褪黑素对噪声应激大鼠胃肠传输功能的影响及其机制

Effect of melatonin on gastrointestinal transit in rats induced by noise stress and its mechanism

目的:探讨褪黑素(MT)对噪声应激大鼠胃肠传输功能的影响及可能机制.方法:将♂SD大鼠40只随机分为空白对照组、对照1,2组和实验1,2组,实验组和对照组分别在应激前30min ip MT(15 mg/kg)和等体积生理盐水.对照和实验1组和以56式冲锋枪射击时产生的120DB(A)的脉冲噪声,对照和实验1组应激1d,对照和实验2组应激3d,建立噪声应激模型.噪声应激后,观察MT在各组大鼠胃内残留率,小肠推进比,血浆中皮质醇、降钙素基因相关肽(CGRP)和胃动素(MTL)的影响.结果:对照1,2组大鼠的胃残留率(54.52%±4.53%,63.56%±5.51% vs 41.41%±7.74%)、小肠推进比(58.42%±8.77%,67.98%±6.63% vs 41.26%±6.08%),血浆皮质醇(1.99±0.08、2.59±0.09 vs 0.95±0.10),MTL浓度(158.09±10.44.180.09±14.85 vs 124.95±7.83)与空白对照组相比明显升高(P<0.01),其血浆CGRP浓度(125.24±8.5,122.02±10.36)与空白对照组(195.03±7.70)相比显著降低;实验1,2组大鼠的胃残留率(44.53%±8.93%,47.52%±4.98%)、小肠推进比(44.18%±4.36%,46.4%±4.96%),血浆皮质醇(1.27±0.14、1.63±0.09),MTL浓度(128.67±10.25,134.29±18.33)与对照组相比显著降低,其血浆CGRP浓度(191.67±10.13,190.04±11.43)与对照组相比显著升高.结论:MT对噪声引起的大鼠胃肠传输功能紊乱具有保护作用,皮质醇、CGRP和MTL在其发病机制中均起到重要作用.

AIM： To study the effects of melatonin on gastrointestinal transit function in rats, and its possible mechanism. METHODS： Forty Sprague-Dawley rats were randomly divided into a blank group, control groups 1 and 2, and experimental groups 1 and 2. Experimental and control groups were treated with 15 mg/kg melatonin by intraperitoneal injection, or the same volume of physiological saline, at 30 min before noise stress. Both groups were stimulated separately by 120 dB（A） impulse noise of type 56 submachine guns to set up noise stress models. Rats in control group 1 and experimental group 1 were subjected to 1 d stress; rats in control group 2 and experimental group 2 were subjected to 3 d stress. We observed the effects of melatonin on stomach residual rate, small intestine transit time and the plasma levels of cortisol, motilin and calcitoningene related peptide （CGRP）. RESULTS： Stomach residual rate and small intestine transit time were significantly increased in control groups 1 and 2 compared with those in the blank group （54.52% ± 4.53%, 63.56% ± 5.51% vs 41.41% ± 7.74%, 58.42% ± 8.77%, 67.98% ± 6.63% vs 41.26% ± 6.08%, P 〈 0.05）. Stomach residual rate and small intestine transit time in experimental group 1 （44.53% ± 8.93%, 44.18% ± 4.36%） and experimental group 2 （47.52% ± 4.98%, 46.4% ± 4.96%） were significantly delayed compared with those in the control group （P 〈 0.01）. However, there was no difference between the experimental group and the blank group. Levels of cortisol and motilin in blood plasma of control 1 and 2 groups were significantly enhanced compared to the blank group （1.99 ± 0.08, 2.59 ± 0.09 vs 0.95 ± 0.10, 158.09 ± 10.44,180.09 ± 14.85 vs 124.95 ± 7.83, P 〈 0.01）; the experimental groups （group 1：1.27 ± 0.14, 128.67 ± 10.25; group 2： 1.63 ± 0.09, 134.29 ± 18.33） were degraded significantly compared to the control group （P 〈 0.01）, but did not change much in comparison with the blank group （P 〉 0.05）. Level of calcitonin-gene related peptide in blood plasma of control groups 1 and 2 was lower than that of the blank group （125.24 ± 8.5, 134.29 ± 18.33 vs 195.03 ± 7.70, P 〈 0.01）, and was higher in the experimental group （191.67 ± 10.13, 190.04 ± 11.43） than in the control group （P 〈 0.01）, but did not significantly differ from blank group （P〉 0.05）. CONCLUSION： Melatonin is effective in preventing gastrointestinal transit in rats induced by noise stress. Cortisol, CGRP and motilin play an important role in the pathogenesis.