Types of Neurons in the Myenteric Plexus of Human Gastric Corpus Identified by Multi-Layer Immunohistochemical Coding and Vagal Tracing.

BACKGROUND

Enteric neurons regulate motility, secretion, blood flow, and immune function of the gut. Characterizing neuron types is essential for understanding how the enteric nervous system works and how it goes wrong in disease.

METHODS

We examined the myenteric plexus of the human gastric corpus from surgical specimens. Multiplexed immunohistochemistry assessed 15 markers, including pan-neuronal (HuC/D), neurotransmitter-related enzymes, nitric oxide synthase (NOS), choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), vesicular acetylcholine transporter (VAChT), the transmitter serotonin (by 5-HT accumulation), neuropeptides substance P (SP), enkephalin (ENK), calcitonin gene-related peptide (CGRP), somatostatin (SOM), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), calcium-binding proteins calbindin (Calb), calretinin (Calret) and the structural protein neurofilament 200 (NF200). These markers were applied to 1084 myenteric neurons from the gastric corpus of 7 individuals. Biotinamide tracing was used to label axons from intramural vagal nerve branches visible at the edge of the preparation.

KEY

RESULTS

Twelve classes of enteric neurons were distinguished by significant associations between immunohistochemical markers ("chemical coding"), including motor neurons and likely interneurons, secretomotor, and vasomotor neurons. Dense clusters of axonal varicosities ("baskets") labeled by VAChT, ENK, SP, or TH were abundant around ChAT+ myenteric cell bodies but disproportionately scarce around NOS+ cells. Vagal baskets labeled by biotinamide did not show an overall preference for either NOS+ or ChAT+ cells.

CONCLUSIONS

Multiple types of human gastric myenteric neurons can be distinguished by their immunohistochemical profiles. Vagal efferent pathways are associated with all classes of myenteric neurons in the gastric corpus, whereas some enteric pathways likely exhibit selective connectivity with integrative potential.