249 | Previous reproductive experience increases the ratio of dopaminergic D1:D2 receptors in the striatum and the effect of a D1 antagonist in postpartum estrous rats

Neuroendocrinology and Neuroimmunology

Author: Gabriella Cecilia Marin Mirande | Email: gabriellamarin@gmail.com

Gabriella Marin , Gabriela Bedó , Marta Antonelli , Annabel Ferreira , Daniella Agrati

1° Universidad de la Republica
2° Universidad de Buenos Aires

Postpartum estrous (PPE) rats, which are maternally and sexually motivated, prefer the pups over a male; however this preference is stronger in females with a previous reproductive experience than in primiparous rats. As mesocorticolimbic dopaminergic system and dopamine in the medial preoptic area have been implicated in the control of maternal motivation, this study aimed to determine if this system differs between primiparous (PRIM) and multiparous (MULT) PPE females. To board this question we employed two strategies: 1) compared the expression of the dopaminergic receptors D1 and D2 in  nucleus accumbens(NAcc), medial prefrontal cortex, medial preoptic area, and dorsal striatum(DS) between these mothers, and 2) compared the effect of the D1 antagonist SCH-23390 on maternal behavior and locomotor activity of PRIM and MULT rats. MULT females exhibited a greater binding to the D1 antagonist [H3]-SCH-23390 than PRIM dams in NAcc and DS, but no differences were detected in other areas. MULT females presented a reduced binding to the D2 antagonist [H3]-nemonapride only in the NAcc shell. Moreover, while 0.025 and 0.05 mg/kg sc of SCH-23390 increased the latency to reunite the litter in the nest and decreased locomotor activity of the dams, the effects of the lower dose were greater in MULT females. These results reveal a possible mechanism that can partially underlay the motivational differences between PRIM and MULT PPE rats.