Effect of in vivo exposure to ambient fine particles (PM) on the density of dopamine D-like receptors and dopamine-induced [S]-GTPγS binding in rat prefrontal cortex and striatum membranes.

Male Sprague-Dawley rats (8-9 weeks-old) were exposed for three days (acute exposure) or eight weeks (subchronic exposure) to purified air or concentrated ambient fine particles, PM (≤2.5 μm; 15 to 18-fold of ambient air; 370-445 μg/m). In membranes from rat prefrontal cortex (PFC) or striatum, the density and function of dopamine D-like receptors (DRs) were assessed by [H]-spiperone binding and dopamine-stimulated [S]-GTPγS binding, respectively. Glial activation was evaluated by immunoperoxidase labeling of the glial fibrillary acidic protein (GFAP). In the PFC, no significant changes in DR density or signaling were observed after the acute and subchronic exposure to PM. In the striatum, acute exposure to PM decreased DR density, with no effect on signaling efficacy, whereas subchronic exposure did not affect DR density but reduced signaling efficacy. Both acute and subchronic exposure to PM induced reactive gliosis in the striatum but not in the PFC. These results indicate that exposure to PM induces astrocyte activation and alters striatal dopaminergic transmission.