[Effects of swimming and epigallocatechin gallate on interstitial proteins expression of myocardium from type 2 diabetic rats].

Objective: To observe the effects of swimming training and/or epigallocatechin gallate(EGCG) on the expression of myocardial interstitial protein and its relationship with transforming growth factor-beta(TGF-β)/Smads signaling pathway in type 2 diabetic rats.

Methods: Male SD rats(SPF grade, 6 weeks old) were fed with high-fat diet for 6 weeks and intraperitoneal injection of streptozotocin(STZ, 30 mg/kg). The rats were randomly divided into four groups: diabetic model group(D), diabetes EGCG group(DG), diabetes exercise group(DE), and diabetes exercise EGCG group(DEG), with 8 rats in each group, and 6 male SD rats in the same batch were added as the normal C group. The rats in the exercise group were given swimming training without load. The swimming time was 15 min/d in the first week, and the time was increased by 15 min a week until it was extended to 90 min/d. The rats in the exercise group were trained for 5 days a week. Rats in the EGCG group(100 mg/kg BW) were intragastrical administered for 7 days. Swimming training and/or EGCG intervention lasted for 12 weeks. 48 hours after the end of the intervention experiment, the rats were fasted overnight for 12 hours. Myocardial collagen I(Col I), collagen IV(Col IV) and fibronectin(FN) protein expression were detected by immunohistochemistry in some left ventricles, hydroxyproline(Hyp) content was detected by colorimetry, TGF-β_1 protein expression was detected by WB, Smad2 and Smad7 mRNA expression were detected by RT-PCR.

Results: The levels of blood glucose, Hyp content, TGF-beta1, Smad2 mRNA, Col I, Col IV, FN of the rats from D group were significantly higher than those of the rats from C group(P<0. 01), but the level of Smad7 mRNA was significantly lower than it of the rats from C group(P<0. 01). Compared with D group, blood glucose, TGF-β_1, Smad2 mRNA expression, Hyp content, Col I, Col IV, FN protein expression in DG group, DE group and DEG group were significantly decreased(P<0. 05 or P<0. 01), and the Smad7 mRNA expression increased significantly(P<0. 05 or P<0. 01). Compared with DG group, blood glucose, Smad2 mRNA expression, Hyp content, Col I, Col IV protein expression in DEG group were significantly decreased(P<0. 05 or P<0. 01), and the myocardial Smad7 mRNA expression was significantly increased(P<0. 05). Compared with DE group, the levels of blood glucose, TGF-β_1, Smad2 mRNA, Hyp content, Col I, Col IV protein expression were significantly decreased in the EGCG group(P<0. 05 or P<0. 01), and the expression of Smad7 mRNA was significantly increased(P<0. 05). Blood glucose, Smad2 mRNA expression, Hyp content, Col I, Col Ⅳ, FN protein expression in(DEG group were significantly higher than those in C group(P<0. 05 or P<0. 01).

Conclusion: 12 weeks swimming training and/or EGCG administration can reduce the expression of myocardial interstitial protein in type 2 diabetic rats, and the combined intervention effect is better.