The Department of Biological Sciences, USC Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, CA 90089.
Physiology and Behavior Laboratory, Eidgenössische Technische Hochschule Zürich, Schwerzenbach 8603, Switzerland.
eNeuro. 2021 Feb 25;8(1). doi: 10.1523/ENEURO.0419-20.2021. Print 2021 Jan-Feb.
Vagal and spinal sensory endings in the wall of the hepatic portal and superior mesenteric veins (PMV) provide the brain with chemosensory information important for energy balance and other functions. To determine their medullary neuronal targets, we injected the transsynaptic anterograde viral tracer HSV-1 H129-772 (H129) into the PMV wall or left nodose ganglion (LNG) of male rats, followed by immunohistochemistry (IHC) and high-resolution imaging. We also determined the chemical phenotype of H129-infected neurons, and potential vagal and spinal axon terminal appositions in the dorsal motor nucleus of the vagus (DMX) and the nucleus of the solitary tract (NTS). PMV wall injections generated H129-infected neurons in both nodose ganglia and in thoracic dorsal root ganglia (DRGs). In the medulla, cholinergic preganglionic parasympathetic neurons in the DMX were virtually the only targets of chemosensory information from the PMV wall. H129-infected terminal appositions were identified on H129-infected somata and dendrites in the DMX, and on H129-infected DMX dendrites that extend into the NTS. Sensory transmission via vagal and possibly spinal routes from the PMV wall therefore reaches DMX neurons via axo-somatic appositions in the DMX and axo-dendritic appositions in the NTS. However, the dearth of H129-infected NTS neurons indicates that sensory information from the PMV wall terminates on DMX neurons without engaging NTS neurons. These previously underappreciated direct sensory routes into the DMX enable a vago-vagal and possibly spino-vagal reflexes that can directly influence visceral function.
肝门静脉和肠系膜上静脉（PMV）壁中的迷走神经和脊神经感觉末梢为大脑提供了对能量平衡和其他功能很重要的化学感觉信息。为了确定它们的髓内神经元靶标，我们将跨突触顺行病毒示踪剂 HSV-1 H129-772（H129）注入 PMV 壁或雄性大鼠的左侧结状神经节（LNG），然后进行免疫组织化学（IHC）和高分辨率成像。我们还确定了 H129 感染神经元的化学表型，以及在迷走神经背核（DMX）和孤束核（NTS）中潜在的迷走神经和脊神经轴突末梢贴附。PMV 壁注射在结状神经节和胸段脊神经根节（DRG）中产生了 H129 感染的神经元。在髓质中，DMX 中的胆碱能节前副交感神经元几乎是 PMV 壁化学感觉信息的唯一靶标。在 DMX 中的 H129 感染的神经元胞体和树突上以及延伸到 NTS 的 H129 感染的 DMX 树突上鉴定出 H129 感染的末梢贴附。因此，来自 PMV 壁的感觉传递通过迷走神经和可能的脊髓途径到达 DMX 神经元，通过 DMX 中的轴体细胞贴附和 NTS 中的轴突树突贴附。然而，H129 感染的 NTS 神经元稀少表明，来自 PMV 壁的感觉信息终止于 DMX 神经元，而不涉及 NTS 神经元。这些以前被低估的直接感觉途径进入 DMX，使迷走神经反射和可能的脊髓神经反射能够直接影响内脏功能。
