Synaptic transmission of baro- and chemoreceptors afferents in the NTS second order neurons

Accorsi‐Mendonça, Daniela; Machado, Benedito H.

doi:10.1016/j.autneu.2012.12.002

Cited by 35 publications

(26 citation statements)

References 60 publications

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“…There is well-documented evidence of direct excitatory projections from 2 nd order NTS peripheral chemoreceptive neurons to the RVLM (see Accorsi-Mendonca and Machado (2013) for review) which mediate sympathoexcitatory effect of peripheral chemoreceptor stimulation. Our model implies that there are at least two more indirect pathways mediated by the respiratory neurons ( Hypothesis 2 ).…”

Section: Discussionmentioning

confidence: 99%

Chemoreception and neuroplasticity in respiratory circuits

Barnett

Abdala

Paton³

et al. 2017

Experimental Neurology

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The respiratory central pattern generator must respond to chemosensory cues to maintain oxygen (O2) and carbon dioxide (CO2) homeostasis in the blood and tissues. To do this, sensorial cells located in the periphery and central nervous system monitor the arterial partial pressure of O2 and CO2 and initiate respiratory and autonomic reflex adjustments in conditions of hypoxia and hypercapnia. In conditions of chronic intermittent hypoxia (CIH), repeated peripheral chemoreceptor input mediated by the nucleus of the solitary tract induces plastic changes in respiratory circuits that alter baseline respiratory and sympathetic motor outputs and result in chemoreflex sensitization, active expiration, and arterial hypertension. Herein, we explored the possibility that the CIH-induced neuroplasticity primarily consists of increased excitability of pre-inspiratory/inspiratory neurons in the pre-Bötzinger complex. To evaluate this hypothesis and elucidate neural mechanisms for the emergence of active expiration and sympathetic overactivity in CIH-treated animals, we extended a previously developed computational model of the brainstem respiratory-sympathetic network to reproduce experimental data on peripheral and central chemoreflexes post-CIH. The model incorporated neuronal connections between the 2nd-order NTS neurons and peripheral chemoreceptors afferents, the respiratory pattern generator, and sympathetic neurons in the rostral ventrolateral medulla in order to capture key features of sympathetic and respiratory responses to peripheral chemoreflex stimulation. Our model identifies the potential neuronal groups recruited during peripheral chemoreflex stimulation that may be required for the development of inspiratory, expiratory and sympathetic reflex responses. Moreover, our model predicts that pre-inspiratory neurons in the pre-Bötzinger complex experience plasticity of channel expression due to excessive excitation during peripheral chemoreflex. Simulations also show that, due to positive interactions between pre-inspiratory neurons in the pre-Bötzinger complex and expiratory neurons in the retrotrapezoid nucleus, increased excitability of the former may lead to the emergence of the active expiratory pattern at normal CO2 levels found after CIH exposure. We conclude that neuronal type specific neuroplasticity in the pre-Bötzinger complex induced by repetitive episodes of peripheral chemoreceptor activation by hypoxia may contribute to the development of sympathetic over-activity and hypertension.

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Section: Discussionmentioning

confidence: 99%

Chemoreception and neuroplasticity in respiratory circuits

Barnett

Abdala

Paton³

et al. 2017

Experimental Neurology

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“…It should be noticed that the NTS is a heterogeneous nucleus, which processes multimodal sensory afferents, including gustatory, nociceptive and enteric inputs (Hill et al, 1983; Rinaman et al, 1989; Du and Zhou, 1990), as well as heterogeneous multimodal input from the carotid body (Kumar and Prabhakar, 2011). Recently, we demonstrated that NTS neurons receiving direct projections from the carotid body present a large variability in the latency of evoked glutamatergic currents, suggesting an intrinsic heterogeneity of the sensory pathways from the carotid body to the NTS (Accorsi-Mendonça et al, 2011; Accorsi-Mendonça and Machado, 2013). …”

Section: Physiology Of the Peripheral Chemoreflex In Mammalsmentioning

confidence: 99%

Evolution and physiology of neural oxygen sensing

et al. 2014

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Major evolutionary trends in animal physiology have been heavily influenced by atmospheric O2 levels. Amongst other important factors, the increase in atmospheric O2 which occurred in the Pre-Cambrian and the development of aerobic respiration beckoned the evolution of animal organ systems that were dedicated to the absorption and transportation of O2, e.g., the respiratory and cardiovascular systems of vertebrates. Global variations of O2 levels in post-Cambrian periods have also been correlated with evolutionary changes in animal physiology, especially cardiorespiratory function. Oxygen transportation systems are, in our view, ultimately controlled by the brain related mechanisms, which senses changes in O2 availability and regulates autonomic and respiratory responses that ensure the survival of the organism in the face of hypoxic challenges. In vertebrates, the major sensorial system for oxygen sensing and responding to hypoxia is the peripheral chemoreflex neuronal pathways, which includes the oxygen chemosensitive glomus cells and several brainstem regions involved in the autonomic regulation of the cardiovascular system and respiratory control. In this review we discuss the concept that regulating O2 homeostasis was one of the primordial roles of the nervous system. We also review the physiology of the peripheral chemoreflex, focusing on the integrative repercussions of chemoreflex activation and the evolutionary importance of this system, which is essential for the survival of complex organisms such as vertebrates. The contribution of hypoxia and peripheral chemoreflex for the development of diseases associated to the cardiovascular and respiratory systems is also discussed in an evolutionary context.

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“…In turn, the CVLM excites preganglionic parasympathetic neurons in the nucleus ambiguus (NA), which also receives excitatory input from the NTS, and projects (via the vagus nerve) to the heart to reduce the heart rate and stroke volume (62, 181). More importantly, the CVLM projects inhibitory (GABAergic) projections to the “vasomotor center” of cardiovascular system, the RVLM (59, 181, 183). The RVLM projects to and synapses on preganglionic sympathetic neurons located in the IMLCC of the spinal cord (59, 179, 182).…”

Section: The Baroreceptor Reflex In Healthy Pregnancy and Preeclampsiamentioning

confidence: 99%

“…The RVLM projects to and synapses on preganglionic sympathetic neurons located in the IMLCC of the spinal cord (59, 179, 182). Inhibition of the RVLM reduces the sympathetic tone to IMLCC, and it is this decrease in sympathetic nerve activity to the blood vessels, heart, and kidneys, that produces a corresponding decrease in mean arterial pressure (180, 181, 183). …”

Section: The Baroreceptor Reflex In Healthy Pregnancy and Preeclampsiamentioning

confidence: 99%

Preeclampsia and the brain: neural control of cardiovascular changes during pregnancy and neurological outcomes of preeclampsia

2016

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Preeclampsia (PE) is a form of gestational hypertension that complicates ~ 5 percent of pregnancies worldwide. Over 70 percent of the fatal cases of PE are attributed to cerebral edema, intracranial hemorrhage, and eclampsia. The etiology of PE originates from abnormal remodeling of the maternal spiral arteries, creating an ischemic placenta that releases factors that drive the pathophysiology. An initial neurological outcome of PE is the absence of the autonomically regulated cardiovascular adaptations to pregnancy. PE patients exhibit sympathetic overactivation, in comparison to both normotensive pregnant and hypertensive non-pregnant females. Moreover, PE diminishes baroreceptor reflex sensitivity (BRS) beyond that observed in healthy pregnancy. The absence of the cardiovascular adaptations to pregnancy, combined with sympathovagal imbalance and a blunted BRS leads to life-threatening neurological outcomes. Behaviorally, the increased incidences of maternal depression, anxiety, and post-traumatic stress disorder (PTSD) in PE are correlated to low fetal birth weight, intrauterine growth restriction (IUGR) and premature birth. This review addresses these neurological consequences of PE that present in the gravid female both during and after the index pregnancy.

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Synaptic transmission of baro- and chemoreceptors afferents in the NTS second order neurons

Cited by 35 publications

References 60 publications

Chemoreception and neuroplasticity in respiratory circuits

Chemoreception and neuroplasticity in respiratory circuits

Evolution and physiology of neural oxygen sensing

Preeclampsia and the brain: neural control of cardiovascular changes during pregnancy and neurological outcomes of preeclampsia

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