Expression of Metabotropic Glutamate Receptors in the Medial Vestibular Nucleus Following Acute Hypotension in Rats / 대한평형의학회지

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 alpha-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.

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 / 대한평형의학회지

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.

The Effects of Glutamate NMDA Receptor Antagonist MK-801 on Gastrointestinal Motility after Middle Cerebral Artery Occlusion in Rats

This study was performed to investigate the role of glutamate neurotransmitter system on gastrointestinal motility in a middle cerebral artery occlusion (MCAO) model of rats. The right middle cerebral artery was occluded by surgical operation, and intestinal transit and geometric center as a parameter of gastrointestinal motility and expression of c-Fos protein in the insular cortex and cingulate cortex were measured at 2 and 12 h after MCAO. Intestinal transit was 66.3+/-7.5% and 62.3+/-5.7% 2 and 12 h after sham operation, respectively, and MCAO significantly decreased intestinal transit to 39.0+/-3.5% and 47.0+/-5.1% at 2 and 12 h after the occlusion, respectively (p<0.01). The geometric center was 5.6+/-0.4 and 5.2+/-0.9 at 2 and 12 h after sham operation, respectively, and MCAO significantly decreased geometric center to 2.9+/-0.8 and 3.0+/-0.3 at 2 and 12 h after the occlusion, respectively (p<0.01). In control animals, injection of atropine decreased intestinal transit to 35.9+/-5.2%, and injection of glutamate NMDA receptor antagonist, MK-801, decreased intestinal transit to 28.8+/-9.5%. Pretreatment with MK-801, a glutamate NMDA receptor antagonist, in the MCAO group decreased intestinal transit to 11.8+/-3.2%, which was significantly decreased compared to MCAO group (p<0.01). MCAO markedly increased the expression of c-Fos protein in the insular cortex and cingulate cortex ipsilateral to the occlusion 2 h after MCAO, and pretreatment with MK-801 produced marked reduction of c-Fos protein expression compared to MCAO group (p<0.01). These results suggest that modulation of gastrointestinal motility after MCAO might be partially mediated through a glutamate NMDA receptor system.

Expression of Glutamate Receptors in the Medial Vestibular Nuclei following Acute Hypotension

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.

Role of the Peripheral Vestibular System on Neuroplasticity Induced by Hypergravity Stimulation

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.

Expression of Phosphorylated ERK1/2 and cFos Proteins in Vestibular Nuclei by Selective Stimulation of Horizontal Semicircular Canal

BACKGROUND: There is a little information about the effect of selective vestibular stimulation on the expression of activity-dependent metabolic markers in the vestibular nuclei. The purpose of this study was to evaluate effect of afferent excitation of the horizontal semicircular canal on expression of phosphorylated ERK1/2 (pERK1/2) and cFos proteins in the vestibular nuclei. METHODS: The horizontal semicircular canal of Sprague-Dawley rats was selectively stimulated by using the sinusoidal horizontal stimulator with 10-minute duration of stimulation. Conventional immunohistochemical method was used to visualize pERK1/2 or cFos immunoreactive neurons in the vestibular nuclei following rotation. RESULTS: Five minutes after stimulation of the horizontal semicircular canal there was a high expression of pERK1/2 protein in the medial vestibular nucleus among 4 major subnuclei of the central vestibular nuclear complex. On the contrary, immunoreactivity of cFos protein was observed in the medial and inferior vestibular nucleus 2 hours after horizontal sinusoidal rotation. The lateral vestibular nucleus was free from the expression of pERK1/2 and cFos proteins in response to excitation of the horizontal semicircular canal. However, in the vestibular nuclei of unilaterally labyrinthectomized rats expression of pERK and cFos proteins was markedly suppressed in ipsi-lesional side as well as contra-lesional side following stimulation of the horizontal semicircular canal. Furthermore no expression of pERK1/2 and cFos protein in the bilateral vestibular nuclei of bilaterally labyrinthectomized rats was noted after stimulation of the horizontal semicircular canal. CONCLUSIONS: Therefore these results of present study suggest that excitatory afferent signals from the peripheral vestibular receptors are essential for protein translation for pERK1/2 and cFos in response to stimulation of the semicircular canal.

Activation of Vestibular Neurons Projecting to Autonomic Brain Stem Nuclei Following Acute Hypotension in Rats

Extracellular regulated protein kinase1/2 (pERK1/2) is one of the major regulatory factors for transcription of the c-fos oncogene in neurons. The purpose of this study was to evaluate the expression of phosphorylated ERK1/2 within the vestibular nuclei (VN) of rats following acute arterial hypotension. Following the acute arterial hypotension induced by rapid hemorrhage, a significant number of pERK1/2-immunoreactive neurons appeared bilaterally in the caudal aspect of the medial and inferior VN. No labeling of pERK1/2 was observed in the lateral VN. The peak expression of pERK1/2 in these nuclei occurred within 5 min after hemorrhage. However, in bilaterally labyrinthectomized rats, the appearance of pERK1/2-immunoreactive neurons was eliminated in the VN. Western blot confirmed the effect of bilateral labyrinthectomy on pERK1/2 protein expression in the medial vestibular nucleus 5 min after hemorrhage. These results suggest that, following acute hypotension, afferent signals from the peripheral vestibular receptors are required for activation of ERK 1/2 in the VN.

Activation of Vestibular Neurons Projecting to Autonomic Brain Stem Nuclei Following Acute Hypotension in Rats

The purpose of the present study was to elucidate the possible involvement of the medial vestibular nucleus (MVN) and inferior vestibular nucleus (IVN) following acute hypotension in the vestibulo- autonomic reflex through vestibulosolitary or vestibuloventrolateral projections. Acute hypotension- induced cFos expression was assessed in combination with retrograde cholera toxin B subunit (CTb) tract tracing. After injection of CTb into the solitary region, CTb-labeled neurons were located prominently around the lateral borders of the caudal MVN and medial border of the IVN. The superior vestibular nucleus also had a scattered distribution of CTb-labeled neurons. After injection of CTb toxin into the unilateral VLM, the distributions of CTb-labeled neurons in the MVN and IVN were similar to that observed after injection into the solitary region, although there were fewer CTb-labeled neurons. In the caudal MVN, about 38% and 13% of CTb-labeled neurons were double-labeled for cFos after injection of CTb into the solitary region and the VLM, respectively. In the IVN, 14% and 7% of CTb-labeled neurons were double-labeled for cFos after injection of CTb into the solitary region and the VLM, respectively. Therefore, the present study suggests that acute arterial hypotension may result in activation of vestibulosolitary pathways that mediate behavioral and visceral reflexes, and vestibuloventrolateral medullary pathways that indirectly mediate vestibulosympathetic responses.

Expression of Immediate-Early Gene Proteins by Transient Occlusion of Anterior Inferior Cerebellar Artery in Vestibular Nuclei of Sprague-Dawley Rats

BACKGROUND: Anterior cerebellar artery (AICA) occlusion results in vestibular dysfunctions because the AICA supplies the vestibular nuclei (VN) in the brain stem as well as the peripheral vestibular organs in the inner ear. The purpose of this study was to evaluate the expression of immediate-early gene products, a metabolic marker of neural excitation in neurons, by AICA occlusion in the VN of Sprague-Dawley rats. METHODS: After chloral hydrate anesthesia all animals were subjected to unilateral AICA occlusion by using a microsurgical clamp for 30 min to induce a transient ischemia. Unilateral labyrinthectomy was chemically undertaken to eliminate vestibular afferent activity. Immunohistochemical staining and image analysis for cFos, FosB, Krox-24, and JunB proteins were performed 2 hours after AICA occlusion. RESULTS: There was a high expression of cFos protein in the bilateral medial and inferior VN 2 hours after AICA occlusion. AICA occlusion induced minimal changes in cFos protein expression in the lateral and superior VN. Mild to moderate expressions of FosB and JunB protein in VN was observed 2 hours after ischemic injury of the brain stem and inner ear. On the contrary, the number of cFos and FosB immunoreactive neurons significantly decreased in the medial vestibular nucleus ipsilateral to the injured labyrinth 2 hours after AICA occlusion in the UL group. CONCLUSIONS: These results suggest that ischemic afferent activity from the peripheral vestibular apparatus is essential for the expression of immediate-early gene products in the medial and inferior VN of rats following AICA occlusion.

Expression of mRNA for Monocyte Chemoattractant Protein-1 in the Sciatic Nerve and Hindlimb Muscle Following Denervation

Migration of inflammatory cells into damaged tissue is essential to host defense mechanisms and immune responses. Monocyte chemoattractant protein-1(MCP-1), a member of the CC or beta-chemokine family is a powerful leukocyte recruitment factor that is relatively specific for monocyte/macrophage. The purpose of present study was to evaluate temporal change of expression of mRNA for MCP-1 in the sciatic nerve and hindlimb muscle of Sprague-Dawley rat. The mid-portion of the sciatic nerve was exposed, cut under aseptic condition and then animals were sacrificed 1, 2, 3, 7, 14 days after denervation of the sciatic nerve. Semiquantitative RT-PCR method and image analysis system were used to analyze change in expression of mRNA for MCP-1. Expression of mRNA for MCP-1 in the distal stump of the denervated sciatic nerve was up-regulated within 1 day and peaked on the second day following transection of the sciatic nerve. Thereafter high expression of mRNA for MCP-1 lasted for 7 days after transection of the nerve. However the expression of mRNA for MCP-1 was rapidly decreased on the 14th day after denervation. Temporal change of expression of mRNA for MCP-1 in the proximal portion of the denervated sciatic nerve was very similar with that of distal one. The gastrocnemius muscle also showed significant increase in expression of mRNA for MCP-1 on the 1st day with maximal expression on the 7th day after denervation of the sciatic nerve. In contrast, the expression of mRNA for MCP-1 in the soleus muscle was lower than the gastrocnemius muscle in the course of the denervation-induced atrophy. Additionally alpha-lipoic acid, a potent antioxidant that is used in treatment for diabetic neuropathy, suppressed significantly expression of mRNA for MCP-1 in the denervated sciatic nerve but not in atrophied hindlimb muscles.

Immunohistochemical Identification of Phosphorylated Extracellular Signal-Regulated Kinase1/2 in Rat Vestibular Nuclei by Unilateral Labyrinthectomy

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

Effect of vestibular end-organs on expression of cFos and FosB injury in the hippocampal formation of rats

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.

Expertise in ICU Nursing: A Qualitative Approach / 간호학회지

The purpose of this research was to uncover the expertise of ICU nursing in Korea, and to describe nurses' practice based on the degree of skill acquisition. A total of 18 ICU nurses participated in the study. The data was collected through individual in-depth interviews and it was managed using the NUDIST 4.0 software program. The data was analyzed using interpretive phenomenology suggested by Benner. Four properties of expertise of ICU nursing were identified. These are 1) concern and love toward patients; 2) knowledge; 3) skill, and 4) abilities in interpersonal relationships. And the characterisitcs of four levels of skill acquisition, that is advanced beginner, competent, proficient, and expert, were described with exemplars. The results of this study might help nurse researchers clarify and elaborate on the concept of expertise in ICU nursing, and enable them to understand how the process of skill acquisition occurs in the ICU setting. They might also help nurse managers establish educational goals for ICU nursing for student or novice nurses.

A study on the change of limb muscle atrophy by the period of limited activities following the heart surgery in congenital heart disease children / 아동간호학회지

In order to investigate the effects of a decreased activity on skinfold thickness, circumference and muscle strength of the extremities during the recovery period following heart surgery, skinfold thinkness, circumference and muscle strength of the extremities were measured on days 0, 3, 6, and 9 following the surgery, and compared with those on the arrival day of intensive care unit. Skinfold thickness was measured using a skinfold caliper(Saehan Cor., Korea), circumference of the limbs were measured with a tape measure, upper extremity strength was determined using the Takeigrip dyanmometer and lower extremity strength was measured by pressing the flatfoot on an electronic digital health meter while lying on a bed. Results from this study were thus : 1. Skinfold thickness of triceps, quadriceps and gastrocnemius muscle on days 3, 6, 9 following the heart surgery was not significantly different from that of on the day of operation. 2. Circumference of midupperarm and midthigh on days 3, 6, 9 following the heart surgery was not significantly different from that of on the day of operation. Circumference of midcalf on days 3, 6 following the heart surgery was not significantly different from that of on the day of operation, while that of midcalf on day 9 following the surgery decreased significantly compared with that of on the day of operation. 3. Muscle strength of the upper extremity was not significantly different from that of on the day of operation, while that of the lower extremity of day 9 following the surgery decreased significantly compared with that of on the day of operation. From these results, it may be concluded that circumference and muscle strength of lower extremity can be decreased due to the postoperative inactivity following heart surgery in congenital heart disease children.