论文标题:GnRH对大鼠消化道内分泌细胞功能影响的研究
Studies on Influence of GnRH on Function of Endocrine Cells in the Digestive Tract of Rats
论文作者 刘晓宁
论文导师 黄威权,论文学位 硕士,论文专业 人体解剖与组织胚胎学
论文单位 第四军医大学,点击次数 84,论文页数 87页File Size3325k
2004-04-01论文网 http://www.lw23.com/lunwen_793953902/ 促性腺激素释放激素;胃泌素;生长抑素;5-羟色胺;免疫组织化学;酶联免疫分析;高效液相色谱;大鼠
GnRH ; Gastrin ; somatostatin ; 5-HT ; Immunohistochemistry;Ensyme-link iramunoassay; HPLC-ECD; Rat
经典的神经内分泌理论认为促性腺激素释放激素(Gonadtropin-releaing hormone，GnRH)是作为生殖系统的一种关键性神经调节物质，以脉冲方式分泌，通过垂体门脉系作用于垂体前叶促性腺激素细胞，刺激卵泡刺激素(follicle stimulating hormone，FSH)和黄体生成素(luteinizing hormone.LH)分泌，这两种激素再刺激卵巢和睾丸分别合成并分泌相应的甾体类性腺激素，从而形成调控生殖器官发育和配子生成的下丘脑-垂体-性腺轴系，调节生殖系统的功能。随后，人们发现GnRH同样广泛存在于外周神经组织，内分泌器官和生殖器官。 我们先前的研究发现，消化道系统既能表达GnRH又能表达GnRH受体。GnRH对胃底腺的壁细胞及平滑肌细胞的功能均起明显的调节作用。但是GnRH对胃肠内分泌细胞的功能是否有调节作用未见报道。消化道内存在多种激素，使得消化道成为体内最大的内 第四军医大学硕士学位论文分泌器官。目前发现多种消化激素既可在消化道内表达又可在多种神经内分泌细胞中表达。本项研究主要研究了消化道内一种新发现的激素GnRH与其他激素的相互作用。通过给大鼠胃腔直接注射GnRH类似物阿拉瑞林(GnRll一A)从而模拟外分泌产生的GnRH，并以免疫组织化学、HPLC一ECD和酶联免疫分析等方法对阿拉瑞林刺激后胃及十二指肠内胃泌素、生长抑素和5一HT免疫反应细胞，血清中胃泌素、生长抑素和5一HT含量进行检测。利用梯度浓度的GnRH类似物对离体的胃窦，十二指肠组织进行体外组织块孵育，收集培养上清液。检测不同浓度阿拉瑞林对消化激素分泌的影响。结果发现:[1〕注射GnRH一A后，肠腔内GnRH类似物能队显增加胃肠壁胃泌素阳性细胞的密度及胃液、血液中胃泌素的含量，说明GnRH对消化道胃泌素的合成及分泌有明显的促进作用。〔2」注射GllRI通一A后，肠腔内GnRH类似物能明显降低胃肠壁生长抑素阳性细胞的密度及血液、胃液中生长抑素的含量，说明G:RH对消化道生长抑素的合成及分泌具有明显的抑制作用:仁3口注射GnRH一A后，胃及十二指肠内5一HT免疫反应阳性细胞密度显著增多，但血清中5一HT含量显著减少。由此表明外分泌的GnRH对于5一HT的释放起明显抑制作用，但对5一HT的合成可能不产主影响。阵」GnRH类似物在10·”m。!/L一10一smol/L之间对大鼠体外十二指肠中胃泌素产生浓度依赖性促进作用，而对生长抑素则是浓度依赖性抑制作用，但在10一smol/L一10一smol/L之间对胃泌素为浓度依赖性抑制作用，对生长抑素为浓度依赖性促进作用。GnRH一A在体外对胃组织的胃泌素、生长抑素的分泌均不起作用。 综上所述，我们认为胃腔内的Gn尺H类似物可能首先和壁细胞上GnRE受体结合，直接抑制壁细胞胃酸的分泌，由于胃酸分泌减少反馈性地刺激胃泌素细胞，促进其合成及分泌胃泌素，胃酸分泌减少同时也反馈性的抑制生长抑素的释放，反馈性地抑制胃肠壁内EC细胞分泌5一HT。GnRH类似物对大鼠十二指肠体外孵育中胃泌 第四军医大学硕士学位论文素、生长抑素是双向调节作用。除此作用外，胃泌素、生长抑素之间还存在着相互调节作用，这可能是GnRH类似物以外分泌的形式直接作用于十二指肠胃泌素、生长抑素细胞的结果。EC细胞是否会有GnRH受体，GnR壬1能否直接抑制5一HT的分泌，是否还存在其它机制，有待进一步研究。
Gonadtropin-releasing hormone(GnRH)is the hypothalamic decapeptide. It plays a central role in the regulation of reproductive functions. Pulsatile release of GnRH from the hypothalamus modulates the differential releaseof LH and FSH from the pituitary gonadotropes via high affinity GnRH receptors (GnRHR). Through the highly integrated secretion and action of the gonadotropins, normal gonadal functions are delicately modulated. LH and FSH stimulate the gonad hormone of ovary and testicle respectively, people found that GnRH consist wildly in per-ipheral nerve tissuses, endocrine organ and reproductive organ.Our previous studies found that GnRH and its receptor coexisted in digestive system .GnRH modulated cell of peptic glands and smooth muscle .However,it is not reported that GnRH modulated endocrine cell in stomach and intestine . Many hormones express in the digestive tract, which make digestive tract a largest endocrine organ in the body. Today these hormones are found widely expressed in neuroendocrine cellout of digestive system. This research project mainly focused on the interaction of GnRH which is newly found expressed in the digestive system and other endocrine hormones in digestive tract. The GnRH-A, Alarelin, was directly injected into the stomach of rats to stimulate exocrine GnRH, then the immunohistochemical SABC, HPLOECD and ELISA methods were be used to observe the change of density of gastrin, somatostatine and 5-HT Immunoreactive positive cells in the stomach and small intestine and the levels of gastrin , somatostatine and 5-HT in the circulating blood. Tissues of gastric antrum and duodenum were incubated with different concentration of GnRH-A in vitro, then the concentration of gastrin and somatostatine in the incubating solution was evalusted using ELISA methed . The results were as follows: [l. The density of gastrin immunoreactive positive cells in the stomach and small intestine were significantly increased in the GnRH-A group than those in the control.The gastrin level in the circulation blood was also increased in the experimental group. [2]The density of somatostatine immunoreactive positive cells were significantly decreased in the stomach and small intestine in the GnRH-A group than those in the control. The somatostatine level in the circulation blood was also decreased in the experimental group. [3] The density of 5-HT immunoreactive positive cells were significantly increased in the stomach and small intestine in the GnRH-A group than those in the conrol.but the 5~H level in the circulating blood was significantly reduced in theexperimental group. Conclusion may be drawed that exocrine GnRH can elevate gastrin synthesis and secretion , depress somatostatine synthesis and secretion, and inhibit the release of 5-HT while not change its synthesis.[4] GnRH-A in 10""mol/L-lO~8mol/L promoted gastrin secretion , whereas it inhibited somatostatin secretion of dudenum .But it in 10"8mol/L-10""mol/L inhibited gastrin secretion .whereas it promoted somatostatin secretion of duodenum in vitro. GnRH-A did not effect significantly gastrin and somatostatin secretion of stomach in vitro.These results suggested that GnRH-A may integrate with GnRH receptor and restrain directely gastric acid secretion in parietal cell. The reducing of gastric acid can stimulate feedbackly gastrin cell, and promote gastrin secretion and synthesis .meanwhile it refrains somatostatine release and depresses 5H-T secretion in EC cell. But GnRH-A may regulate gastrin and somatostatin secretion by double direction in vitro. In additional, gastrin and somatostatin may regulate each other. It is not sure whether there were GnRH receptors in EC cell and GnRH restrain directely 5-HT secretion or there have some other mechanism. These remain to study .
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