Environmental enrichment decreases cell surface expression of the dopamine transporter in rat medial prefrontal cortex

Rats raised in an enriched environmental condition (EC) exhibit a decreased (35%) maximal velocity (V_max) of [³H]dopamine (DA) uptake in medial prefrontal cortex (mPFC) compared with rats raised in an impoverished condition (IC); however, no differences between EC and IC groups in V _max for [³H]DA uptake were found in nucleus accumbens and striatum. Using biotinylation and immunoblotting techniques, the present study examined whether the brain region-specific decrease in DA transporter (DAT) function is the result of a reduction in DAT cell surface expression. In mPFC, nucleus accumbens and striatum, total DAT immunoreactivity was not different between EC and IC groups. Whereas no differences in cell surface expression of DAT were found in nucleus accumbens and striatum, DAT immunoreactivity in the biotinylated cell surface fraction of mPFC was decreased (39%) in EC compared with IC rats, consistent with the magnitude of the previously observed decrease in V_max for [³H]DA uptake in mPFC in EC rats. These results suggest that the decrease in DAT cell surface expression in the mPFC may be responsible for decreased DAT function in the mPFC of EC compared with IC rats, and that there is plasticity in the regulatory mechanisms mediating DAT trafficking and function.