title: Melatonin treatment during the incubation of sensitization attenuates methamphetamine-induced locomotor sensitization and MeCP2 expression.
abstract: Behavior sensitization is a long-lasting enhancement of locomotor activity after exposure to psychostimulants. Incubation of sensitization is a phenomenon of remarkable augmentation of locomotor response after withdrawal and reflects certain aspects of compulsive drug craving. However, the mechanisms underlying these phenomena remain elusive. Here we pay special attention to the incubation of sensitization and suppose that the intervention of this procedure will finally decrease the expression of sensitization. Melatonin is an endogenous hormone secreted mainly by the pineal gland. It is effective in treating sleep disorder, which turns out to be one of the major withdrawal symptoms of methamphetamine (MA) addiction. Furthermore, melatonin can also protect neuronal cells against MA-induced neurotoxicity. In the present experiment, we treated mice with low dose (10mg/kg) of melatonin for 14 consecutive days during the incubation of sensitization. We found that melatonin significantly attenuated the expression of sensitization. In contrast, the vehicle treated mice showed prominent enhancement of locomotor activity after incubation. MeCP2 expression was also elevated in the vehicle treated mice and melatonin attenuated its expression. Surprisingly, correlation analysis suggested significant correlation between MeCP2 expression in the nucleus accumbens (NAc) and locomotion in both saline control and vehicle treated mice, but not in melatonin treated ones. MA also induced MeCP2 over-expression in PC12 cells. However, melatonin failed to reduce MeCP2 expression in vitro. Our results suggest that melatonin treatment during the incubation of sensitization attenuates MA-induced expression of sensitization and decreases MeCP2 expression in vivo.
authors.affiliation: Department of Anatomy, School of Medicine, Shandong University, Jinan, Shandong 250012, China.
authors.forename: Jintao
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Anatomy, School of Medicine, Shandong University, Jinan, Shandong 250012, China.
authors.forename: Dexiao
authors.initials: D
authors.lastname: Zhu
authors.affiliation: Department of Anatomy, School of Medicine, Shandong University, Jinan, Shandong 250012, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Anatomy, School of Medicine, Shandong University, Jinan, Shandong 250012, China.
authors.forename: Guibao
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Psychiatry, School of Medicine, Shandong University, Jinan, Shandong 250012 China.
authors.forename: Zengxun
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Anatomy, School of Medicine, Shandong University, Jinan, Shandong 250012, China. Electronic address: sunjinhao@gmail.com.
authors.forename: Jinhao
authors.initials: J
authors.lastname: Sun
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002491:Central Nervous System Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008694:Methamphetamine / Q000494:pharmacology*; D051783:Methyl-CpG-Binding Protein 2 / Q000378:metabolism*; D051379:Mice; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D016716:PC12 Cells; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism; D051381:Rats
chemical_list: D002491:Central Nervous System Agents; C497393:Mecp2 protein, mouse; C497394:Mecp2 protein, rat; D051783:Methyl-CpG-Binding Protein 2; D008694:Methamphetamine; D008550:Melatonin
keywords: Incubation; MeCP2; Melatonin; Methamphetamine; Nucleus accumbens; Sensitization