2.6. AAV‐YB‐1 virus BAT in situ injection

YB‐1 overexpression adeno‐associated virus was purchased from Hanheng Biology and injected into BAT of mice of 12‐month‐old (n = 8) in situ at the concentration of 1. AT. The control group (n = 8) was injected with empty vector. The procedure of in situ injection is as follows. The mice were anaesthetised with 0.15 mL/20 g of 1% Pentobarbital. The anaesthetised mice were placed on the workbench, and a 2 cm surgical incision was cut on the back of the mice after shaving and disinfection. Carefully separate the fascia and white adipose tissue around the BAT under the skin, and inject 3 ~ 4 points of bat on both sides with a micro sampler. After completion, the skin at the edge of the surgical incision was disinfected with compound iodine, sutured, and then disinfected again.