The development of gluconeogenic enzymes in the liver and kidney of fetal and newborn foals.

This research studies the development of enzymes involved in glucose production in the kidneys and livers of unborn and newborn horses. The results demonstrate that the maturity of glucose-producing capacity in horses occurs later than in other species and could be connected to the rise in cortisol levels just before birth.

Study of Gluconeogenic Enzymes in Horses

• The research took measurements of several enzymes involved in glucose creation: glucose-6-phosphatase (G6P), fructose diphosphatase, phosphoenolpyruvate carboxykinase (PEPCK), aspartate and alanine transferases in the kidney and liver of unborn foals ranging from 100 to 318 days of gestation and immediately after birth.
• All five enzymes were detected in the fetal liver and kidney at the youngest gestational age studied, indicating they are present early in the developmental process.
• Enzyme activities were lower in foals than in the mothers and did not change much during gestation for most enzymes. There were, however, notable exceptions in the form of renal PEPCK and renal and hepatic G6P, which did increase as gestation progressed.

Changes at Birth and Late Gestation

• Upon birth, the activities of G6P and PEPCK in both the liver and kidney were found to be higher than in late gestation or in adult animals, suggesting a significant increase in these enzymes’ activities at birth.
• Most other enzymes didn’t exhibit noticeable changes in their activities at birth.
• In late gestation (80-90% of the gestation period), G6P and PEPCK activities were observed to be lower in the foal compared to those in other species at the same gestational stage.
• Similarly, the increase in enzyme activity in the period leading up to and following birth (the perinatal period) occurs closer to term in the foal than in most other species. This suggests that the foal’s capacity to produce glucose, or glucogenic capacity, matures later than that of other species.

Implications

• The observed late maturation of the foal’s glucogenic capacity suggests a link to the pre-birth rise in fetal cortisol, which is a pattern also noted in other species. This could indicate a role for cortisol in the development of glucose-producing capacity.
• This understanding of the development and regulation of gluconeogenesis in horses could be important for animal health and nutrition. It could inform specialized care or nutritional guidelines for pregnant mares and newborn foals.