Identification of the Nodose Ganglia and TRPV1 in Swine

Abstract

The vagal nerve is the tenth cranial nerve (CN) and is the only CN to extend through the neck into the thorax and abdomen. As a component of the autonomic nervous system, the vagal nerve innervates the visceral organs, including the lung. The majority of the bronchopulmonary sensory nerves are unmyelinated (C-fiber) afferents of the vagal nerve. The cell bodies of the visceral afferent fibers of the vagus nerve are located bilaterally in the inferior ganglion-also termed the nodose ganglia (NG). More recently, transient receptor potential vanilloid type 1 (TRPV1) channels have been identified and are expressed on the vagal C-fiber afferents, which play an important role in the cholinergic reflex pathway [1][2][3]. TRPV1 channels are nonselective cation channels and polymodal transducers that are known to be activated by increasing temperature, acidity (hydrogen ion), and endogenous inflammatory mediators [1][2][3].Although differences exist between swine and human anatomy, the patterns of the vagal nerve are largely similar and closer in size than standard rodent models [4]. Data are limited on identifying autonomic neurons and associated cell bodies, including the NG in swine [5,6]. The importance and study of pulmonary neurobiology in acute lung injury is gaining momentum and often requires the use of large animal models, including swine. With no previous reports of the identification and subsequent histopathologic confirmation of the NG and TRPV1 in swine, we provide our experiences in identifying the NG in common crossbred piglets used in an acute lung injury model investigating the

Functional Vagotopy in the Cervical Vagus Nerve of the Domestic Pig: Implications for the Study of Vagus Nerve Stimulation

“…In some subjects we observed that the ESL and ISL first formed a single nerve bundle and then bifurcated into the ISL and ESL. In other subjects, the ESL and ISL exited the nodose ganglion as two separate nerve bundles, and both of these arrangements confirmed the findings of Hayes et al (Hayes et al 2013) ( Figure 3). The second location with variation in anatomy was the length of the recurrent laryngeal from its bifurcation from the vagal trunk to its insertion point into the muscle (Table 2, Figure 4).…”

“…The second implication of a more caudal nodose ganglion is the neuronal composition of the ganglion itself. In rodent and guinea pig, neurons with particular attributes were found to have discrete localizations within the nodose ganglion (Hayes et al 2013;Travagli et al 2003). These studies suggest that motor efferent fibers linked to unwanted side effects may have a discrete location, or vagotopy, to separate them from VNS target fibers at the level of the nodose.…”

“…It is necessary to understand how well anatomical features in animal models approximate the human to optimize new electrode designs and stimulation strategies for eventual human deployment. The domestic pig may be an appropriate model for VNS given the similarity to human with respect to autonomic control of cardiovascular function and diameter of the cervical vagus (Ding, Tufano, and German 2012;Hayes et al 2013;Tosato et al 2006;Trevathan et al 2019). However, there are no studies characterizing the anatomical features of the pig cervical vagus that would impact onand off-target engagement by VNS.…”

Simple and reproducible approaches for the collection of select porcine ganglia

“…This approach helps to avoid accidental collection of other ganglia that are in the region such as the cranial cervical ganglion 14 . Moreover, this approach provides a very simple strategy to identify the nodose ganglion (via tracing of the nerve towards the skull); such descriptions are lacking in other resources 15,16 .…”

Transient Receptor Potential Vanilloid 1 in animal tissues: An overview to highlight similarities and differences with human species

“…Swine TRPV1 was recently investigated in the study of Hayes et al [42] concerning the role of vagal nerve in the pulmonary neurobiology of acute lung injury. Authors explained that although differences exist between swine and human anatomy, the patterns of the vagal nerve are largely similar and closer in size than standard rodent models and for these reasons they tried to use swine as animal model to investigate human acute lung injury.…”