Hedonic Sensitivity to Natural Rewards Is Affected by Prenatal Stress in a Sex-Dependent Manner

The study explored the impact of prenatal stress (PRS) on the enjoyment of natural rewards, specifically milk chocolate, in male and female rats, revealing sex-dependent effects. PRS increased chocolate preference and dopamine levels in the nucleus accumbens (NAc) in male rats, while decreasing serotonin levels in the NAc and prefrontal cortex (PFC). This was associated with increased dihydrotestosterone (DHT) levels, which could be reversed by the DHT-lowering drug finasteride. Conversely, PRS decreased chocolate preference in female rats, along with lower estradiol levels and reduced dopamine and serotonin levels in the NAc and PFC. Estradiol supplementation in females reversed these effects. The study also noted changes in estrogen and serotonin receptor mRNA levels in the hypothalamus, which were corrected by hormone treatments. The findings suggest that early life stress can lead to long-lasting changes in the brain's reward system, influenced by sex hormones. The number of rats used in the study ranged from 4 to 9 for hormonal manipulation and 7 to 8 for behavior and endocrinology studies, with statistical analyses supporting the conclusions.