Figure 2.

Metformin inhibits collagen I deposition and IL1β and CCL2 mRNA expression in a burn rat model. (A) A burn rat model is shown. Various concentrations of metformin (0, 1, 10, 100 mM) were subcutaneously injected into the dorsal burn wounds of the rats. (B,C) The rats’ skins were harvested at 14 d post−burn. Hematoxylin and eosin staining was performed on rat skin tissues under different treatments. The results of the HE stainings are shown. Scale bar = 200 μm. The statistical analysis of dermis thickness is shown in the bar graph. (D,E) Masson staining of rat skin tissues under different treatments. Statistical analysis of collagen volume fractions is shown in the bar graph. Scale bar = 100 μm. (F,G) A representative blot of three independent experiments is presented. Western blots of collagen I and GAPDH were scanned and densitometric unit ratios plotted. (H,I) Polarized light images of picrosirius red staining. Collagen III appears as fine green fibers. The areal percent of collagen III is quantified in the bar graph. Scale bar = 50 μm. (J,K) IHC for collagen III. Statistical analysis of relative ODs shown in the bar graph. Scale bar = 50 μm. (L,M) IHC for fibronectin. Statistical analysis of relative ODs shown in the bar graph. Scale bar = 50 μm. (N,O) RT−PCR analysis of IL1β and CCL2 mRNA relative expression in burned rat skin treated with or without metformin. All data are expressed as the means ± SDs of values (n = 12). ns: no significance. * p < 0.05 and *** p < 0.001. Control: normal rat skin, PBS (10 mM): burned rat skin treated with BPS (10 mM), Met (100 mM): burned rat skin treated with metformin (10 mM).