Visceral afferent mechanisms in the gastrointestinal tract

在本项目中，我们打算测试的假设，G-蛋白耦合两个兴奋性受体的肌间AH神经元。采用细胞内电记录方法研究了GTP-γ-s和百日咳毒素（PTX）对sloW EPSPs的影响。以及对P物质（SP）的兴奋性反应。结果发现，慢EPSP和SP反应进行性下降，3.75小时后消失。超极化后电位不受PTX的影响。GTP-gamma-s注射导致慢EPsP样行为的进行性增加。在GTP-γ-s之后，SP-诱导的去极化无限延长，导致在初始反应之后不能诱发反应。结果是一致的G蛋白参与耦合兴奋性受体在AH! 2型神经细胞本项目的第二个目的是验证远端结肠肌间神经元中钙结合蛋白免疫反应性（IR）的表达与其电生理和形态学特征相关的假设。钙结合蛋白-IR的分析后，NB标记的神经元的精确形态，揭示了免疫组织化学。3个不表达Calbindin-1R的SLP神经元记录到AH/2型电生理特性，6个为Calbindin-1R，4个为S/1型，2个既无S/1型也无AH/2型电特性。这些结果表明，Calbindin-1R在豚鼠远端结肠肌间神经元中的分布不同于在小肠中的分布。我们的结论是，钙结合蛋白-IR可以被用来作为一个指标或预测的形态，也不是在豚鼠远端结肠肌间神经元的电生理。

In the present project we intended to test the hypothesis that G-proteins coupled both excitatory receptors of myenteric AH neurons. Intracellular methods of electrical recording were used to investigate the effects of GTP-gamma-s and pertussis toxin (PTX) on sloW EPSPs. as well as excitatory responses to substance P (SP). lmpalements were maintained for 5.5hours to evaluate the effects of PTX.Slow EPSPs and SP responses declined progressively and disappeared after 3.75hrs. Hyperpolarizing after-potentials were unaffected by PTX.GTP-gamma-s injection resulted in a progressive increase in slow EPsP-like behavior. Atter GTP-gamma-s, SP-ioduced depolarization was infinitely prolonged resulting in inability to evoke responses after an initial response. The results are consistent with the involvement of G-protein in coupling excitatory receptors in AH! type 2 neurans. The second purpose of this project was to test the hypothesis that the expression of calbindin immunoreactivity(lR)in distal colonic myenteric neurons can be correlated with their electrophysiological and morphological characteristics. After analysis of calbindin-lR,the precise morphology of NB-labeled neurons was revealed by immunoperoxidase histochemistry. All of the MLP neutons and 13% of SLP neurons were calbindin-lR.AH/Type 2 physiological properties were recorded from 3 SLP neurons not expressing calbindin-lR.Six of the SLP neurons were calbindin-lR,4 had S/type 1 and 2 had neither S/Type l nor AH/type 2 electrical properties. These results suggest that the distribution of calbindin-lR in distal colonic myenteric neurons is different from that in the small intestine in the guinea pig. We conclude that calbindin-lR can be used as an indicator or predictor of neither the morphology nor the electrophysiology of myenteric neurons in the guinea pig distal colon.