Structure and Functions of the Vagus Nerve in Mammals

Ottaviani, Matteo Maria; Macefield, Vaughan G.

doi:10.1002/cphy.c210042

Cited by 20 publications

(8 citation statements)

References 201 publications

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“…This report investigates the impact of micromagnetic stimulation (μMS) of the vagus nerve in vivo on a rodent model using two different general anesthetics. Ottaviani et al [49] reported that the structure and fuctions of the vagus nerve in mammals vary significantly. Therefore, any study on vagus nerve stimulation implant development is probably a proof-of-concept study as the structure and function of the human vagus nerve varies significantly from that of other mammals.…”

Section: Discussionmentioning

confidence: 99%

Impact of anesthesia on micromagnetic stimulation (μMS) of the vagus nerve

Saha,

Van Helden,

Hopper

et al. 2024

Biomed. Phys. Eng. Express

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To treat diseases associated with vagal nerve control of peripheral organs, it is necessary to selectively activate efferent and afferent fibers in the vagus. As a result of the nerve’s complex anatomy, fiber-specific activation proves challenging. Spatially selective neuromodulation using micromagnetic stimulation(µMS) is showing incredible promise. This neuromodulation technique uses microcoils(µcoils) to generate magnetic fields by powering them with a time-varying current. Following the principles of Faraday’s Law of Electromagnetic Induction, a highly directional electric field is induced in the nerve from the magnetic field. In this study on rodent cervical vagus, a solenoidal-shaped μcoil was oriented at an angle to left and right branches of the nerve. The aim of this study was to measure changes in the mean arterial pressure (MAP) and heart rate (HR) following μMS of the vagus. The µcoils were powered by a single-cycle sinusoidal current varying in pulse widths(PW = 100, 500, and 1000 µsec) at a frequency of 20 Hz. Under the influence of isoflurane, µMS of the left vagus at 1000 µsec PW led to an average drop in MAP of 16.75 mmHg(n = 7). In contrast, µMS of the right vagus under isoflurane resulted in an average drop of 11.93 mmHg in the MAP(n = 7). Surprisingly, there were no changes in HR to either right or left vagal µMS suggesting the drop in MAP associated with vagus µMS was the result of stimulation of afferent, but not efferent fibers. In urethane anesthetized rats, no changes in either MAP or HR were observed upon μMS of the right or left vagus(n = 3). These findings suggest the choice of anesthesia plays a key role in determining the efficacy of μMS on the vagal nerve. Absence of HR modulation upon μMS could offer alternative treatment options using VNS with fewer heart-related side-effects.

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Section: Discussionmentioning

confidence: 99%

Impact of anesthesia on micromagnetic stimulation (μMS) of the vagus nerve

Saha,

Van Helden,

Hopper

et al. 2024

Biomed. Phys. Eng. Express

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“…The vagus nerve is the largest, longest, and most special cranial nerve, with a wide range of distribution. The vagus nerve has anatomical asymmetry and central vagal circuits asymmetry ( 6 , 36 ). RVNS and LVNS exert different effects on the brain ( 13 ).…”

Section: Discussionmentioning

confidence: 99%

Right vagus nerve stimulation improves motor behavior by exerting neuroprotective effects in Parkinson’s disease rats

Wang¹,

Su²,

Xiao³

et al. 2022

Ann Transl Med

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Background: Parkinson's disease (PD) is a common movement disorder disease. Left vagus nerve stimulation (LVNS) is a potential treatment option for PD. Compared with the left vagus nerve, the right vagus nerve is more closely connected with the midbrain dopaminergic neurons, which are the lesion locations of PD. However, whether right vagus nerve stimulation (RVNS) has a therapeutic effect on PD has not yet been studied. Therefore, in this study, we studied the therapeutic effect and underlying mechanism of RVNS using a PD rat model. Methods:To establish the PD rat model, 8-week-old male Sprague-Dawley rats were intraperitoneally injected with rotenone for 21 days. The cuff electrodes were implanted into the right cervical vagal carotid sheaths of the rats. The right vagus nerve was continuously stimulated for 14 days using a radio stimulation system. Behavioral tests were performed before and after stimulation. Finally, tyrosine hydroxylase (TH), vesicular monoamine transporter 2 (VMAT2), and α-synuclein in the midbrain, including the substantia nigra (SN) and ventral tegmental area (VTA), were detected by immunofluorescence.Results: A markedly lower distance traveled and rearing number was observed in the rotenone, rotenone + sham, and rotenone + RVNS groups compared to the vehicle group. After the stimulation days, the distance traveled and rearing number were both higher in the rotenone + RVNS group compared to the rotenone and rotenone + sham groups (P<0.01, P<0.0001). A remarkable increase in distance traveled and rearing number was observed in the rotenone + RVNS group after stimulation. TH expression in the vehicle group was significantly up-regulated than the other groups. RVNS markedly up-regulated TH expression level. A significantly higher expression of α-synuclein was observed in the rotenone, rotenone + sham, and rotenone + RVNS groups compared to the vehicle group. The expression of α-synuclein was lower in the rotenone + RVNS group compared to the rotenone and rotenone + sham groups. A markedly higher VMAT2 expression was observed in the vehicle group compared to other groups. RVNS significantly up-regulated VMAT2 expression. Conclusions:The improved motor behavior and neuroprotective effects on the midbrain dopaminergic neurons in the PD rat model suggest that RVNS could be used as a potential treatment for PD.

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“…The vagus nerve (VN), a significant part of the gut-brain axis, connects the enteric nervous system with the CNS. It is composed of 80% afferent and 20% efferent fibers [ 81 ], which innervate structures in the head, neck, thorax, and abdomen [ 82 ]. While belonging to the parasympathetic division of the autonomic nervous system, the function of this nerve is primarily sensory, and it is dominated by sensory axons [ 82 ].…”

Section: Gut Metabolites Indirectly Affect Microglia Via the Structur...mentioning

confidence: 99%

Gut Metabolites Acting on the Gut-Brain Axis: Regulating the Functional State of Microglia

Deng¹,

Yi²,

Xiong³

et al. 2024

Aging and disease

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The gut-brain axis is a communication channel that mediates a complex interplay of intestinal flora with the neural, endocrine, and immune systems, linking gut and brain functions. Gut metabolites, a group of small molecules produced or consumed by biochemical processes in the gut, are involved in central nervous system regulation via the highly interconnected gut-brain axis affecting microglia indirectly by influencing the structure of the gut-brain axis or directly affecting microglia function and activity. Accordingly, pathological changes in the central nervous system are connected with changes in intestinal metabolite levels as well as altered microglia function and activity, which may contribute to the pathological process of each neuroinflammatory condition. Here, we discuss the mechanisms by which gut metabolites, for instance, the bile acids, short-chain fatty acids, and tryptophan metabolites, regulate the structure of each component of the gut-brain axis, and explore the important roles of gut metabolites in the central nervous system from the perspective of microglia. At the same time, we highlight the roles of gut metabolites affecting microglia in the pathogenesis of neurodegenerative diseases and neurodevelopmental disorders. Understanding the relationship between microglia, gut microbiota, neuroinflammation, and neurodevelopmental disorders will help us identify new strategies for treating neuropsychiatric disorders.

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Structure and Functions of the Vagus Nerve in Mammals

Cited by 20 publications

References 201 publications

Impact of anesthesia on micromagnetic stimulation (μMS) of the vagus nerve

Impact of anesthesia on micromagnetic stimulation (μMS) of the vagus nerve

Right vagus nerve stimulation improves motor behavior by exerting neuroprotective effects in Parkinson’s disease rats

Gut Metabolites Acting on the Gut-Brain Axis: Regulating the Functional State of Microglia

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