Purinergic neurotransmission in the gut

描述（由申请人提供）：肠神经系统（ENS）是位于肠壁内的自主神经系统的分支。ENS控制胃肠（GI）运动、分泌和局部血流。ENS可以执行这些复杂的功能，因为它包含GI反射和整合所需的所有神经元元件（感觉神经元、中间神经元和运动神经元）。ENS包含14种不同类型的神经元，释放不同的神经递质。每种神经递质也有多种受体。此外，ENS中的突触可能由突触前神经末梢释放的神经递质和突触后细胞表达的受体编码。拟采用细胞内电生理、免疫组织化学和分子生物学方法研究肠道神经肌肉传递。该提案有三个具体目标。具体目标1将检验以下假设：存在两个独立的抑制神经群供应肌肉层。一个子集使用一氧化氮（NO）作为主要的神经递质，而第二个群体是嘌呤能（ATP和/或b-烟酰胺腺嘌呤二核苷酸是神经递质）。这些研究将表明，ATP/b-NAD和NO从神经末梢的释放是由不同类型的Ca 2+通道控制的。针对囊泡核苷酸（VNUT）抗体的抗体将用于定位嘌呤能神经。这些研究还将利用P/Q型和R型Ca 2+通道突变小鼠。具体目标2将集中在肌间神经丛中的中间神经元表达的Ca 2+通道。在口-肛方向投射的中间神经元释放乙酰胆碱（ACh）和ATP作为快速突触递质，而在肛门-口方向投射的神经元释放ACh。这些研究将验证以下假设：R-、N-和P/Q型Ca 2+通道由口投射通路中的神经元表达，而只有N-和P/Q型Ca 2+通道由肛门投射通路中的神经末梢表达。这些研究还将使用野生型和P/Q型和R型Ca 2+通道突变小鼠。具体目标3将集中于K+通道作为结肠中肠平滑肌张力和神经肌肉传递的调节剂。这些研究将利用大电导Ca 2+激活的K+（BK）通道敲除小鼠的b1亚基。意义：肠突触机制的紊乱导致胃肠道动力障碍。肠神经元及其突触功能的改变也可能导致内脏痛。因此，肠神经回路和突触传递的更完整的理解将提供深入了解胃肠道动力障碍的病理生理学。这些信息将有助于开发新的药物治疗常见的动力障碍。

DESCRIPTION (provided by applicant): The enteric nervous system (ENS) is the division of the autonomic nervous system that resides within the gut wall. The ENS controls gastrointestinal (GI) motility, secretion and local blood flow. The ENS can perform these complex functions because it contains all the neuronal elements (sensory neurons, interneurons and motorneurons) required for GI reflexes and integration. The ENS contains 14 different types of neurons that release different neurotransmitters. There are also multiple receptors for each neurotransmitter. In addition, synapses in the ENS may be coded by the neurotransmitters released from presynaptic nerve terminals and by receptors expressed by postsynaptic cells. The proposed studies will use intracellular electrophysiological, immunohistochemical and molecular biological methods to study enteric neuromuscular transmission. There are 3 specific aims in this proposal. Specific aim 1 will test the hypothesis that there are two separate populations of inhibitory nerves supplying the muscle layers. One subset uses nitric oxide (NO) as the primary neurotransmitter while the second population is purinergic (ATP and/or b-nicotinamide adenine dinucleotide are the neurotransmitters). These studies will show that release of ATP/b-NAD and NO from nerve terminals is controlled by different Ca2+ channel types. An antibody against the vesicular nucleotide (VNUT) antibody will be used to localize purinergic nerves. These studies will also make use of P/Q type and R-type Ca2+ channel mutant mice. Specific aim 2 will focus on Ca2+ channels expressed by interneurons in the myenteric plexus. Interneurons which project in an oral-anal direction release acetylcholine (ACh) and ATP as fast synaptic transmitters, while neurons that project in an anal-oral direction release ACh. These studies will test the hypothesis that R-, N- and P/Q type Ca2+ channels are expressed by neurons in the orally-projecting pathway while only N- and P/Q type Ca2+ channels are expressed by nerve terminals in the anally-projecting pathway. These studies will also use wild type and P/Q-type and R-type Ca2+ channel mutant mice. Specific aim 3 will focus on K+ channels as regulators of gut smooth muscle tone and neuromuscular transmission in the colon. These studies will make use of a b1 subunit of the large conductance Ca2+-activated K+ (BK) channel knockout mouse. Significance: Disturbances in enteric synaptic mechanisms contribute to GI motility disorders. Changes in the function of enteric neurons and their synapses might also contribute to visceral pain. Therefore, a more complete understanding of enteric neural circuits and synaptic transmission would provide insights into the pathophysiology of GI motility disorders. This information would help to develop new drug treatments for common motility disorders.