The Effect of Glycyl-Glutamine Dipeptide Concentration on Enzyme Activity, Cell Proliferation and Apoptosis of Jejunal Tissues from Weaned Piglets

An experiment was conducted in a singly factorial design to study the effect of glycyl-glutamine dipeptide on enzyme activity, cell proliferation and apoptosis of jejunal tissues from weaned piglets at different glycyl-glutamine concentration levels of 2, 4, 10, 20, and 30 mmol L−1, respectively. The glutaminase activity, diamine oxidase (DAO) activity, cell peoliferation, apoptosis, and perotein metabolism were measured by the tissue culture method in vitro using jejunal tissues. The immunohistochemical method was used to study the cell proliferation and apoptosis of jejunal tissues. The results showed that compared to the blank control, the percentage and MOD value of BrdU-positicve cells incubated with glycyl-glutamine dipeptide solution were significantly (P<0.05) increased. Accordingly, the percentage and MOD value of caspase-3-positive cells from tissue incubated with glycyl-glutamine dipeptide were notably lower (P<0.05) than that from the control treatment. The glycyl-glutamine dipeptide increased the glutaminase activity, DAO activity and protein content of jejunal tissues, as the dipeptide concentration was on the rise (P<0.05). These results indicated that glycyl-glutamine dipeptide affected the jejunum development and adaptation of weaned piglets, and the function might be fulfilled by enhancing the glutamine-related enzyme activity, thereby increasing the consumption of glutamine, and then improving the jejunal cell proliferation and suppressing cell apoptosis. The effects of glycyl-glutamine dipeptide relied in a dose-dependent manner, and the maximum effect was achieved at 20-30 mmol L−1 glycyl-glutamine dipeptide.