2.17. Mice and MPTP‐PD model

Animal welfare and experimental procedures were carried out strictly in accordance with the Guide for the Care and Use of Laboratory Animals (National Institutes of Health, USA) and the related ethical regulations of our university. All efforts were made to minimize animals' suffering and to reduce the number of animals used. Animal studies are reported in compliance with the ARRIVE guidelines (Kilkenny, Browne, Cuthill, Emerson, & Altman, 2010; McGrath, Drummond, McLachlan, Kilkenny, & Wainwright, 2010) and with the recommendations made by the British Journal of Pharmacology. C57BL/6 mice (male, 10–12 weeks old, 23–25 g) were purchased from Model Animal Genetics Research Center of Nanjing University (Nanjing, China). The animals were housed, five per cage with food and water ad libitum, on a 12‐hr light/dark cycle with lights on at 06:00 hr and controlled (22–23°C) temperature.

The MPTP‐PD model was prepared as described previously (Jackson‐Lewis & Przedborski, 2007). Adult male C57BL/6 mice were randomly divided into five groups (10 mice per group). The control group was treated with PBS (vehicle). Mice were injected intraperitoneally with MPTP (dissolved in PBS) in a final concentration of 25 mg·kg⁻¹ daily for five consecutive days. One hour after MPTP injection, mice were given 2.5 or 5 mg·kg⁻¹ andrographolide intraperitoneally once a day for 12 days. Levodopa was orally administered (75 mg·kg⁻¹) as a positive control. After the final treatment, behavioural procedures including pole test, beam hang test, rotarod task, and open field and forced swimming tests were conducted to assess behavioural changes. All the evaluators were blinded to the treatment groups.