Animals and treatments
All animal procedures were approved by the Ethics Committee of The Affiliated Nanhua Hospital, University of South China. 6-8 weeks old C57BL/6 mice (20-22g) were housed with free access to food and water. Mice were trained to adjust to a behavioral device for 5 consecutive days, and mice that exhibited poor motor performance in the behavioral tests were not retained in this study. A total of 40 animals were enrolled in this study, animals were randomly assigned to each group.
On day 6, mice were anesthetized with a mixture of ketamine (90 mg/kg, i.p.) and xylazine (10 mg/kg, i.p.). Following this, mice were injected with LPS (5 μg dissolved in 2 μl PBS) or saline vehicle following stereotaxic coordinates measured from the bregma (Lateral: 1.3 mm; Posterior: 2.8 mm; Ventral to the surface of the dura mater: 4.5 mm). The needle was retained in the left side of the substantia nigra for a period of 10 minutes. The day after LPS injection, mice were intra-peritoneally injected with 40 mg/kg/d luteolin (Catalog: L409168; Aladdin, China,) or saline for consecutive 9 days. Subsequently, mice were subjected to behavioral tests to evaluate motor performance on days 16 and 17. Afterward, mice were sacrificed by decapitation, and samples were collected for further analysis. The experimental time schedule is given in Fig. 1.