Visceral afferent mechanisms in the gastrointestinal tract

在本项目中，我们打算测试G蛋白偶联肌间AH神经元的两个兴奋性受体的假设。采用细胞内电记录的方法，观察三七总皂甙、S和百日咳毒素对慢电位的影响。以及对P物质(SP)的兴奋反应。静息5.5小时以评估PTX的疗效。缓慢的EPSPS和SP反应进行性下降，3.75小时后消失。PTX对超极化后电位无影响。注射GTP-γ-S可使慢EPsP样行为进行性增加。在GTP-伽马-S后，SP引起的去极化被无限延长，导致不能在初始反应后引起反应。这一结果与G蛋白参与了兴奋性受体偶联有关。2型神经元。本项目的第二个目的是验证一种假设，即在远端结肠肌间神经元中钙结合蛋白免疫反应性(LR)的表达与其电生理和形态特征有关。通过对Calbindin-LR的分析，用免疫组织化学方法显示了NB标记神经元的精确形态。3个不表达Calbindin-1R的SLP神经元记录到AH/2型生理特性，6个SLP神经元为Calbindin-LR，4个S/1型和2个SLP神经元既没有S/L型电特性，也没有AH/2型电特性。这些结果表明，Calbindin-LR在豚鼠远端结肠肌间神经元中的分布与在小肠中的分布不同。我们认为，Calbindin-LR既可以作为豚鼠远端结肠肌间神经元的形态指标，也可以作为肌间神经元电生理的预测指标。

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.