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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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