Chen Bao Nan, Humenick Adam G, Hibberd Timothy James, Yew Wai Ping, Wattchow David A, Dinning Phil G, Costa Marcello, Spencer Nick J, Brookes Simon J H
Human Physiology, Medical Bioscience, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia.
Department of Surgery, Flinders Medical Centre, Bedford Park, SA, Australia.
Front Neurosci. 2024 Jan 16;17:1313057. doi: 10.3389/fnins.2023.1313057. eCollection 2023.
Viscerofugal neurons (VFNs) have cell bodies in the myenteric plexus and axons that project to sympathetic prevertebral ganglia. In animals they activate sympathetic motility reflexes and may modulate glucose metabolism and feeding. We used rapid retrograde tracing from colonic nerves to identify VFNs in human colon for the first time, using preparations with multi-layer immunohistochemistry.
Colonic nerves were identified in isolated preparations of human colon and set up for axonal tracing with biotinamide. After fixation, labeled VFN cell bodies were subjected to multiplexed immunohistochemistry for 12 established nerve cell body markers.
Biotinamide tracing filled 903 viscerofugal nerve cell bodies ( = 23), most of which (85%) had axons projecting orally before entering colonic nerves. Morphologically, 97% of VFNs were uni-axonal. Of 215 VFNs studied in detail, 89% expressed ChAT, 13% NOS, 13% calbindin, 9% enkephalin, 7% substance P and 0 of 123 VFNs expressed CART. Few VFNs contained calretinin, VIP, 5HT, CGRP, or NPY. VFNs were often surrounded by dense baskets of axonal varicosities, probably reflecting patterns of connectivity; VAChT+ (cholinergic), SP+ and ENK+ varicosities were most abundant around them. Human VFNs were diverse; showing 27 combinations of immunohistochemical markers, 4 morphological types and a wide range of cell body sizes. However, 69% showed chemical coding, axonal projections, soma-dendritic morphology and connectivity similar to enteric excitatory motor neurons.
Viscerofugal neurons are present in human colon and show very diverse combinations of features. High proportions express ChAT, consistent with cholinergic synaptic outputs onto postganglionic sympathetic neurons in prevertebral ganglia.
内脏传出神经元（VFNs）的细胞体位于肌间神经丛，其轴突投射至交感神经节前神经节。在动物中，它们可激活交感运动反射，并可能调节葡萄糖代谢和进食。我们首次使用多层免疫组织化学制剂，通过结肠神经的快速逆行追踪来鉴定人类结肠中的VFNs。
在分离的人类结肠制剂中识别结肠神经，并用生物素酰胺进行轴突追踪。固定后，对标记的VFN细胞体进行12种已确立的神经细胞体标志物的多重免疫组织化学检测。
生物素酰胺追踪标记了903个内脏传出神经细胞体（n = 23），其中大部分（85%）在进入结肠神经之前有向口腔方向投射的轴突。形态学上，97%的VFNs为单轴突。在详细研究的215个VFNs中，89%表达ChAT，13%表达NOS，13%表达钙结合蛋白，9%表达脑啡肽，7%表达P物质，123个VFNs中0个表达CART。很少有VFNs含有钙视网膜蛋白、VIP、5HT、CGRP或NPY。VFNs常被密集的轴突曲张篮包围，这可能反映了连接模式；VAChT+（胆碱能）、SP+和ENK+曲张在它们周围最为丰富。人类VFNs多种多样；显示出27种免疫组织化学标志物组合、4种形态类型和广泛的细胞体大小范围。然而，69%表现出与肠兴奋性运动神经元相似的化学编码、轴突投射、胞体-树突形态和连接性。
内脏传出神经元存在于人类结肠中，表现出非常多样的特征组合。高比例表达ChAT，这与椎前神经节中节后交感神经元上的胆碱能突触输出一致。
