Research in Vestibular Science

Original Articles

Pathways of Neurogenic and Humoral Control in the Vestibulosympathetic Reflex of Conscious Rats: Guang Shi Jin, Gyoung Wan Lee, Sang Eon Park, Yuan Zhe Jin, Byung Rim Park; Res Vestib Sci. 2015;14(4):110-116.

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Abstract PDF: 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.

Role of the Cerebral Cortex on Vestibular Compensation Following Unilateral Labyrinthectomy in Rats: Hyun Kwang Ryoo, Seung Bum Yang, Min Sun Kim, Byung Rim Park; Res Vestib Sci. 2015;14(3):75-82.

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Abstract PDF: Objective: The cerebral cortex can modulate vestibular functions through direct control of neuronal activities in the vestibular nuclei. The purpose of this study was to investigate the effect of unilateral cortical lesion or cortical stimulation on static vestibular symptoms and vestibular nuclear activities at the acute stage of vestibular compensation following unilateral labyrinthectomy (UL) in rats.
Methods
The photothrombic ischemic injury using rose bengal was induced in the primary motor cortex or primary sensory cortex, and electrical stimulation was applied to the primary motor cortex, primary sensory cortex, or sencondary sensory cortex, respectively, in unilateral labyrinthectomized rats. Static vestibular symptoms including ocular movement and postural deficits, and expression of c-Fos protein in the medial vestibular nucleus (MVN) were measured.
Results
Lesion of the motor cortex produced a marked postural deficit with paralytic weakness in the hindlimb contralateral to UL. Number of spontaneous nystagmus in animals receiving cortical lesion was significantly increased 2, 6, and 12 hours after UL compared with animals being UL only. Lesion of the primary motor cortex or stimulation of the S2 sensory cortex decreased expression of c-Fos protein in MVN following UL compared with UL only group. Electrical stimulation of S2 sensory areas caused significant reduction of static vestibular symptoms and decreased expression of c-Fos protein in MVN 24 hours following UL.
Conclusion
The present results suggest that cerebral cortex involves in recovery of static vestibular symptoms during vestibular compensation following UL.

Role of the Peripheral Vestibular End Organ in the Expression of c-Fos Protein in the Medial Vestibular Nucleus Following Occlusion of the Anterior Inferior Cerebellar Artery: Nari Kim, Jae Hee Lee, Myoung Ae Choi, Byung Geon Park, Min Sun Kim, Byung Rim Park; Res Vestib Sci. 2012;11(2):51-58.

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Abstract PDF: Background and Objectives: The present study investigated the role of the peripheral vestibular end organ in vestibular symptoms and temporal changes in expression of c-Fos protein in the vestibular nuclei following anterior inferior cerebellar artery (AICA) occlusion using rats with unilateral or bilateral labyrinthectomy. Materials and Methods: Expression of c-Fos protein in the vestibular nuclei was measured 2, 12, 24, and 48 hours after AICA occlusion. Results: Unilateral AICA occlusion significantly induced expression of c-Fos protein bilaterally in the medial, inferior, superior, and lateral vestibular nuclei. Following AICA occlusion, the medial vestibular nucleus (MVN) showed the highest expression of c-Fos protein among the 4 vestibular nuclei. The expression of c-Fos protein was asymmetric between the bilateral MVN, showing higher expression in the MVN contralateral to the side of AICA occlusion compared to the ipsilateral MVN. The degree of asymmetry in c-Fos protein expression between the bilateral MVN peaked 12 hours after AICA occlusion. The expression of c-Fos protein gradually decreased 24 hours after AICA occlusion and returned to control levels 48 hours after AICA occlusion. Unilateral labyrinthectomy significantly decreased expression of c-Fos protein in the MVN ipsilateral to the side of labyrinthectomy following AICA occlusion. Moreover, bilateral labyrinthectomy significantly decreased expression of c-Fos protein in the bilateral MVN flowing AICA occlusion. Conclusion: These results suggest that afferent signals from the peripheral vestibular end organ are crucial to the expression of c-Fos protein in the MVN following AICA occlusion and that expression of c-Fos protein is sustained for 24 hours after AICA occlusion.

C-fos Expression of Vestibular Nucleus in C57BL/6 Mouse Under the 7 Tesla Ultra High Magnetic Field: Mi Joo Kim, Min Joo Jung, Ji Hye Bae, Eun Ji Lee, Duk Hyun Kim, Gyu Cheol Han; Res Vestib Sci. 2011;10(1):26-29.

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Abstract PDF: Background and Objectives: A typical side effect of super high magnetic field is dizziness and it is expected that 7 Tesla (T) super high magnetic field will have temporary influence on vestibular nucleus. Prevalence rate of dizziness generally increases with advancing years, so this study discusses whether the influence of 7 T super high magnetic field differs depending on the age. Materials and Methods: C57BL/6 mice weighting from 10-40 g were categorized into 4-week-old and 16-week-old groups. They were exposed to 7 T magnetic field and immunohistochemical staining was done to observe expression of c-fos protein in vestibular nucleus of mice. Results: Control group with normal vestibular system did not show c-fos protein. However, mice exposed to 7 T magnetic field showed c-fos expression selectively on medial and lateral parts of vestibular nucleus and there was no significant difference of c-fos expression between both sides (p<0.05). There was statistically significant difference between the different age group: 16-week-old mice group showed higher number of cells expressing c-fos protein than 4-week-old mice group did (p<0.05). Conclusion: It is statistically significant that 7 T super high magnetic field is more influential to older age group.

Changes in the Gastrointestinal Motility following Unilateral Labyrinthectomy: Jae Hee Lee, Gyoung Wan Lee, Suck Jun Choi, Eun Ho Park; Res Vestib Sci. 2009;8(1):15-22.

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Abstract PDF: Background and Objectives The temporal changes and the role of glutamate receptors in the recovery of vestibulogastrointestinal symptoms following unilateral labyrinthectomy (UL) were investigated in this study. Vestibulogastrointestinal symptoms were evaluated in terms of gastric emptying and intestinal transit. Materials and Methods Expression of the c-Fos protein was observed in the solitary tract nucleus (STN) and rostral ventrolateral medullary nucleus (RVLM). These were measured at 0.5, 2, 6 and 24 h following UL in rats. Results Gastric emptying and intestinal transit were significantly decreased for 6 h post UL and recovered to control levels within 24 h. Pretreatment of UL animals with MK-801 significantly increased the gastric emptying and intestinal transit. Bilateral labyrinthectomy significantly decreased the gastric emptying and intestinal transit compared to the intact labyrinthine animals but significantly increased when compared to UL animals. The expression of c-Fos protein was significantly increased in STN and RVLM compared to the control animals for 6 h post UL and recovered to control levels within 24 h. The expression was significantly decreased in animals that were pretreated with MK-801. Conclusion These results suggest that UL decreases the gastrointestinal motility, which recovers to control levels within 24 h post UL. Glutamate plays an important role in the recovery of vestibulogastrointestinal symptoms following UL. Key Words: Gastric emptying; c-Fos protein; Glutamate; Gastrointestinal Motility; Unilateral labyrinthectomy

Role of the Peripheral Vestibular System on Neuroplasticity Induced by Hypergravity Stimulation: Jae Hyo Lee, Gyoung Wan Lee, Han Su Park, Jae Hee Lee, Dong Ok Choi, Myoung Ae Choi, Byung Rim Park; J Korean Bal Soc. 2006;5(2):213-223.

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Abstract PDF: Background
and Objectives: Altered environmental gravity, including both hypo- and hypergravity, may result in space adaptation syndrome. To explore the characteristics of this adaptive plasticity, the expression of immediate early gene c-fos mRNA in the vestibular system following an exposure to hypergravity stimulus was determined in rats. Materials and Method: The animals were subjected to 2 G force (two-fold earth's gravity) stimulus for 3 hours, and were examined at post-stimulus hours 0, 2, 6, 12, and 24. Real time reverse transcription-polymerase chain reaction (RT-PCR) was adopted to analyze temporal changes in the expression of c-fos mRNA.
Results
The hypergravity stimulation produced the expression of c-fos mRNA in the vestibular ganglion, medial vestibular nucleus, inferior vestibular nucleus, hippocampus, vestibulocerebellum, and vestibular cortex. The peak expression occurred at hour 6 in the animals hypergravity-stimulated for 3 hours. Bilateral labyrinthectomy significantly attenuated the degree of up-regulation in c-fos mRNA expression. MK-801, an NMDA receptor antagonist, also significantly attenuated the degree of up-regulation in c-fos mRNA expression.
Conclusion
These results indicate that the adaptive neuroplasticity in response to an altered gravity occurs in the vestibular-related organs in the central nervous system, in which peripheral vestibular receptors and NMDA receptors play an important role. Key Words : Hypergravity, Neuronal plasticity, Vestibule, c-fos gene

Effect of Ginkgo biloba on Expression of c-Fos Protein in the Vestibular Nuclear Complex following Unilateral Labyrinthectomy in Rats: Dong Ok Choi, Sun Kyung Kim, Myung Ae Choi, Moon Young Lee, Min Sun Kim, Eun Ho Park, Byung Rim Park; J Korean Bal Soc. 2003;2(2):163-169.

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Abstract PDF: Background
and Objectives: The neuroprotective effect of Ginkgo biloba has been demonstrated in several in vivo and in vitro models. The effect of Ginkgo biloba on vestibular compensation following unilateral labyrinthectomy (UL) was investigated. Material and Methods: Spontaneous nystagmus and c-Fos protein expression were measured following UL in Sprague-Dawley rats with pretreatment of Ginkgo biloba (50 mg/kg, i.p.).
Results
After pretreatment with Ginkgo biloba (50 mg/kg, i.p.) expression of c-Fos protein in the vestibular nuclear complex and frequency of spontaneous nystagmus were measured till 24 hours after UL. UL produced spontaneous nystagmus with frequency of 124±2.2 beats/min at post-op 2 hrs and 70±3.1 beats/min at post-op 24 hrs. Pretreatment with Ginkgo biloba significantly decreased the frequency of spontaneous nystagmus till post-op 24 hrs compared to control group (p<0.05). UL produced marked expression of c-Fos protein in bilateral medial vestibular nucleus, inferior vestibular nucleus, and superior vestibular nucleus, and the number of expression was significantly higher in contralateral vestibular nuclei to the lesion than ipsilateral vestibular nuclei at post-op 2 hrs (p<0.01). The number of c-Fos protein expression was decreased with time and significantly higher in ipsilateral vestibular nuclei than contralateral ones at post-op 24 hrs (p<0.01). Pretreatment with Ginkgo biloba significantly decreased the number of c-Fos protein expression following UL (p<0.01) and abolished the asymmetry of c-Fos protein expression in bilateral vestibular nuclei at post-op 24 hrs.
Conclusion
These results suggest that Ginkgo biloba may facilitate vestibular compensation following UL through modulation of neurotransmitters and neuroprotective effects.

Spatio-temporal Changes on c-Fos Protein Expression in the Brain Stem Nuclei following Arsanilate-induced Unilateral Labyrinthectomy in Rats: Jae Hyo Kim, Chang Ig Choi, Moon Young Lee, Min Sun Kim, Byung Soo Soh, Eun Ho Park, Byung Rim Park; J Korean Bal Soc. 2003;2(1):86-94.

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Abstract PDF: Spatio-temporal changes on c-Fos protein expression were investigated in vestibular compensation following unilateral labyrinthectomy (UL) induced by injection of arsanilate into the middle ear cavity, chemical labyrinthectomy, or surgical labyrinthectomy in medial vestibular nuclei (MVN), prepositus hypoglossal nuclei (PrH), and inferior olivary nuclei (ION) of Sprague-Dawley rats. Number of spontaneous nystagmus in surgical labyrinthectomy group was 28.2±1.2 beats/10 sec at post-op 2 hs and the nystagmus disappeared 76 hs after UL. In chemical labyrinthectomy group, spontaneous nystagmus occurred 6 hs after UL and increased up to maximum at 12 hs and disappeared 96 hs. Head deviation in surgical labyrinthectomy group reached a peak at post-op 2 hs and recovered to control level at 144 hs, but chemical labyrinthectomy produced head deviation 24 hs after UL and increased degree of the deviation over time till 144 hs. Expression of c-Fos protein in surgical labyrinthectomy group at post-op 2 hs was 81±19.4 cells in ipsilateral MVN to the lesion side and 212±60 cells in contralateral MVN, which showed severe asymmetry between bilateral MVN, and decrease of c-Fos protein expression was more in contralateral MVN than in ipsilateral MVN at 6 hs. Chemical labyrinthectomy expressed more c-Fos protein in contralateral MVN 6 hs after UL and in ipsilateral MVN 12 hs after UL, which showed asymmetry of c-Fos protein expression between bilateral MVN. And the expression in ipsilateral MVN of chemical labyrinthectomy group was increased gradually 48 hs after UL and reached a peak at 72 hs. In chemical labyrinthectomy group, expression of c-Fos protein in PrH was increased more in ipsilateral than in contralateral 6 hs after UL and more in contralateral 12 hs after UL, and ION showed more expression of c-Fos protein in contralateral than in ipsilateral 6 hs after UL through 72 hs. These results suggest that the course of vestibular compensation and the temporal expression of c-Fos protein in the brain stem nuclei following UL differed between surgical and chemical labyrinthectomy.

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