title: Effects of circadian disruption on methamphetamine consumption in methamphetamine-exposed rats.
abstract: BACKGROUND
  A substantial number of clinical studies indicate associations between sleep abnormalities and drug abuse; however, the role played by the circadian system in the development of addiction is largely unknown.
  
  
  OBJECTIVE
  The aim of this study was to examine the effects of experimentally induced chronic jet lag on methamphetamine consumption in a rat model of methamphetamine drinking.
  
  
  METHODS
  Male Sprague-Dawley rats (n = 32) were housed in running wheel cages in a 12:12 h light:dark cycle. One group of rats (n = 16) was given 2 weeks of forced methamphetamine consumption (0.01 % in drinking water; meth pre-exposed) while a second group (n = 16, not pre-exposed) received water only. This was followed by a 2-week abstinence period during which half of the animals from each group were exposed to four consecutive 6-h advancing phase shifts of the light:dark cycle, while the other half remained on the original light:dark cycle. Methamphetamine consumption was assessed in all rats following the deprivation period using a two-bottle choice paradigm.
  
  
  RESULTS
  Methamphetamine consumption was initially lower in methamphetamine pre-exposed versus not pre-exposed rats. However, during the second week following abstinence, consumption was significantly higher in phase-shifted rats of the methamphetamine pre-exposed group compared to all other groups.
  
  
  CONCLUSIONS
  These data reveal an effect of circadian rhythm disturbance on methamphetamine consumption and suggest that dysregulation of the circadian system be considered in the etiology of relapse and addiction.
authors.affiliation: Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, 1670 Discovery Drive, Suite 110, Charlottesville, VA, 22911, USA.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Doyle
authors.forename: Hanting
authors.initials: H
authors.lastname: Feng
authors.forename: Garrett
authors.initials: G
authors.lastname: Garber
authors.forename: Michael
authors.initials: M
authors.lastname: Menaker
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Lynch
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002755:Choice Behavior / Q000187:drug effects; D002940:Circadian Rhythm / Q000187:drug effects*; D020179:Jet Lag Syndrome / Q000523:psychology; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D017440:Photoperiod; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome / Q000523:psychology
chemical_list: D000697:Central Nervous System Stimulants; D008694:Methamphetamine