Brainstem interneurons necessary for vestibular influences on sympathetic outflow

Steinbacher, B. C.; Yates, Bill J.

doi:10.1016/0006-8993(96)00141-2

Cited by 17 publications

(15 citation statements)

References 13 publications

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“…In all cases, postmortem analysis of histological sections revealed that the injection cannula was placed in the target region, and there was no evidence of cell loss outside of the vestibular nuclei. Even if damage had occurred in brain stem areas adjacent to the medial and inferior vestibular nuclei, previous studies in acute preparations demonstrated that inactivation of these regions does not diminish the amplitude of vestibulosympathetic responses (30). Thus it seems likely that the effects of the ibotenic acid injections were related to the destruction of vestibular nucleus neurons.…”

Section: Discussionmentioning

confidence: 92%

Effects of bilateral vestibular nucleus lesions on cardiovascular regulation in conscious cats

Mori¹,

Cotter²,

Arendt³

et al. 2005

Journal of Applied Physiology

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The vestibular system participates in cardiovascular regulation during postural changes. In prior studies (Holmes MJ, Cotter LA, Arendt HE, Cas SP, and Yates BJ. Brain Res 938: 62-72, 2002, and Jian BJ, Cotter LA, Emanuel BA, Cass SP, and Yates BJ. J Appl Physiol 86: 1552-1560, transection of the vestibular nerves resulted in instability in blood pressure during nose-up body tilts, particularly when no visual information reflecting body position in space was available. However, recovery of orthostatic tolerance occurred within 1 wk, presumably because the vestibular nuclei integrate a variety of sensory inputs reflecting body location. The present study tested the hypothesis that lesions of the vestibular nuclei result in persistent cardiovascular deficits during orthostatic challenges. Blood pressure and heart rate were monitored in five conscious cats during nose-up tilts of varying amplitude, both before and after chemical lesions of the vestibular nuclei. Before lesions, blood pressure remained relatively stable during tilts. In all animals, the blood pressure responses to nose-up tilts were altered by damage to the medial and inferior vestibular nuclei; these effects were noted both when animals were tested in the presence and absence of visual feedback. In four of the five animals, the lesions also resulted in augmented heart rate increases from baseline values during 60°nose-up tilts. These effects persisted for longer than 1 wk, but they gradually resolved over time, except in the animal with the worst deficits. These observations suggest that recovery of compensatory cardiovascular responses after loss of vestibular inputs is accomplished at least in part through plastic changes in the vestibular nuclei and the enhancement of the ability of vestibular nucleus neurons to discriminate body position in space by employing nonlabyrinthine signals. vestibular system; excitotoxicity; compensation; multisensory integration A SUBSTANTIAL BODY OF EVIDENCE from experiments on both animal and human subjects has demonstrated that the vestibular system contributes to adjusting vascular resistance and blood pressure during movement and changes in posture. Electrical or selective natural stimulation of vestibular receptors in cats elicits alterations in activity of sympathetic efferents innervating vascular smooth muscle (for review, see Refs. 21,37,40,41,44). In baroreceptor-denervated animals, vestibular-elicited alterations in sympathetic nerve activity can produce changes in blood pressure (35) and blood flow to specific vascular beds (20). Similarly, in humans, modulation of vestibular nerve activity through head-down neck flexion (11,16,26,27,29), linear acceleration of the body (38), caloric stimulation of the ear (8, 9), or off-vertical-axis rotation (19) elicits alterations in sympathetic nerve firing. Prior studies have also considered whether loss of vestibular inputs may result in susceptibility for blood pressure instability during postural changes. Elderly human subjects, who experience a loss of both ...

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Section: Discussionmentioning

confidence: 92%

Effects of bilateral vestibular nucleus lesions on cardiovascular regulation in conscious cats

Mori¹,

Cotter²,

Arendt³

et al. 2005

Journal of Applied Physiology

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“…Neurons in the lateral and ventrolateral medullary reticular formation, including those whose axons could be antidromically activated from the RVLM, responded to electrical stimulation of vestibular afferents at shorter latency than did RVLM neurons (277, 316). In addition, chemical lesions of the lateral medullary reticular formation abolished VSR (275, 276). The responses to body rotations of neurons in the medullary lateral tegmental field were similar to those of VSR, supporting the notion that this region serves as a relay between the vestibular nuclei and RVLM (212).…”

Section: Neural Pathways That Mediate Vestibulosympathetic Responsesmentioning

confidence: 98%

“…5 (62, 145, 146, 170, 202, 276, 286, 288, 289, 323, 328). These responses could be excitatory, inhibitory, or consist of a combination of excitation and inhibition.…”

Section: Characteristics Of Vestibulo-sympathetic Reflexes In Animal mentioning

confidence: 99%

Vestibulo‐Sympathetic Responses

Yates

Bolton

Macefield

2014

Comprehensive Physiology

144

130

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Evidence accumulated over 30 years, from experiments on animals and human subjects, has conclusively demonstrated that inputs from the vestibular otolith organs contribute to the control of blood pressure during movement and changes in posture. This review considers the effects of gravity on the body axis, and the consequences of postural changes on blood distribution in the body. It then separately considers findings collected in experiments on animals and human subjects demonstrating that the vestibular system regulates blood distribution in the body during movement. Vestibulosympathetic reflexes differ from responses triggered by unloading of cardiovascular receptors such as baroreceptors and cardiopulmonary receptors, as they can be elicited before a change in blood distribution occurs in the body. Dissimilarities in the expression of vestibulosympathetic reflexes in humans and animals are also described. In particular, there is evidence from experiments in animals, but not humans, that vestibulosympathetic reflexes are patterned, and differ between body regions. Results from neurophysiological and neuroanatomical studies in animals are discussed that identify the neurons that mediate vestibulosympathetic responses, which include cells in the caudal aspect of the vestibular nucleus complex, interneurons in the lateral medullary reticular formation, and bulbospinal neurons in the rostral ventrolateral medulla (RVLM). Recent findings showing that cognition can modify the gain of vestibulosympathetic responses are also presented, and neural pathways that could mediate adaptive plasticity in the responses are proposed, including connections of the posterior cerebellar vermis with the vestibular nuclei and brainstem nuclei that regulate blood pressure.

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“…Neuroanatomical pathways exist between the vestibular and cardiovascular systems of animals 1–3 . Therefore, it is not surprising that engagement of the vestibular system can alter arterial pressure and blood flow.…”

Section: Introductionmentioning

confidence: 99%

“…Neuroanatomical pathways exist between the vestibular and cardiovascular systems of animals. [1][2][3] Therefore, it is not surprising that engagement of the vestibular system can alter arterial pressure and blood flow. Electrical stimulation of the vestibular nerves in animals results in changes in sympathetic activity to different vascular beds.…”

Section: Introductionmentioning

confidence: 99%

The Vestibulosympathetic Reflex In Humans: Neural Interactions Between Cardiovascular Reflexes

Ray

Monahan

2002

Clin Exp Pharmacol Physiol

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1. Over the past 5 years, there has been emerging evidence that the vestibular system regulates sympathetic nerve activity in humans. We have studied this issue in humans by using head-down rotation (HDR) in the prone position. 2. These studies have clearly demonstrated increases in muscle sympathetic nerve activity (MSNA) and calf vascular resistance during HDR. These responses are mediated by engagement of the otolith organs and not the semicircular canals. 3. However, differential activation of sympathetic nerve activity has been observed during HDR. Unlike MSNA, skin sympathetic nerve activity does not increase with HDR. 4. Examination of the vestibulosympathetic reflex with other cardiovascular reflexes (i.e. barorereflexes and skeletal muscle reflexes) has shown an additive interaction for MSNA. 5. The additive interaction between the baroreflexes and vestibulosympathetic reflex suggests that the vestibular system may assist in defending against orthostatic challenges in humans by elevating MSNA beyond that of the baroreflexes. 6. In addition, the further increase in MSNA via otolith stimulation during isometric handgrip, when arterial pressure is elevated markedly, indicates that the vestibulosympathetic reflex is a powerful activator of MSNA and may contribute to blood pressure and flow regulation during dynamic exercise. 7. Future studies will help evaluate the importance of the vestibulosympathetic reflex in clinical conditions associated with orthostatic hypotension.

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Brainstem interneurons necessary for vestibular influences on sympathetic outflow

Cited by 17 publications

References 13 publications

Effects of bilateral vestibular nucleus lesions on cardiovascular regulation in conscious cats

Effects of bilateral vestibular nucleus lesions on cardiovascular regulation in conscious cats

Vestibulo‐Sympathetic Responses

The Vestibulosympathetic Reflex In Humans: Neural Interactions Between Cardiovascular Reflexes

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