The effects of rearing condition on methamphetamine self-administration and cue-induced drug seeking

• Published in: Drug and alcohol dependence 2012-08, Vol.124 (3), p.288-298
• Main Authors: Lü, Xiuyi, Zhao, Chun, Zhang, Li, Ma, Baomiao, Lou, Zhongze, Sun, Yan, Chen, Junfeng, Wu, Wei, Beveridge, Thomas J.R, Zhou, Wenhua, Liu, Yu
• Format: Article
• Language: English
• Subjects: Addictive behaviors; Adolescence; Adult and adolescent clinical studies; Animals; Behavior, Animal - drug effects; Biological and medical sciences; Central Nervous System Stimulants - administration & dosage; Cues; Drug addiction; Drug-Seeking Behavior - physiology; Environment; Environmental enrichment; Extinction; Housing, Animal; Male; Medical sciences; Memory - drug effects; Methamphetamine; Methamphetamine - administration & dosage; Motor Activity - drug effects; Neuropharmacology; Pharmacology. Drug treatments; Psychiatry; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease); Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Psychopharmacology; Rats; Rats, Sprague-Dawley; Reinstatement; Self Administration; Spatial memory; Water
• ISSN: 0376-8716; 1879-0046
• DOI: 10.1016/j.drugalcdep.2012.01.022

Abstract Background Little is known about the effect of different rearing conditions on the effects of methamphetamine and whether the introduction of enriched rearing conditions at different stages of development could produce different behavioral outcomes. Methods In Experiment 1, rats were reared in either enriched (EE) or isolated environments (IE) from PND 21 to 60. In Experiment 2, two groups of animals were handled in the same fashion as those in Experiment 1. Additional two groups were housed in IE during the first 20 or 30 days and then housed under EE for the remaining 20 or 10 days respectively. Locomotor activity and Morris Water Maze were tested. The effects of rearing conditions on methamphetamine (METH) self-administration were investigated. Results IE animals exhibited higher levels of locomotion than EE animals, but EE animals showed enhanced Morris Water Maze performance. Animals reared in IE for 30 and 40 days more readily acquired METH self-administration, compared to those reared in IE for 20 and in EE for 40 days respectively. However, the effect of rearing conditions was only seen at the lowest dose tested under FR schedule and breakpoints obtained from PR schedule were not significantly affected. Those reared in IE for 20 and EE for 40 days animals produced significantly fewer responses during the extinction and cue-induced reinstatement of METH self-administration, compared with animals reared in IE for 30 and 40 days, respectively. Conclusion Rearing condition plays a significant role in locomotor activity, spatial memory and behavioral effects of METH.