慢性应激对大鼠胃肠动力功能及下丘脑室旁核催产素水平的影响

The effects of mild stress to gastrointestinal motility and oxytocin in hypothalamic paraventricular nucleus of rats

目的研究慢性不可预见性温和应激（CUMS）状态下大鼠胃肠动力功能的变化及其可能的机制。方法将大鼠随机分为空白对照组和应激模型组，采用21d慢性不可预见性温和刺激结合孤养方式复制大鼠慢性应激模型，对照观察两组大鼠在体胃肠道墨水推进率以及离体肠管收缩性的差异，并利用免疫组化方法，比较两组大鼠下丘脑室旁核（／VN）催产素（OT）样免疫阳性物质的表达。结果（1）造模结束，模型组大鼠体重增加量、糖水偏好f分别（69．97±9．81）g，（49．05±5．98）g]低于对照组[分别（116．27±13．60）g，（83．51±3．08）g]（P〈0．001），旷场实验中模型组水平得分、垂直得分[分别（24．00±13．52）分，（3．90±2．51）分]低于对照组[分别（53．60±27．98）分，（11．50±8．85）分]（P〈0．05）；（2）模型组大鼠墨水推进率[（67．33±6．24）％]低于对照组[（76．83±10．00）％]（P〈0．05），离体肠管收缩幅度和收缩频率[分别（1．37±0．18）g，（0．58±0．02Ss—1]低于对照组[分别（1．88±0．13）g，（0．62±0．04）S-1]（P〈0．05）；（3）模型组大鼠下丘脑室旁核催产素免疫阳性物质大量表达[（59．17±16．08）个]，与对照组[（6．07±3．71）个]比较显著增加（P〈0．001）。结论慢性应激可造成大鼠胃肠动力功能下降，这些变化可能与室旁核内催产素表达增多有关。

Objective To study the changes of gastrointestinal movement function in rats with chronic un- predictable mild stress（CUMS） and explore the mechanisms underlying it. Methods The rats were divided into stress model group and control group. The stress model rats were induced by 21-day chronic unpredictable mild stress as well as social-isolated fed. The rate of ink propulsion of gastrointestinal tract and the contraction of intesti- nal canal in rats were observed. Immunohistochemistry was adopted to detect the expression of OT in rats. Results （ 1 ） After the models were induced, weight-gain and sucrose preference of model group （ （ 69.97 ± 9.81 ） g, （49.05 ±5.98）g） were lower than those in control group（ （ 116.27 ± 13.60）g, （83.51 ±3.08）g） （P〈0. 001 ） ,and both the crossing-score and rearing-score （ （24.00 ± 13.52 ） , （3.90 ± 2.51 ） ） were lower than those in control group （ （53.60 ± 27.98 ）, （ 11.50 ± 8.85 ） ） in the open-field test. （ 2 ） The rate of ink propulsion of model group （ （ 67.33 ± 6.24 ） % ） was decreased when compared to the control group （ （ 76.83 ± 10.00 ） % ） （P 〈 0.05 ） , and the intestinal canal contraction amplitude and contraction frequency（ （1.37 ± 0.18 ）g, （0.58 ± 0.02 ）S-1 ） were lower than those in control group （ （ 1.88 ± 0.13 ） g） , （0.62 ± 0.04） S-1 ） （P 〈 0.05 ）. （ 3 ） Compared with the con- trol group （ 6.07 ± 3.71 ） , OT immunoreactive substance was increased in model group （59.17 ± 16.08 ） of rats （P 〈 0. 001 ）. Conclusion Chronic stress can cause the decrease in gastrointestinal movement function of rats. These changes may be related to the increased expression of OT in paraventricular nucleus.