Increased expression of cannabinoid receptor 1 in the nucleus accumbens core in a rat model with morphine withdrawal

• Published in: Brain research Vol. 1531; pp. 102 - 112
• Main Authors: Yuan, Wei-Xin, Heng, Li-Jun, Ma, Jie, Wang, Xing-Qin, Qu, Li-Juan, Duan, Li, Kang, Jun-Jun, Chen, Liang-Wei, Gao, Guo-Dong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 19.09.2013; Elsevier
• Subjects: Analgesics; animal models; Animals; antagonists; Biological and medical sciences; brain; Cannabinoid receptor 1; Cannabinoid system; cannabinoids; Conditioned place preference; Disease Models, Animal; drug abuse; drug therapy; electron microscopy; fluorescence; fluorescent antibody technique; Male; Medical sciences; morphine; Morphine Dependence - metabolism; Morphine withdrawal; Neurology; Neuropharmacology; Nucleus Accumbens - metabolism; Nucleus accumbens core; Pharmacology. Drug treatments; Psychodysleptics: hallucinogen; Psychology. Psychoanalysis. Psychiatry; Psychopharmacology; Rats; Rats, Sprague-Dawley; Rats, Wistar; Receptor, Cannabinoid, CB1 - biosynthesis; relapse; Rimonabant; Substance Withdrawal Syndrome - metabolism; Up-Regulation - physiology; Nucleus accumbens core; Cannabinoid receptor 1; Conditioned place preference; Morphine withdrawal; Rimonabant; Cannabinoid system; Animal model; Rat; Rodentia; Central nervous system; Opiates; Morphine; Basal ganglion; Narcotic analgesic; Cannabinoid; Encephalon; Nucleus accumbens; Vertebrata; Mammalia; Animal; Cannabinoid receptor
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2013.07.047

Abstract Relapse is a major clinical problem and remains a major challenge in the treatment of drug addiction. There is strong evidence that the endocannabinoid system of the nucleus accumben core (NAcc) is involved in drug-seeking behavior, as well as in the mechanisms that underlie relapse to drug use. To reveal the mechanism that underlies this finding, we examined the expression pattern of the cannabinoid receptor 1 (CB1-R) in the NAcc of SD rats that had been undergoing morphine withdrawal (MW) for 1 day, 3 days and 3 weeks (acute, latent and chronic phases, respectively). Morphine exposure induced conditioned place preference (CPP) in rats. Significant increase of CB1-R expression in NAcc was observed in animals in the 1 day, 3 days and 3 weeks morphine withdrawal compare to the control group. Immunofluorescence labeling showed axonal fibers or terminals by fluorescence microscope observation. Immunoelectron microscopy detection showed silver-gold particles located in the presynaptic membranes that mainly give rise to symmetrical synapses. Quantitative electron microscopy showed an increase in number of CB1-R-positive terminals in the morphine withdrawal groups and the number of immunogold particles was significantly increased at these inhibitory terminals. We also confirmed that infusions of the CB1-R antagonist rimonabant into the NAcc attenuated the CPP during morphine withdrawal. Our present data have thus indicated that increasing pattern of CB1-R expression in the NAcc during above morphine withdrawal phases, which might underlie the relapse associated drug seeking behavior after morphine withdrawal.