前庭康复过程中Ⅰ组代谢性谷氨酸受体亚型mGluR5在前庭内侧核中的变化

目的：观察单侧迷路破坏术后前庭内侧核（MVN）内Ⅰ组代谢性谷氨酸受体亚型mGluR5的表达变化。方法：成年雄性Wistar大鼠30只,分为迷路破坏组（24只）和对照组（6只）,前者破坏单侧迷路,对照组手术方式相同但保持迷路完好。单侧迷路破坏术后,通过免疫组织化学、原位杂交组织化学法检测不同存活时间（术后12h、36h、7d）2组动物MVN内mGluR5的表达变化。结果：单侧迷路破坏术后可诱导同侧MVN区Ⅰ组代谢性谷氨酸受体亚型mGluR5增高,术后12h最高,术后36h开始降低,至术后7d后和对照组差异无统计学意义;对侧和术侧的变化趋势相同。结论：单侧迷路破坏术后可诱导MVN区Ⅰ组代谢性谷氨酸受体亚型mGluR5增高。初级前庭传入或中枢前庭神经元的静息放电降低可能与Ⅰ组代谢性谷氨酸受体亚型mGluR5增高有关,但其在前庭代偿中的作用尚有待研究。     

单侧迷路切除术后GABAA受体α3亚型在大鼠前庭神经核中的表达

目的观察单侧迷路切除术后大鼠前庭神经核复合体内GABAA受体α3亚型的表达变化。方法成年雄性Wistar大鼠24只,分为迷路破坏组(18只)和对照组(6只),前者破坏单侧迷路,对照组手术方式相同但保持迷路完好。单侧迷路切除术后,通过免疫组织化学、Western blot的方法检测不同存活时间(术后1 d、3 d、7 d)组动物前庭神经复合体内γ-氨基丁酸A受体α3亚型的表达变化。结果术后1 d、3 d、7 d组两侧比较及术后1 d、3 d、7 d组与对照组比较差异均无显著性意义。结论在前庭代偿的早期,前庭神经复合体内γ-氨基丁酸A受体α3亚型表达的变化极可能没有涉及前庭代偿。     

单侧迷路切除术后大鼠前庭神经核γ-氨基丁酸A受体β1亚型表达

目的观察单侧迷路切除术后大鼠前庭神经核复合体内γ-氨基丁酸(gamma-aminobutyric acid,GABA)A受体β1亚型的表达变化。方法成年雄性Wistar大鼠48只,分为实验组(36只)和对照组(12只),前者破坏单侧迷路,对照组手术方式相同但保持迷路完好。单侧迷路切除术后,分别用免疫组织化学法和免疫印迹法按照上述分组方式,检测不同存活时间(术后1、3、7天)组动物前庭神经复合体内GABAA受体β1亚型的表达变化。结果术后1、3、7夭组大鼠左右两侧比较及与对照组比较差异均无显著性意义。结论在前庭代偿的早期,前庭神经复合体内GABAA受体β1亚型表达无变化。     

前庭代偿过程中GABAA受体α1亚型在前庭内侧核中的变化

目的 观察单侧迷路破坏术后前庭内侧核(medial vestibular nuclei, MVN)内γ-氨基丁酸A受体(gamma-aminobutyric acid A receptor, GABAA receptor)α1亚型的表达变化.方法 将24只大鼠随机分为术后1、3、7天组和假手术组,每组6只,前三组切除大鼠一侧迷路,第4组行假手术,利用免疫组织化学、原位杂交组织化学的方法,观察术后1、3、7天组前庭内侧核区GABAA受体α1亚型表达的变化,及其在前庭代偿中可能的作用 ,并与假手术组进行比较.结果 手术后1天、3天、7天组行为学上开始均有前庭静态症状,术后7天时前庭静态症状均消失,假手术组无相关症状出现.免疫组织化学、原位杂交组织化学方法前庭内侧核中各组手术侧与对侧比较及术后1天、3天、7天组与假手术组比较,GABAA受体α1亚型表达差异均无统计学意义(P>0.05).结论 在前庭代偿的早期,GABAA受体α1亚型表达的变化可能没有涉及前庭代偿.     

反复发作性眩晕豚鼠前庭内侧核毒蕈碱受体M2、M3表达的研究

目的制造豚鼠迷路瘘管导致的反复发作的眩晕模型,观察不同时程豚鼠前庭内侧核(MVN)毒蕈碱受体M2、M3亚型的表达变化。以探讨前庭代偿的可能机制。方法选择成年实验用豚鼠88只,并随机分配为A组(假手术组,8只)、B组(单侧迷路损毁组,40只)、C组(迷路瘘管+耳镜鼓气组,40只)。B、C组手术后,依据豚鼠所需不同存活时间(术后1天、3天、1周、2周、3周)随机选取8只,A组作为对照组存活3周。所有豚鼠灌流后取脑干,用免疫组织化学染色,观察前庭内侧核毒蕈碱受体M2、M3亚型的表达变化,并与假手术组比较。结果 B、C组术后均可导致双侧MVN区毒蕈碱受体M2、M3亚型表达减少,术后1天表达最少,术后3天至术后7天表达有逐渐增加趋势,术后7天时B组和假手术组比较表达无差异,而C组和假手术组比较表达差异具有统计学意义(P<0.05)。直到术后2周,C组和假手术组比较表达无差异。B、C组术后各时期(术后2周前)相比,C组的表达弱于B组。各组对侧的变化趋势和术侧相同。结论1.豚鼠MVN存在毒蕈碱受体M2、M3亚型,且M3受体的表达可能不及M2受体的丰富。它们可能在前庭代偿的早期促进了前庭代偿的正常进行。2.前庭代偿除胆碱能系统参与外,可能还涉及到其他神经递质或化学物质的参与。3.进一步证明迷路瘘管导致的反复发作性眩晕模型的造模是成功的。     

天麻素对前庭功能障碍大鼠前庭内侧核组胺受体表达的影响

目的 观察天麻素对单侧迷路破坏(Unilateral labyrinthectomy,UL)后大鼠前庭内侧核(Medial vestibular nucleus,MVN)组胺受体H1、H2、H3亚型表达的影响,探讨天麻素对前庭功能损伤大鼠的干预作用及机制.方法 将99只健康SD大鼠随机分为空白对照组(n=9)、假手术组...     

前庭代偿过程中代谢性谷氨酸受体I组在大鼠小脑绒球中的表达

目的：阐明大鼠小脑绒球中代谢性谷氨酸受体I组在前庭代偿过程中的作用。方法：用RT-PCR方法对单侧迷路切除术后前庭代偿过程中代谢性谷氨酸受体I组在小脑绒球中的表达进行研究。结果：代谢性谷氨酸受体I组在双侧绒球中均有表达,双侧的手术组和对照组比较均差异有统计学意义,而双侧之间无差异。结论：大鼠小脑绒球存在代谢性谷氨酸受体I组,在前庭代偿过程中有变化,表明其参与前庭代偿的过程。     

单侧迷路切除术后毒蕈碱受体亚型在大鼠小脑绒球中的变化

目的:观察左侧迷路切除术后大鼠小脑绒球内毒蕈碱受体M1、M3、M5亚型的表达变化。方法:利用RT-PCR的方法,切除大鼠一侧迷路,观察小脑绒球毒蕈碱受体M1、M3、M5亚型表达的变化,及其在前庭代偿中可能的作用。结果:单侧迷路切除术(UL)后可诱导双侧绒球内毒蕈碱受体M1、M3、M5亚型减少,术后1 d最少,此后3~7 d处于上升趋势,7 d时和假手术组比较表达差异无统计学意义。各组手术两侧比较均差异无统计学意义。结论:UL后可诱导绒球内毒蕈碱受体M1、M3、M5亚型减少,但其在前庭代偿中的作用尚有待研究。     

前庭学

20011707豚鼠一侧前庭损毁后前庭内侧核GFAP表达/吴子明…//第四军医大学学报一2001,22(6)一518~521 目的:观察左侧迷路切除后前庭内侧核(MVN)胶原纤维酸性蛋白(GFAP)的表达变化。方法:左侧迷路切除后,不同存活时间行前庭内侧核GFAP二步法免疫组化染色。结果:一侧迷路切除(UL)后可诱导双侧MVN区星形胶质细胞GFAP免疫反应增强,且术侧大于未损侧,GFAP反应在术后10h已较正常对照增强,ZOh强于loh,此后4oh至ZOdGFAP反应处于下降趋势。结论:UL后可诱导MVN区胶质细胞GFAP免疫反应增强。初级前庭传入或中枢前庭神经元的静息放电降…     

单侧迷路切除后γ-氨基丁酸A受体亚单位在大鼠小脑绒球中的表达

目的观察单侧迷路切除术后大鼠小脑绒球内γ-氨基丁酸A(gamma-amino butyric acid A,GABAA)受体α3、β1、δ亚单位的表达变化。方法成年雄性Wistar大鼠24只,随机分为迷路破坏组(18只)和对照组(6只),前者破坏单侧迷路,对照组手术方式相同但保持迷路完好。通过免疫组织化学法检测术后不同存活时间(术后1、3、7天)两组动物小脑绒球内GABAA受体α3、β1、δ亚单位的表达变化。结果单侧迷路切除术后大鼠术侧小脑绒球内GABAA受体β1、δ亚单位增加,术后1天最多,此后3~7天处于下降趋势,7天时和对照组比较表达无差异。α3亚单位在小脑绒球的染色很弱,各组两侧比较及术后1、3、7天与对照组比较均无明显差异。结论单侧迷路切除后大鼠术侧小脑绒球内GABAA受体β1、δ亚单位增加;双侧前庭中枢神经元的静息放电的平衡可能与GABAA受体β1、δ亚单位绒球内的增加有关;α3亚单位可能并非GABAA受体在小脑绒球主要的结构与功能亚单位。     

Comparison of protein kinase activity and protein phosphorylation in the medial vestibular nucleus and prepositus hypoglossi in labyrinthine-intact and labyrinthectomized guinea pigs

The aim of the present study was to compare in vitro protein expression, protein kinase activity and protein phosphorylation in the medial vestibular nucleus (MVN) and prepositus hypoglossi (PH) from labyrinthine-intact guinea pigs and from guinea pigs at various stages of vestibular compensation following unilateral labyrinthectomy (UL). The ipsilateral (I-MVN) and contralateral (C-MVN) MVN, and the ipsilateral (I-PH) and contralateral (C-PH) PH, were dissected from 3 naive labyrinthine-intact guinea pigs and 55 guinea pigs at 10 hs or 53 hs following a surgical UL or sham operation. Tissue extracts were incubated with [gamma-33P]ATP+/-Ca2+, phorbol 12, 13 dibutyrate and phosphatidylserine or +/- Ca2+ and calmodulin, to enhance protein kinase C (PKC) or calcium calmodulin kinase (CaMK) activity, respectively. Data were analysed as the ratio of activated to basal 33P incorporation detected by phosphorimaging. There were similar total protein and phosphoprotein profiles in the MVN and PH, as well as both PKC and CaMKII activity, suggesting that the MVN and PH are similar in the way that proteins undergo rapid modification by phosphorylation. During the development of vestibular compensation, a 46 kDa band in C-PH displayed higher PKC-mediated phosphorylation from 10 hs post-UL compared to sham controls. Significantly greater PKC-mediated phosphorylation of proteins of approximately 18, 46 and 75 kDa was observed in C-PH at 10 hs compared to 53 hs post-UL and in most cases the phosphorylation was greater in C-PH than in the C-MVN. These results suggest that between 10 and 53 hs post-UL, PKC-mediated phosphorylation changes mainly in the C-PH rather than the ipsilateral or contralateral MVN.     

Long-term potentiation and depression after unilateral labyrinthectomy in the medial vestibular nucleus of rats

We previously demonstrated in rat brainstem slices that high-frequency stimulation (HFS) of the vestibular afferents induces long-term potentiation (LTP) in the ventral part (Vp) of the medial vestibular nucleus (MVN) and long-term depression (LTD) in the dorsal part (Dp). Both LTP and LTD depend on N-methyl-D-aspartate receptor activation, which increases synaptic efficacy; however, in the Dp, LTP reverses to LTD because of the activation of gamma-aminobutyric acid-ergic neurons. Here we show that the probability of inducing long-term effects in the MVN of rat brainstem slices is altered after unilateral labyrinthectomy (UL). In fact, LTP occurs less frequently in the ventral contra-lesional side compared with sham-operated rats. In the dorsal ipsi-lesional side, LTD is reduced and LTP enhanced, while the opposite occurs in the dorsal contra-lesional side. These changes in synaptic plasticity may be useful for re-balancing the tonic discharge of the MVN of the two sides during vestibular compensation, and for enhancing the dynamic responses of the deafferented MVN neurons in the long term.     

前庭损伤后脑干相关神经元C-FOS的表达

目的观察大鼠内耳前庭损伤后，在静止和角加速度刺激状态下双侧前庭神经核C—FOS阳性表达的改变，初步探讨前庭代偿机制。方法将60只SD大鼠分为5组（12只，组）：（1）无手术组；（2）单耳前庭神经切断手术组；（3）单耳前庭神经切断手术对照组；（4）双耳前庭神经切断手术组；（5）双耳前庭神经切断手术对照组，每组一半动物给予角加速度刺激。用免疫组化ABC法观察C—FOS在前庭神经核、舌下神经前置核的神经元表达的改变。结果在静止状态下，正常鼠和手术对照组鼠的双侧前庭神经核、舌下神经前置核无C—FOS阳性神经元；给予旋转刺激后，双侧前庭神经核、舌下神经前置核皆有C—FOS阳性神经元。单耳手术组术后24小时．同侧前庭神经内核、对侧舌下神经前置核有C—FOS阳性神经元，旋转刺激后双侧前庭神经核、舌下神经前置核皆有C—FOS阳性神经元。双耳手术组24小时，在静止状态和角加速度刺激状态下，双侧前庭神经核、舌下神经前置核皆无C—FOS阳性神经元。结论一侧前庭损伤后，同侧前庭神经内核、对侧舌下神经前置核C—FOS阳性神经元在前庭代偿早期可能起启动突触联系的作用。     

Relationship of static and dynamic mechanisms in vestibuloocular reflex compensation

OBJECTIVES/HYPOTHESIS: We tested the hypothesis that recovery of dynamic oculomotor behavior (specifically the vestibuloocular reflex [VOR]) after a unilateral labyrinthectomy (UL) is independent from static deficit recovery (e.g., spontaneous nystagmus). This hypothesis predicts that VOR recovery from peripheral vestibular lesions that do not cause static symptoms, such as unilateral semicircular canal plugging (UCP), would have a similar time course and magnitude as recovery from a lesion that creates both a static and dynamic imbalance, such as UL. Furthermore, animals compensated after UCP would be expected to retain their compensated VOR response after the additional insult of ipsilateral labyrinthectomy. STUDY DESIGN: An experimental study in the Mongolian gerbil animal model. METHODS: The horizontal VOR was measured from both eyes using infrared video-oculography on gerbils before and after UCP, UL, or ipsilateral labyrinthectomy after a previous UCP. Eye movements were recorded during yaw rotation in the dark. RESULTS: UL resulted in a more severe acute deficit than the UCP. Over several weeks, the UCP animals compensated their horizontal VOR, particularly on rotation toward the intact side, quicker and more completely than the UL animals. Animals that underwent ipsilateral labyrinthectomy 8 to 11 weeks after UCP demonstrated preservation of the improved gain, particularly on rotation toward the intact labyrinth. However, the difference between the UL groups with or without precedent UCP was not retained after 72 hours, and long-term compensation was poorest in the UL after UCP group. CONCLUSIONS: Plasticity in dynamic vestibular reflexes induced by UCP is preserved after a subsequent UL. However, neurologic events during the first and second day after UL appear to limit, change, or suppress the long-term dynamic compensation of the VOR, regardless of whether the animal had a previous UCP.     

Effects of pre-flocculectomy on Fos expression and NMDA receptor-mediated neural circuits in the central vestibular system after unilateral labyrinthectomy

In this study in order to elucidate the role of the flocculus in the whole process of vestibular compensation from the very early stage to the chronic stage, we first examined unilateral labyrinthectomy (UL)-induced spontaneous nystagmus (SN), a behavioral marker of vestibular compensation, and Fos expression, a marker of neural activity, in the vestibular brainstem in pre-unilateral flocculectomized (pre-UF) rats. UL in pre-UF rats caused more severe vestibulo-ocular deficits at the very early stage than it did in floccular-intact rats. Fos expression occurred in the medial vestibular nucleus contralateral to the UL side (contra-MVe) and the prepositus hypoglossal nucleus ipsilateral to the UL side (ipsi-PrH), whereas Fos expression was never seen after UL in floccular-intact rats. Therefore, these findings suggest the UL in pre-UF rats activates the contra-MVe and ipsi-PrH neurons and causes great imbalance between intervestibular nuclear activities, inducing more severe vestibular symptoms at the very early stage than those in floccular-intact rats. Next, we observed MK801 (a specific antagonist on the NMDA receptor)-induced SN in pre-UF rats at the chronic stage after UL. MK801 administration to pre-UL rats caused reappearance of SN even 14 days after UL, while administration to floccular-intact rats at a post-UL interval of 14 days never induced decompensation. Therefore, these findings suggest that the flocculus takes part in NMDA receptor-mediated neural circuits involved in vestibular compensation and modifies the neural interactions at the chronic stage after UL. Taken together, those results suggest that the flocculus plays important roles in the restoration of a balance between intervestibular nuclear activities, to reduce vestibular symptoms during the very early stage, and thereafter in the modification of NMDA receptor-mediated neural interactions in the central vestibular system at the chronic stage.     

Effects of Pre-flocculectomy on Fos Expression and NMDA Receptor-mediated Neural Circuits in the Central Vestibular System after Unilateral Labyrinthectomy

In this study in order to elucidate the role of the flocculus in the whole process of vestibular compensation from the very early stage to the chronic stage, we first examined unilateral labyrinthectomy (UL)-induced spontaneous nystagmus (SN), a behavioral marker of vestibular compensation, and Fos expression, a marker of neural activity, in the vestibular brainstem in pre-unilateral flocculectomized (pre-UF) rats. UL in pre-UF rats caused more severe vestibulo-ocular deficits at the very early stage than it did in floccular-intact rats. Fos expression occurred in the medial vestibular nucleus contralateral to the UL side (contra-MVe) and the prepositus hypoglossal nucleus ipsilateral to the UL side (ipsi-PrH), whereas Fos expression was never seen after UL in floccular-intact rats. Therefore, these findings suggest the UL in pre-UF rats activates the contra-MVe and ipsi-PrH neurons and causes great imbalance between intervestibular nuclear activities, inducing more severe vestibular symptoms at the very early stage than those in floccular-intact rats. Next, we observed MK801 (a specific antagonist on the NMDA receptor)-induced SN in pre-UF rats at the chronic stage after UL. MK801 administration to pre-UL rats caused reappearance of SN even 14 days after UL, while administration to floccular-intact rats at a post-UL interval of 14 days never induced decompensation. Therefore, these findings suggest that the flocculus takes part in NMDA receptor-mediated neural circuits involved in vestibular compensation and modifies the neural interactions at the chronic stage after UL. Taken together, those results suggest that the flocculus plays important roles in the restoration of a balance between intervestibular nuclear activities, to reduce vestibular symptoms during the very early stage, and thereafter in the modification of NMDA receptor-mediated neural interactions in the central vestibular system at the chronic stage.     

Effect of baclofen on neuronal activity in the medial vestibular nucleus after unilateral surgical labyrinthectomy in rats

Conclusions: Ipsilateral and contralateral medial vestibular nuclei (MVN) neurons respond differently to systemic injection of baclofen (4-amino-3-(4-chlorophenyl)-butanoic acid), illustrating the plastic changes of the type B γ-aminobutyric acid (GABA_B) receptor during vestibular compensation. Objectives: To investigate the responsiveness of MVN neurons to baclofen during the early, partially compensated period after unilateral surgical labyrinthectomy. Materials and methods: MVN were localized using field potentials evoked by electrical stimulation, along with a stereotaxic atlas of rat brain. Neuronal activity in MVN was recorded and analyzed in rats that had undergone labyrinthectomy with and without administration of baclofen. Results: After left labyrinthectomy the mean discharge rate in ipsilesional MVN decreased, but it was nearly restored by postoperative day 8. Baclofen (3 mg/kg) reversed the mean discharge rates between bilateral MVN at days 4 and 8 after surgical labyrinthectomy. In addition, the reduction ratio of the right MVN neurons was higher than that of the left MVN neurons.