Abstract
Drug addiction is a chronic brain disease characterized by the uncontrolled use of a substance. Due to its relapsing nature, addiction is difficult to treat, as individuals can relapse following even long periods of abstinence and, it is during this time, that they are most vulnerable to overdose. In America, opioid overdose has been increasing for decades, making finding new treatments to help patients remain abstinent and prevent overdose deaths imperative. Recently, glucagon-like peptide-1 (GLP-1) receptor agonists have shown promise in reducing motivated behaviours for drugs of abuse. In this study, we test the effectiveness of the GLP-1 analogue, liraglutide (LIR), in reducing heroin addiction-like behaviour, and the potential side effects associated with the treatment. We show that daily treatment with LIR (0.1 mg/kg sc) increases the latency to take heroin, reduces heroin self-administration, prevents escalation of heroin self-administration and reduces drug-induced reinstatement of heroin-seeking behaviour in rats. A 1-h pretreatment time, however, was too short to reduce cue-induced seeking in our study. Moreover, we showed that, while LIR (0.1, 0.3, 0.6 and 1.0 mg/kg sc) supported conditioned taste avoidance of a LIR-paired saccharin cue, it did not elicit intake of the antiemetic kaolin in heroin-naïve or heroin-experienced rats. Further, 0.1 mg/kg LIR did not produce great disruptions in food intake or body weight. Overall, the data show that LIR is effective in reducing heroin taking and heroin seeking at doses that do not cause malaise and have a modest effect on food intake and body weight gain.