MODULATION OF D1 DOPAMINE RECEPTORS IN THE NUCLEUS ACCUMBENS AFFECTS PARENTAL AND INFANTICIDAL BEHAVIOR IN FEMALE AND MALE (C57BL6) MICE

Pup-naïve adult female mice typically display parental behavior (PB) when exposed to pups for the first time, while males exhibit infanticidal behavior (IB). This is due to sex differences in the processing of pup´s related stimuli by cortical, hypothalamic, and limbic brain regions. Previous studies in rats suggest that agonism of the dopaminergic receptor D1 (D1R) in the nucleus accumbens (NAcc) facilitates PB, while its blockade delays it. However, its role in IB remains unclear.
We investigated if bilateral injections of the D1R agonist (0.25 or 0.5µg / 0.2µl of SKF-38393) or antagonist (0.5 or 1.0µg / 0.2µl of SCH-23390) into the NAcc facilitated/disrupted PB and IB in virgin pup-naïve female and male mice, respectively. Fifteen minutes after injection, pup-directed behavior was recorded, followed by an open-field test. Animals were re-exposed to pups on the following day.
In both sexes, D1R agonism and antagonism increased and decreased locomotor activity, respectively, compared to vehicle.
In females, D1R agonism did not facilitate PB and induced some delay in the response. D1R antagonism delayed PB, and effect that partially persisted on next day.
In males, D1R agonism did not affect IB. However, D1 antagonism increased non-parental animals reducing IB and, at high doses, resulted in persistent inhibition of IB on the following day.
These findings suggest that part of the effects observed were due to changes in locomotor activity. However, agonism and antagonism of D1R induced different effects on PB and IB, supporting the idea that dopamine modulates PB and IB differently.