Fig. 4.

Effects of PRS on nigrostriatal dopaminergic transmission and indirect and direct pathways in adulthood (4-month-old rats).

PRS reduced DA release in the striatum of adult rats. Microdialysis studies in freely moving rats (Fig. 4A) showed a significant decrease in veratridine-stimulated DA release in the striatum of PRS rats (n = 5 rats/group). A reduction in preloaded [³H]-DA release was also observed in striatal synaptosomes challenged with depolarizing concentrations of K⁺ (Fig. 4B) (n = 5 rats/group). Immunoblot analysis (Fig. 4C) revealed that PRS caused a significant reduction in striatal D₁ receptor protein levels, with no changes in the levels of D₂ receptors and A_2A adenosine receptors (n = 6 rats/group). Despite the reduction in D₁ receptor protein levels, the ability of the D₁ receptor agonist, SKF-38393, to enhance cAMP formation (n = 6/rats/group) was unchanged in the striatum of PRS rats (n = 6 rats/group) (Fig. 4D). In contrast, PRS reduced D₂ receptor signaling (n = 7–8 rats/group, Fig. 4E) and amplified A_2A receptor signaling (n = 4 rats/group, Fig. 4F) in the striatum. CONT vs. PRS *p < 0.05; ***p < 0.001; treatment vs. basal $$$p < 0.001.