Expression of cyclooxygenase genes in the jejunum of horses during low-flow ischemia and reperfusion.

This research investigates how the expression of two cyclooxygenase (COX) genes changes in the horse jejunum during periods of low blood flow (ischemia) and resumption of normal blood flow (reperfusion), as well as the stability of reference (housekeeping) genes in the same conditions.

Objective and Methodology

• The researchers aimed to analyze the expression of cyclooxygenase (COX) genes, specifically COX-1 and COX-2, in the jejunum tissue of horses during arterial low-flow (ischemia) and reperfusion. They observed the expression stability of eight reference housekeeping genes under these circumstances as well.
• The experiment was done with five healthy adult horses. Two segments of each horse’s intestine (jejunum) were brought out of the body surgically while the horse was under anesthesia. One segment was considered the control, kept at baseline values, while the other was taken through a reduced blood flow period (ischemia), caused by limiting blood flow to just 20% of normal for 75 minutes, followed by 75 minutes of restored blood flow (reperfusion).
• Biopsy samples were taken from the experimental segments before ischemia, after the ischemia period, and following reperfusion. Samples were also taken from the control segments before and after the process. All horses were euthanized 24 hours post-ischemia, and further samples were collected.
• The biopsy samples were analyzed histologically, and total RNA was extracted from the tissues. Using quantitative real-time PCR assays, the researchers measured the expression of COX genes and the stability of eight housekeeping genes.

Results and Conclusion

• Both COX-1 and COX-2 genes were found to be expressed normally in baseline samples. However, when the blood flow was limited, COX-2 gene expression significantly increased at every measurement point in time following the interruption, opposed to baseline values.
• Among the housekeeping genes studied, β-actin and hypoxanthine phosphoribosyltransferase were found to be the most stably expressed under these conditions. In contrast, glyceraldehyde 3-phosphate dehydrogenase and β-2 microglobulin exhibited the least stable expression.
• The researchers concluded that limiting the blood flow (ischemia) resulted in upregulation of COX-2 gene expression in the horse jejunum. They also found that housekeeping genes, often used as internal standards in gene expression studies, may not remain stable during low-flow ischemia and reperfusion in this type of tissue.