Effect of pyrrolizidine alkaloid-induced hepatic disease on plasma amino acid patterns in the horse.

This research study explores the changes in plasma amino acid patterns in horses suffering from liver disease caused by ingestion of plants with pyrrolizidine alkaloids. The study found specific alterations in the levels of various amino acids and noted that these changes are similar to those seen in humans and other animals with liver disease.

Introduction and Methodology

• The research involved studying 6 clinically normal adult horses, with the aim of observing any changes in plasma amino acid patterns during hepatic (liver) disease. The disease was artificially induced by feeding the horses plants containing pyrrolizidine alkaloids, chemicals known to be toxic to the liver.
• The levels of various amino acids in the plasma were monitored and compared to their usual levels, allowing researchers to identify any significant changes and draw conclusions based on this data.

Findings

• Upon the death of these horses, the values of several amino acids—including glutamine, proline, tyrosine, asparagine, lysine, histidine, alanine, phenylalanine, methionine, aspartic acid, and ornithine—showed significant increases.
• Contrarily, no significant changes were observed in the levels of glycine, valine, isoleucine, tryptophan, and arginine.
• Furthermore, a notable reduction was found in the levels of citrulline. Simultaneously, the level of ammonia in the blood increased fourfold.
• Alpha-Aminoadipic acid and alpha-aminobutyric acid were undetectable in healthy horses. However, in horses with severe liver disease, these acids were found in the plasma.
• The study also observed a decrease in the ratio of branched chain amino acids (isoleucine + leucine + valine) to phenylalanine and tyrosine, dropping from around 0.5 in healthy horses to just 1.3 in the diseased ones.

Conclusion

• The results showed similar changes in plasma amino acid patterns to those found in humans and other animals suffering from liver disease, suggesting a correlation across different species when facing liver diseases.