Abstract：Scutellarin (Scu) has many beneficial effects clinically such as heat-clearing, detoxicating, expansion of blood vessels and improving microcirculation. The protective effects of scutellarin on improving the heat resistant of pig kidney proximal tubular (LLC-PK1) cells were studied by measuring expressions of heat shock protein 72 (HSP 72), B-cellymphoma/leukemia-2 (Bcl-2) and Bcl-2 associated X protein (Bax) of the cells treated with different concentrations of Scu. The LLC-PK1 cells cultured in vitro were randomly divided into five groups including 37 ℃ control group (Ⅰ), 42 ℃ heat stress group (Ⅱ), 1×10-5 mol/L Scu-treated group (Ⅲ), 1×10-6 mol/L Scu-treated group (Ⅳ) and 1×10-7 mol/L Scu-treated group (Ⅴ), respectively. The total RNA and protein in all groups of cells were extracted, then the mRNA and protein content of HSP72, Bax and Bcl- 2 in the cells were detected by qPCR and Western blot, respectively. Our results showed that the mRNA and protein expression of HSP72 and Bax all increased significantly (P＜0.05), Bcl-2/Bax ratio decreased significantly in groupⅡ compared with groupⅠ(P＜0.05), while expression of Bcl-2 had no significant difference (P＞0.05). Treatments with various concentrations of Scu significantly increased both expressions of Bcl-2 in group Ⅳ and HSP72 in groups Ⅳ andⅤcompared with groupⅡ(P＜0.05) at mRNA and protein level, while neither HSP72 nor Bcl-2 in group Ⅲ had any significant differences. The mRNA and protein expressions of Bax in Scu- treated groups were obviously decreased compared with groupⅡ. The protein ratios of Bcl-2/Bax in both group Ⅳ and Ⅴ were significantly increased compared with groupⅡ(P＜0.01). All above results indicated that Scu could induce HSP72 expression, increase Bcl-2/Bax ratio and enhance heat resistance of LLC- PK1 cells under heat stress condition. Our result enriches the theory of heat stress response in cells cultured in vitro, which provides theoretical basis for improving the cell resistance to heat shock in practice.
