Donat M E, Wong K, Staines W A, Krantis A
Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ontario, Canada.
J Auton Nerv Syst. 1999 Jul 7;77(1):4-12. doi: 10.1016/s0165-1838(99)00023-5.
Carbon monoxide (CO), like nitric oxide (NO), is a putative gaseous neurotransmitter. CO is produced by the enzyme heme oxygenase (HO) acting on a family of heme-containing compounds. Two isomers of HO have been characterized (HO-1, HO-2). In the CNS and in peripheral ganglia HO-2 occurs in a majority of neurons. NO and CO function as transmitters of enteric neurons but the relative distribution of enteric neurons utilizing these gaseous transmitters is unknown in rodent. We have studied the distribution of HO-2 immunoreactivity and NO synthase (NOS) activity within the rat ileum.
Tissue sections and primary neuronal cell cultures were incubated with a HO-2 specific antibody, and then assessed or reprocessed for NOS activity using NADPH-dependent diaphorase staining.
HO-2 immunoreactivity was expressed in subpopulations of myenteric and submucosal neurons. Approximately 45% of the ganglion cells in tissue section were HO-2 positive. This was similar in proportion to those found to stain for NOS activity, and 10% of HO-2 positive neurons also contained NOS. HO-2 immunoreactivity was also found in epithelial cells within the villi, and in interstitial cells around the myenteric plexus and within the smooth muscle. In culture, the distribution and colocalisation of HO-2 and NOS positive neurons was similar to that in tissue sections. We identified labelled neurons as either Dogiel Type I or II; only Type II cells colocalized NOS and HO-2.
Neurons, endocrine-like cells and interstitial cells with the capacity for CO production are distributed throughout the ileum and some neurons have the capacity to synthesize both NO and CO as gaseous messengers.
一氧化碳（CO）与一氧化氮（NO）一样，被认为是一种气态神经递质。CO由血红素加氧酶（HO）作用于一系列含血红素的化合物产生。已鉴定出HO的两种异构体（HO-1、HO-2）。在中枢神经系统和外周神经节中，大多数神经元中存在HO-2。NO和CO作为肠神经元的递质发挥作用，但在啮齿动物中，利用这些气态递质的肠神经元的相对分布尚不清楚。我们研究了大鼠回肠中HO-2免疫反应性和一氧化氮合酶（NOS）活性的分布。
将组织切片和原代神经元细胞培养物与HO-2特异性抗体孵育，然后使用依赖于烟酰胺腺嘌呤二核苷酸磷酸（NADPH）的黄递酶染色评估或重新处理以检测NOS活性。
HO-2免疫反应性在肌间神经丛和黏膜下神经元亚群中表达。组织切片中约45%的神经节细胞HO-2呈阳性。这一比例与检测到NOS活性的细胞比例相似，并且10%的HO-2阳性神经元也含有NOS。在绒毛内的上皮细胞以及肌间神经丛周围和平滑肌内的间质细胞中也发现了HO-2免疫反应性。在培养物中，HO-2和NOS阳性神经元的分布及共定位与组织切片中的情况相似。我们将标记的神经元鉴定为I型或II型多极神经元；只有II型细胞同时含有NOS和HO-2。
具有产生CO能力的神经元、类内分泌细胞和间质细胞分布于整个回肠，并且一些神经元具有合成NO和CO这两种气态信使的能力。
