The cannabinoid receptor 2 agonist, β-caryophyllene, reduced voluntary alcohol intake and attenuated ethanol-induced place preference and sensitivity in mice Shamma Al Mansouri a,1 , Shreesh Ojha b,1 , Elyazia Al Maamari a , Mouza Al Ameri a , Syed M Nurulain b , Amine Bahi a, ⁎ ,1 a Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates b Department of Pharmacology & Therapeutics, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates abstract article info Article history: Received 18 May 2014 Received in revised form 15 June 2014 Accepted 27 June 2014 Available online 3 July 2014 Keywords: AM630 β-Caryophyllene CB 2 receptors Conditioned place preference LORR Two-bottle choice Several recent studies have suggested that brain CB 2 cannabinoid receptors play a major role in alcohol reward. In fact, the implication of cannabinoid neurotransmission in the reinforcing effects of ethanol (EtOH) is becoming increasingly evident. The CB 2 receptor agonist, β-caryophyllene (BCP) was used to investigate the role of the CB 2 receptors in mediating alcohol intake and ethanol-induced conditioned place preference (EtOH-CPP) and sensitivity in mice. The effect of BCP on alcohol intake was evaluated using the standard two-bottle choice drink- ing method. The mice were presented with increasing EtOH concentrations and its consumption was measured daily. Consumption of saccharin and quinine solutions was measured following the EtOH preference tests. Finally, the effect of BCP on alcohol reward and sensitivity was tested using an unbiased EtOH-CPP and loss of righting- reflex (LORR) procedures, respectively. BCP dose-dependently decreased alcohol consumption and preference. Additionally, BCP-injected mice did not show any difference from vehicle mice in total fluid intake in a 24- hour paradigm nor in their intake of graded concentrations of saccharin or quinine, suggesting that the CB 2 recep- tor activation did not alter taste function. More importantly, BCP inhibited EtOH-CPP acquisition and exacerbated LORR duration. Interestingly, these effects were abrogated when mice were pre-injected with a selective CB 2 re- ceptor antagonist, AM630. Overall, the CB 2 receptor system appears to be involved in alcohol dependence and sensitivity and may represent a potential pharmacological target for the treatment of alcoholism. © 2014 Elsevier Inc. All rights reserved. 1. Introduction Alcohol dependence is a serious medical, social and economic problem in terms of morbidity, mortality and disability worldwide. According to the World Health Organization (WHO), alcohol depen- dence is responsible for 4% of global disease which is slightly lower than that caused by smoking (4.1%) and hypertension (4.4%) (WHO, 2004). In recent years, accumulating evidence suggests an in- teraction between alcohol dependence and the endocannabinoid system (ECS) wherein the endogenous bioactive lipid-derived endocannabinoid ligands act through the cannabinoid receptors CB 1 and CB 2 , which couple to the Gα i/o class of G-proteins and have presynaptic or postsynaptic distribution in the brain (Breivogel and Childers, 1998). They also serve as retrograde transmitters in central synapses. The ECS has been shown to play an important role in drug abuse and dependence (Maldonado et al., 2006) including the rein- forcing effects of alcohol (Erdozain and Callado, 2011), opioids (Manzanedo et al., 2004), nicotine (Viveros et al., 2007) and cocaine (Tanda, 2007). Since the discovery of ECS, accumulating evidence has demonstrated that alcohol interacts with ECS and the cannabi- noid receptors CB 1 and CB 2 play an important and pervasive role in the etiology of alcohol dependence suggesting that these receptors could be a potential therapeutic target (Basavarajappa, 2007; Onaivi, 2009). The pharmacological blockade or genetic ablation of CB 1 receptors shows decreased operant self-administration of EtOH and voluntary consumption of EtOH in rodents (Onaivi, 2009; Onaivi et al., 2008a; Vinod et al., 2008). Numerous preclinical studies have demonstrated that activation of CB 1 receptor facilitates EtOH consumption (Klugmann et al., 2011) while antagonism of CB 1 re- ceptor reduces the motivational properties of EtOH with no effect Pharmacology, Biochemistry and Behavior 124 (2014) 260–268 Abbreviations: BCP, β-caryophyllene; CPP, conditioned-place preference; EtOH, etha- nol; BEC, blood ethanol concentration; ECS, endocannabinoid system; LORR, loss of righting reflex. ⁎ Corresponding author at: Department of Anatomy, College of Medicine & Health Sciences, United Arab Emirates University, PO Box 17666, Al Ain, United Arab Emirates. Tel.: +971 3 7137 516; fax: +971 3 7672 033. E-mail address: amine.bahi@uaeu.ac.ae (A. Bahi). 1 These authors contributed equally to this work. http://dx.doi.org/10.1016/j.pbb.2014.06.025 0091-3057/© 2014 Elsevier Inc. All rights reserved. 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