The Metabolic Responses to L-Glutamine of Livers from Rats with Diabetes Types 1 and 2

Abstract

There are several claims about the beneficial effects of supplementing L-glutamine to both type 1 and type 2 diabetes. The purpose of the present study was to provide detailed knowledge about the fate of this amino acid in the liver, the first organ that receives the compound when ingested orally. The study was done using the isolated perfused rat liver, an experimental system that preserves the microcirculation of the organ and that allows to measured several parameters during steady-state and pre steady-state conditions. L-Glutamine was infused in the portal vein (5 mM) and several parameters were monitored. Livers from type 1 diabetic rats showed an accelerated response to L-glutamine infusion. In consequence of this accelerated response livers from type 1 diabetic rats presented higher rates of ammonia, urea, glucose and lactate output during the first 25–30 minutes following L-glutamine infusion. As steady-state conditions approached, however, the difference between type 1 diabetes and control livers tended to disappear. Measurement of the glycogen content over a period of 100 minutes revealed that, excepting the initial phase of the L-glutamine infusion, the increased glucose output in livers from type 1 diabetic rats was mainly due to accelerated glycogenolysis. Livers from type 2 diabetic rats behaved similarly to control livers with no accelerated glucose output but with increased L-alanine production. L-Alanine is important for the pancreatic β-cells and from this point of view the oral intake of L-glutamine can be regarded as beneficial. Furthermore, the lack of increased glucose output in livers from type 2 diabetic rats is consistent with observations that even daily L-glutamine doses of 30 g do not increase the glycemic levels in well controlled type 2 diabetes patients.

Effects of Anthocyanin Extracts from Bilberry (Vaccinium myrtillus L.) and Purple Potato (Solanum tuberosum L. var. ‘Synkeä Sakari’) on the Plasma Metabolomic Profile of Zucker Diabetic Fatty Rats

“…A clinical study has found a significant positive correlation between the plasma level of glutamate and insulin resistance, and an increase in glutamine/glutamate ratio predicted a reduced risk for developing diabetes. , Increased glutamine and decreased glutamate might be associated with increased levels of glucagon-like peptide-1, enhancement of the vesicle trafficking of GLUT4, and improvement in insulin secretion and insulin sensitivity. , In our current study, the M group had a significantly lower glutamine/glutamate ratio compared to the groups Con and ND, and the treatment with the purple potato anthocyanin extract rich in acylated anthocyanins significantly increased the glutamine/glutamate ratio, indicating improved insulin secretion and/or insulin sensitivity. The nonacylated bilberry anthocyanin extract did not show clear impact on the glutamine/glutamate ratio.…”

The role of oxidant stress and gender in the erythrocyte arginine metabolism and ammonia management in patients with type 2 diabetes

“…On the other hand, an intra-portal load of L-glutamine in rat with experimentally-induced type 1 DM generates increased glucose output, accompanied by enhanced urea and ammonia production [40]. These might be providing a background to explain the enhanced blood levels for ammonia and urea found in our patients with type 2 DM ( Figs 1, 2, 4 and 5 ).…”

Insulin degludec and glutamine dipeptide modify glucose homeostasis and liver metabolism in diabetic mice undergoing insulin-induced hypoglycemia

“…The glucose output in livers from D, DG and DIR+G was high after starting perfusion with KH alone, but with a continuous decline up to 30 min. This phenomenon mainly reflects glucose release from the glycogen stores, which are usually higher in diabetic animals (Comar et al, 2016). The declining rates of glucose and lactate at the beginning of the perfusion (0-30 min) can be best appreciated by evaluating the AUC, which correspond to the total amounts released during the initial 30 min.…”