Animals
Male C57BL/6 mice (weight 25-28 g, 7 weeks old, Orient Bio Inc, Seongnam, Korea, MGI Cat# 5656552, RRID:MGI:5656552) were kept a full automatically temperature and humidity controlled room (22\(\pm\)3, 50%, 12 h light and dark cycle) with free access to food and water. Animal experiments were followed by the Korea Institute of Science and Technology Animal Care Committee guidelines and approved by the Korea Institute of Science and Technology Animal Care and Use Committee (KIST-2018-077). Furthermore, animal studies are reported in compliance with the ARRIVE guidelines (McGrath & Lilley, 2015).
The mice were randomly divided into 5 groups in each animal experiments. The group for the first study was composed like a vehicle-treated control group (1, Control), SA 20 mg·kg-1-treated control group (2, SA20), vehicle-treated MPTP group (3), SA 10 mg·kg-1-treated MPTP group (4, SA10), and SA 20 mg·kg-1-treated MPTP group (5, SA20). In the second study, the 5 groups are vehicle-treated control group (1, Control), vehicle-treated MPTP group (2), Ropinirole 5 mg·kg-1-treated MPTP group (3, RO), SA 20 mg·kg-1-treated MPTP group (4, SA), and both SA 20 mg·kg-1 and SR 25 mg·kg-1-treated MPTP group (5, SA+SR). Mice were injected 30 mg·kg-1MPTP (i.p.) dissolved in PBS on five consecutive days with or without SA (p.o), SR and ropinirole (i.p.), which were treated 30 min before MPTP injection. SR was intraperitoneal administered at 30 min before SA treatment in the combination of SA and SR group. The treatment dose of SA was followed by previous neurological studies and all reagents were dissolved in PBS, but SR was dissolved in 5:5:90 DMSO·cremophor-1·PBS-1 vehicle followed by previous study of Welch et al. (Kim et al., 2010; Lee et al., 2012; Welch, Billon, Valfort, Burris & Flaveny, 2017). After the behavioral tests, the mice were euthanized with CO2inhalation and then SNpc tissues were collected and stored at -80.