Effect of Exercise on Aversion to Acute Opioid Withdrawal in Mice
Each year, in the United States, approximately 750,000 people are dependent on heroin (Kosten, 2003), the most commonly abused opioid, making heroin dependence a pressing issue. Continued opioid use may involve both positive reinforcement (reward) and negative reinforcement (avoiding the negative consequences of drug withdrawal). The focus of this study was acute opioid withdrawal, which can be produced by the administration of the opiate antagonist naloxone following a single dose or short-term exposure to morphine. The present study explored the effect of a behavioral manipulation (exercise) on the aversive effects of acute morphine withdrawal in mice. Conditioned place aversion (CPA) was chosen as the animal model to study this effect. Separate groups of mice were either given two hour access to running wheels for eight days before CPA and then tested (Group Before), or given access to running wheels after CPA, and then tested (Group After). Both groups went through a CPA schedule of two pairings of morphine (10 mg/kg) followed by the opioid antagonist naloxone (0.32 mg/kg) four hours later. As expected, acute opioid withdrawal produced a reliable CPA effect. The magnitude of CPA was decreased in the wheel running groups (Before and After). Thus, exercise appears to decrease the aversive properties of opioid withdrawal. Given the results of this study, it can be hypothesized that exercise might be a useful treatment for formally opioid-dependent patients who are in an abstinence period.
Franklin and Marshall College Archives, Undergraduate Honors Thesis 2007
- F&M Theses Collection