ω3脂肪酸对脓毒症大鼠骨骼肌蛋白酶体活性的作用机制

Study of effects of ω3 fatty acid on skeletal muscle proteasome activity in rats with sepsis

目的探讨ω3脂肪酸对脓毒症大鼠骨骼肌蛋白酶体活性的作用机制。方法 30只SD大鼠随机分为5组:空白组、模型组、假手术组、常规TPN组和ω3脂肪酸组。模型组采用盲肠结扎穿刺术复制脓毒症模型,假手术组仅翻动盲肠,不做结扎处理。实验期间大鼠禁食不禁水,ω3脂肪酸组给予加用ω3脂肪酸的肠外制剂,TPN组未加用ω3脂肪酸外,其余成分相同。其余3组仅给予生理盐水肠外注射。在模型复制前5d即开始连续给予相应治疗。分别于造模第16和24小时检测20S蛋白酶体活性及不同亚基C2和C8亚基的活性。结果 16小时点各组伸趾长肌的20S蛋白酶体活性:空白组与假手术组间差异无显著性(P>0.05)。与空白组相比,模型组的20S蛋白酶体活性明显增加(P<0.05)。与模型组比较,TPN组活性下降,但差异无显著性(P>0.05);而ω3脂肪酸组的20S蛋白酶体活性显著下降(P<0.05)。24小时点的20S蛋白酶体活性比较:模型组、TPN组和ω3脂肪酸组的20S蛋白酶体活性均比空白组明显增加(P<0.05),3组间比较差异无显著性(P>0.05)。16小时点各组伸趾长肌的C2亚基mRNA表达水平比较:空白组与假手术组间比较差异无显著性(P>0.05)。与空白组相比,模型组的C2mRNA表达明显增加(P<0.05)。与模型组比较,TPN组C2基因转录水平下调,但差异无显著性(P>0.05);ω3脂肪酸组的C2亚基基因转录水平明显下降(P<0.05)。24小时点的各组大鼠伸趾长肌C2亚基基因转录水平变化趋势与16小时点一致。16小时点的空白组与假手术组大鼠伸趾长肌C8mRNA表达均差异无显著性(P>0.05)。与空白组相比,模型组的C8mRNA表达明显增加(P<0.05)。与模型组比较,TPN组和ω3脂肪酸组的C8基因转录水平均没有显著下降(P>0.05)。24小时点的各组大鼠伸趾长肌C8亚基基因转录水平变化趋势与16小时点一致。结论ω3脂肪酸能够降低脓毒症大鼠骨骼肌内20S蛋白酶体活性及C2亚基活性,但对16及24小时点C8亚基的基因转录水平无影响。

Objective To study the effects of ω3 fatty acid on skeletal muscle proteasome activity in rats with sepsis.Methods Thirty SD mice were randomly divided into five groups.Laparotomy only,laparotomy and cecal ligation plus punctures （CLP） were performed in sham operation group and sepsis group,respectively.Paraenteral nutrition plus ω3 fatty acid were given in ω3 group,while only paraenteral nutrition was given to total paraenteral nutrition （TPN） group.Paraenteral saline injection was performed in blank control group.Mice were fasted during experiments.Corresponding treatments were initiated 5 days before model establishment.The activities of proteasome and C2/C8 subunits were assessed at 16 h and 24 h.Results There was no significant difference in the activity of 20S proteasome between blank control group and sham operation group at 16 h （P0.05）.Meanwhile,it was significantly increased in model group,comparing with that in blank control group （P0.05）.Although it was reduced in TPN and ω3 groups,comparing with that in model group,significant difference was only observed in ω3 group （P0.05）.There was significantly increase of activity of 20S proteasome in model,TPN and ω3 groups,comparing with that in blank control group at 24 h （P0.05）,though there was no significant difference observed among the 3 groups.There was no significant difference in expression of C2 mRNA between those in blank control and sham operation groups at 16 h or 24 h（P0.05）.Meanwhile,it was significantly increased in model group,comparing with that in blank control group （P0.05）.Although the C2 mRNA expression level was reduced in TPN and ω3 groups,comparing with that in model group,significant difference was only observed in ω3 group （P0.05）.There was no significant difference in expression of C8 mRNA between those in blank control and sham operation groups at 16 h or 24 h （P0.05）.Meanwhile,it was significantly increased in model group,comparing with that in blank control group （P0.05）.No significant reduction in C8 mRNA expression was observed between model group,TPN or ω3 group （P0.05）.Conclusion ω3 fatty acid can reduce the 20S proteasome activity and C2 subunit mRNA expression in skeletal muscle.No effect of ω3 fatty acid on C8 mRNA is observed.