generation of hypnotics.
  
  
  OBJECTIVE
  We investigated whether MLT acted as a sleep promoter or a modulator of sleep temporal timing related to cardiovascular and body temperature (Tb) adaptations to sleep induction. The pharmacological effects of MLT on sleep were compared with zolpidem (ZP) and diazepam (DZ).
  
  
  METHODS
  The radiotelemetry system was used to record the electrocorticogram [slow wave sleep (SWS), paradoxical sleep (PS)], Tb, blood pressure and heart rate in six Wistar rats. DZ (3 mg/kg and 6 mg/kg), ZP (1, 3, 5 and 10 mg/kg) and MLT (2.5 and 5 mg/kg) were delivered intraperitoneally during light (L) and dark (D) periods.
  
  
  RESULTS
  MLT increased the number of sleep cycles (L: 30%, D: 110%) and total duration (P<0.05) of PS (L: 70%, D: 150%). In return, ZP (10 mg/kg) presented no effect during L but increased total (40%) and mean duration (37%) of SWS during the D period. DZ modified mean duration of SWS (L: -27%, D: +26%) and increased total duration of SWS (+47%). ZP and DZ induced a more pronounced decrease in Tb than MLT but only DZ induced tachycardia and hypertension.
  
  
  CONCLUSIONS
  We showed that MLT could not promote sleep and its cardiovascular adaptations despite hypothermia, but modulated the period of ultradian sleep cycles. DZ and ZP promoted sleep and induced hypothermia during the D period. Only DZ disrupted sleep architecture and induced adverse effects on cardiovascular parameters.
authors.affiliation: UMR INRA-CNRS-Université de Tours 6073, Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France. Francois.Mailliet@tours.inra.fr
authors.forename: F
authors.initials: F
authors.lastname: Mailliet
authors.forename: P
authors.initials: P
authors.lastname: Galloux
authors.forename: D
authors.initials: D
authors.lastname: Poisson
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D001831:Body Temperature / Q000187:drug effects* / Q000502:physiology; D003975:Diazepam / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012894:Sleep Stages / Q000187:drug effects* / Q000502:physiology; D013686:Telemetry / Q000379:methods; D000077334:Zolpidem
chemical_list: D000975:Antioxidants; D006993:Hypnotics and Sedatives; D011725:Pyridines; D000077334:Zolpidem; D008550:Melatonin; D003975:Diazepam