AEN surgery

For bilateral AEN sectioning, rats were initially anesthetized using isoflurane (5%/vol initial induction, then 2–3%/vol maintenance, in 95% O₂ and 5% CO₂) and then placed in a stereotaxic device (Kopf Instruments, Tujunga CA). Under aseptic conditions, the orbit was exposed and the eyeball was retracted laterally. Using a stereoscopic surgical microscope, the AEN was identified within the orbit as it passed through the anterior ethmoidal foramen. The AEN was separated from the accompanying artery and vein. In all animals that received AEN sectioning, a 1 mm piece of nerve was removed from the AEN, which confirmed the denervation. In Sham animals, the AEN was isolated but left intact. Surgical procedures were repeated contralaterally. Ketoprofen (3–5 mg/kg sc) was used as a postsurgical analgesic for animals recovering from AEN surgery (3 and 9 day rats) both immediately after the surgery and again 24 h later.