Fig. 1

Effect of intragastric and intraarticular metformin on articular cartilage degradation in the destabilization of the medial meniscus (DMM)-induced OA mice model. a Representative scanning electron microscopy (SEM) images of the articular cartilage of the tibia plateau. Stripped cartilage, with a large area of exfoliation and exposed subchondral bone, was observed in the IGS and IAS groups. Mice in the IGM and IAM groups presented with slightly stripped cartilage and superficial avulsion. b Safranin O-fast green staining for frontal sections of knee at 8 weeks after surgery. The IGS and IAS groups presented with severe cartilage damage and less Safranin O staining. The IGM and IAM groups displayed a moderate degree of cartilage damage and loss of Safranin O staining. c Osteoarthritic changes in knee joints as quantified with the Osteoarthritis Research Society International (OARSI) score. Samples from the IGS and IAS groups showed more severe articular cartilage destruction compared with those from the IGM or IAM group. Data were expressed as the mean ± 95% confidence intervals. *p < 0.05; **p < 0.01. Statistical significance was calculated using one-way ANOVA with Tukey’s post hoc test. IGS, intragastric saline administration; IAS, intraarticular saline injection; IGM, intragastric metformin administration; IAM, intraarticular metformin injection