孤束核微量注射一氧化氮合酶抑制剂对应激性大鼠胃黏膜损伤的影响

Influence of microinjection of nitric oxide synthase inhibitors into nucleus tractus solitarius on stress gastric mucosa injury in ratsci

目的:观察孤束核微量注射选择性诱导型一氧化氮合酶抑制剂氨基胍和非选择性一氧化氮合酶抑制剂NG-硝基-L-精氨酸甲酯对应激大鼠胃黏膜损伤的影响。方法:实验于2005-09/12在咸宁学院医学院生理教研室完成。①选用70只雄性SD大鼠,2～3月龄。按随机抽签法将大鼠分为5组:正常对照组、模型组、氨基胍组、精氨酸甲酯组、生理盐水组,每组14只。正常对照组正常饲养。模型组大鼠造成应激性溃疡模型:禁食24h,禁水2h后,乙醚轻度麻醉,四肢及头部束缚于木板上,待大鼠清醒后,将木板垂直浸入23℃水中,水面平胸骨剑突处,浸水6h。生理盐水组、氨基胍组、精氨酸甲酯组大鼠于浸水应激前30min通过脑立体定位仪分别进行孤束核微量注射生理盐水0.2μL,氨基胍2μg(0.2μL),NG-硝基-L-精氨酸甲酯2μg(0.2μL),2种药品均为Sigma公司产品。②大鼠浸水6h后,应用LDF-3型激光多普勒血流仪测量胃黏膜血流量,参照Guth标准计算胃溃疡指数(数值越大,损伤越严重),以精密pH试纸和NaOH溶液滴定法分别测定胃液pH、胃液量及胃液酸度。③组间计量资料差异比较采用t检验。结果:大鼠70只均进入结果分析。①胃溃疡指数:氨基胍组明显低于生理盐水组和模型组犤(21.1±4.2),(34.9±5.1),(35.2±4.7)分,P<0.01犦;精氨酸甲酯组与生理盐水组和模型组比较,差异不明显(P>0.05)。②胃黏膜血流量:模型组和生理盐水组明显低于正常对照组和氨基胍组犤(158.2±39.4),(161.7±38.6),(312.6±34.5),(251.3±39.1)mV,P<0.01犦;精氨酸甲酯组高于模型组和生理盐水组,但差异不明显(P>0.05)。③胃液量和胃液酸度:模型组和生理盐水组明显多于或高于正常对照组和氨基胍组(P<0.05～0.01),精氨酸甲酯组与模型组和生理盐水组相近(P>0.05)。④pH值:模型组和生理盐水组明显低于正常对照组和氨基胍组(1.24±0.27,1.32±0.28,2.34±0.23,2.25±0.25,P<0.05～0.01),精氨酸甲酯组与模型组和生理盐水组相近(P>0.05)。结论:孤束核微量注射一氧化氮合酶抑制剂对应激大鼠胃黏膜损伤有保护作用,氨基胍的作用效果优于NG-硝基-L-精氨酸甲酯。

AIM： To observe the effects of microinjection of the selective induced nitric oxide synthase （iNOS） inhibitor aminoguanidine （AG） and non-selective nitric oxide synthase （NOS） inhibitor NC-nitro-L-arginine methyl ester （L-NAME） into nucleus tractus solitarius on stress gastric mucosa injury in rats. METHODS： The experiment was conducted in the Department of Physiology, Xianning College from September to December 2005.①Totally 70 male SD rats aged 2-3 months were selected and randomly divided into 5 groups： normal group, model group, AG group, L-NAME group and normal saline group with 14 rats in each group. The rats in the control group were fed normally; the rats in the model group were established into models of stress ulcer： After forbidden food for 24 hours and water for 2 hours, the rats under ether anesthesia were bound the legs and head to board. When the rats came back, the board was vertically immersed into water at 23 ℃, the surface of which got to the xiphoid cartilage for 6 hours. The normal saline group, AG group and L-NAME group were separately microinjected 0.2 μL normal saline, 2μg （0.2 μL） AG and 2 μg （0.2 μL） N^G;-nitro-L- NAME （the two medicine were products of Sigma Company） into nucleus tractus solitarius by the Brain Stereotaxic Frame 30 minutes before stressing. ②After stressing for 6 hours, the LDF-3 type Laser Doppler Flowmetry was adopted to measure the gastric mucosa blood flow （GMBF） and the gastric ulcer index （the greater the value, the more serious the damage） was calculated according to the Guth standard. The pH value, amount of gastric juice and acidity were measures by the paper of pH and the method of NaOH dropping.③Comparison of measurement data between groups was performed by t-test. RESULTS： All the 70 rats entered the result analysis. ①Ulcer index： The AG group was obviously lower than the saline group and model group [（21.1±4.2）, （34.9±5.1）, （35.2±4.7） scores, P 〈 0.01], and no significant difference was found between the L-NAME group and the normal sanline group （P 〉 0.05）. ②GMBF： The model and saline groups were significantly lower than the normal control group and AG group [（158.2±39.4）, （161.7±38.6）, （312.6±34.5）, （251.3±39.1） mV, P 〈 0.01]; although the L-NAME group was higher than the saline group, there was no significant difference （P 〉 0.05）. ③Amount of gastric juice and acidity： The model and saline groups were more or higher than the control group and AG group （P 〈 0.05-0.01）; the L-NAME group was similar to the model and saline group （P 〉 0.05）.③pH value： The model group and normal saline group were markedly lower than the normal control group and AG group （1.24±0.27, 1.32±0.28, 2.34±0.23, 2.25±0.25, P 〈 0.05-0.01）, and the L-NAME group was similar to the model and saline group （P 〉 0.05）. CONCLUSION： Microinjection of the iNOS inhibitors into nucleus tractus solltarius has protective effect on gastric mucosa lesion in rats. The effect of selective iNOS inhibitor AG is better than non-selective NOS inhibitor NO-nitro-L-NAME.