2.2. Animal model
All experimental procedures were carried out in accordance with the animal experiment guidelines of Jiangsu University and were supervised and approved by the Animal Experiment Committee of Jiangsu University. 8~10 weeks old male C57BL/6J mice weighing 22-25g were purchased from the Experimental Animal Center of Jiangsu University. All animals are housed in a room controlled by temperature and humidity and can eat and drink freely in a 12-hour light/dark cycle. For MPTP induction, mice were i.p. injected with MPTP dissolved in normal saline at a dose of 20 mg/kg per day for 7 days. For HMGB1 A Box, mice received recombinant A Box protein i.v. dissolved in saline for 7 days at a dose of 5 mg/kg for 7 days. The recombinant HMGB1 A Box is expressed and purified by our lab, and the steps refer to our previous work (Tianet al. , 2020). For clodronate liposomes (LIPSOMA), mice were i.v. one day in advance, a total of 3 times, 100μl per mouse each time, in order to fully deplete circulating monocytes. The other mice were injected with saline as control. 7 days later, after isoflurane anesthesia, all mice were perfused with PBS and the brains of mice were then obtained and further processed. Mice requiring brain slices were perfused with 4% paraformaldehyde after PBS perfusion. After obtaining the brain, the brain was fixed in paraformaldehyde, then dehydrated in 20% and 30% sucrose-PBS solution respectively, and then made continuous frozen sections (30μm thick) of SN.