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目的观察早期应用重组人生长激素(rhGH)对严重烧伤大鼠小肠粘膜上皮细胞凋亡的作用并探讨其可能的作用机制。方法42只成年雄性Wistar大鼠随机分为对照组(n=6只)、烧伤组(n=18只)和GH组(n=18只)。后两组造成25%总体表面积Ⅲ度烫伤,立即腹腔注射地塞米松80 mg/kg,从伤后2 h开始连续3 d分别皮下注射等渗盐水和rhGH[1.33 U/(kg.d)]。于伤后12、24和72 h,HE染色观察末端回肠粘膜组织形态,TUNEL法检测小肠粘膜上皮细胞凋亡形态及凋亡率,荧光法检测肠粘膜细胞Caspase-3酶活性变化。结果烧伤组肠粘膜形态结构及上皮细胞损伤严重,GH组明显减轻,基本接近对照组。在伤后各时相点,烧伤组及GH组肠粘膜上皮细胞凋亡率均较对照组显著增加(P<0.01),但GH组显著低于烧伤组(P<0.01),两组均于伤后24 h达高峰[(15.40±3.21)%vs(38.80±6.98)%];烧伤组及GH组Caspase-3酶活性亦明显高于对照组(P<0.05),GH组明显低于烧伤组(P<0.05),亦于伤后24 h达高峰[(156.13±4.66)U/mg vs(214.60±9.29)U/mg]。结论早期应用rhGH能明显抑制严重烧伤大鼠肠粘膜上皮细胞凋亡,可能通过下调Caspase-3酶活性抑制肠粘膜细胞凋亡,减轻肠粘膜损伤,维护其形态结构与屏障功能。
Objective To observe the effect of early application of recombinant human growth hormone (rhGH) on apoptosis of small intestinal mucosal epithelial cells in rats with severe burns and to explore its possible mechanism. Methods Forty-two adult male Wistar rats were randomly divided into control group (n = 6), burn group (n = 18) and GH group (n = 18). The latter two groups were given a scald of 25% of the total surface area of degree III. Immediate dexamethasone (80 mg / kg) was injected intraperitoneally and isotonic saline and rhGH [1.33 U / (kg · d)] were injected subcutaneously . At 12, 24 and 72 h after injury, the morphology of terminal ileum mucosa was observed by HE staining. The apoptotic rate and apoptotic rate of intestinal mucosal epithelial cells were detected by TUNEL assay. Caspase-3 activity was detected by fluorescence assay. Results The intestinal mucosa morphology and epithelial cell injury in the burn group were severe, GH group was significantly reduced, basically close to the control group. Compared with the control group, the apoptosis rate of intestinal mucosa epithelial cells in burn group and GH group increased significantly (P <0.01), but the GH group was significantly lower than that in burn group (P <0.01) The peak at 24 h after injury was (15.40 ± 3.21)% vs (38.80 ± 6.98)%. Caspase-3 activity in burn group and GH group was also significantly higher than that in control group (P <0.05) (P <0.05), and peaked at 24 h (156.13 ± 4.66 U / mg vs 214.60 ± 9.29 U / mg). Conclusion Early application of rhGH can significantly inhibit the apoptosis of gut epithelial cells in severely burned rats, which may inhibit the apoptosis of intestinal mucosa cells, decrease the damage of intestinal mucosa, and maintain its morphological structure and barrier function by down-regulating the activity of Caspase-3.