Figure 1

Experimental design. Rats (SD, male, 200–250 g) were divided into five groups [8–10 animals per each group: saline-treated group, L-DOPA-treated group, L-DOPA and GPS (25 or 50 mg/kg)-treated group, L-DOPA and GP-EX (50 mg/kg)-treated group] and PD models were established by 6-OHDA lesion (8 μg/2 μl). Three weeks after the 6-OHDA lesion, the apomorphine-induced rotational test was carried out to assess the efficacy of the 6-OHDA lesion. L-DOPA (25 mg/kg, i.p.) and benserazide (15 mg/kg, i.p.) treatment was started 6 weeks after the 6-OHDA lesion once a day for 22 days. Either GPS (25 and 50 mg/kg, p.o.) or GP-EX (50 mg/kg, p.o.) was given 30 min prior to L-DOPA treatment once a day for 22 days. The AIMs were scored for 1 min every 20 min for total 180 min after L-DOPA treatment on the indicated day. On day-22, after behavioral measurements, the animals were sacrificed for biochemical analyses.