Morphology of P2X3‐immunoreactive basket‐like afferent nerve endings surrounding serosal ganglia and close relationship with vesicular nucleotide transporter‐immunoreactive nerve fibers in the rat gastric antrum

Abstract

We previously reported P2X3 purinoceptor (P2X3)‐expressing vagal afferent nerve endings with large web‐like structures in the subserosal tissue of the antral lesser curvature, suggesting that these nerve endings were one of the vagal mechanoreceptors. The present study investigated the morphological relationship between P2X3‐immunoreactive nerve endings and serosal ganglia in the rat gastric antrum by immunohistochemistry of whole‐mount preparations using confocal scanning laser microscopy. P2X3‐immunoreactive basket‐like subserosal nerve endings with new morphology were distributed laterally to the gastric sling muscles in the distal antrum of the lesser curvature. Parent axons ramified into numerous nerve fibers with pleomorphic flattened structures to form basket‐like nerve endings, and the parent axons were originated from large net‐like structures of vagal afferent nerve endings. Basket‐like nerve endings wrapped around the whole serosal ganglia, which were characterized by neurofilament 200 kDa‐immunoreactive neurons with or without neuronal nitric oxide synthase immunoreactivity and S100B‐immunoreactive glial cells. Furthermore, basket‐like nerve endings were localized in close apposition to dopamine beta‐hydroxylase‐immunoreactive sympathetic nerve fibers immunoreactive for vesicular nucleotide transporter. These results suggest that P2X3‐immunoreactive basket‐like nerve endings associated with serosal ganglia are the specialized ending structures of vagal subserosal mechanoreceptors in order to increase the sensitivity during antral peristalsis, and are activated by ATP from sympathetic nerve fibers and/or serosal ganglia for the regulation of mechanoreceptor function.

Three‐Dimensional Ultrastructure of Flower‐Spray Nerve Endings in the Rat Carotid Sinus

“…This antibody was previously used in immunohistochemistry for sensory nerve endings (Hirakawa et al. 2021a, 2021b; Yamamoto and Nakamuta 2018).…”

“…Immunohistochemistry with this antibody labeled sympathetic postganglionic nerve fibers in the rat carotid body and stomach (Hirakawa et al. 2021b; Yokoyama, Yamamoto, et al. 2020).…”

“…Immunoblotting analyses of this antibody labeled a single band of approximately 70 kDa in rat carotid body homogenates (Kato et al 2013). Immunohistochemistry with this antibody labeled sympathetic postganglionic nerve fibers in the rat carotid body and stomach (Hirakawa et al 2021b;.…”

“…An immunoblotting analysis of this antibody labeled a broad band at approximately 57 kDa in P2 × 3transfected HEK293 cells (Vulchanova et al 1997) and a 64-kDa band in a mouse dorsal root ganglion lysate (Cho and Chaban 2012). This antibody was previously used in immunohistochemistry for sensory nerve endings (Hirakawa et al 2021a(Hirakawa et al , 2021bYamamoto and Nakamuta 2018).…”

“…An immunoblotting analysis of this antibody recognized two isoforms of 75 and 50 kDa in mouse retinal and cerebral cortical homogenates, and these bands were eliminated when the antibody was preincubated with an excess of the antigen (Ho et al 2015). This antibody was previously used in immunohistochemistry for Type I cells in the rat carotid body ) and peripheral nerve fibers in the stomach (Hirakawa et al 2021b).…”