Sympathetic Pathways Target Cholinergic Neurons in the Human Colonic Myenteric Plexus
Dominic R Parker1,2, Lukasz Wiklendt1, Adam Humenick1
1Laboratory of Neurogastroenterology, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia.
Frontiers in Neuroscience
|April 4, 2022
Summary
Sympathetic nerves in the gut preferentially target excitatory cholinergic neurons over inhibitory nitrergic neurons. This specific connection helps explain how the sympathetic nervous system controls human colonic motility.
Area of Science:
- Neuroscience
- Gastroenterology
- Autonomic Nervous System Research
Background:
- The sympathetic nervous system regulates human colonic motility via enteric neurons.
- Noradrenergic axons in the myenteric plexus are key modulators, but their specific targets are unknown.
Purpose of the Study:
- To determine the precise associations between noradrenergic varicosities and specific types of enteric neurons in the human colon.
Main Methods:
- Utilized multi-layer immunohistochemistry on human colonic tissue.
- Labeled neurons for pan-neuronal markers (HuC/D), catecholaminergic (TH), Enkephalin (ENK), cholinergic (ChAT), and nitrergic (NOS).
- Employed confocal microscopy and 3D reconstruction to quantify varicosity density near myenteric cell bodies.
Main Results:
- Noradrenergic varicosities showed higher density near cholinergic (ChAT+/NOS-) neurons compared to nitrergic (ChAT-/NOS+) neurons.
- Enkephalin-immunoreactive varicosities also preferentially contacted cholinergic neurons.
Conclusions:
- Developed a novel method to quantify nerve varicosity-neuron associations.
- Sympathetic axons preferentially target cholinergic excitatory neurons over nitrergic inhibitory neurons in the human colon.
- This specific neural connectivity likely mediates sympathetic inhibition of colonic motility.
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