Perinatal development of bilirubin UDP-glycosyltransferase activities in rat liver

Area of Science:

• Hepatology
• Developmental Biology
• Biochemistry

Background:

• Liver enzyme activity and its developmental timeline are crucial for understanding neonatal physiology and potential health issues.
• Bilirubin conjugation is a key detoxification pathway in the liver, particularly important during the perinatal period.

Purpose of the Study:

• To investigate the presence and in vivo activity of bilirubin UDP-glucuronyltransferase and UDP-xylosyltransferase in fetal rat liver.
• To explore the implications of UDP-glucose dehydrogenase deficiency on intracellular nucleotide sugar concentrations in fetal rat liver.

Main Methods:

• Enzyme assays were performed on rat liver tissue from day 19 of gestation onwards.
• Bilirubin-glucuronide levels were analyzed in hepatocytes of 21-day-old fetal rat liver.
• The study considered known data on UDP-glucose dehydrogenase activity in fetal and neonatal rat liver.

Main Results:

• Bilirubin UDP-glucuronyltransferase and UDP-xylosyltransferase activities were detected in rat liver starting from day 19 of fetal life.
• Bilirubin-glucuronide was found in hepatocytes of 21-day-old fetal liver, confirming in vivo enzyme activity.
• Despite UDP-glucose dehydrogenase deficiency, no glucosides were detected in fetal hepatocytes.

Conclusions:

• Bilirubin conjugation enzymes are active in fetal rat liver prior to birth, suggesting a functional role during development.
• The presence of bilirubin-glucuronide supports in vivo enzyme activity, though cellular secretion mechanisms may still be immature.
• The interplay between enzyme activity, nucleotide sugar availability, and secretion capacity influences liver function during fetal development.