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

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(P0.05);24 h时LPS+VIP组TLR4、BD3和MD2 mRNA表达明显低于LPS组(P0.05)。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。

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

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.