【作者】 纪丽珍；

【导师】 艾洪滨；

【作者基本信息】 山东师范大学 ， 动物学， 2012， 硕士

【摘要】 大鼠束缚-浸水应激致急性胃粘膜损伤的外周神经机制，众多文献获得的结果表明，胃运动机能亢进、胃酸分泌增多是2个主要因素。而胃运动机能亢进、胃酸分泌增多主要是由于应激过程中支配胃肠道的副交感神经活动加强导致的。支配胃肠道的副交感神经起源于延髓的迷走背核、疑核，而胃肠道的感觉神经直接投射到延髓的孤束核、最后区。因此，迷走背核、孤束核、最后区（这3个部位合称迷走复合体）和疑核便构成了调控胃肠机能的主要初级中枢。众所周知，在延髓以上调控胃肠机能的较高级中枢是下丘脑、杏仁复合体等部位。这些部位与胃肠之间的功能联系、纤维联系，以及在束缚-浸水应激过程中对胃肠机能的调控作用问题，已有较多文献报道，有些问题已基本研究清楚。哺乳动物调控胃肠机能的最高级中枢是大脑皮层，尤其是前额叶皮层。有文献报道，前额叶是唯一向下丘脑有直接投射的新皮层。我们研究室的研究结果显示，大鼠束缚-浸水应激过程中内侧前额叶皮层（主要是边缘前皮层PL和边缘下皮层IL）神经元的活动加强（Fos蛋白表达显著增多）。那么，边缘前皮层PL和边缘下皮层IL对胃运动机能、胃酸分泌机能有无调控作用？损伤这2个部位，束缚-浸水应激过程中胃运动机能和胃酸分泌机能有何变化？这些问题均未见文献报道。因此，设计了本研究方案，对这些问题进行了初步探讨。本研究分急性实验和慢性实验2部分。急性实验又包括：1）分别电刺激左侧PL和IL，观察胃运动的变化情况。刺激参数为：频率30Hz，强度0.2mA，波宽0.5ms，刺激持续时间5min。本实验共分为2组：PL组和IL组，用水囊法+BL-420E生物机能实验系统记录大鼠的胃运动曲线，以收缩波的频率、总时程、平均时程、总幅度、平均幅度、胃运动指数（5min内所有胃运动的（幅度×时程）之和）及收缩分数（总时程/5min×100%）为指标评估胃的运动机能，分别统计电刺激PL或IL前后胃运动的变化情况。结果显示：电刺激左侧PL或IL后，与刺激前相比，胃运动均无显著性变化。提示：正常大鼠麻醉状态下PL和IL对胃运动无调节作用。2）分别电刺激左侧PL和IL，观察胃酸分泌量的变化，同时记录呼吸频率和心率。刺激参数同1）小组，但刺激持续时间为10min。实验同样分为PL组和IL组，用灌流法收集胃液并用酸碱滴定法检测胃酸分泌量，以H+分泌量作为统计指标。灌流液的收集，以15min的收集液为1个样品。刺激前收集3个样品，取其平均值作为刺激前的胃酸分泌量，刺激后收集3个样品，分别与刺激前的结果进行比较，观察统计刺激前后胃酸分泌量的变化。结果显示：电刺激PL或IL后，与刺激前相比，胃酸分泌量均没有显著性差异。这一结果提示：正常大鼠麻醉状态下PL和IL对胃酸分泌无调节作用。上述2项结果表明：在正常生理状态下，大鼠内侧前额叶（mPFC）与延髓胃肠基本中枢之间可能不存在直接的调控关系，但也可能是麻醉掩盖了PL和IL的作用。慢性实验也包括2部分：1）电损毁大鼠PL、IL，观察束缚-浸水应激前及应激4h过程中胃运动的变化。损毁参数：阳极直流电，1.5mA，4s，2次。实验分四组：一组为假手术组，二组为损毁双侧PL和IL组，三组为单纯损毁双侧PL组，四组为单纯损毁双侧IL组。损毁后饲养96h，然后束缚-浸水应激并记录胃运动。统计指标同急性实验1）。结果显示：①束缚-浸水应激前，在清醒状态下，损毁组大鼠的胃运动各指标与假手术组相比均无显著性差异。提示：大鼠mPFC在正常生理状态下不参与胃功能活动的调控，与是否麻醉无关；②损毁双侧PL和IL组的大鼠在应激过程中的胃运动，无论是与自身应激前相比，还是与假手术组应激过程中相比，胃运动机能均受到显著抑制；单纯损毁双侧IL组大鼠在应激第4h的胃运动总幅度，与假手术组相比显著降低，而单纯损毁双侧PL组则无显著性变化。提示：大鼠PL和IL对束缚-浸水应激过程中的胃运动具有一定的调控作用。2）电损毁大鼠PL和IL，观察束缚-浸水应激4h后大鼠胃酸分泌量的变化。损毁参数与1）相同。实验分2组：一组为假手术组，二组为损毁双侧PL和IL组。采用幽门结扎法收集胃液，并检测胃酸分泌量。以胃液量、H+分泌量和H+浓度作为统计指标，比较假手术组和损毁组大鼠在束缚-浸水应激4h后胃液分泌量的差异。结果：两组之间各指标均无显著性差异。提示：大鼠PL和IL对束缚-浸水应激状态下的胃酸分泌无明显的调节作用。上述2项结果表明：PL和IL都在一定程度上参与调节束缚-浸水应激过程中的胃运动，IL对胃运动的调控作用更显著一些，且二者协同的作用更大一些，从而在应激过程中引起胃运动亢进，而对胃壁腺细胞的活动无明显调节作用。更多还原

【Abstract】 Numerous studies showed that, gastric motility hyperfunction and gastric acid over-secretionwere two key factors of gastric mucosal injury induced by the restraint water-immersion stressin peripheral in rats. The two factors were incited by the parasympathetic hyperactivity in stress.The parasympathetic nerves innervating the gastrointestinal tract are mainly originated from thedorsal motor nucleus of the vagus (DMV) and the nucleus ambiguous (NA) in the medullaoblongata, and the gastrointestinal sensory nerves are mostly projected to the nucleus of solitarytract (NTS) and area postrema (AP). So, the DMV, NTS, AP (the three parts are called thedorsal vagal complex, DVC) and NA constitute the primary center of the gastrointestinalfunction. As well we know, the senior center regulating the gastrointestinal function is in thehypothalamus and amygdaloid complex. Large number of papers reported the fibers linkbetween the two centers and gastrointestinal tract, and the regulatory mechanism in the restraintwater-immersion stress. But the most senior central pathway is not clear. The prefrontal cortexis the only cortex projecting directly to hypothalamus, and activities of the prefrontal cortex(especially PL and IL) neurons were increased during the restraint water-immersion stress in therat (the results from our lab). Therefore it can be surmised that the prefrontal cortex mayberegulate gastric function during the restrain water-immersion stress in rats. In this study, it isplaned to explore the function of the prefrontal cortex from the point of gastric motility andgastric acid secretion.The article was composed of acute experiments and chronic experiments.The acute experiments:1) The left PL and IL were electrically stimulated respectively to monitor the changes ofgastric motility. The parameters of stimulation were square-wave pulses of 30Hz, 0.2mA, 0.5msand the stimulating time lasted 5min. To do this, two groups of experiments were performed:PL group and IL group. Gastric motility curves were recorded with intraluminal balloons andthe Physiological Signal Recording System(BL-420E). The frequency, average duration, total duration, average amplitude, total amplitude, index of motility and contraction fraction of thegastric contraction waves were taken as the indexes to estimate the gastric motility function.The above indexes within 5min before and after stimulation were analyzed. The results showedthere was no significant effect on gastric motility no matter PL or Il was electrically stimulated.It prompted us that PL and IL have no regulation on gastric motility in normal rats underanesthesia.2) PL and IL were electrically stimulated respectively to monitor the changes of gastric acidsecretion, respiratory rate and heart rate. The parameters of stimulation and the groups ofexperiments were the same as 1), but the stimulating time lasted 10min. Gastric acid in whichthe amounts of H+was taken as index was collected with perfusion technique and was detectedby acid-base titration. Gastric juice was collected every 15min for three times before and afterstimulation respectively. The average amounts of H+before stimulation was compared with thedata after stimulation. The results showed that gastric acid secretion had no significant changesbefore and after stimulation. It was supposed that PL and IL have no regulation on gastric acidsecretion in normal rats under anesthesiaThe upper two results showed that there were no relationships between mPFC andgastrointestinal primary center, but anesthesia might obscure the role of the PL and IL under thenormal physiological state.The chronic experiment:1) Electrolytic lesions were placed in PL, and IL. Changes of gastric motility before andduring 4h restraint water-immersion stress were monitored. PL and IL were destroyed with DCcurrent (1.5mA, 4s) two times. Four groups of experiments, including group of control, groupof bilateral PL and IL lesions, group of bilateral PL lesions and group of bilateral IL lesions,were performed. Four days later, the rats were restrained, and were immersed in cold water(21±1℃) for 4h. Gastric motility was recorded at the same time. Statistical indexes were thesame as the acute experiments 1). The results showed that:①Before the restraintwater-immersion stress, there were no significant differences in all gastric motility indexesbetween the control group and the experimental groups under the awake state. It could beconcluded that mPFC did not participate in the regulation of functional activity of the stomach under normal physiological conditions, and anesthesia had no influence.②The gastric motilityof the bilateral PL and IL lesions group was significantly inhibited during the restraintwater-immersion stress, compared no matter with before stress or with the control group.Comparing with the control group, the bilateral IL lesions group had a significant reduction ofthe total amplitude in the fourth hour, but there were no significant changes in the group ofbilateral PL lesions. It was supposed that PL and IL regulate gastric motility under the restraintwater-immersion stress in rats.2) Electrolytic lesions were placed in PL and IL, and changes of gastric acid secretion weremonitored also under the restraint water-immersion stress. The parameters of stimulation werethe same as 1). Two groups of experiments, including group of bilateral PL and IL lesions,group of its control. Pylorus ligation method was used to collect gastric juice, and thesupernatant after centrifugation was got for acid-base titration. Gastric juice volume, amountsof H+and concentration of H+were taken as the statistical indexes. The results showed thatthere were no significant differences between the tow groups. It was supposed that PL and ILhave no regulation on gastric acid secretion under the restraint water-immersion stress.It could be concluded that PL and IL, to some extent, were involved in regulating the gastricmotility during the restraint water-immersion stress, and the function of IL is prior and therewere synergistic effects between PL and IL. PL and IL have no regulatory effect on gastricgland cells.更多还原