2.8 Stereotactic virus injection
Rats were anesthetized with isoflurane (Shenzhen RWD Life Science Co., Ltd., Shenzhen, China) and placed in an automated stereotactic aperture (RWD 68001). A small incision was made in the head to expose the skull, and a small craniotomy was performed. Rats were injected bilaterally in the BLA (coordinates: AP: –2.6 mm; ML: ± 4.8 mm; DV: –8.4 mm; bregma zero) using a 1-µL glass microsyringe for microinjection. The injection volume (500 nL/hemisphere) and rate (60 nL/minute) were controlled by an injection pump (RWD 68606). After the injection, the microsyringe was left in place for at least 10 minutes to prevent the virus from spreading through the injector track, and the injector was then slowly removed. The incision was closed with disposable sterile sutures and needles; for postoperative care, rats were administered an i.p. injection of benzylpenicillin dissolved in saline. The conditions of the rats were carefully observed until they recovered, and the rats were then placed in their original cages. Behavioral tests were performed 3 weeks after virus injection.