Effects of Giant Salamander Protein Peptide and Its Maillard Reaction Product on Blood Glucose, Lipid Levels, Immune Function,and Anti-fatigue Activity in Vivo

Objective: To investigate the impact of giant salamander protein peptide (CGS) and its Maillard reaction product (CGSXyU) on lowering blood glucose and lipid levels in type Ⅱ diabetic mice and enhancing immunomodulatory functions in immunosuppressed mice, and anti-fatigue effects in normal mice. Methods: Mice were randomly assigned to a blank control group, a model control group, a positive control group (200 mg/kg metformin), a low-dose sample group (CGS/CGSXyU-L, 50 mg/kg), and a high-dose sample group (CGS/CGSXyU-H, 200 mg/kg). Following the successful induction of diabetes with 100 mg/kg alloxan, the mice underwent gavage treatment for 3 weeks, after which their fasting blood glucose levels, serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels were measured. Mice were randomly assigned to a blank control group, a model control group, a positive control group (50 mg/kg levamisole), a low-dose sample group (CGS/CGSXyU-L, 50 mg/kg), and a high-dose sample group (CGS/CGSXyU-H, 200 mg/kg). Following successful modeling with 100 mg/kg cyclophosphamide, the mice underwent gavage for three weeks, during which their body weights were recorded, and changes in organ indices and cytokine levels were assessed. Similarly, mice were randomly divided into a blank control group, a positive control group (200 mg/kg taurine), a low-dose sample group (CGS/CGSXyU-L, 50 mg/kg), and a high-dose sample group (CGS/CGSXyU-H, 200 mg/kg). They were subjected to gavage for four weeks, after which the mice's weight-bearing swimming time, urea nitrogen levels, creatine kinase activity, serum lactate levels, and antioxidant enzyme activity were measured. Results: The CGS/CGSXyU-L/H treated group of mice exhibited reduced fasting blood glucose concentration, serum total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C), along with elevated high-density lipoprotein cholesterol (HDL-C) levels. CGSXyU-H significantly enhanced the body weight (P<0.05), organ index, and levels of immune cytokines (IL-6, IL-10, TNF-α, IFN-γ) in immunocompromised mice. The CGS/CGSXyU-L/H treatment group demonstrated increased time in weight-bearing swimming, reduced creatine kinase activity and serum lactate levels, the BUN level in the CGS-H and CGSXyU-L/H groups decreased, while the GSH-Px activity significantly increased in the CGSXyU-H group (P<0.05), the SOD activity in the CGS-H and CGSXyU-L/H groups also increased. Conclusion: The protein peptides from Andrias davidianus and their Maillard reaction products regulate blood glucose and lipid metabolism in type Ⅱ diabetes mice, bolster immune function in immunocompromised mice, and effectively improve the anti-fatigue capacity in normal mice.