Experimental Study On The Effect Of Sesamin On The Degeneration Of Intervertebral Disc Cartilage Endplates In Rats

Objective: Low back pain(LBP)is one of the most common causes of disability.It imposes a huge economic burden on individuals,families and society.Intervertebral disc degeneration(IDD)has been shown to be an important cause of LBP.Cartilaginous endplate(CEP)is one of the important structures of the intervertebral disc(IVD)and is a transport channel for IVD nutrients and metabolites,and when the CEP cells age and change in structure,it leads to impaired nutrient metabolism and mechanical changes leading to IDD.Therefore,CEP degeneration is considered to be an important predisposing factor for IDD,so it is important to investigate the molecular mechanism of CEP degeneration and find drugs to alleviate CEP degeneration for the clinical treatment of IDD.Sesamin plays an anti-inflammatory and anti-apoptotic role in skeletal diseases to slow down the disease progression,while its mechanism of action in CEP degeneration is still less studied.In this study,we demonstrated that sesamin is the main active ingredient in the treatment of CEP degeneration in intervertebral discs,and also investigated the mechanism of sesamin on CEP degeneration in a degenerative chondrocyte model,therefore,this study aims to further investigate the effect of sesamin on CEP degeneration in rats by constructing a rat CEP degeneration model in a complex in vivo model.Methods: Thirty-six SD rats were selected and randomly divided into sham-operated group(Sham group),model group(Model group)and sesquiterpene treatment group(Treatment group);the target IVD segments were modeled by open-abdominal needle puncture,and saline gavage treatment was started in Sham and Model groups and sesquiterpene gavage treatment was started in Treatment group after 2 weeks of modeling.Four weeks after modeling,the rats were executed and the CEP tissues were removed.QRT-PCR and Western Blot were performed to observe the degradation of Extracellular matrix(ECM)and the effect of sesquiterpene treatment on CEP tissues.Immunohistochemical studies were performed to analyze the apoptosis and inflammation of rat CEP tissues.Results: The Sham group showed intact upper and lower CEP structure,thinning thickness,reduced chondrocytes,and moderately diminished staining;compared to the Sham group,the Model group showed a small amount of connective tissue proliferation in the lower cartilage end plate,replacing the original tissue,reduced chondrocytes,and moderately diminished staining,indicating that the rat CEP degeneration model was successfully constructed.QRT-PCR results showed that the degenerated rat CEP had The QRT-PCR results showed that a disintegrin and metalloproteinase with thrombospondin motifs 5(ADAMTS5)and matrix metalloproteinases 13(MMP13)Western Blot experiments showed that the expression levels of ADAMTS5 and MMP13 were significantly increased in the CEP of degenerated rats,while the expression levels of type II collagen(Type II Collagen Alpha 1,Col2a1)were decreased,and the abovementioned expression was reversed in the Treatment group.The treatment group decreased the expression of ADAMTS5 and increased the expression of COL2.Immunohistochemical results showed that the number of positive interleukin-1 beta(IL-1β)and interleukin 18(IL-18)stained cells in the Model group was significantly higher than that in the Sham group,while the number of positive stained cells in the Treatment group was significantly lower.The number of BCL-2-associated X(BAX)positive staining cells in the Model group was significantly higher than that in the Sham group,while that in the Treatment group was significantly lower than that in the Model group.The number of B-cell lymphoma-2(BCL-2)positive staining cells in the Model group was lower than that in the Sham group,while the number of positive cells in the Treatment group was significantly higher than that in the Model group.Conclusion: Sesamin delays CEP degeneration in rats.Sesamin reduced the mRNA and protein expression levels of ADAMTS5 and MMP13,and elevated the mRNA and protein expression levels of COL2,thereby delaying the ECM degradation of rat CEP.Sesamin reduced the expression levels of IL-1β and IL-18 in rat degenerative CEP,and attenuated the inflammatory response in degenerative CEP.Sesamin reduced BAX and elevated the number of BCL2-positive stained cells,indicating that it delayed apoptosis in rat CEP.