Increased social reward behavior in adolescent male and female rats prenatally exposed to alcohol is associated with altered dopamine receptor expression

Abstract

Prenatal alcohol exposure (PAE) has detrimental consequences on cognitive, physiological, and social development. Adolescence, characterized by increased exploration, risk-taking, and social interaction, is a critical developmental stage that may amplify social deficits caused by PAE. I examined how PAE affects social reward behaviour across sex and developmental stages using a social reward task to measure preferences for social, non-social, and neutral stimuli at postnatal day (P)30, P40, P50, and P70. PAE rats exhibited greater social preference than controls during training sessions. On a progressive ratio test, PAE rats also had a greater social preference compared to controls. Extinction testing showed PAE males persisted in responding to the previously social side, resisting the control typical shift to a non-social preference. Dopamine receptor Western Bolt analysis revealed sex- and age-specific effects. Both PAE males and females showed increased D2 receptor expression in the nucleus accumbens at P30 and P50. In contrast, D3 receptor expression was decreased in the nucleus accumbens of P30 PAE males. In the medial amygdala, PAE females exhibited reduced D3 expression at P40 and P70, while PAE males showed similar reductions at P30 and P50. These findings suggest that PAE disrupts the development of social motivation and dopamine receptor expression, with distinct effects based on sex and developmental stage. The observed increases in D2 expression, coupled with decreases in the inhibitory D3 receptor, may contribute to the heightened social motivation in PAE rats by shifting the balance of dopamine signaling toward increased reward sensitivity and reduced behavioural inhibition.