Expression of cyclooxygenase-1 and -2 in the left dorsal colon after different durations of ischemia and reperfusion in horses.

The research article explores the role of cyclooxygenase enzymes (COX-1 and COX-2) in horse colon tissue that is exposed to different durations of ischemia and reperfusion, a sequence of oxygen deprivation and restoration, to better understand the repair process in this context.

Objective and Sample Population

• The aim of this study was to examine the expression and distribution of COX-1 and COX-2 in the healthy and ischemic-injured left dorsal colon in horses, using tissue samples from 40 horses.

Procedures

• The tissue samples were collected during anaesthesia, before the commencement of ischemia, after 1 hour of ischemia, 1 hour of ischemia along with a 30-minute reperfusion, 2 hours of ischemia, 2 hours of ischemia with a 30-minute reperfusion, and finally, 2 hours of ischemia followed by an 18-hour reperfusion.
• Histomorphometric analyses were executed to characterize the morphological injury inflicted by the ischemia and reperfusion.
• Immunohistochemical analyses were performed so as to characterize the expression and distribution of COX-1 and COX-2 enzymes.

Results

• Both COX-1 and COX-2 were found to be expressed in the control tissues before the induction of ischemia and were dominantly located in the cells in the lamina propria of the tissues.
• Ischemic injury substantially amplified the expression of COX-2 in epithelial cells on the colon surface and in crypts, and a similar noteworthy increment in COX-1 expression was observed in the epithelial cells.

Conclusions and Clinical Relevance

• Based on the role of COX-2, the study suggests that the increased activity of COX-2 in surface epithelium and crypt cells following an ischemic injury in the equine colon may signify the initial stage of the repair process.