Premium
The asymmetric innervation of the circular and longitudinal muscle of the mouse colon differently modulates myogenic slow phasic contractions
Author(s) -
Traserra Sara,
Villarte Sonia,
Traini Chiara,
Palacin Sara,
Vergara Patri,
Vannucchi Maria Giuliana,
Jimenez Marcel
Publication year - 2020
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1111/nmo.13778
Subject(s) - interstitial cell of cajal , electrical impedance myography , electrophysiology , purinergic receptor , inhibitory postsynaptic potential , medicine , endocrinology , contractility , neuromuscular transmission , anatomy , circular muscle , biology , myenteric plexus , chemistry , receptor , immunohistochemistry , smooth muscle , vasodilation
Background Neuromuscular transmission has been extensively studied in the circular layer of the mouse colon where a co‐transmission of purines acting on P2Y 1 receptors and NO has been previously described. However, the corresponding mechanisms in the longitudinal layer are less known. Methods Electrophysiological and myography techniques were used to evaluate spontaneous phasic contractions (SPC) and neural‐mediated responses in the proximal, mid, and distal colon devoid of CD1 mice. Immunohistochemistry against c‐kit and PDGFRα was performed in each colonic segment. Key Results SPC were recorded in both muscle layers at a similar frequency being about four contractions per minute (c.p.m.) in the proximal and distal colon compared to the mid colon (2 c.p.m.). In non‐adrenergic, non‐cholinergic conditions, L‐NNA (1 mmol/L) increased contractility in the circular but not in the longitudinal layer. In the longitudinal muscle, both electrophysiological and mechanical neural‐mediated inhibitory responses were L‐NNA and ODQ (10 µmol/L) sensitive. NaNP (1 µmol/L) caused cessation of SPC and the response was blocked by ODQ. Neither ADPßS (10 µmol/L) nor CYPPA (10 µmol/L), which both targeted the purinergic pathway, altered longitudinal contractions. PDGFRα + cells were located in both muscle layers and were more numerous compared with cKit + cells, which both formed a heterologous cellular network. A decreasing gradient of the PDGFRα labeling was observed along the colon. Conclusion An inhibitory neural tone was absent in the longitudinal layer and neuronal inhibitory responses were mainly nitrergic. Despite the presence of PDGFRα + cells, purinergic responses were absent. Post‐junctional pathways located in different cell types might be responsible for neurotransmitter transduction.