Glutamine-enriched parenteral nutrition regulates the activity and expression of intestinal glutaminase.

The aim of this study was to examine the effect of glutamine-enriched parenteral nutrition on the activity, expression and distribution of glutaminase mRNA within the small intestine of rats. Central venous lines were inserted into 30 male Wistar rats before they were fed for 6 days with either: (a) conventional parenteral nutrition, (b) 2.5% glutamine-enriched parenteral nutrition, or (c) rat food ad libitum. Jejunal glutaminase activity per milligram of dry matter was greatest in the animals fed rat food (0.94+/-0.29), intermediate in the glutamine supplemented rats (0.69+/-0.19) and least in the rats nourished with conventional parenteral nutrition (0.55+/-0.24) (P<0.05). The data for glutaminase expression exhibited a similar trend (P<0.05). In situ hybridisation analysis confirmed that glutaminase is expressed in the mucosa along the whole length of the small intestine. It was concluded that provision of glutamine alters the activity and expression of glutaminase in intestinal enterocytes. The results suggest that glutamine increases glutaminase activity by promoting the accumulation of intestinal glutaminase mRNA.