Effects of Dopamine Receptor Activation and Antagonism on Social Motivation in Mice

Abstract

Dopamine (DA), a neurotransmitter, plays a role in motivation, learning, mating, and aggression in humans. The present study experimentally investigates the effects of mesolimbic DA receptor activation and antagonism on social motivation in male and female C57BL/6J mice. Subjects (N=60), aged 8-10 weeks, were randomly assigned to receive Levodopa, DA antagonist, or saline intraperitoneal (i.p.) injections before completing a social motivation task. A stopwatch was used to record the time it took for a mouse to cross barriers of increasing height and the time spent in nose-nose orientation with the stimulus mouse. Two mixed-design, three-way ANOVAs were used to explore the dependent variables of time spent sniffing and time spent crossing barriers. The results indicated a number of significant interactions. Levodopa did not significantly alter time to cross barriers or sniff time as compared to saline, while the DA antagonist significantly increased the time spent crossing barriers and significantly decreased sniff time. Between-subjects comparisons indicated sex effects for both time spent sniffing and time spent crossing barriers.