Figure 1.

Effect of the mGlu₄ positive allosteric modulator, PHCCC, on 25 mM KCl-evoked [³H]-D-aspartate release in rat nigral tissue prisms. (A) Release profile showing the effect of 30 µM PHCCC, given with a sub-threshold concentration of L-AP4 (1 µM), on release evoked by the second KCl stimulus (S2). Horizontal bars indicate the periods of contact with KCl or drug/vehicle. Data are mean ± SEM (n= 3 from a single experimental run). (B–E) Graphs of S2/S1 ratio showing concentration-dependent effects of PHCCC, combined with L-AP4 (1 µM), on [³H]-D-aspartate release. Data are mean ± SEM (n= 6). *P < 0.05, **P < 0.01, significantly different from vehicle; #P < 0.05, ##P < 0.01, significantly different from PHCCC alone; ∞∞P < 0.01, significantly different from L-AP4 alone. The presence (+) or absence (−) of drugs is indicated.