Age-Dependent Effects of Prenatal Stress on the Corticolimbic Dopaminergic System Development in the Rat Male Offspring

We have previously demonstrated that prenatal stress (PS) exerts an impairment of midbrain dopaminergic (DA) system metabolism especially after puberty, suggesting a particular sensitivity of DA development to variations in gonadal hormonal peaks. Furthermore we demonstrated that PS alters the long term androgens profile of the rat male offspring from prepubertal to adult stages. In this work we evaluated the sexual hormones activational effects on the DA system by analysing PS effects on the dopaminergic D2-like (D2R) and on the gonadal hormones receptor levels on cortical and hippocampal areas of prepubertal and adult male offspring. We further evaluated the dendritic arborization in the same areas by quantifying MAP2 immunoexpresion. Our results show that PS affected oestrogen receptor alpha (ER alpha) expression: mRNA er1s and ER alpha protein levels were decreased on prefrontal cortex and hippocampus of adult offspring. Moreover, PS reduced D2R protein levels in hippocampus of prepubertal rats. Morphological studies revealed that prepubertal PS rats presented decreased MAP2 immunoexpression in both areas suggesting that PS reduces the number of dendritic arborizations. Our findings suggest that PS exerts long-term effects on the DA system by altering the normal connectivity in the areas, and by modulating the expression of D2R and ER alpha in an age-related pattern. Since the developing forebrain DA system was shown to be influenced by androgen exposure, and PS was shown to disrupt perinatal testosterone surges, our results suggest that prenatal insults might be affecting the organizational role of androgens and differentially modulating their activational role on the DA development.