Ontogeny of Small Intestinal Glutaminase and Glutamine Synthetase in the Rat: Response to Dexamethasone

Abstract

The ontogeny of small intestinal glutaminase (GA) and glutamine synthetase (GS) was studied with relation to the maternal administration of dexamethasone (DEX). Pregnant Sprague-Dawley rats were administered 0.2 mg/kg of DEX or saline twice daily on days 19 and 20 of gestation. Activity of GA did not increase from the fetus to the 10-day-old rat; however, GS activity increased 7-fold. DEX induced doubling of GA activity and mRNA, but only a slight increase is GS activity and mRNA was observed in the fetus. GA and GS activities appear to be regulated by different mechanisms.

Activities of Enzymes Involved in Glutamine Metabolism in Connection with Energy Production in the Gastrointestinal Tract Epithelium of Newborn, Suckling and Weaned Piglets

“…Glutaminase activity in the small intestine of rats was shown not to change for up to 10 days after birth [9]. However, by the end of the suckling period [10] and by the time of weaning [8] the activity of glutaminase in epithelial cells from the rat small intestine had increased.…”

Free Amino Acids in Human Milk: A Potential Role for Glutamine and Glutamate in the Protection Against Neonatal Allergies and Infections

“…Whereas, human intestinal cells can also convert glutamate into glutamine, this process is limited due to the low glutamine synthetase activity in the small intestine (89,90). In the neonatal period, this ability may be further limited as studies in young rats demonstrated that glutamine synthetase activity is particularly low in the pre-weaning period (91,92). Remarkably, IECs as well as immune cells cannot function properly without the availability of exogenous glutamine (93).…”