title: Effect of circadian rhythm disturbance on morphine preference and addiction in male rats: Involvement of period genes and dopamine D1 receptor.
abstract: It is claimed that a correlation exists between disturbance of circadian rhythms by factors such as alteration of normal light-dark cycle and the development of addiction. However, the exact mechanisms involved in this relationship are not much understood. Here we have studied the effect of constant light on morphine voluntary consumption and withdrawal symptoms and also investigated the involvement of Per1, Per2 and dopamine D1 receptor in these processes. Male wistar rats were kept under standard (LD) or constant light (LL) conditions for one month. The plasma concentration of melatonin was evaluated by enzyme-linked immunosorbent assay (ELISA). Real-time PCR was used to determine the mRNA expression of Per1, Per2 and dopamine D1 receptor in the striatum and prefrontal cortex. Morphine preference (50mg/L) was evaluated in a two-bottle-choice paradigm for 10 weeks and withdrawal symptoms were recorded after administration of naloxone (3mg/kg). One month exposure to constant light resulted in a significant decrease of melatonin concentration in the LL group. In addition, mRNA levels of Per2 and dopamine D1 receptor were up-regulated in both the striatum and prefrontal cortex of the LL group. However, expression of Per1 gene was only up-regulated in the striatum of LL rats in comparison to LD animals. Furthermore, after one month exposure to constant light, morphine consumption and preference ratio and also severity of naloxone-induced withdrawal syndrome were significantly greater in LL animals. It is concluded that exposure to constant light by up-regulation of Per2 and dopamine D1 receptor in the striatum and prefrontal cortex and up-regulation of Per1 in the striatum and the possible involvement of melatonin makes animals vulnerable to morphine preference and addiction.
authors.affiliation: Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: B
authors.initials: B
authors.lastname: Garmabi
authors.affiliation: Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran; Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Iranian Institute for Reduction of High-Risk Behaviors, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: N
authors.initials: N
authors.lastname: Vousooghi
authors.affiliation: Research Center of the Laboratory Animals, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Vosough
authors.affiliation: Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Yoonessi
authors.affiliation: Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Bakhtazad
authors.affiliation: Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran; Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Iranian Institute for Reduction of High-Risk Behaviors, Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Department of Cognitive Neuroscience, Institute for Cognitive Science Studies, Tehran, Iran; Genomics Center, School of Advanced Sciences, Tehran Medical Branch, Islamic Azad University, Tehran, Iran; School of Cognitive Sciences, Institute for Studies in Theoretical Physics and Mathematics, Tehran, Iran. Electronic address: Zarinmr@ams.ac.ir.
authors.forename: M R
authors.initials: MR
authors.lastname: Zarrindast
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D004195:Disease Models, Animal; D008297:Male; D008550:Melatonin / Q000097:blood; D009020:Morphine / Q000008:administration & dosage; D009021:Morphine Dependence / Q000503:physiopathology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009294:Narcotics / Q000008:administration & dosage; D056950:Period Circadian Proteins / Q000378:metabolism*; D010775:Photic Stimulation / Q000009:adverse effects / Q000379:methods; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000378:metabolism*; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology
chemical_list: D009292:Narcotic Antagonists; D009294:Narcotics; C539024:Per1 protein, rat; C513311:Per2 protein, rat; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; D009270:Naloxone; D009020:Morphine; D008550:Melatonin
keywords: Per1; Per2; circadian rhythm; constant light; dopamine D1 receptor; morphine