血管活性肠肽对内毒素性休克大鼠肠道TLR4、MD2和BD3 mRNA表达的影响

Effect of vasoactive intestinal peptide on intestinal TLR4,MD2 and BD3 expression in rats with endotoxic shock

目的探讨血管活性肠肽(vasoactive intestinal peptide,VIP)对细菌脂多糖(lipopolysaccharide,LPS)致休克大鼠肠道组织TLR4、MD2和BD3 mRNA表达的影响。方法 40只SD大鼠,随机分为LPS组(15只)、LPS+VIP组(15只)和对照组(10只)。LPS组尾静脉注射LPS(E.coli O55B5)10 mg/kg;LPS+VIP组尾静脉注射LPS 10 mg/kg后注射VIP 5 nmol/kg;对照组尾静脉注射等容量生理盐水。分别于注射后6 h和24 h处死,留取结肠组织标本,RT-PCR检测结肠组织TLR4、MD2和BD3 mRNA表达,光镜下观察24 h时肠组织病理变化。结果①肠组织病理改变:注射LPS后大鼠肠黏膜坏死脱落,微绒毛结构消失,结缔组织明显充血,大量的炎性细胞浸润。采用VIP治疗后病变明显减轻。②TLR4、MD2和BD3 mRNA表达:注射VIP后6 h、24 h,肠组织TLR4、MD2和BD3 mRNA表达升高(P<0.05);24 h时LPS+VIP组TLR4、BD3和MD2 mRNA表达明显低于LPS组(P<0.05)。结论 LPS致内毒素性休克大鼠肠道损伤时,肠组织TLR4、MD2和BD3 mRNA表达增强。VIP可减轻LPS所致肠道黏膜损伤,其机制可能与下调重要的炎症基因TLR4、MD2和BD3 mRNA表达有关。

Objective To investigate the effect of vasoactive intestinal peptide （VIP） on TLR4,MD2 and BD3 mRNA expression in endotoxin （lipopolysaccharide,LPS） induced shock.Methods Forty Sprague-Dawley rats were randomly divided into 3 groups：LPS shock group （n =15）,LPS ＋ VIP group （n =15）,and control group （n =10）.LPS shock model was established by LPS （E.coli O55B5 10 mg/kg） with tail intravenous injection.The rats in LPS ＋ VIP group were given VIP intravenous injection （5 nmol/kg） followed by LPS,the rats in control group were given normal saline.The rats were sacrificed at 6 h,24 h after being injected.The colon tissues were collected.The TLR4,MD2 and BD3 mRNA expression were detected by RT-PCR from the colon tissues.Pathological changes of the colon tissues were observed by microscope 24 h after LPS injection.Results ① Intestinal mucosa showed edema or necrotic change with structure of the microvilli disappeared after LPS injection.The inestinal lesion in LPS ＋ VIP group were milder than LPS group.② The expression of TLR4,MD2 and BD3 mRNA were significantly higher in LPS shock group compared with those of the control group （P ＜ 0.05）.TLR4,MD2 and BD3 mRNA expression on 24 h was down regulated in LPS ＋ VIP shock subgroup than those in LPS shock subgroup （P ＜ 0.05）.Conclusion Expression of TLR4,MD2 and BD3 mRNA were up-regulated on LPS induced intestinal colitis in rats.VIP mitigated intestinal injury by LPS,which may be related to TLR4,MD2 and BD3 mRNA down-regulation of expression.The effect of VIP may suggest a protective mechanism in severe infection.