Isolation Rearing-Induced Reduction of Brain 5α-Reductase Expression: Relevance to Dopaminergic Impairments

The study demonstrated that isolation rearing (IR), a model of early chronic psychosocial stress in rats, led to significant reductions in the expression of 5α-reductase (5AR) isoenzymes 1 and 2 in the nucleus accumbens (NAcc) and medial prefrontal cortex (mPFC), which are crucial regions of the dopaminergic system. This reduction was functionally significant as it correlated with decreased levels of the neurosteroids allopregnanolone (AP) and allotetrahydrodeoxycorticosterone (THDOC) in the brain cortex of IR-subjected rats, although plasma levels of AP did not differ significantly between IR and socially reared (SR) rats. The findings suggested that the decrease in 5AR expression might underlie the changes in dopamine efflux associated with IR, highlighting the role of 5AR in stress response through neurosteroid synthesis and modulation of GABAA receptors.