Effects of allopurinol on endotoxin-induced increase in serum xanthine oxidase in the horse.

This study investigates the effects of allopurinol, a medication typically used for gout, on endotoxin-induced serum xanthine oxidase activity in horses. It indicates that allopurinol may potentially help in reducing the increase in xanthine oxidase activity due to endotoxin exposure in horses.

About the Research

• The research was conducted on 34 adult, healthy horses of both sexes. The enzyme activity in the serum of these horses was determined using a modified bovine milk enzyme kinetic assay.
• Xanthine oxidase is an enzyme that plays a key role in the purine catabolism pathway, a metabolic pathway that leads to the formation of uric acid. This enzyme has been implicated in the pathogenesis of certain diseases due to its ability to form reactive oxygen species, such as superoxide radicals.

Main Findings and Experiment Design

• The optimal conditions for the maximal activity of the enzyme were a pH of 7.8 and a temperature of 28 degrees Celsius.
• The serum was frozen for four days at -70 degrees Celsius without any loss in enzyme activity.
• The horses were also given various doses (25, 50, and 75 micrograms per kg body weight, intraperitoneally) of endotoxin (lipopolysaccharide D1 Escherichia coli O26:B6), which had been previously shown to cause moderate to severe systemic clinical signs of endotoxemia in horses. This endotoxin significantly increased the serum xanthine oxidase activity in a dose-related manner.
• When horses were pre-treated with allopurinol (5 and 50 mg/kg, intravenously), it significantly reduced this endotoxin-induced increase in xanthine oxidase activity.

Implications and Significance

• The results of this study suggest that xanthine oxidase may be involved in the development of endotoxemia, a condition characterized by the presence of endotoxins in the blood, which can potentially lead to sepsis.
• The researchers also propose that allopurinol may have potential therapeutic value in managing endotoxin related systemic diseases in horses, as it has been shown to reduce the increase in serum xanthine oxidase activity resulting from endotoxin administration.
• The researchers recommend further evaluation of allopurinol for its potential therapeutic application in managing systemic diseases related to endotoxins in horses.