Objective To investigate the effect of tea polyphenols (TP) on sarcopenia in the rat model of type 2 diabetes mellitus (T2DM) by regulating the Wnt/β-catenin pathway.

Methods Thirty 8-week-old SD rats were assigned into a control group (n=10) and a modeling group (n=20) according to body weight. The aged T2DM model was induced by a high-sugar and high-fat diet combined with injection of D-galactose and streptozotocin (STZ). Fasting blood glucose (FBG) ≥16.7 mmol/L and elevated P53 protein expression mark the occurrence of diabetes and aging. The relative wet weight of gastrocnemius muscle was compared among the control, model, and TP intervention (administration with TP at 300 mg/kg for 8 consecutive weeks after modeling for 7 weeks) groups. The area of intermuscular adipose tissue was observed via hematoxylin-eosin staining and semi-quantitatively analyzed. The expression levels of proteins including Wnt10b, β-catenin, PPAR-γ, and CEBPB in the gastrocnemius muscle were determined by Western blot.

Results The TP intervention group had lower FBG, higher relative wet weight of gastrocnemius muscle, and lower intermuscular fat infiltration (a decrease of 18.60%) at the end of the intervention than the model group (all P<0.05). TP intervention improved the pancreatic tissue structure in shape and area and alleviated the vacuolation of islet cells compared with the model group. In addition, TP intervention up-regulated the expression of Wnt10b and β-catenin while down-regulating the expression of PPARγ and CEBPB (all P<0.05).

Conclusions TP intervention may improve muscle mass and reduce fat infiltration in the gastrocnemius muscle by activating the Wnt/β-catenin signaling pathway that regulates the differentiation of adipocytes.