Topographical distribution and morphology of TH-IR and VAChT-IR axons in the antrum, pylorus, and duodenum of rats

Abstract

The autonomic nervous system plays an essential role in controlling gastrointestinal functions including a variety of physiological functions such as the regulation of motility, gut secretion, and vascular flow. Tyrosine hydroxylase (TH) and vesicular acetylcholine transporter (VAChT) are commonly used markers for sympathetic and parasympathetic innervation, respectively. However, the regional distribution and morphology of TH-IR and VAChT-IR axons in the submucosa and mucosa are not well documented. In this study, the rat antrum-pylorus-duodenum (APD) were transversely and longitudinally sectioned. A Zeiss M2 imager was used to scan the serial sections of each APD (each section montage consisted of 50–100 all-in-focus maximal projection images). To determine the detailed structures of TH-IR and VAChT-IR axons, we used the confocal microscope to scan the regions of interest. We found that (1) TH-IR axons innervated the muscular, submucosal, and mucosal layers. In the muscular layer, the submucosa and the mucosa, TH-IR varicose axons innervated the muscles and innervated blood vessels. In the villi, TH-IR axons were presented. (2) VAChT-IR axons heavily innervated the muscular, submucosal, and mucosal layers. In the muscular layer, VAChT-IR varicose axons densely innervated the muscles and myenteric neurons were VAChT positive. In the submucosa and mucosa, VAChT-IR axons innervated as well. In the villi, VAChT-IR axons were densely innervated. (3) TH-IR and VAChT-IR axons were found not co-localized in the muscular, submucosal, and mucosal layers. This work provided a comprehensive view of the distribution and morphology of TH-IR and VAChT-IR axons in the APD at single cell/axon/varicosity scale. This data will be used to create a 3D mapping of the TH-IR and VAChT-IR axons innervation of the APD in rats. This study was supported by NIH HEAL/SPARC U01 NS113867-01 and NIH R15HL137143-01A1. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.