The Effect of Jiaxinan Decoction on the Content of Myocardial Collagen in a Rat Model of Thyroxin-induced Myocardial Hypertrophy

Objective To probe into the mechanisms underlying the effect of jiaxinan in the treatment of myocardial hypertrophy induced by thyroxin in the rat. Methods 40 adult SD rats were randomly divided into 4 equal groups: group A, normal control; group B, model; group C, model+high dose jiaxinan ; group D ,model+low dose jiaxinan.A model of myocardial hypertrophy for each rat of group B,C and D was set up by a daily hypodermic injection of 1 mg·kg -1 of L-thyroxin for 10 consecutive days. Beginning from the 6 th day of the experiment, rats of group A and B were given each 2 mL of pure water by gastrogavage, q.d.,for 11 consecutive days .Meanwhile, animals of group C and D were given each 2 mL of the stock solution of jiaxinan (containing 4 g·mL -1 of the crude drug )and 2 mL of 1∶2 diluted stock solution of jiaxinan(containing 2 g·mL -1 of the crude drug ) by gastrogavage ,q.d., respectively, for 11consecutive days. Rats of all 4 groups were then sacrificed and heart samples taken for examination . Results The average ratio of the weight of the left ventricle to the body weight in rats of group B(model)was higher than that in rats of group A (normal control)(P0.01).The myocardial content of collagen and the Ⅰ/Ⅲ collagen ratio in rats of group B(model) were higher than those in rats of group A(P0.01).In contrast ,these parameters in rats of group C and D that had been treated with high and low dose jiaxinan were lower than those of group B (model)(P 0.01). Conclusion The traditional Chinese medicine jiaxinan was shown to alleviate myocardial hypertrophy induced by thyroxin in rats .It also lowered the myocardial content of collagen, modulated and optimized the Ⅰ/Ⅲ collagen ratio in the murine myocardium .