The role of dorsal hippocampal dopamine D1-type receptor inhibition, using SCH23390, on social learning, feeding behavior and social interactions in male and female mice. (#272)
The neurotransmitter dopamine has been found to be involved in many biologically relevant behaviors, such as food intake, social learning and social interactions. Our previous systemic work (Choleris et al., 2011) implicates the involvement of dopamine D1-type (D1 and D5) receptors in the well established social transmission of food preferences paradigm in mice; however, the brain region(s) underlying this effect remains unknown. The ventral tegmental area has dopaminergic neuronal projections to many limbic structures, including the hippocampus, a structure well known for its role in learning and memory processes, as well as social learning. We have infused the dopamine D1-type receptor antagonist, SCH23390 (at 1, 2, 4 and 6 μg/μL), directly into the Cornu Ammonis 1 (CA1) region of adult male and female CD1 mice 15 minutes before a 30-minute social interaction where mice had the opportunity to acquire a food preference from a same-sex conspecific. We found that the highest dose of SCH23390 blocked social learning in both female and male mice, although the total amount of food consumed remained unaffected. These results are consistent with our previous systemic work implicating D1-type receptors selectively in social learning, but not feeding behavior. Video analysis of the social interactions further revealed that the social learning deficit was not due to reduced exposure to the socially carried food odor since oronasal investigation was not affected by SCH23390 treatment. An olfactory discrimination control task using 6 μg/μL of SCH23390 also revealed that both male and female mice could discriminate between the two food-types used in the social learning test. Thus, intra-CA1 SCH23390 may have impaired social learning specifically. These results may help our understanding of the role that hippocampal dopamine D1-type receptors play in the ‘social brain’. Supported by NSERC.