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Evaluation of Anti-ulcer Potential of Sphenodesme involucrata var. paniculata (C.B. Clarke) Munir Leaves on Various Gastric Aggressive Factors
Published in Parimelazhagan Thangaraj, Phytomedicine, 2020
P. S. Sreeja, K. Arunachalam, Parimelazhagan Thangaraj
Gastric acid secretion is a complex, continuous process in which multiple, central, and peripheral factors contribute to a common end point: the secretion of H+ by parietal cells. Neuronal (acetylcholine, ACh), paracrine (histamine), and endocrine (gastrin) factors/physiological agonists, all regulate the acid secretion. Their specific receptors (muscarinic, H2, and cholecystokinin receptor 2, respectively) are on the basolateral membrane of parietal cells in the stomach and also on enterochromaffin-like cells (ECLs; cells seen close to parietal cells and are the source of histamine in the stomach). The receptors seen on ECLs have a role in regulating the release of histamine. The dorsal motor nucleus of the vagal nerve, the hypothalamus, and the solitary tract nucleus are the important structures for the central nervous system stimulation of the gastric acid secretion. Efferent fibers originating in the dorsal motor nuclei descend to the stomach via the vagus nerve and synapse with the ganglion cells of the enteric nervous system (Wallace and Sharkey 2011; Yandrapu and Sarosiek 2015).
Brainstem Mechanisms of Gustation
Published in Robert H. Cagan, Neural Mechanisms in Taste, 2020
David V. Smith, Takayuki Marui
The anatomical organization of the gustatory system in the brainstem closely parallels the general visceral afferent projections of the vagus nerve. In mammals, both the special visceral afferent (taste) fibers and general visceral sensory (vagal) fibers terminate within the nucleus of the solitary tract (nucleus tractus solitarius, NTS), with considerable overlap in their projections.51–56 Dissociation of gustatory vs. general visceral function within this anatomical substrate is often difficult.6,57,58 However, in certain species of fish, the entire facial lobe, most of the vagal lobe, and their secondary connections have developed as part of an enormously hypertrophied gustatory apparatus.1,6,59,60
Baroreceptor and Chemoreceptor Afferent Processing in the Solitary Tract Nucleus
Published in I. Robin A. Barraco, Nucleus of the Solitary Tract, 2019
Robert B. Felder, Steven W. Mifflin
The caudal one-third of the solitary tract nucleus (NTS) occupies a unique position in the brainstem as the first central nucleus to receive sensory information from mechanosensitive and chemosensitive receptors innervating the heart and vascular tree.1 From a neurophysiologist’s perspective, the convergence of primary afferent information from a variety of cardiovascular sensory receptors onto this small population of neurons provides a unique opportunity to explore the mechanisms by which neurons in the central nervous system process afferent information from the cardiovascular system. The sensory input to neurons in NTS can, in theory, be controlled and quantified, and cellular responses to “natural” inputs can be examined in a relatively simple system. In cardiovascular-related nuclei beyond NTS, the interpretation of integrative processes must always be tempered by the history of unknown prior afferent interactions in NTS and elsewhere, and a greater reliance on less specific forms of stimulation (e.g., electrical or chemical stimulation of other brainstem nuclei) often becomes necessary.
Neurological manifestations and pathogenic mechanisms of COVID-19
Published in Neurological Research, 2022
Matteo Galea, Michaela Agius, Neville Vassallo
It has been demonstrated that SARS-CoV-2 can directly infect neural cells, using human induced pluripotent stems cell (iPSC)- derived BrainSphere models [9]. Then, for successful further invasion, the virus would need to exploit trans-synaptic transfer. The latter would involve membranous-coating-mediated presynaptic exocytosis and postsynaptic endocytosis, as shown for the swine hemagglutinating encephalomyelitis virus (HEV) [10]. Thus, SARS-CoV-2 may directly infect peripheral nerve cell endings in tissues and through trans-synaptic propagation undergo retrogressive penetration back to the CNS [11,12]. Indeed, considering that the virus infects both the respiratory and gastrointestinal systems, it may be possible that SARS-CoV-2 may gain access to the vagus nerve (cranial nerve X). From there, it may undergo retrograde transmission to the brainstem and infect the solitary tract nucleus and the nucleus ambiguous, as well as the medullary respiratory control center, further disrupting respiratory function in conjunction with direct viral infection in lung tissue [13,14]. Another route involving vagal retrograde dissemination might originate from the oropharyngeal mucosa, since just before entering the skull, the vagus makes connections with the glossopharyngeal nerve (cranial nerve IX) fibers. Additional pathways for neuroinvasion may involve other organs and tissues innervated by the vagal nerve, such as the heart, kidneys, adrenal medulla and the spleen [15]. However, it should be stated that use of the vagus for SARS-CoV-2 neuroinvasion remains hypothetical, since no direct proof has yet been published [16].
Combined effects of angiotensin receptor blocker use and physical training in hypertensive men
Published in Clinical and Experimental Hypertension, 2022
Tábata de Paula Facioli, Stella Vieira Philbois, Bruno Augusto Aguilar, Ana Catarine Veiga, Hugo Celso Dutra de Souza
In fact, clinical and experimental studies have shown that in pathophysiological conditions, such as heart failure, hypertension, diabetes, and obesity, the cardiac autonomic modulation is altered (2,15). Hypertensive volunteers have impaired HRV and BRS, as seen in our study. This reduction in HRV may be due to a cardiac autonomic rearrangement, characterized mainly by sympathetic hyperactivity (16,17). This sympathetic hyperactivity seems to be associated with increased chemoreceptor sensitivity and reduced baroreceptor sensitivity, thereby promoting chronic excitatory stimulus in the sympathetic tone (18). Some authors have also suggested other mechanisms, such as the importance of the participation of angiotensin II in the central nuclei involved in autonomic cardiovascular control, interfering with the autonomic sympathetic impulse and impairing baroreflex function (19,20). However, the action of angiotensin II on autonomic cardiovascular control seems to be much more complex. For example, it has been suggested that the angiotensin II depressant action on the baroreflex function involves the solitary tract nucleus (NTS) (21) via an endothelial nitric oxide synthase activation pathway, and nitric oxide (NO) would promote the release of the inhibitory neurotransmitter-GABA (22).
Gustatory rhinitis in multiple system atrophy
Published in Acta Oto-Laryngologica Case Reports, 2021
Kaoru Yamakawa, Kenji Kondo, Akihiko Unaki, Hideto Saigusa, Kyohei Horikiri, Tatsuya Yamasoba
Our patient complained of rhinorrhea only during eating. The central gustatory pathway ascends from the solitary tract nucleus in the medulla, up to the parvicellular part of the posteromedial ventral thalamus [10]. Moreover, collateral pathways project to the hypothalamus, which controls autonomic nerve reaction, through the parasympathetic nucleus of the brainstem, superior/inferior salivary nucleus, and dorsal nucleus of the vagus nerve [11]. Synucleinopathies present with severe neurodegeneration of the dorsal nucleus of the vagus nerve [7,12]. It can be assumed that parasympathetic dysfunction of the dorsal nucleus of the vagus nerve provides positive feedback to the hypothalamus, which stimulates the salivary nucleus simultaneously, leading to gustatory rhinitis.