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Comparative Anatomy of Medullary Vagal Nerve Nuclei
Published in Sue Ritter, Robert C. Ritter, Charles D. Barnes, Neuroanatomy and Physiology of Abdominal Vagal Afferents, 2020
The solitary tract is a longitudinal bundle of poorly myelinated and unmyelinated axons which extends from the rostral medulla to the commissure of Cajal, lying just caudal to the obex. The axons of the solitary tract include both primary sensory fibers and higher order “association” fibers. In general, primary sensory fibers from cranial nerves VII (facial), IX (glossopharyngeal) and X (vagus) enter the solitary tract at their level of entrance into the brainstem. There is a tendency for the majority of sensory fibers from each cranial nerve to terminate within the solitary nucleus at, or somewhat caudal to, its level of entrance into the brainstem. Thus, the majority of vagal sensory fibers terminates in the posterior part of the nucleus of the solitary tract. This tendency should not, however, be construed as a hard and fast rule since in many vertebrates some vagal fibers ascend within the solitary tract to reach more rostral levels of the nucleus.
Baroreflex Failure
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
The medullary origin of the vagal fibers reflects the diversity of function that characterizes this nerve. The somatic efferent fibers originate in the nucleus ambiguus of the ventrolateral medulla. The visceral efferent fibers originate in the dorsal motor nucleus of the vagus. The visceral afferent fibers have cell bodies in the nodose ganglion, from which their central processes pass to the nucleus of the solitary tract. The cell bodies of the somatic afferent fibers lie in the jugular ganglion and their central processes terminate principally in the dorsal part of the nucleus of the spinal trigeminal tract.
Functional Connections of the Rostral Nucleus of the Solitary Tract in Viscerosensory Integration of Ingestion Reflexes
Published in I. Robin A. Barraco, Nucleus of the Solitary Tract, 2019
The nerves that supply sensory innervation to the tongue and palate synapse centrally in rostral portions of the nucleus of the solitary tract (NST). The subnuclear locations to which these nerves project have recently been characterized in order to define regions involved in processing taste and general sensations from the oral cavity and in neural outflow to other brainstem regions, including pre-oromotor pathways.15-19 There is a rostral to caudal somatotopic representation of the oral cavity in the NST (Figure 2). The chorda tympani and greater superficial petrosal nerves which innervate taste buds on the anterior tongue and anterior palate, respectively, project to the rostral extreme of the NST. The glossopharyngeal nerve, which supplies taste and general somatosensory innervation to the caudal tongue, projects more caudally in the NST than the anterior tongue and palate nerves. Vagal branches that supply laryngeal taste buds project to the caudal-most gustatory regions.
GDF15: a potential therapeutic target for type 1 diabetes
Published in Expert Opinion on Therapeutic Targets, 2022
Soumyadeep Sarkar, John T. Melchior, Hayden R. Henry, Farooq Syed, Raghavendra G. Mirmira, Ernesto S. Nakayasu, Thomas O. Metz
As outlined previously, T1D is an autoimmune disease; however, metabolic and neurological implications contribute significantly to the progression of T1D. It is well documented that the sympathetic and parasympathetic nervous systems regulate various branches of glucose homeostasis, including regulation of hormone secretion (insulin & glucagon) and maintenance of β cell populations in our body [86]. Therefore, researchers have started investigating the neuronal contribution to diabetes pathology [87–89]. To this end, as mentioned earlier, GFRAL receptors are present in the brainstem, nucleus of the solitary tract (NTS), and hypothalamus, implying a possible regulation of glucose homeostasis by GDF15 through stimulation of sympathetic and parasympathetic signaling [12,90,91]. This link is another addition to the growing list of potential GDF15 crosstalk with factors responsible for T1D, ultimately bolstering the therapeutic potential of GDF15 (Figure 3).
Maternal protein restriction affects cardiovascular, but not respiratory response to L-glutamate microinjection into the NTS of conscious rats
Published in Nutritional Neuroscience, 2021
D. S. Alves, D. F. S. Barbosa, V. O. Nogueira, Y. Tourneur, D. A. F. Fontes, J. L. Brito-Alves, J. H. Costa-Silva
Maternal low protein diet induced-hypertension has been demonstrated to be associated with an increase in the cardiovascular sympathetic tone in adulthood [16]. The sympathetic nervous system is regulated by different sites in the brainstem, mainly by the neurons located in the ventral medulla [28], which determine the central sympathetic outflow; also by the neurons located in dorsal medulla, which receive inputs from peripheral baroreceptors and chemoreceptors, regulating the presympathetic neuron activity of the ventral medulla. The neurons of the nucleus of the solitary tract (NTS), in the dorsal medulla, are reported to be essential for the processing and coordination of respiratory and sympathetic activities [29]. The NTS is the first synaptic station of the cardiorespiratory afferent inputs, including peripheral chemoreceptors, baroreceptors and pulmonary stretch receptors [29]. There is evidence indicating that the excitatory amino acid L-glutamate is the neurotransmitter released by the afferents of the different cardiovascular reflexes in the NTS [8] ;the different subtypes of ionotropic receptors (NMDA and non-NMDA) play an important role in this neurotransmission [8].
Fremanezumab for the preventive treatment of migraine in adults
Published in Expert Review of Clinical Pharmacology, 2019
Luana Lionetto, Martina Curto, Giusy Ylenia Cisale, Matilde Capi, Fabiola Cipolla, Martina Guglielmetti, Paolo Martelletti
CGRP results from tissue-specific splicing of the primary RNA transcripts of the calcitonin (CT)/CGRP gene [18]. It is synthesized by sensory nerves and released following the activation of voltage-dependent calcium uptake from motor neurons at the neuromuscular junction and sensory neurons of spinal cord [17]. In situ hybridization identified CGRP mRNA in a large portion of the trigeminal neurons [19] even if CGRP receptors were found only in one-third of the ganglion neurons [20]. The stimulation of trigeminal ganglion leads to the CGRP release that activates the inflammatory cytokines and nitric oxide from ganglionic glial cells [21–23]. Therefore, CGRP may play a role in migraine pathophysiology by mediating the neurogenic inflammation and the transmission of trigeminovascular nociceptive signal from intracranial vessels to central nervous system [24]. CGRP is also expressed in motor neurons of the hypoglossal nucleus, including the nucleus of the solitary tract, parabrachial nucleus, central amygdaloid nucleus, ventromedial posterior nucleus of the thalamus, and insular cortex suggesting that CGRP may play a role in taste and ingestive behaviors [25]. Beyond the nervous system, CGRP has a widespread expression in the reproductive and immune system, bone, heart, lung and gastrointestinal tract [26] where it can induce inflammatory and immune responses [27].