title: Familiar companions diminish cocaine conditioning and attenuate cocaine-stimulated dopamine release in the nucleus accumbens.
abstract: This study aimed to assess the impact of companions on the rewarding effects of cocaine. Three cage mates, serving as companions, were housed with each experimental mouse throughout cocaine-place conditioning in a cocaine-induced conditioned place preference (CPP) paradigm using conditioning doses of 10 and 20mg/kg. The presence of companions decreased the magnitude of the CPP. At 20mg/kg, cocaine stimulated dopamine (DA) release in the nucleus accumbens as evidenced by a significant decrease in total (spontaneous and electrical stimulation-provoked) DA release in accumbal superfusate samples. The presence of companions prevented this cocaine-stimulated DA release; such a reduction in cocaine-induced DA release may account for the reduction in the magnitude of the CPP in the presence of the companions. Furthermore, cocaine pretreatment (2.5mg/kg) was found to prevent the companion-produced decreases in cocaine (10mg/kg/conditioning)-induced CPP as well as the cocaine (10mg/kg)-stimulated DA release. Moreover, the presence of methamphetamine (MA) (1mg/kg)-treated companions decreased cocaine (20mg/kg/conditioning)-induced CPP and prevented the cocaine (20mg/kg)-stimulated DA release. Finally, the presence of companions decreased the magnitude of the CPP could not seem to be accounted for by cocaine-stimulated corticosterone (CORT) release. Taken together, these results indicate that familiar companions, regardless of their pharmacological status, may exert dampening effects on CPP induced by moderate to high conditioning doses of cocaine, at least in part, by preventing cocaine-stimulated DA release in the nucleus accumbens.
authors.affiliation: Institute of Behavioral Medicine, National Cheng Kung University College of Medicine, Tainan 701, Taiwan, ROC.
authors.forename: Wen-Yu
authors.initials: WY
authors.lastname: Tzeng
authors.affiliation: Department of Health Psychology, Chang Jung Christian University, Tainan 711, Taiwan, ROC.
authors.forename: Chian-Fang G
authors.initials: CF
authors.lastname: Cherng
authors.affiliation: Department of Physiology and Pharmacology, Chang-Gung University, Taoyuan 333, Taiwan, ROC.
authors.forename: Shyi-Wu
authors.initials: SW
authors.lastname: Wang
authors.affiliation: Institute of Behavioral Medicine, National Cheng Kung University College of Medicine, Tainan 701, Taiwan, ROC. Electronic address: lungyu@mail.ncku.edu.tw.
authors.forename: Lung
authors.initials: L
authors.lastname: Yu
mesh_terms: D000818:Animals; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D003042:Cocaine / Q000008:administration & dosage*; D003216:Conditioning, Operant / Q000187:drug effects; D003345:Corticosterone / Q000097:blood; D004298:Dopamine / Q000378:metabolism*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D033062:Friends / Q000523:psychology*; D066298:In Vitro Techniques; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism; D012201:Reward
chemical_list: D000697:Central Nervous System Stimulants; D018765:Dopamine Uptake Inhibitors; D008694:Methamphetamine; D003042:Cocaine; D004298:Dopamine; D003345:Corticosterone
keywords: Cocaine; Conditioned place preference; Conditioning; Dopamine; Nucleus accumbens; Social interaction