Microinjection pump

Two hours after resuscitation, the rats in the CPR + PBS group received a 15 μL intracerebroventricular injection of PBS, while rats in the CPR + N‐BMSCs group and CPR + HP‐BMSCs group received a single injection of 15 μL PBS containing 1 × 10⁶ N‐BMSCs or HP‐BMSCs to the left lateral ventricle. Pentobarbital was given if additional anaesthesia was necessary. The anaesthetised rats were secured in a stereoscopic frame (RWD Life Science) and a small incision was made to expose the skull. The skull position was adjusted until the bregma‐lambda axis was horizontal. A hole (coordinates: P—0.8 mm, L—1.5 mm, D—3.9 mm) was drilled into the skull using a mini‐drill (RWD Life Science). The infusions were administered at a rate of 1 μL/min using a 25 μL Hamilton syringe (Hamilton) that was connected to a microinjection pump (RWD Life Science). After injection, the needle remained in position for 15 min to prevent reflux. The holes were covered with medical bone wax (Johnson & Johnson), and the incision was sutured.

Mice were fixed in a stereotaxic frame (RWD, Shenzhen, China) under isoflurane anesthesia. Two holes were drilled in the skull of each mouse above the intended site of injection (BLA: AP – 1.4 mm, ML ± 3.4 mm, DV – 4.7 mm; vHip: AP – 3.1 mm, ML ± 3.3 mm, DV – 4.2 mm); 150–200 nl of the virus was delivered by 40 nl/min at each intended site through a Hamilton microsyringe with a microinjection pump (RWD, Shenzhen, China). After each injection, the needle was left in place for >10 min to allow for the diffusion of the virus and then slowly withdrawn.

Mice anaesthetized with 1.25% avertin (20 ml/kg) were fixed on a stereotaxic tube, the cannula (62,204, RWD, China) was embedded 1 mm deep in the right ACC brain region, and then the mice were placed in cages alone for 2 weeks to recover. Ten minutes before EA, 300 nl of CB1R antagonist AM251 was diluted to a concentration of 2.5 mg/mL (4.50 mM) using 100 μl Dimethyl sulfoxide (DMSO) + 400 μl PEG300 + 50 μl Tween-80 (MedChemExpress, United States) injected into the ACC region at a rate of 30 nl/min through a microinjection pump (RWD, China) connecting the cannula. The control group was injected with the same amount of artificial cerebrospinal fluid by the same method. The behavioural test was performed 30 min after EA.