Effect of L-tryptophan on intestinal glucagon like peptide-1(GLP-1) in streptozotocin (stz) induced diabetic rat model

Introduction and Aim: The management of diabetes is a great challenge in this era due to several factors. The financial burden of the medications and the complications of diabetes create management demanding especially in the Indian population. A high protein-rich diet is beneficial in controlling hyperglycemia in diabetic patients. Different amino acids play roles in reducing blood glucose levels in diabetes. Certain amino acids trigger hypoglycemia in diabetes by inducing the gut hormone, Glucagon-like peptide-1(GLP-1) secretion. L-tryptophan is one among them and is present in many of the food items like poultry, beans, seeds, nuts, etc., This study using albino rats focuses on the effect of L-tryptophan on intestinal GLP-1 secretion in diabetic rats by evaluating the blood glucose level, intestinal GLP-1, and intestinal histology of diabetic rats after tryptophan administration. Materials and Methods: Single dose of intraperitoneal injection of STZ (50mg/kg) used to develop diabetic model and orogastric gavage of tryptophan (50mg/kg) was done. Intestinal GLP-1 and blood glucose assay and intestinal histology were the parameters studied. Results: The results showed a significant reduction in blood glucose level and an increased secretion of intestinal GLP-1(p=0.001) in diabetic rats by tryptophan administration and recovery was seen in intestinal histology. In conclusion, in our study, the administration of L-tryptophan in diabetic rats induced a hypoglycemic effect by GLP-1 secretion and restored normal histology. Conclusion: Tryptophan administration showed hypoglycemic effect on diabetic rats as the blood glucose level was reverted to normal and the hypoglycemic effect of L-tryptophan in diabetic rats could be due to increased GLP-1 secretion.