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Expression of Metabotropic Glutamate Receptors in the Medial Vestibular Nucleus Following Acute Hypotension in Rats
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Myoung Ae Choi, Nari Kim, Sang Eon Park, Byung Geon Park, Min Sun Kim, Byung Rim Park
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Res Vestib Sci. 2012;11(4):131-137.
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 Abstract
- Background and Objectives: Acute hypotension induces expression of c-Fos protein and phosphorylated extracellular signal-regulated kinase (pERK), and glutamate release in the vestibular nuclei. Expression of c-Fos protein and pERK is mediated by the excitatory neurotransmitter, glutamate. In this study, the signaling pathway of glutamate in the vestibular nuclei following acute hypotension was investigated. Materials and Methods: Expression of metabotropic glutamate receptors (mGluRs) was measured by Western blotting in the medial vestibular nucleus following acute hypotension in rats. Results: Expression of pGluR1 Ser831, a subtype of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, peaked at 30 minutes after acute hypotension insult, and expression of pNR2B, a subtype of N-methyl-D-aspartate (NMDA) receptors, peaked at 2 hours after acute hypotension insult. Acute hypotension induced expression of Homer1a and group I mGluR in the medial vestibular nucleus. Expression of mGluR1 and mGluR5 peaked at 6 hours following acute hypotension insults. Conclusion: These results suggest that afferent signals from the peripheral vestibular receptors, resulting from acute hypotension insult, are transmitted through group I mGluRs as well as AMPA and NMDA receptors in the vestibular system.
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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
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Nari Kim, Jae Hee Lee, Myoung Ae Choi, Byung Geon Park, Min Sun Kim, Byung Rim Park
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Res Vestib Sci. 2012;11(2):51-58.
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Abstract
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- 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.
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Expression of Glutamate Receptors in the Medial Vestibular Nuclei following Acute Hypotension
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Jae Hee Lee, Myoung Ae Choi, Dong Ok Choi, Bo Kyoung Kim, Seok Min Hong, Byung Rim Park
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J Korean Bal Soc. 2007;6(1):29-35.
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Abstract
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- Acute hypotension induced excitation of electrical activities and expression of c-Fos protein and pERK in the vestibular nuclei. In this study, to investigate the excitatory signaling pathway in the vestibular nuclei following acute hypotension, expression of NR2A and NR2B subunits of glutamate NMDA receptor and GluR1 subunit of glutamate AMPA receptor was determined by RT-PCR and Western blotting in the medial vestibular nucleus 30 min after acute hypotension in rats. Acute hypotension increased expression of NR2A, NR2B, and pGluR1 in the medial vestibular nuclei. These results suggest that both of NMDA and AMPA glutamate receptors take part in transmission of excitatory afferent signals following acute hypotension.
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Role of the Peripheral Vestibular System on Neuroplasticity Induced by Hypergravity Stimulation
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Jae Hyo Lee, Gyoung Wan Lee, Han Su Park, Jae Hee Lee, Dong Ok Choi, Myoung Ae Choi, Byung Rim Park
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J Korean Bal Soc. 2006;5(2):213-223.
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Abstract
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- 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
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Immunohistochemical Identification of Phosphorylated Extracellular Signal-Regulated Kinase1/2 in Rat Vestibular Nuclei by Unilateral Labyrinthectomy
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Myoung Ae Choi, Dong Ok Choi, Kwang Yong Kim, Moon Young Lee, Byung Rim Park, Min Sun Kim
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J Korean Bal Soc. 2003;2(2):170-174.
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Abstract
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- This study evaluated the expression of phosphorylated signal-regulated kinase1/2 (pERK1/2), which is one of the main factors regulating transcription of the cfos oncogene in neurons, in the vestibular nuclei of Sprague-Dawley rats following unilateral labyrinthectomy (UL). Surgical UL was performed to eliminate afferent signals from the peripheral vestibular receptors in the inner ear, under a surgical microscope, 2 hours after anesthesia. Significant numbers of pERK1/2 immunoreactive neurons were seen in the superior, medial, and inferior vestibular nuclei. There were more pERK1/2 immunoreactive cells in the vestibular nuclei contralateral than in the vestibular nuclei ipsilateral to the injured labyrinth, which resulted in significant asymmetric expression of pERK1/2 immunoreactive cells. Subsequently, the pERK1/2 immunoreactivity decreased rapidly, disappearing 90 min after labyrinthectomy. No pERK1/2 labeling was seen in the lateral vestibular nucleus. These results suggest that intracellular signal pathways for the activation of extracellular signal-regulated kinase in the vestibular nuclei are involved in lesion-neural plasticity in the vestibular system.
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Effect of vestibular end-organs on expression of cFos and FosB injury in the hippocampal formation of rats
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Min Sun Kim, Myoung Ae Choi, Dong Ok Choi, Byung Gon Cho, Yuan Zhe Jin, Jae Hyo Kim, Davy Kry, Byung Rim Park
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J Korean Bal Soc. 2002;1(2):223-234.
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Abstract
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- It is well known that the hippocampal formation requires primary vestibular sensory information to generate spatial memory during self motion in human. The purpose of the present study was to evaluate the effect of unilateral deafferentation of vestibular sensory information on cFos and FosB proteins, a family of immediate early gene-related proteins known as metabolic marker for neural excitation in the hippocampal formation of rats. Adult Sprague-Dawley rats weighing 250 - 300 g were surgically ablated of the peripheral vestibular system in the inner ear and sacrificed at 2, 6, 24, 48, 72 hours after surgical operation. Immunohistochemical staining and Western blot method were adapted to see change in expression of cFos and FosB proteins in the hippocampal formation. A significant change of Fos B immunoreactivity was observed in granular cell layer of the dentate gyrus, CA1 subfield of the hipocampus at 2 hours after unilateral labyrinthectomy. Thereafter, the number of FosB like immunoreactive neurons in these areas increased rapidly, peaked at 48 hours post operatively time. Western blot for FosB protein supported further time-dependent change of FosB revealed by immunohistochemical staining. In addition, granular cell layer showed more significant expression of FosB LI neurons in the caudal dentate gyrus than the rostral one. In contrast, moderate number of cFos LI neurons was detected in polymorphic cell layer of the dentate gyrus, pyramidal cell layer of CA1, and subiculum but not in granular cell layer of the dentate gyrus at 2 hours after labyrinthectomy. The number of cFos LI neurons in the hippocampal formation was rapidly decreased at 6 hours and then returned to basal value 24 hours after operation. These results suggest that unilateral ablation of the peripheral vestibular sensory information elicit spatio-temporal differences of cFos and FosB expressions in the hippocampal formation of rats.
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