| It has been proved that mechanical stimulation can greatly affect the remodeling of condylar cartilage in the past research. But the mechanism of that is still unclear. The research on other tissue and cell have demonstrated that integrin and G proteins play an important role in the mechanical regulation, however, such research on condylar cartilage have not been seen. To explore the influences of Static pressure on condylar cartilage remodeling and possible mechanism about that, the condylar cartilages of SD rat 6 days after born were loaded by static pressure through a self-made device in this research, the influences of static pressure on tissue structure, ultrastructure and synthesize of type II collagen of condyalr cartilage were investigated. An immunohistochemistry method was used to observe the changes of expression of alpha-2 and beta-1 integrin under different pressure to find probable relationship between integrin and remodeling, and G-protein antagonist was added to investigate it's effect on mechanical regulation.Part I : The cartilages were pressed at 100KPa and 300KPa for different duration. The thickness of proliferative zone and transitional zone were measured by computer. The results showed as following.1. In the control group, the condylar cartilage can be divided intofibrous zone, proliferative zone, transitional zone and hypertrophic zone. During 12h's culture, the cartilage structure didn't show obvious change. When G-protein antagonist was added, the structure didn't change.2. Static pressure can affect the thickness of proliferative zone, when cartilage was pressed at 100KPa for 12h, the thickness of proliferative zone declined. However, pressure at 300KPa has no obvious influence on the thickness of proliferative zone in 12h. There were no abnormal changes in cartilage structure under differnnt pressure.3. Static pressure at 100KPa or 300KPa has no obvious effect on thickness of transitional zone.4. After G-protein antagonist was added, both pressure at 100KPa and 300KPa static pressure have no obvious effects on the thickness of both proliferative zone and transitional zone.Part II: By immunohistochemistry method, the expression of type II collagen under different pressure were measured quantitatively, and G-protein antagonist was added to observe its effect on expression of type II collagen. The results showed as bellows: The type II collagen positive cell most lay in the boundary between transitional zone and hypertrophic zone. The positive reaction located in cytoplasm. In 100KPa group, after cartilages were pressed for 4h and 8h, the intensity of type II collagen increased obviusly, but after 12h it became similar as control group. In 300KPa group, the intensity of type II collagen kept higher than that of control group and 100KPa group during 12h's loading. G-protein antagonist had great influences on the effects mentioned above. Expression of type II collagen declined obviously in 300KPa group compared with the300KPa without antagonist group, but it was still higher than that of control in 4h and 8h. While under 100KPa pressure, type II collagen in the group with antagonist was higher only on 8h than that of the group without antagonist.Part III: After cartilages were pressed at 100KPa, 300KPa for 4, 12h, the ultrastrucrure of condyalr cartilage were investigated by transmission electron microscope. It was found as bellow.1. When cartilages were pressed at 100KPa for 4h, the chondrocytes showed better proliferative and metabolic condition compared to control group. Chromatin level increased, the nucleolus located in periphery of karyon, rough endoplasmic reticulum dilated. The homologous cell group can be seen in certain area. When pressed for 12h, most cells still showed good condition, but some cells began to senesce. The quantity of rough endoplasmic reticulum declined, hepatin granule accumulated, lipochrome appeared in some cells.2. When cartilages were pressed at 100KPa, the chondrocytes showed similar condition as 100K... |
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