Premium
Muscarinic acetylcholine receptors in the mouse esophagus: focus on intraganglionic laminar endings ( IGLE s)
Author(s) -
Hübsch M.,
Neuhuber W. L.,
Raab M.
Publication year - 2013
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.12161
Subject(s) - vesicular acetylcholine transporter , cholinergic , acetylcholine , muscarinic acetylcholine receptor , nodose ganglion , anterograde tracing , esophagus , retrograde tracing , biology , vagus nerve , cholinergic neuron , myenteric plexus , anatomy , muscarinic acetylcholine receptor m2 , neuroscience , pathology , medicine , receptor , endocrinology , choline acetyltransferase , immunohistochemistry , immunology , nucleus , stimulation
Background IGLE s represent the only low‐threshold vagal mechanosensory terminals in the tunica muscularis of the esophagus. Previously, close relationships of vesicular glutamate transporter 2 ( VGLUT 2) immunopositive IGLE s and cholinergic varicosities suggestive for direct contacts were described in almost all mouse esophageal myenteric ganglia. Possible cholinergic influence on IGLE s requires specific acetylcholine receptors. In particular, the occurrence and location of neuronal muscarinic acetylcholine receptors (mAChR) in the esophagus were not yet characterized. Methods This study aimed at specifying relationships of VGLUT 2 immunopositive IGLE s and vesicular acetylcholine transporter ( VAC hT)‐immunopositive varicosities using pre‐embedding electron microscopy and the location of mAChR1‐3 (M1‐3) within esophagus and nodose ganglia using multilabel immunofluorescence and retrograde tracing. Key Results Electron microscopy confirmed synaptic contacts between cholinergic varicosities and IGLE s. M1‐ and M2‐immunoreactivities (‐iry; ‐iries) were colocalized with VGLUT 2‐iry in subpopulations of IGLE s. Retrograde Fast Blue tracing from the esophagus showed nodose ganglion neurons colocalizing tracer and M2‐iry. M1‐3‐iries were detected in about 80% of myenteric ganglia and in about 67% of myenteric neurons. M1‐ and M2‐iry were present in many fibers and varicosities within myenteric ganglia. Presynaptic M2‐iry was detected in all, presynaptic M3‐iry in one‐fifth of motor endplates of striated esophageal muscles. M1‐iry could not be detected in motor endplates of the esophagus, but in sternomastoid muscle. Conclusions & Inferences Acetylcholine probably released from varicosities of both extrinsic and intrinsic origin may influence a subpopulation of esophageal IGLE s via M2 and M1‐receptors.