Vagal Intramuscular Arrays: The Specialized Mechanoreceptor Arbors That Innervate the Smooth Muscle Layers of the Stomach Examined in the Rat. Issue 4 (13th October 2015)

• Record Type: Journal Article
• Authors: Powley, Terry L.; Hudson, Cherie N.; McAdams, Jennifer L.; Baronowsky, Elizabeth A.; Phillips, Robert J.
• Is Part Of: Journal of comparative neurology. Volume 524:Issue 4(2016)
• Page Start: 713
• Page End: 737
• Publication Date: 2015-10-13
• Subjects: antrum -- corpus -- forestomach -- nodose -- vagus -- visceral afferent -- RRID:AB_354750 -- RRID:nif‐0000‐10294; Comparative neurobiology -- Periodicals; Neurology -- Periodicals; 616
• DOI: 10.1002/cne.23892
• Languages: English
• ISSNs: 0021-9967

Abstract

ABSTRACT: The fundamental roles that the stomach plays in ingestion and digestion notwithstanding, little morphological information is available on vagal intramuscular arrays (IMAs), the afferents that innervate gastric smooth muscle. To characterize IMAs better, rats were given injections of dextran biotin in the nodose ganglia, and, after tracer transport, stomach whole mounts were collected. Specimens were processed for avidin–biotin permanent labeling, and subsets of the whole mounts were immunohistochemically processed for c‐Kit or stained with cuprolinic blue. IMAs (n = 184) were digitized for morphometry and mapping. Throughout the gastric muscle wall, IMAs possessed common phenotypic features. Each IMA was generated by a parent neurite arborizing extensively, forming an array of multiple (mean = 212) branches averaging 193 µm in length. These branches paralleled, and coursed in apposition with, bundles of muscle fibers and interstitial cells of Cajal. Individual arrays averaged 4.3 mm in length and innervated volumes of muscle sheet, presumptive receptive fields, averaging 0.1 mm 3 . Evaluated by region and by muscle sheet, IMAs displayed architectural adaptations to the different loci. A subset (32%) of circular muscle IMAs issued specialized polymorphic collaterals to myenteric ganglia, and a subset (41%) of antral longitudinal muscle IMAs formed specialized net endings associated with the serosal boundary. IMAs were concentrated in regional patterns that correlated with the unique biomechanical adaptations of the stomach, specifically proximal stomach reservoir functions and antral emptying operations. Overall, the structural adaptations and distributions of the IMAs were consonant with the hypothesized stretch receptor roles of the afferents. J. Comp. Neurol. 524:713–737, 2016. © 2015 Wiley Periodicals, Inc. Abstract : Intramuscular arrays, potential stretch receptors, are the only vagal sensory terminals that directly innervate the smooth muscle layers of the stomach wall. Given the functional importance of these recently discovered afferents, the present experiment evaluated the morphometry, mapped the gastric distributions, and characterized the regional specializations of the endings.