Fig. 3

Changes in baseline threshold of nociceptive sensitivity to mechanical and thermal stimulation in MPTP-induced PD model mice and L-DOPA-treated PD model mice. a Hindpaw withdrawal latency of MPTP-treated mice was significantly reduced in the von Frey test (n = 15 per group, p < 0.001, unpaired Student’s t-test). b The thermal nociceptive response to constant thermal stimulation was increased in MPTP-treated group in the hot plate test (n = 15 per group, p < 0.005, 48 °C; p < 0.05, 53 °C, unpaired Student’s t-test). c The nociceptive responses to laser heat stimulation of the tail was increased in MPTP-treated mice (n = 16 for saline- and n = 14 for MPTP-treated group, p < 0.0001, unpaired Student’s t-test). d Motor dysfunction was eliminated in PD model mice by subcutaneous injection of L-DOPA in the rotarod test (n = 10 for saline and n = 9 for L-DOPA group, p < 0.001, two-way ANOVA). e In the von Frey test, MPTP-induced hyperalgesia to mechanical stimuli was ameliorated by subcutaneous injection of L-DOPA (n = 10 for saline and n = 9 for L-DOPA group, p < 0.05, unpaired Student’s t-test). f and (g) Subcutaneous injection of L-DOPA did not ameliorate MPTP-induced thermal hyperalgesia in the hot plate and the tail flick tests (n = 10 for saline and n = 9 for L-DOPA group)