Cyclooxygenase-2 mRNA expression in equine nonglandular and glandular gastric mucosal biopsy specimens obtained before and after induction of gastric ulceration via intermittent feed deprivation.

The research examined the expression of an enzyme named COX-2 in the stomachs of horses, particularly during gastric ulcers. The enzyme was consistently found in one type of stomach tissue, and seemingly involved in the healing process of ulcers.

Research Context

• The research was primarily focused on understanding the role of cyclooxygenase-2 (COX-2), an enzyme, in the gastric tissues of horses.
• Various studies have suggested that COX-2 plays a crucial role in the physiological and pathological processes, including inflammation and cancer. However, its contribution to the gastro intestinal tract remained largely unclear.
• Therefore, the scientists decided to measure the expression of COX-2 in stomach tissue samples, taken from horses before, during, and after a trial where the horses would experience intermittent feed deprivation to induce gastric ulceration.

Methodology

• Initially, a group of nine horses of mixed breeds was used to obtain stomach tissue samples.
• Six horses of this group were used to obtain gastric biopsy samples, half of which along with three more then participated in the trial of intermittent feed deprivation nine weeks later.
• Post the feed-deprivation trial, researchers extracted nonulcerated and ulcerated gastric mucosa samples – tissues from the lining of the stomach from these horses.
• They then used a procedure called quantitative PCR (polymerase chain reaction) to measure the quantity of COX-2 mRNA – the molecule that helps in making the COX-2 enzyme.
• Also, they performed immunohistochemical staining using a polyclonal anti-COX-2 antibody on full-thickness postmortem gastric biopsy samples to reveal the presence of COX-2 in these tissues.

Findings

• Through the abovementioned tests, they discovered that COX-2 mRNA was expressed in all glandular gastric mucosal samples (a type of gastric tissue) but was only present in non-glandular samples when an ulcer was present or healing.
• More specifically, 12 out of 14 non-ulcerated glandular mucosal samples were found to be testing positive for COX-2, however, it was weak or absent in non-ulcerated non-glandular samples.
• But COX-2 staining was stronger in regenerating tissue at the rims of ulcers and erosions, indicating its possible role in healing ulcers.

Conclusion and Implications

• COX-2 enzyme was found to be consistently present in horses’ glandular stomach lining, although it’s uncertain how it contributes to protecting the gastric mucosa.
• The research overall demonstrated that the enzyme and its products may play a role in repairing gastric ulcers as its presence increased during ulcer healing.
• The discovery about COX-2 points to the need for considering these roles when prescribing COX-2-specific inhibitors (drugs) for horses suffering from gastric ulcers because unnecessary blocking of this enzyme might obstruct the natural healing process of gastric ulcers.