Abstract
Objective—To characterize the expression of the cyclooxygenase (COX)-1 and COX-2 isoforms in naturally occurring ulcers of the nonglandular portion of the stomach in horses.
Specimen Population—38 specimens from ulcerated stomachs and 10 specimens from healthy stomachs.
Procedures—Specimens were collected at an abbatoir; for each specimen of squamous gastric mucosa, 1 portion was fixed in neutral-buffered 10% formalin for immunohistochemical analysis and another was frozen at −70°C for immunoblotting analysis. Immunoreactivity to 2 antibodies, MF241 (selective for COX-1) and MF243 (selective for COX-2), was evaluated by a veterinary pathologist using a scoring system. Expression of COX-1 and COX-2 was confirmed by use of immunoblotting analyses.
Results—All specimens from healthy stomachs strongly expressed COX-1, whereas only 2 of 10 expressed COX-2. The expression of both isoforms varied greatly in the ulcerated mucosal specimens. Expression of COX-1 was significantly lower and expression of COX-2 was significantly higher in ulcerated versus healthy specimens.
Conclusions and Clinical Relevance—Increased expression of COX-2 in gastric ulcers of the squamous portion of the stomach in horses suggested a role for this enzyme in gastric ulcer healing.
