The Effect Of Notch Signaling Pathway Study Of Apoptosis Of Articular Chondrocytes Of Knee Osteoarthritis

Objective:To detect the expression of Notch1、Bax、Bcl-2 gene in rat knee joint cartilage cells in a state of activation and inactivation of the Notch signaling pathway, preliminary study of mechanism of Notch Signaling pathway on experimental rat knee osteoarthritis chondrocytes apoptosis. Methods: Part 1:Taking 32 Rats, established the right knee osteoarthritis models use the method of Hulth. 4 weeks later, random selection of two rats, observed the morphological changes of right knee and took pathology examination to prove the model successful. The remaining 30 were randomly divided into three groups. continue feeding, injecting different reagents in the articular cavity respectively on week2、week5.The activator group was injected Jagged1(25ng/kg), an activator of Notch signaling, to intra-articular; the inhibitor group was injected γ-secretase inhibitor(DAPT,100ng/kg) to intra-articular; the control group was injected PBS buffer to intra-articular.Part 2: The rats were sacrificed at 8 weeks of articular cavity injection. Took the right knee articular cartilage speciments of femoral condyle, observed the degeneration of articular cartilage of three groups. stained for HE and observed by microscope, used the system of Mankin’s marking makring. and used the immunohistochemistry to detect the expression of Notch1、Bax、Bcl-2. Result:(1)visual inspection: the joints of activator group were obvious swelling, tibial and femoral condylar cartilage surface was not flat, articular cartilage were destructed obviously,some have ulcers and cracks, some regions of articular cartilage loss, revealing the subchondral bone, a large of osteophyte emerged on the margin. the articular cartilage surface of inhibition group were smooth, no swelling of joints, cartilage more complete, a small amount of softening focus, no ulcers and cracks, no osteophyte formation; the surface of articular cartilage of control were less smooth,the damaged of articular cartilage was light, a small amount of osteophyte was formed,part of the cartilage have cracks,even a small ulcers appears.(2)stained for HE: surface layer of cartilages of the activator group have a large of defect area, disorganized cells and chondrocytes were unclear, cartilage cells reduced, tidal lines disappeared, cartilaginous structures completely destroyed, partial region Focal hyperplasia.;4 layer of articular cartilage structure of inhibition group were clearly distinguishable, Cartilage damage unconspicuous, surface regular, smooth and complete, cells arranged rule, tidal line clear; 4-layer structure of joint cartilage of control can discriminate, cartilage cells decreased in most areas, cartilage cells showed diffuse hyperplasia, tidal line was not complete. Mankin’s score of the activator group was higher than the control group, there was a significant difference between the groups(P<0.05); Mankin’s score of the inhibition group was lower than the control group, there was a significant difference between the groups(P<0.05); Mankin’s score of the activator group was higher than the inhibition group, there was a significant difference between the groups(P<0.05).(3)Immunohistochemical staining:the Notch1、Bax expression of chondrocyte in the activator group was higher than the control group, there was a significant difference between the groups(P<0.05); the Notch1、Bax expression of chondrocyte in inhibition group was lower than the control group, there was a significant difference between the groups(P<0.05); the Notch1、Bax expression of chondrocyte in the activator group was higher than the inhibition group,there was a significant difference between the groups(P<0.05). the Bcl-2 expression of chondrocyte in the activator group was lower than the control group, there was a significant difference between the groups(P<0.05); the Bcl-2 expression of chondrocyte in inhibition group was higher than the control group, there was a significant difference between the groups(P<0.05); the Bcl-2 expression of chondrocyte in the activator group was lower than the inhibition group, there was a significant difference between the groups(P<0.05).(4)The ratio of Bcl-2/Bax: the ratio of Bcl-2/Bax in activator group was lower than the control group, there was a significant difference between the groups(P<0.05);the ratio of Bcl-2/Bax in inhibition group was higher than the control group, there was a significant difference between the groups(P<0.05); the ratio of Bcl-2/Bax in activator group was lower than the inhibition group,there was a significant difference between the groups(P<0.05). Conclusions:Activating Notch signaling pathways can aggravate osteoarthritis, inhibit Notch signaling pathway can reduce osteoarthritis, Notch signaling pathway may be associated with the development and progression of OA; activating Notch signaling pathway may aggravate osteoarthritis by raised Bax protein,reduced Bcl-2 protein, thus facilitating the chondrocyte apoptosis and aggravate osteoarthritis; inhibiting Notch signaling pathway may restrain osteoarthritis by raised Bcl-2 protein,reduced Bax protein,thus inhibit the chondrocyte apoptosis and reduce osteoarthritis.