title: Basolateral amygdalar D2receptor activation is required for the companions-exerted suppressive effect on the cocaine conditioning.
abstract: The presence of companions renders decreases in cocaine-stimulated dopamine release in the nucleus accumbens and cocaine-induced conditioned place preference (CPP) magnitude. Limbic systems are widely believed to underlie the modulation of accumbal dopamine release and cocaine conditioning. Thus, this study aimed to assess whether intact basolateral nucleus of amygdala (BLA), dorsal hippocampus (DH), and dorsolateral striatum (DLS) is required for the companions-exerted suppressive effect on the cocaine-induced CPP. Three cage mates, serving as companions, were arranged to house with the experimental mice in the cocaine conditioning compartment throughout the cocaine conditioning sessions. Approximately 1week before the conditioning procedure, intracranial ibotenic acid infusions were done in an attempt to cause excitotoxic lesions targeting bilateral BLA, DH and DLS. Albeit their BLA, DH, and DLS lesions, the lesioned mice exhibited comparable cocaine-induced CPP magnitudes compared to the intact and sham lesion controls. Bilateral BLA, but not DH or DLS, lesions abolished the companions-exerted suppressive effect on the cocaine-induced CPP. Intact mice receiving intra-BLA infusion of raclopride, a selective D2 antagonist, 30min prior to the cocaine conditioning did not exhibit the companions-exerted suppressive effect on the cocaine-induced CPP. Intra-BLA infusion of Sch23390, a selective D1 antagonist, did not affect the companions-exerted suppressive effect on the CPP. These results, taken together, prompt us to conclude that the intactness of BLA is required for the companions-exerted suppressive effect on the cocaine-induced CPP. Importantly, activation of D2 receptor in the BLA is required for such suppressive effect on the CPP.
authors.affiliation: Department of Physiology, National Cheng Kung University College of Medicine, Tainan 70101, Taiwan, ROC.
authors.forename: Wen-Yu
authors.initials: WY
authors.lastname: Tzeng
authors.affiliation: Department of Health Psychology, Chang Jung Christian University, Tainan 71101, Taiwan, ROC.
authors.forename: Chian-Fang G
authors.initials: CG
authors.lastname: Cherng
authors.affiliation: Department of Physiology, National Cheng Kung University College of Medicine, Tainan 70101, Taiwan, ROC; Institute of Basic Medical Sciences, National Cheng Kung University College of Medicine, Tainan 70101, Taiwan, ROC. Electronic address: lungyu@mail.ncku.edu.tw.
authors.forename: Lung
authors.initials: L
authors.lastname: Yu
authors.affiliation: Institute of Basic Medical Sciences, National Cheng Kung University College of Medicine, Tainan 70101, Taiwan, ROC.
authors.forename: Ching-Yi
authors.initials: CY
authors.lastname: Wang
mesh_terms: D000818:Animals; D001245:Association Learning / Q000187:drug effects* / Q000502:physiology; D066272:Basolateral Nuclear Complex / Q000187:drug effects* / Q000502:physiology; D003042:Cocaine / Q000008:administration & dosage*; D003216:Conditioning, Operant / Q000187:drug effects* / Q000502:physiology; D065127:Dopamine D2 Receptor Antagonists / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D007051:Ibotenic Acid / Q000494:pharmacology; D008297:Male; D051379:Mice; D020891:Raclopride / Q000494:pharmacology*
chemical_list: D065127:Dopamine D2 Receptor Antagonists; D018765:Dopamine Uptake Inhibitors; D018690:Excitatory Amino Acid Agonists; D007051:Ibotenic Acid; D020891:Raclopride; D003042:Cocaine
keywords: Cocaine; Dopamine receptor; Dopamine release; Memory; Stimulant