Figure 8. Rapamycin showed a cartilage-protective role in a rat model. A total of 60 SD rats were randomly divided into four groups: 15 rats in the IL-18 treatment group which received 50 μl IL-18 solution (100 ng/ml); 15 rats in the rapamycin treatment group which received 50 μl rapamycin solution (100 nM); 15 rats in the IL-18 + rapamycin treatment group which received 50 μl IL-18 + rapamycin solution (100 ng/ml and 100 nM respectively); 15 rats in the control group which received an equal volume of vehicle. (A) Rats were euthanized after 8 weeks of treatment, and the knees were preserved in 4% paraformaldehyde solution. 4% paraformaldehyde-fixed knees were decalcified and embedded in paraffin, then sectioned at 5 μm thickness. Sections of the interior joint were stained with safranin O-fast green (SO). (B) Aggrecan, MMP13, Atg5, and Caspase3 were detected by immunohistochemistry.