The Repairative Effect And Mechanism Of Low Power Laser For The Enthesiopathy Of Achilles Tendon Of Rats

Objective:In this experiment, electrical stimulation method was used to establish the rats model with Achilles tendon enthesiopathy.Then to observe the influence of Low power laser therapy (LLLT) from different angles and levels of tissue morphology biomechanics, biochemistry, molecular biology and so on.Discuss the mechanism of low power laser therapy on Achilles tendon enthesiopathy.Explore the application of low power laser in the clinical practice of sports medicine, to promote the restoration of tendon injuries and provide the theory basis.Methods:The experiment adopted two kinds of model-jumping by the electricity and LPLT:96male Wistar rats were selected randomly as the control group (n=8) and the exercise group (n=88), the rats of exercise group were divided randomly into two groups again:①The exercise control group (n=8)②Nature healing group (n=40). According to the time of samples been taken, the groups were further allocated to1,2,3,7,14d after exercising. Each group has8rats.③LLLT group (n=40) LLLT groups were also allocated to1,2,3,7’,14d after exercising. Each group has8rats. The rats of exercise were trained for5weeks, and then we use the LLLT on the rats of LLLT groups depending on the different needs. Text methods and Index:①Use the HE dyeing and transmission electron microscope to observe the Achilles tendon cells and change of collagen fiber structure in rats.②Instron3365universal material testing machine determines the stiffness of the Achilles tendon, maximum load and other biological mechanical performance index.③Samples alkaline hydrolysis measures the contents of hydroxyproline of the tendon.④Determining the Achilles tendon protein polysaccharide、Collagen-Ⅰ、Collagen-Ⅲ、TGF-β1MMP-1and TIMP-1content with ELISA.⑤The expression of Collagen-ImRNA、Collagen-ⅢmRNA、 TGF-β1mRNA、MMP-1mRNA and TIMP-1mRNA level were analyzed by real-time quantitative PCR technique.Results:①After low power laser therapy, observing with HE dyeing and transmission electron microscope, found the collagen fiber arrangement tend to be neat, crosslinking reduce, tendon cells become larger and increases gradually, suggests that low power laser therapy can promote the regeneration of the Achilles tendon enthesiopathy in rats.②After7days, compared with the Natural healing group stiffness and maximum load of LLLT group began to appear the significant difference (P<0.05).③After14days, LLLT group compared with Natural healing group, hydroxyproline content appears significant difference (P<0.05).④Potein synthesis polysaccharide increase gradually after the low power laser, compared with Natural healing group, after7days it began to appear significant difference (P<0.05)⑤With the passage of time, LLLT group collagen-ImRNA expression gradually increased.The collagen-I protein initial decreased slightly and then increased.After7days the change appeared significant difference (P<0.05) and after14days the change appeared very significant difference (P<0.01) compared with the Natural healing group.⑥The mRNA and protein of collagen-III in tendon decrease with time passed by.After14days the mRNA appeared significant difference (P<0.05) compared with Natural healing group.But the significant difference of protein synthesis appeared in day7.⑦The mRNA expression and protein synthesis of TGF-β1decreased with time.After7days the mRNA and protein content in LLLT group appeared significant difference (P<0.05) compared with Natural healing group.⑧After3days the mRNA of MMP-1in LPLT group appeared significant difference (P<0.05) compared with Natural healing group, and sustained in the7th and14th day.And the significant difference (P<0.05) of protein content appeared in the7th day.⑨After7days the mRNA and protein content of TIMP-1appeared significant difference (P<0.05) and very significant difference (P<0.01) in the14th day compared with Natural healing group.Conclusion:①Low power laser has some effects on enthesiopathy of the Achilles tendon.②Low power laser promote enthesiopathy Achilles tendon tissue recovery by activating the tendon cells.③Low power laser can regulate metabolism of rat Achilles tendon and improve the biomechanical performance, so as to promote the Achilles tendon repair.④Low power laser can upregulate the protein content of polysaccharide in rat Achilles tendon, reduce scarring and promote the tendon healing.⑤Low power laser can increase hydroxyproline content in Achilles tendon, promote collagen-I synthesis and accelerate the Achilles tendon repair.⑥Low power laser can improve collagen-Ⅰ and collagen-Ⅲ expression, participate in the Achilles tendon repair, speed up the early healing of Achilles tendon enthesiopathy.⑦Low power laser irradiation can delay TGF-β1decline, make TGF-β1keep in the appropriate level, reduce scar formation and speed up the Achilles tendon enthesiopathy healing.⑧Low power laser can balance MMP-1and TIMP-1synthesize, downregulate MMP-1/TIMP-1ratio, reduce the degradation of collagen and promote the Achilles tendon repair.