2.1. Animal

Experiments were conducted in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals, and all experimental protocols were approved by the Medicine Animal Welfare Committee of the Third Xiangya Hospital of Central South University (Approval NO: 201703121; Changsha, China). 11-week-old male db/db mice with a C57BLKS/JNju background (db/db; BKS.Cg-Dock7^{m +/+} Lepr^db/J) and control db/m mice with the same background were obtained from Model Animal Research Center of Nanjing University (Nanjing, China).