Effects of body condition score (BCS) on steroid- and eicosanoid-metabolizing enzyme activity in various mare tissues during winter anoestrus.

The research article explores the impact of different Body Condition Scores (BCS) on the activity of certain enzymes in horses. Essentially, the study found that while the BCS did not significantly alter enzyme activity, there were considerable tissue variations, highlighting the liver’s critical role in metabolism.

Objective and Methodology

• The primary goal of the research was to determine the activity of steroid and eicosanoid metabolizing enzymes in horses with varied BCS.
• The researchers used a sample size of twenty non-pregnant, anoestrous mares. The BCS of these mares was noted prior to euthanasia.
• After euthanasia, tissue samples were collected from multiple organs: liver, kidney, adrenal gland, ovary and endometrium.
• The researchers determined the activities of enzymes Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A), and uridine 5′-diphospho-glucuronosyltransferase (UGT) using luminogenic substrates.
• The MIXED process of SAS was utilized to test the influence of the BCS on enzyme activity and to identify differences between tissues.

Results

• The study found an increased CYP1A activity in the adrenals of BCS 5 versus BCSs 4 and 6, and a higher CYP1A activity in the liver of BCS 4.
• Meanwhile, CYP1A activity was found to be 100-fold higher in the liver than in other organs: the adrenal, ovary, and kidney.
• CYP2C activity was also significantly higher (100-fold) in the liver than in the adrenal gland, ovary and endometrium.
• Furthermore, CYP3A activity was only detectable in the liver, and UGT activity in the kidney was lower in BCS 4 compared to BCSs 5 and 6.
• The UGT activity was three times higher in the liver than in the kidney and nine times higher in the kidney than in the ovary and endometrium.

Conclusion

• Despite the Body Condition Scores (BCS), the activity of steroid- and eicosanoid-metabolizing enzymes in horses didn’t notably change.
• However, substantial differences in these enzyme activities were observed across various tissues.
• The results indicated the liver’s dominant role in metabolic activities in horses, similar to other livestock species. This indicates that despite changes in body condition, the liver’s metabolic function remains robust.