Healthy male c57bl 6 mice

Healthy male C57BL/6 mice (7–9 weeks old, 20–25 g) were purchased from the Beijing Vital River Laboratory Animal Technology Co., Ltd., Beijing, China. The sample size of the animals was determined based on previous studies [23 (link)]. Mice were placed in separate cages (22 ± 1°C, 60% humidity, under a 12-hour light/dark cycle) and allowed to eat and drink freely. All animal experiments in this study were approved by the Ethics Committee of the Affiliated Hospital of Shandong University of Traditional Chinese Medicine (Jinan, China) and conducted according to the guidelines of the International Association for the Study of Pain. Every effort was made to minimize the number of animals used and their pain.

Healthy male C57BL/6 mice (8–10 weeks old) were purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd. (Beijing, China). The mice were bred at the Tongji Medical College and maintained under SPF conditions for at least 1 week before any experiment. All animal studies were approved by the Animal Care and Use Committee in Tongji Hospital (TJH-201612001).