Investigation of the effect of L-theanine on glucose and lipid metabolism in rats treated with Doxorubicin

Doxorubicin (DXN) is a powerful chemotherapeutic agent, commonly used to treat solid tumors and hematologic malignancies. It has side effects on glucose and lipid metabolism. It is known to induce oxidative stress and inflammation. L-theanine (LT) is a non-protein amino acid found in tea. It has multiple biological benefits, including regulating glucose and lipid metabolism and exhibiting anti-inflammatory activity. Our study aimed to evaluate the effectiveness of LT on the parameters involved in glucose and lipid metabolism in Wistar rats treated with DXN. This study involved 28 rats with four groups (n=7/group): Control, DXN, DXN+LT200, and DXN+LT400. DXNs were applied at 6 mg/kg/dose (3 doses on the 4th, 11th, and 18th days), and 200 and 400 mg/kg/day of LT treatments were given by oral gavage for 21 days. The levels of insulin, isthmin-1 (ISM1), zinc-α glycoprotein (ZAG), free fatty acids (FFA), glutathione peroxidase 4 (GPx4), tumor necrosis factor-alpha (TNF-α), and reduced and oxidized glutathione (GSH and GSSG, respectively) were determined in serum and/or liver tissue by using commercial kits, and serum iron (Fe) and liver malondialdehyde (MDA) by colorimetric methods. While DXN administration increased cholesterol, triglyceride, ISM1, and ZAG levels in the serum and liver, LT treatment, particularly at 400 mg/kg/day, decreased the levels of these parameters. DXN also increased serum iron levels and decreased insulin levels. LT treatment reversed these effects. In conclusion, the presence study suggested that insulin, ISM1, and ZAG proteins may play roles in DXN's effects on glucose and lipid metabolism. LT treatment had the potential to alter these effects. Further studies are needed to elucidate the effects of DXN and LT treatments on parameters involved in metabolism regulation.