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Pathways of Neurogenic and Humoral Control in the
Vestibulosympathetic Reflex of Conscious Rats
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Guang Shi Jin, Gyoung Wan Lee, Sang Eon Park, Yuan Zhe Jin, Byung Rim Park
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Res Vestib Sci. 2015;14(4):110-116.
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 Abstract
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- Objective: The vestibular system contributes control of blood pressure during postural
changes through the vestibulosympathetic reflex. In the vestibulosympathetic reflex,
afferent signals from the peripheral vestibular receptors are transmitted to the vestibular
nuclei, rostral ventrolateral medullary nuclei, and then to the intermediolateral cell
column of the thoracolumbar spinal cord. Physiological characteristics of the vestibulosympathetic
reflex in terms of neurogenic and humoral control of blood pressure
were investigated in this study.
Methods
Conscious rats with sinoaortic denervation were used for removal of
baroreceptors in reflex control of blood pressure, and hypotension was induced by
intravenous infusion of sodium nitroprusside (SNP). Expression of c-Fos protein was
measured in the medial vestibular nuclei (MVN), rostral vestrolateral medullary nuclei
(RVLM), and intermediolateral cell column (IMC) in T4-7, and levels of blood
epinephrine were measured following SNP-induced hypotension.
Results
SNP-induced hypotension significantly increased expression of c-Fos protein
in the MVN, RVLM, and IMC, also significantly increased level of blood epinephrine
compared to normotensive control animals.
Conclusion
These results suggest that the vestibulosympathetic reflex regulates blood
pressure through neurogenic control including MVN, RVLM, and IMC, also through
humoral control including epinephrine secretion by the adrenal medulla following
SNP-induced hypotension. The physiological characteristics of the reflex may contribute
to basic treatment of impairment of blood pressure control during postural changes.
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Role of Central Vestibular Pathway on Control of Blood Pressure During Acute Hypotension in Rats
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Yuan Zhe Jin, Guang Shi Jin, Min Sun Kim, Byung Rim Park
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J Korean Bal Soc. 2005;4(2):189-200.
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Abstract
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- Background
and Objectives: Central role of the vestibular system on control of blood pressure and interrelationships between the vestibular nucleus and solitary nucleus during acute hypotension were investigated in bilateral labyrinthectomized (BLX) or sinoaortic denervated (SAD) rats. Changes of electrical activity in the medial vestibular nucleus (MVN), solitary tract nucleus (STN), and rostral ventrolateral medullary nucleus (RVLM) were investigated in rats in while acute hypotension was induced by sodium nitroprusside (SNP).
Results
Evoked potential in MVN neuron caused by electrical stimulation of the peripheral vestibular system was composed of 3 waves with latencies of 0.48±0.10 ms, 1.04±0.09 ms and 1.98±0.19 ms. Electrical stimulation to MVN or RVLM increased blood pressure. MVN at the induction of acute hypotension showed excitation in 61% of type I neurons and inhibition in 68% of type II neurons. In STN, acute hypotension produced excitation in 62.1% of neurons recorded in intact abyrinthine animals, inhibition in 72.3% of neurons recorded in BL animals, and excitation in 60% of recorded neurons in SAD animals. In RVLM, acute hypotension produced excitation in 66.7% of neurons recorded in intact labyrinthine animals and inhibition in 64.9% of neurons recorded in BL animals. In spatial distribution of STN neurons responded to acute hypotension, excitatory responses were mainly recorded in rostral and ventral portion, and inhibitory responses were mainly recorded in caudal and lateral portion. In RVLM, excitatory responses were mainly recorded in rostral and dorsomedial portion, and inhibitory responses were mainly recorded in caudal and ventrolateral portion.
Conclusion
These results suggest that afferent signals from the peripheral vestibular receptors are transmitted to STN through the vestibular nuclei and assist to the baroreceptors for controlling blood pressure following acute hypotension.
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