Opioid Abuse after Traumatic Brain Injury: Evaluation Using Rodent Models
Technical Report,01 Jul 2011,30 Jun 2015
Virginia Commonwealth University Richmond United States
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This project evaluated the effect of a moderate-level brain injury on risk for opioid abuse using preclinical models in rats. We assessed the effect of brain injury on the rewarding effects of oxycodone in three rat self-administration procedures and found significant differences in the acquisition and maintenance of oxycodone self-administration behavior between brain-injured and control rats. Data showed brain injured rats acquired self-administration behavior at lower doses, took higher total doses of oxycodone and worked significantly harder for a single infusion of drug suggesting oxycodone had stronger rewarding effects following injury. Conversely, brain-injured subjects showed lower responding in a model of relapse to oxycodone self administration. Testing of oxycodone for analgesic strength and development of tolerance showed no difference between sham controls and brain injured subjects. Nor was there any difference detected in the development of dependence. Overall, the analgesia studies demonstrate that moderate brain injury does not result in an altered pain state or diminished response to oxycodone analgesia and the dependence studies show withdrawal is not more severe. However, the self-administration studies suggest that brain-injured subjects could be at increased risk for developing opioid substance abuse disorders.