4.3. OBX Surgery

After a seven-day adaption, rats were subjected to bilateral OBX according to the previously described methods [62,63]. Rats were anesthetized with 2% pentobarbital sodium (50 mg/kg, intraperitoneal injection (i.p.)) and fixed in stereotaxic apparatus. After the skull was exposed, two holes were drilled on either side of the midline (2 mm in diameter, 8 mm anterior to bregma, and 2 mm lateral to the midline). The removal of olfactory bulbs was performed by aspiration with a blunt syringe needle attached to a vacuum pump. The holes were filled with absorbable collagen sponge immediately to control the bleeding and then the wound was sutured. Sham-operated rats experienced the same procedures, but their bulbs were left intact. After surgery, the rat was housed in an individual cage and given penicillin sodium (10,000 U in normal saline, i.p.) once a day for three consecutive days to prevent probable infection.