应激对大鼠胃黏液-碳酸氢盐屏障影响的实验研究

The response of rat gastric mucus bicarbonate barrier to the water restraint induced stress

目的观察应激对大鼠胃壁结合黏液及碳酸氢盐分泌的影响，探讨应激影响胃碳酸氢盐分泌的机制。方法40只SD大鼠等分为对照组和应激1h、2h和4h组，以水浸束缚方法制备应激模型，测定各组大鼠胃壁结合黏液量和黏液凝胶层厚度。另取30只SD大鼠等分为3组，A组予奥美拉唑以抑制胃酸分泌，B组予奥美拉唑和左旋硝基精氨酸甲酯，C组予奥美拉唑、L-精氨酸和左旋硝基精氨酸甲酯，采用灌注滴定法测定应激后2h胃碳酸氢盐分泌量。结果对照组与应激1h、2h和4h组胃壁结合黏液量分别是（0．137±0．03）、（0．143±0．012）、（0．066±0．016）和（0．016±0．017）吸光度／g组织；黏液凝胶层厚度分别是（71．08±5．85）、（74．50±12．85）、（57．63±6．45）和（51．35±2．84）μm。与对照组比，应激1h组结合黏液量及凝胶层厚度差异无统计学意义（P〉0．05），而应激2h、4h组显著低于对照组及应激1h组（P〈0．01）。3组大鼠应激状态下胃碳酸氢盐分泌速率均呈下降趋势，应激2h内胃碳酸氢盐分泌量分别为（9．3±2．6）、（14．0±2．7）和（7．6±1．4）μmol（P〈0．01）。结论应激状态下胃壁结合黏液量、黏液凝胶层厚度和胃碳酸氢盐分泌量进行性降低，提示应激后胃黏液-碳酸氢盐屏障受损，内源性一氧化氮参与介导了应激抑制胃碳酸氢盐分泌的过程。

Objective To observe the stress responses of gastric adherent mucus and bicarbonate secretion and investigate the mechanisms of stress-induced bicarbonate secretion. Methods Forty SD rats were equally divided into the control group and 1, 2 or 4 hrs after stress groups. The amount of glandular adherent mucus and the mucus gel thickness were measured. Another thirty rats were equally divided into A, B and C groups. The rats in group A received omeprazole to inhibit acid secretion. The rats in group B received omeprazole and NG-nitro-L-arginine methyl ester （L-NAME） to inhibit endogenous NO synthesis. The rats in group C received omeprazole, L-NAME and L-arginine （L-Arg） to antagonize L-NAME. All rats were treated with restrained water immersion to induce stress. Gastric bicarbonate secretion was determined by measuring the difference of the alkalinity between the lavage and drainage solutions. Results The adherent mucus quantity in the four groups were （0. 137 ± 0. 03）, （0. 143 ± 0.012）, （0. 066 3 ± 0. 016） and （0. 016 1 ± 0. 016 7）A/g, respectively. The mucus gel thickness were （71.08 ± 5.85）, （74.50 ± 12.85）, （57.63± 6.45） and （51.35 ± 2.84）μm, respectively. There was no statistic difference between the 1 h, group and the control group. However, the adherent mucus quantity and mucus gel thickness were significant less in 2 hrs and 4 hrs groups, compared to the control（P 〈 0. 01）. The gastric bicarbonate secretion rate decreased progressively in all the three groups. The total amount of gastric bicarbonate secretion were （9.3 ± 2.6）, （14.0 ± 2.7） and （7.6 ± 1.4）μmol （P 〈 0.01） within 2 hrs under stress, respectively. Conclusions The results suggest that the mucus quantity and the mucus gel thickness decreased significantly under stress conditions, and gastric alkaline secretion was inhibited, which may be mediated by endogenous NO.