Systemic injection of an H4 receptor agonist induces a decrease in CREB and pCREB levels in the cerebellar vermis and prefrontal cortex in mice

Studies have shown that an injection with the histamine H4 receptor agonist VUF-8430 modulates emotional memory processes. In the present study, the aim was to verify if intraperitoneal (ip) injection of VUF-8430 (500 ng/kg) in mice affects the synthesis of proteins required for memory consolidation processes by activating the phosphorylation of CREB (pCREB) in classical structures linked to emotional memory (prefrontal cortex, amygdala, and hippocampus) and the cerebellar vermis, a structure that has also been recently implicated in emotional memory. The results obtained using western blot analysis demonstrated that VUF-8430 induced a decrease in CREB and pCREB levels in the cerebellar vermis and prefrontal cortex, suggesting that this dose impaired the activation of cell signaling pathways in these structures. There was no change in protein expression in the amygdala and hippocampus. Our results are preliminary, and further investigations are needed to investigate the role of the H4 receptors in the central nervous system.

Based on cAMP-CREB-BDNF pathway to explore mechanism of antidepressant effect of Bupleuri Radix and Paeoniae Alba Radix drug pair / 中草药

Objective To investigate the antidepressant effect of Bupleuri Radix and Paeoniae Alba Radix drug pair based on the cAMP-CREB-BDNF pathway. Methods The rat depression model was established by CUMS. The contents of cAMP, p-CREB, BDNF, and PDE4 in rat hippocampal and cAMP levels in rat plasma were determined by ELISA. The expression of BDNF mRNA in hippocampus, hypothalamus, and cortex were measured by RT-PCR. Results Compared with the model group, the positive drug group and Bupleuri Radix and Paeoniae Alba Radix drug pair can reverse the cAMP content in the hippocampus and plasma and the decreased contents of CREB and BDNF in the rat hippocampus. At the same time, the positive drug group, Bupleuri Radix, and Paeoniae Alba Radix can increase the expression of BDNF mRNA in hippocampus, cortex, and hypothalamus of rats. Conclusion The Bupleuri Radix and Paeoniae Alba Radix drug pair has obviously antidepressant effect on CUMS rat model, which can achieve antidepressant effect by regulating cAMP-CREB-BDNF pathway.

Effects of DNMT1-siRNA on the pain behavior and the expression of SOCS1,p-ERK,p-CERB in CCI rats / 临床麻醉学杂志

Objective To investigate the effects of DNMT1 on neuropathic pain behavior and neuropathic pain modulation.Methods Thirty-two male SD rats, weighing 200-250 g, were randomly assigned into 4 groups (n =8 each):sham operation group (group S),chronic constrictive injury group (group CCI),CCI+ DNMT1-siRNA group (group CDS),CCI+ control-siRNA group (group CCS).Group CDS were intrathcally injected of DNMT1-siRNA (2 μg/10 μl),and group CCS were intrathcally injected of control-siRNA 7,8,9 days after operation.Mechanical withdrawal threshold (MWT)and thermal withdrawal latency (TWL)were measured before operation and on day 3,5,7,9,12,14 after operation.The rats were then sacrificed and L4-L6 segments of the spinal cord were removed for determination of SOCS1,p-ERK,p-CREB expression using Western blot on day 14.Results Compared with group S,MWT and TWL in group CCI and CCS were significantly decreased on day 3,5,7,9,12,14 after operation (P <0.05).Compared with group CCS,MWT and TWL in group CDS were significantly increased on day 9,12,14 after operation (P < 0.05 ). Compared with group S and CDS,SOCS1 was significantly downregulated,p-ERK and p-CREB were significantly upregulated in group CCI and CCS (P <0.05 ).Conclusion Intrathcal injection of DN-MT1-siRNA significantly relieves neuropathic pain by upregulating SOCS1,downregulating p-ERK and p-CREB in rats spinal cords.

Change of MicroRNA-134, CREB and p-CREB expression in epileptic rat

Objective: To To investigate the changes of MicroRNA-134, CREB and p-CREB expression in epileptic rat brains in order to elucidate the molecular mechanisms of epilepsy, providing new ideas for clinical treatment. Methods: Sixty-four Spraque-Dawley (SD) rats were divided into groups randomly, including control group, six hours after seizure group, 24-hour group, three-day group, one-week group, two-week group, four-week group, and eight-week group. All groups were placed under a pilocarpine-induced epilepsy model except the control group, and all rats were decapitated in different points of time. Brain specimens were taken for quantitative PCR experiments, immunohistochemistry and Western blot experiments. The results of the epilepsy model groups and the control group were compared. Results: There were no significant differences between the six hours after seizure group, the 24-hour group and the control group about the MicroRNA-134 levels. MicroRNA-134 in the hippocampus tissue of the three-day group significantly reduced compared with the control group; same result was observed with the one-week, two-week, four-week and eight-week groups. The CREB and p-CREB levels in the three-day group’s rat hippocampus significantly increased compared with the control group; and the high levels of CREB and p-CREB were constantly maintained in the one-week, two-week, four-week and eight-week groups. Conclusions: The MicroRNA-134 level of the epileptic rat hippocampus is significantly lower than normal after three days, and continues to maintain a low level; while CREB and p-CREB levels are rsignificantly increased after three days, and continue to remain at a high level. MicroRNA-134 plays a role in inhibiting synaptic plasticity by inhibiting CREB and p-CREB expressions.

Change of MicroRNA-134, CREB and p-CREB expression in epileptic rat

OBJECTIVE@#To To investigate the changes of MicroRNA-134, CREB and p-CREB expression in epileptic rat brains in order to elucidate the molecular mechanisms of epilepsy, providing new ideas for clinical treatment.@*METHODS@#Sixty-four Spraque-Dawley (SD) rats were divided into groups randomly, including control group, six hours after seizure group, 24-hour group, three-day group, one-week group, two-week group, four-week group, and eight-week group. All groups were placed under a pilocarpine-induced epilepsy model except the control group, and all rats were decapitated in different points of time. Brain specimens were taken for quantitative PCR experiments, immunohistochemistry and Western blot experiments. The results of the epilepsy model groups and the control group were compared.@*RESULTS@#There were no significant differences between the six hours after seizure group, the 24-hour group and the control group about the MicroRNA-134 levels. MicroRNA-134 in the hippocampus tissue of the three-day group significantly reduced compared with the control group; same result was observed with the one-week, two-week, four-week and eight-week groups. The CREB and p-CREB levels in the three-day group's rat hippocampus significantly increased compared with the control group; and the high levels of CREB and p-CREB were constantly maintained in the one-week, two-week, four-week and eight-week groups.@*CONCLUSIONS@#The MicroRNA-134 level of the epileptic rat hippocampus is significantly lower than normal after three days, and continues to maintain a low level; while CREB and p-CREB levels are rsignificantly increased after three days, and continue to remain at a high level. MicroRNA-134 plays a role in inhibiting synaptic plasticity by inhibiting CREB and p-CREB expressions.

Change of MicroRNA-134, CREB and p-CREB expression in epileptic rat

Objective: To To investigate the changes of MicroRNA-134, CREB and p-CREB expression in epileptic rat brains in order to elucidate the molecular mechanisms of epilepsy, providing new ideas for clinical treatment. Methods: Sixty-four Spraque-Dawley (SD) rats were divided into groups randomly, including control group, six hours after seizure group, 24-hour group, three-day group, one-week group, two-week group, four-week group, and eight-week group. All groups were placed under a pilocarpine-induced epilepsy model except the control group, and all rats were decapitated in different points of time. Brain specimens were taken for quantitative PCR experiments, immunohistochemistry and Western blot experiments. The results of the epilepsy model groups and the control group were compared. Results: There were no significant differences between the six hours after seizure group, the 24-hour group and the control group about the MicroRNA-134 levels. MicroRNA-134 in the hippocampus tissue of the three-day group significantly reduced compared with the control group; same result was observed with the one-week, two-week, four-week and eight-week groups. The CREB and p-CREB levels in the three-day group's rat hippocampus significantly increased compared with the control group; and the high levels of CREB and p-CREB were constantly maintained in the one-week, two-week, four-week and eight-week groups. Conclusions: The MicroRNA-134 level of the epileptic rat hippocampus is significantly lower than normal after three days, and continues to maintain a low level; while CREB and p-CREB levels are rsignificantly increased after three days, and continue to remain at a high level. MicroRNA-134 plays a role in inhibiting synaptic plasticity by inhibiting CREB and p-CREB expressions.

Predominant D1 Receptors Involvement in the Over-expression of CART Peptides after Repeated Cocaine Administration

The aim of this study was to investigate the involvement of dopaminergic receptors (DR) in behavioral sensitization, as measured by locomotor activity, and the over-expression of cocaine- and amphetamine-regulated transcript (CART) peptides after repeated administration of cocaine in mice. Repeated administrations of cocaine induced behavioral sensitization and CART over-expression in mice. The levels of striatal CART mRNA were significantly increased on the 3rd day. CART peptides were over-expressed on the 5th day in the striata of behaviorally sensitized mice. A higher proportion of CART+ cells in the cocaine-treated mice were present in the nucleus accumbens (NAc) shell than in the dorsolateral (DL) part of caudate putamen (CP). The concomitant administration of both D1R and D2R antagonists, SCH 23390 (D1R selective) and raclopride (D2R selective), blocked cocaine induced-behavioral sensitization, CART over-expression, and cyclic adenosine 5'-monophosphate (cAMP)/protein kinase A (PKA)/phospho-cAMP response element-binding protein (pCREB) signal pathways. SCH 23390 more predominantly inhibited the locomotor activity, CART over-expression, pCREB and PKA activity than raclopride. Cocaine induced-behavioral sensitization was also attenuated in the both D1R and D2R knockout (KO) mice, respectively. CART over-expression and activated cAMP/PKA/pCREB signal pathways were inhibited in the D1R-KO mice, but not in the D2R-KO mice. It is suggested that behavioral sensitization, CART over-expression and activated cAMP/PKA/pCREB signal pathways induced by repeated administration of cocaine could be more predominantly mediated by D1R.

Expression and significance of signaling pathway of miR-134/CREB/pCREB in patients with epilepsy and in epileptic rats / 中国实验动物学报

Objective To investigate the expression of microRNA-134 ( miR-134 ) , CREB and pCREB in the temporal lobe tissue of patients and epileptic rats and to explore their roles in pathogenesis of epilepsy.Methods Tempo-ral lobe tissue samples of 14 patients with refractory epilepsy and 10 non-epileptic patients, and hippocampus and brain tis-sue samples of 42 rats were used in this study.Forty-two healthy adult male Sprague-Dawley rats were randomly divided in-to 6 epilepsy groups (24 h, 72 h, 7 d, 14 d, 30 d, and 60 d after kindling epilepsy) and a normal control group (n=6 for all groups) .The rat model of epilepsy was generated by intraperitoneal injection of 127 mg/kg lithium chloride and 16-20 h later, 35 mg/kg pilocarpine.In the temporal lobe tissue of patients and hippocampal tissue of rats, the expression level of miR-134 was detected by real-time polymerase chain reaction.The expression levels of CREB and pCREB were de-termined by Western blot, and CREB and pCREB localization was assessed by immunohistochemistry.Results Compared with the control rats, the expression of miR-134 was significantly decreased in the temporal lobe tissue of experimental rats at 72 h,7 d,14 d, 60 d after kindling (P＜0.05),and no significant change at 24 h and 30 d after kindling (P>0.05). Expression of miR-134 in patients with refractory epilepsy was significantly lower than that of the controls ( P＜0.05 ) , while up-regulation of CREB expression was at the same time points (P＜0.05).Up-regulation of pCREB expression was at all the time points after kindling (P＜0.05).CREB and p-CREB expressions were seen in the nuclei of neurons, and significantly higher in patients with refractory epilepsy and epileptic rats.Conclusions The expression of miR-134 is sig-nificantly decreased and that of CREB and pCREB was significantly increased in the temporal lobe tissue of patients with re-fractory epilepsy and the hippocampal tissue of epileptic rats.These findings indicate that the signaling pathway of miR-134/CREB/pCREB may play an important role in the pathogenesis of epilepsy.

Fluoxetine Increases the Expression of NCAM140 and pCREB in Rat C6 Glioma Cells

OBJECTIVE: Dysfunction of neural plasticity in the brain is known to alter neural networks, resulting in depression. To understand how fluoxetine regulates molecules involved in neural plasticity, the expression levels of NCAM, NCAM140, CREB and pCREB, in rat C6 glioma cells after fluoxetine treatment were examined. METHODS: C6 cells were cultured after 20 min or after 6, 24 or 72 h treatments with 10 microM fluoxetine. Immunocytochemistry was used to determine the effect of fluoxetine on the expression of NCAM. Western blot analysis was used to measure the expression levels of NCAM140 and CREB and the induction of pCREB after fluoxetine treatment. RESULTS: NCAM expression following 72-h fluoxetine treatment was significantly increased around cell membranes compared to control cells. Cells treated with fluoxetine for 6 and 72 h showed a significant increase in NCAM140 expression compared to cells treated for 20 min. The level of pCREB in the cells treated with fluoxetine for 72 h not only increased more than 60%, but was also significantly different when compared with the other treatment times. The 72-h fluoxetine treatment led to the increase of NCAM140 and the phosphorylation of CREB in C6 cells. CONCLUSION: Our findings indicate that fluoxetine treatment regulates neuronal plasticity and neurite outgrowth by phosphorylating and activating CREB via the NCAM140 homophilic interaction-induced activation of the Ras-MAPK pathway.

Effects of tianeptine and lithium on expression of pCREB in hippocampus of chronic stress depression rats / 中华行为医学与脑科学杂志

Objective To research the effects of tianeptine and lithium on expression of pCREB in hippocampus of chronic stress depression rats. Methods All the experimental rats were divided by random into : Group of depression,Group of tianeptine,Group of lithium and Group of control. The rats of Group of depression, Group of tianeptine and Group of lithium were applied stress for 21 days,and meanwhile Group of control had no stress. The rats of Group of tianeptine were fed with tianeptine (50 mg/kg) , Group of lithium were fed with lithium (60 mg/kg) , while another groups were fed with normal sodium of the same volume. The ethology examination was performed by using method of open-field and experiment of fluid consumption. The expression of pCREB was detected by Western-blotting method. Results After the chronic stress,the horizontal crossing numbers,the erection times,the modification times and the percentage of sacchar-consumption of the rats of Group of depression were 23.2±23.0;8. 1 ±7.2; 3.6 ±3.5 and (55.4 ±11.7)% respectively, which were less than Group of control (46.0±18.9;20.3±11.3;8.4±2.7 and (68.5 ±8.2)% ; P＜0.01). The horizontal crossing numbers(28. 1 ±23.0) ,the erection times(12. 1 ± 9.4) and the modification times(5.5 ±3.2) of Group of tianeptine are less than those of Group of control (P ＜ 0. 05), but no significant difference compared with Group of depression; the percentage of sacchar-consumption(62.7 ± 10.6) % ,Group of tianeptine was more than Group of depression (P＜ 0.05 ) , but no obvious difference with Group of control. The horizontal crossing numbers, the erection times, the modification times and the percentage of sacchar-consumption of Group of lithium were less than those of Group of control (P ＜ 0.05), more than those of Group of depression but no significant difference (P ＞ 0.05). In Westernblotting method,the level of pCREB in the hippocampus of Group of depression was less than that of Group of control (P＜ 0.01); that of Group of tianeptine was more than that of Group of depression (P ＜ 0.01) but no obvious difference with Group of control; that of Group of lithium was less than that of Group of control (P＜0. 01) and more than Group of depression (P＜0.01). Conclusion Tianeptine could reverse the reduction of expression of pCREB in hippocampus of chronic stress depression rats and lithium partly did it.

Modulation by the GABAB receptor siRNA of ethanol-mediated PKA-alpha, CaMKII, and p-CREB intracellular signaling in prenatal rat hippocampal neurons / 대한해부학회지

Fetal alcohol syndrome (FAS) is a developmental neuropathology resulting from in utero exposure to ethanol; many of ethanol's effects are likely to be mediated by the neurotransmitter gamma-aminobutyric acid (GABA). We studied modulation of the neurotransmitter receptor GABABR and its capacity for intracellular signal transduction under conditions of ethanol treatment (ET) and RNA interference to investigate a potential role for GABA signaling in FAS. ET increased GABAB1R protein levels, but decreased protein kinase A-alpha (PKA-alpha), calcium/calmodulin-dependent protein kinase II (CaMKII) and phosphorylation of cAMP-response element binding protein (p-CREB), in cultured hippocampal neurons harvested at gestation day 17.5. To elucidate GABAB1R response to ethanol, we observed the effects of a GABABR agonist and antagonist in pharmacotherapy for ethanol abuse. Baclofen increased GABABR, CaMKII and p-CREB levels, whereas phaclofen decreased GABABR, CaMKII and p-CREB levels except PKA-alpha. Furthermore, when GABAB1R was knocked down by siRNA treatment, CaMKII and p-CREB levels were reduced upon ET. We speculate that stimulation of GABAB1R activity by ET can modulate CaMKII and p-CREB signaling to detrimental effect on fetal brain development.

Effects of sleep deprivation on learning and memory and pCREB level in hippocampus of mice / 中华行为医学与脑科学杂志

Objective To observe the effects of sleep deprivation(SD)on learning and memory and phos-phorylated cyclic AMP responsive element binding protein(pCREB) expression in hippocampus of mice,and to explore the mechanism of cognitive change after SD. Methods Twenty female C57BL/6J mice were randomly divided into sleep deprivation group(SD, n = 10) and normal cage control group (CC,n = 10). Touch method was used to establish the sleep deprivation model. 30 days after SD,all the animals were subjected for Morris Water Maze (MWM) to test mean escape latency and percentage of time spent in the target quadrant. pCREB level in hippocampus was tested with Western blot. Results The mean escape latency in SD group in the second and third day of MWM was (29.31 ±4.93) s and (25.33 ±5.06)s, respectively, and was longer than that in CC group ((26.05 ±5.96)s and (19.35 ±7. 85)s,respectively). Mice in SD group spent less time in the target quadrant than that in CC group((23.61 ±9.86)% and (37.46 ±7. 51)%,.respectively, P<0.05). Results of Western blot for pCREB revealed that the pCREB level in hippocampus in sleep deprivation group was significantly lower than that in control group(0.71 ±0.03 and 0.82 ±0.06, respectively, P<0.01) . Conclusion The impairment of spatial learning and memory ability in sleep deprivation animals may be associated with the reduction of pCREB in hippocampus.

Chronic Treatment of Fluoxetine Increases Expression of NCAM140 in the Rat Hippocampus

OBJECTIVES: Most of the mechanisms reported for antidepressant drugs are the enhancement of neurite outgrowth and neuronal survival in the rat hippocampus. Neural cell adhesion molecule 140(NCAM140) has been implicated as having a role in cell-cell adhesion, neurite outgrowth, and synaptic plasticity. In this report, we have performed to elucidate a correlation among chronic antidepressant treatments, NCAM140 expression, and activation of phosphorylated cyclicAMP responsive element binding protein(pCREB) which is a downstream molecule of NCAM140-mediated intracellular signaling pathway in the rat hippocampus. METHODS: Fluoxetine(10mg/kg) was injected acutely(daily injection for 5days) or chronically(daily injection for 14days) in adult rats. RNA and protein were extracted from the rat hippocampus, respectively. Real-time RTPCR was performed to analyze the expression pattern of NCAM140 gene and western blot analyses for the activation of the phosphorylation ratio of CREB. RESULTS: Chronic fluoxetine treatments increased NCAM140 expression 1.3 times higher than control in rat hippocampus. pCREB immunoreactivity in the rat hippocampus with chronic fluoxetine treatment was increased 4.0 times higher than that of control. CONCLUSION: Chronic fluoxetine treatment increased NCAM140 expression and pCREB activity in the rat hippo-campus. Our data suggest that NCAM140 and pCREB may play a role in the clinical efficacy of antidepressants promoting the neurite outgrowth and neuronal survival.

Striatal CREB Phosphorylation Following Cued/Response Learning in the Water Maze Differ in Two Inbred Strains of Mice

Much evidence shows that the hippocampus and striatum play roles as important neural substrates for spatial/place and cued/response learning, respectively. This experiment was conducted to investigate the engagement of the striatum in cued/response learning. The engagement of the striatum was assessed after either place or cue training by determining levels of cAMP response element-binding protein (CREB) and phosphorylated CREB (pCREB) in these two mouse strains. Results revealed that striatal CREB levels in both strains of mice were not significantly increased after cued/response learning comparing to place training mediated by the hippocampus. However, striatal pCREB of DBA/2 mice was significantly higher after cued/response training in comparison to place learning, while striatal pCREB levels on C57BL/6 mice did not differ in cued learning versus place learning. These findings indicate that striatal pCREB, specifically associated with cued/response learning, is closely tied to differences in cued/responses strategy preference between C57BL/6 and DBA/2 mice.

Effects of valproate sodium on phosphorylatted cAMP responsive element binding protein after hippocampal neuronal epileptiform discharge in rat / 重庆医科大学学报

Objective:To investigate the effects of valproate sodium on P-CREB1 after hippocampal neuronal epileptiform discharge in rat.Methods:The neonate wistar rats were decapitated quickly to obtain the hippocampal neuron,Which were cultured in vitro,After the epileptiform discharge model of neuron was established,neurons were divided into control group,model group,low valproate dose group(50mg/L) and high dose group(100mg/L).Expression positions of P-CREB1 after epileptiform discharge were examined by immunofluorescence technique,and Western blot was used to examine the expression intensity of P-CREB1 in different group.Results:Through immunofluorescence,P-CREB1 was observed in the nucleus of each group,and the most intensive expression was found in model group.Through western blot,the expression tendency was found to be the same as the former Results,Moreover,after added valproate sodium,the expression of P-CREB1 decreased,and there was statistical significance of the difference between low valproate dose and high dose(P

Effects of intrathecal ketamine on the expression of pCREB in the spinal cord of morphine tolerant rats / 上海第二医科大学学报

0.05) in tail flick test.MPE% in group MK was always higher than group M and descended more slowly than group M,especially from the d4 to d8(P0.05). Conclusion Ketamine could block the development of morphine tolerance partly due to its inhibition effect on pCREB protein.

pCREB IN GLUTAMATE CONTAINING NEURONS GREATLY UPREGULATED IN RAT AMYGDALA AFTER A STRESS BY FORCED SWIMMING / 神经解剖学杂志

Amygdala (AM) plays crucial roles in emotional learning, memory and behavior. These functions of AM are carried out by three main subnuclei (lateral nucleus, basolateral nucleus and central nucleus) in AM and closely related with a transcription factor, cAMP- responsive element binding protein (CREB) in the neurons of the AM. CREB can be phosphorylated (pCREB) in many kinds of neuronal processes to regulate the synthesis of proteins for the formation of memory processes. In order to identify what neuronal types express pCREB and how the pCREB levels changed at different time intervals after an emotional stress stimulation, the present study is designed to investigate pCREB-, glutamate (Glu)- and parvalbumin (PV)- immunoreactive (IR) profiles in AM and the levels of pCREB in AM after a stress of forced swimming (FS). The results showed that the pCREB expressed in the Glu-IR neurons but not in the PV-IR neurons, and the expression level of the pCREB increased dramatically after the stress. The present results suggested that pCREB modulates the emotional processes through the Glu-IR neurons and that the pCREB greatly upregulated to response to the emotional stimuli.

Effects of morphine on neurosteroidogenesis of primary cultured rat cerebral cortical neurons / 中国药理学通报

Aim To investigate the effect and mechanism of action of chronic morphine treatment on the neurosteroidogensis of primary cultured rat cerebral cortical neurons(CCNs).Methods The effect of morphine on the production of pregnenolone(PREG),dehydroepiandrosterone(DHEA),allopregnanolone(AP),pregnenlolone sulfate(PS)and dehydroepiandrosterone sulfate(DS)in cell culture media was measured by solid-phase extraction and LC-MS,with methyltestosterone(MT)or estrogen sulfate(ES)as internal standards.The dependence-like changes of CCNs were determined by testing the p-CREB level in the nuclear lysates using western blot.Results Compared with the control group,morphine treatment significantly reduced levels of PREG and DS respectively;opioid agonist DAMGO significantly reduced levels of PREG,DS and PS respectively,and increased the level of AP significantly.Compared with the morphine group,?-opioid-antagonist CTAP concomitant with morphine increased the level of PREG significantly.Compared with the control group,chronic morphine treatment or DAMGO treatment significantly increased the level of p-CREB in the CCNs.Compared with the morphine treatment group,?-antagonsit CTAP significantly reduced the level of p-CREB.Conclusion ?-opioid receptor mediated the inhibitory effect of morphine on levels of neurosteroids,and changes of neurosteroid levels might be related to morphine dependence.

Activation of cAMP-Response Element Binding Protein in the Brain Stem Nuclei during Vestibular Compensation in Unilateral Labyrinthectomizied Rats / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The p-CREB (phospholyated form of cAMP/calcium response element binding protein) was known to be one of transcription factors for immediate early genes in the brain stem nuclei. The purpose of this present study was to evaluate time-dependent expression of p-CREB and investigate the effect of MK801, non-competitive NMDA channel blocker, on p-CREB expression following unilateral labyrinthectomy (ULX). MATERIALS AND METHODS: Adult Sprague-Dalwey rats weighing 250-300 g were divided into a control group and an unilateral labyrinthetomy (ULX) group. The intraperitoneal injection of MK801 was administered either 30 min before or 24 hrs after ULX. The ABC immunohistochemical staining and digital image analysis system were used to measure the p-CREB expression in neuronal cells. RESULTS: The peak level of p-CREB expressions in 4 major vestibular nuclei was observed bilaterally with the other brain stem nuclei including reticular formation and olivary complex at 30 min following ULX. Thereafter, the p-CREB immunoreactivity in these nuclei was reduced rapidly to the control level for 6 hrs after ULX. Treatment of MK801 for 30 min preceding ULX decreased p-CREB immunoreactivity significantly in both the injured and intact sides of the 4 major vestibular nuclei with dose-dependent relationship. However, MK801 did not affect the change of p-CREB immunoreactivity in bilateral vestibular complex 24 hrs after ULX. CONCLUSION: These results suggest that cAMP/calcium response element binding protein plays an important role in the initial events of vestibular compensation in which its activity is in part regulated by NMDA receptor.