黄芪甲苷对光老化小鼠皮肤中转化生长因子-β信号通路的影响

目的 探讨黄芪甲苷对皮肤光老化的保护机制.方法 BALB/c小鼠分为模型组、模型+基质组、模型+黄芪甲苷组、正常对照组.RT-PCR测定转化生长因子β受体Ⅱ(TGF-βRⅡ)、Smad 7的mRNA表达水平,免疫组化观察TGF-βR Ⅱ、Smad 7在小鼠皮肤组织中的蛋白表达情况.结果 正常对照组中,TGF-βR Ⅱ、Smad 7的灰度值比值分别为0.5688±0.0439、0.5900 ±0.0585,阳性表达率分别为(53.00 ±4.72)%、(47.50±3.81)%;模型组中,TGF-βR Ⅱ、Smad 7的灰度值比值分别为0.2588±0.0283、0.8637±0.0514,阳性表达率分别为(28.20±5.24)%、(82.06±2.18)%;模型+基质组中,TGF-βR Ⅱ、Smad 7的灰度值比值分别为0.2653±0.0456、0.8553±0.0575,阳性表达率分别为(28.74±2.28)%、(82.62±4.02)%;模型+黄芪甲苷组中TGF-βRⅡ、Smad 7的灰度值比值分别为0.3767±0.0374、0.7131±0.0410,阳性表达率分别为:(41.64±2.59)%、(64.36±2.62)%.皮肤组织中TGF-βRⅡ和Smad灰度值比值4组小鼠间比较,F值分别为80.98和736.80,TGF-βRⅡ和Smad 7的阳性表达率4组小鼠间比较,F值分别为45.36和132.25,P值均<0.01.与正常对照组相比,模型组TGF-βR Ⅱ mRNA和蛋白表达明显降低,Smad 7 mRNA和蛋白表达显著升高(P值均<0.01).与模型组和模型+基质组比较,模型+黄芪甲苷组TGF-βRⅡ mRNA和蛋白表达明显升高,Smad 7 mRNA和蛋白表达显著下调(P值均<0.01).模型+基质组TGF-βR Ⅱ、Smad 7的mRNA和蛋白表达与模型组相比差异无统计学意义(P值均>0.01).结论 黄芪甲苷可以通过上调TGF-βRⅡ表达和下调Smad 7表达而改变TGF-β通路的信号转导参与抗光老化.

Abstract：

Objective To study the protective mechanism of astragaloside on skin photoaging. Methods BALB/c mice were randomly divided into four groups: model group irradiated with ultraviolet rays (UV), model plus matrix group pretreated with the matrix before UV irradiation, model plus astragaloside group pretreated with astragaloside 0.08% cream before UV irradiation, normal control group received no irradiation or pretreatment. After 4-week irradiation, the mice were sacrificed, and skin tissues were resected from the back of these mice. Then, reverse transeription PCR (RT-PCR) and immunohistochemistry were performed to detect the mRNA and protein expression of TGF-βR Ⅱ and Smad 7, respectively. Gray scale ratio was used to represent the mRNA levels of TGF-βR Ⅱ and Smad 7. Results There was a significant difference in the mRNA level (F = 80.98, 736.80, respectively, both P < 0.01) and protein positivity rate (F = 45.36,132.25, respectively,both P < 0.01) of TGF-βR Ⅱ and Smad 7 among the 4 groups. The mRNA level and protein positivity rate of TGF-βR Ⅱwere 0.2588±0.0283 and (28.20 ± 5.24)% respectively in the model group, significantly lower than those in the normal control group0.5688 ± 0.0439, (53.00 ± 4.72)%, both P < 0.01] and model plus astragaloside group 0.3767 ± 0.0374, (41.64 ± 2.59)%, both P< 0.01]; on the contrary, the mRNA level and protein positivity rate of Smad 7 in the model group 0.8637 ± 0.0514, (82.06 ± 2.18)%] were significantly higher than those in the normal control group 0.5900 ± 0.0585, (47.50±3.81)%, both P < 0.01] and model plus astragaloside group 0.7131 ± 0.0410, (64.36 ± 2.62)%, both P< 0.01]. In the model plus astragaloside group, the mRNA level and protein positivity rate of TGF-βR Ⅱ were significantly higher than in the model plus matrix group 0.2653 ± 0.0456, (28.74 ± 2.28)%, both P < 0.01], while those of Smad 7 were statistically lower than in the model plus matrix group 0.8553 ± 0.0575, (82.62 ± 4.02)%, both P < 0.01]. However,no significant difference was observed in the mRNA level or protein positivity rate of TGF-βR Ⅱ or Smad 7 between the model group and model plus matrix group (all P > 0.01). Conclusion Astragaloside can prevent skin photoaging by the alteration of TGF-β pathway via up-regulating TGF-βR Ⅱ expression and down-regulating Smad 7 expression.