2.2 Surgery for cannula implantation
Rats were anesthetized with isoflurane anaesthesia (5% induction and
2% maintenance) and placed in a stereotaxic frame. A unilateral and a
bilateral guide cannula (OD 0.64 mm×I.D. 0.25 mm, CC 1.2 mm, RWD Life
science Co Ltd., Shenzhen, China) were chronically implanted in the
lateral ventricle (-0.8 mm AP; -1.5 mm ML; -3.5 mm DV) and mPFC (PrL:
+3.2 mm AP; ±0.60 mm ML; −2.6 mm DV, IL: +3.2 mm AP; ±0.6 mm ML; −3.8 mm
DV) (Paxinos & Watson, 1986), respectively. The cannula and three
anchor screws were bonded to the skull with dental acrylic and dental
cement. After surgery, rats were placed in a heated pad and observed for
at least 30 min, then returned to its original cage. Rats were handled
and checked for signs of pain and distress at least once daily. Topical
analgesic (lidocaine/prilocaine cream) was used to prevent signs of pain
and/or discomfort for at least 2-3 days. The rats were intramuscularly
injected with penicillin (400000 IU kg-1) for at least
3 days and allowed to recover for 7 days before the experiments began.