Local effect of ¿¿-opioid receptor antagonism on evoked phasic dopamine release in the nucleus accumbens in rats (2016)

Undergraduates: Haley Barefoot, Tatiana Shnitko, PhD; Saleem M. Nicola, PhD Elle Brightbill

Faculty Advisor: Donita Robinson
Department: Chemistry

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Rewards are a major factor in decision making, both for normal executive function and in the case of several psychiatric disorders, such as addiction. Dopamine is thought to play a vital role in the reward system, and the nucleus accumbens (NAc) is a subcortical structure which can be modulated by dopamine. The NAc contains ¿¿-opioid receptors, which have been demonstrated to regulate tonic dopamine levels in the NAc. This study is interested in investigating the effect of ¿¿-opioid receptor antagonism on phasic dopamine release in the NAc of rats. To test this, the ¿¿-opioid receptor antagonist CTAP was infused into the NAc core where dopaminergic neuron terminals reside. Fast-scan cyclic voltammetry was used to measure electrically-evoked dopamine release directly adjacent to the drug infusion site while simultaneously infusing the drug. It was found that high dose CTAP blocked evoked dopamine release immediately following drug infusion, while low dose CTAP had no significant effect. We are currently expanding the dose-response curve. These data indicate that ¿¿-opioid receptor antagonists regulate phasic dopamine release at the level of the NAc in a dose-dependent manner. Further studies can be done to investigate this pharmacological effect as well as consider the behavioral implications for the demonstrated physiological effect in the NAc core.