title: Nerve fibers that were not stained with the non-specific acetylcholinesterase (NsAchE) method, and TRPV1- and IB4-positive nerve fibers in the rat cornea.
abstract: Previously, we noticed the presence of nerve fiber-like structures in a whole mount preparation of the rat cornea that had not been stained with the non-specific acetylcholinesterase (NsAchE) method. These nerve-like fibers were projected into the central area of the cornea, forming a mesh-like pattern. The aim of this study is to examine the properties of these mesh-like fibers using the following two methods: their sensitivity to capsaicin and the detection of isolectin B4 (IB4)- and capsaicin receptor TRPV1 (transient receptor potential vanilloid 1)-reactivities. The mean disappeared area of non-stained fibers after NsAchE treatment was 26% of the total areas in the neonatally capsaicin-treated cornea. Bunches composed of fine IB4-positive nerve fibers were seen in a whole mount preparation. There were connections between the bunches, producing a mesh-like pattern similar to that of the fibers that were not stained with NsAchE. Fine TRPV1-immunoreactive (ir) nerve fibers were also shown to form bunches, with connections between each bunch observed in whole mount preparations. Thus, TRPV1-ir nerve fibers seem to densely innervate the rat corneal subepithelial stroma and are distinct from the NsAchE-positive nerve fibers. The TRPV1-ir fine nerve fibers overlapped with the IB4-positive nerve fibers, suggesting that the mesh-like fibers that were not stained with NsAchE are fine nociceptive sensory nerve fibers because of their sensitivity to capsaicin and similar distribution pattern to IB4- and TRPV1-positive nerve fibers.
authors.affiliation: Pediatric Dentistry, Tokushima University Hospital, Tokushima , Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Akio
authors.initials: A
authors.lastname: Hiura
authors.forename: Masato
authors.initials: M
authors.lastname: Mitome
authors.forename: Kazunori
authors.initials: K
authors.lastname: Ishimura
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002211:Capsaicin / Q000494:pharmacology; D003315:Cornea / Q000294:innervation*; D009412:Nerve Fibers / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure*; D037121:Plant Lectins / Q000378:metabolism; D051381:Rats; D013194:Staining and Labeling; D050916:TRPV Cation Channels / Q000378:metabolism
chemical_list: C045475:Griffonia simplicifolia lectins; D037121:Plant Lectins; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; D000110:Acetylcholinesterase; D002211:Capsaicin