大鼠面神经完全切断后面神经核内OMgp的表达

目的:通过建立大鼠面神经完全切断损伤模型,观察面神经损伤后脑干内OMgp表达的变化。方法:对36只大鼠分别行左侧面神经茎乳孔切断术,于术后1、3、5、7、14、21d取大鼠脑干含面神经核团部分,应用免疫组织化学方法检测面神经核中OMgp的变化及其对面神经元凋亡的影响。结果:OMgp分布于正常SD大鼠面神经各亚核,面神经损伤后OMgp与假手术对照侧相比较均下降,免疫组织化学方法显示5～14d下降明显并显示神经元细胞凋亡增加,图像分析OMgp灰度值与假手术对照侧比较,差异有统计学意义(P0.05)。结论:OMgp对神经网络的重建有重要意义,同时在面神经损伤中发挥重要作用。     

面神经损伤后降钙素基因相关肽在大鼠面神经核中的表达

目的研究降钙素基因相关肽(calcitonin gene-related peptide,CGRP)在面神经损伤后再生过程中面神经核中的表达。方法健康SD大鼠分别行左侧面神经茎乳孔切断术,术后饲养3、7、14、21、28、35d,取出脑干含面神经核团部分,用免疫组化及图像分析技术,观察面神经核中CGRP的变化。结果CGRP分布于正常SD大鼠面神经各亚核,面神经损伤后3d,损伤侧的面神经核中CGRP比对照侧增强,图像分析CGRP灰度值与对照侧比较,差异有统计学意义(P<0.05);损伤后7d达最高峰(P<0.05),以后渐减。结论损伤导致CGRP在面神经运动神经元中的表达增加,提示CGRP在面神经再生修复过程中发挥调理作用。     

Distribution of facial motoneurons innervating the common facial muscles of the rabbit and rat

The distribution of the facial neurons that innervate several facial muscles was determined in the rabbit and the rat by examining the retrograde transport of horseradish peroxidase (HRP). The target muscles were musculus levator nasolabialis, m. levator labii superioris, m. zygomaticus, and m. buccinator pars buccalis, as well as m. parietoauricularis and m. depressor anguli oris in the rabbit and m. levator auricularis posterioris in the rat. Localization of the retrogradely labeled neurons within the ipsilateral facial nucleus was confirmed for all facial muscles examined. Our results showed that m. levator nasolabialis was innervated by neurons located in the dorsal subnucleus, while the motoneurons innervating m. buccinator pars buccalis were distributed within the dorsal part of the intermediate subnucleus of the facial nucleus in the both species. Localization of the labeled motoneurons innervating m. zygomaticus and m. levator labii superioris showed the difference in the distribution within the facial nucleus among the species. Neurons innervating m. parietoauricularis and m. levator auricularis posterioris were localized in somewhat different subregions of the medial subnucleus in these species. M. depressor anguli oris was innervated by the neurons distributed within the intermediate subnucleus of the facial nucleus in the rabbit. Thus, our findings revealed that there is species-specific motor innervation pattern in rabbits and rats, despite several movement of the face is supplied by the homologous facial muscles.     

Calcitonin gene-related peptide increases in rat facial motoneurons after peripheral nerve transection

The rat facial nerve was transected and the retrograde reaction studied in the facial nucleus using light and electron microscopic immunohistochemistry and radioimmunoassay for calcitonin gene-related peptide (CGRP). An initial increase of CGRP-immunoreactivity (IR) was noted at 15 h after axotomy, thereafter CGRP-IR continued to rise to maximal levels around day 6 after which it gradually decreased and reached normal levels again after 5-6 weeks. Immunoreactive CGRP was found to fill the perikarya of facial motoneurons extending into dendrites and axons. Possible functional implications of CGRP as a neuroregulatory molecule during nerve regeneration are discussed.     

外源性FGF-2对损伤面运动神经元降钙基因相关肽表达的调节

目的:研究外源性成纤维细胞生长因子－２(ｆｉｂｒｏｂｌａｓｔｇｒｏｗｔｈｆａｃｔｏｒ,ＦＧＦ－２)对损伤面运动神经元降钙基因相关肽(ｃａｌｃｉｔｏｎｉｎｇｅｎｅ－ｒｅｌａｔｅｄｐｅｐｔｉｄｅ,ＣＧＲＰ)代谢的调节作用。方法:采用大鼠面神经损伤模型,在损伤面神经近侧断端加人外源性ＦＧＦ－２,同时以生理盐水做对照,观察面运动神经元ＣＧＲＰ兔疫阳性细胞数和灰度值。结果:与生理盐水组比较,ＦＧＦ－２Ⅰ组和ＦＧＦ－２Ⅱ组损伤侧面运动神经元ＣＧＲＰ染色强度明显下降(灰度值百分比:Ｐ＜０．０１);ＦＧＦ－２Ⅱ组损伤侧面运动神经元ＣＧＲＰ阳性细胞数减少(阳性细胞数比:Ｐ＜０．０５)。结论:外源性ＦＧＦ－２对损伤面运动神经元ＣＧＲＰ的表达有负向调节作用。     

Electrophysiological properties of rat phrenic motoneurons during perinatal development

Past studies determined that there is a critical period at approximately embryonic day (E)17 during which phrenic motoneurons (PMNs) undergo a number of pivotal developmental events, including the inception of functional recruitment via synaptic drive from medullary respiratory centers, contact with spinal afferent terminals, the completion of diaphragm innervation, and a major transformation of PMN morphology. The objective of this study was to test the hypothesis that there would be a marked maturation of motoneuron electrophysiological properties occurring in conjunction with these developmental processes. PMN properties were measured via whole cell patch recordings with a cervical slice-phrenic nerve preparation isolated from perinatal rats. From E16 to postnatal day 1, there was a considerable transformation in a number of motoneuron properties, including 1) 10-mV increase in the hyperpolarization of the resting membrane potential, 2) threefold reduction in the input resistance, 3) 12-mV increase in amplitude and 50% decrease duration of action potential, 4) major changes in the shapes of potassium- and calcium-mediated afterpotentials, 5) decline in the prominence of calcium-dependent rebound depolarizations, and 6) increases in rheobase current and steady-state firing rates. Electrical coupling among PMNs was detected in 15-25% of recordings at all ages studied. Collectively, these data and those from parallel studies of PMN-diaphragm ontogeny describe how a multitude of regulatory mechanisms operate in concert during the embryonic development of a single mammalian neuromuscular system.     

Muscarinic modulation of recruitment threshold and firing rate in rat oculomotor nucleus motoneurons

Above recruitment threshold, ocular motoneurons (Mns) show a firing rate linearly related with eye position. Current hypothesis suggests that synaptic inputs are determinant for establishing the recruitment threshold and firing rate gain in these Mns. We investigated this proposal by studying the cholinergic modulation in oculomotor nucleus Mns by intracellular recordings in rat brain slice preparation. All recorded Mns were silent at their resting membrane potential. Bath application of carbachol (10 microm) produced a depolarization and a sustained firing that was not silenced on returning membrane potential to the precarbachol value via DC injection. In response to similar membrane depolarization or equal-current steps, carbachol-exposed Mns produced a higher firing rate and a shorter spike afterhyperpolarization phase with lower amplitude. The relationship between injected current and firing rate (I-F) was linear in control and carbachol-exposed Mns. The slope of these relationships (I-F gain) decreased with carbachol exposure. Bath application of agonist and antagonist of nicotinic and muscarinic acetylcholine receptors in addition to immunohistochemical studies support the notion that muscarinic receptors are primarily involved in the preceding responses. We conclude that muscarinic inputs play an important role in determining the recruitment threshold and firing rate gain observed in oculomotor Mns in vivo.     

Monosynaptic inputs from the nucleus tractus solitarii to the laryngeal motoneurons in the nucleus ambiguus of the rat

The cricothyroid (CT) and the posterior cricoarytenoid (PCA) muscles in the larynx are activated by the laryngeal motoneurons located within the nucleus ambiguus; these motoneurons receive the laryngeal sensory information from the nucleus tractus solitarii (NTS) during respiration and swallowing. We investigated whether the neurons in the NTS projected directly to the laryngeal motoneurons, and what is the synaptic organization of their nerve terminals on the laryngeal motoneurons using the electron microscope. When wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) was injected into the NTS after cholera toxin subunit B-conjugated HRP (CT-HRP) was injected into the CT muscle or the PCA muscle, the anterogradely WGA-HRP-labeled terminals from the NTS were found to directly contact the retrogradely CT-HRP-labeled dendrites and soma of both the CT and the PCA motoneurons. The labeled NTS terminals comprised about 4% of the axosomatic terminals in a section through the CT motoneurons, and about 9% on both the small (PCA-A) and the large (PCA-B) PCA motoneurons. The number of labeled axosomatic terminals containing round vesicles and making asymmetric synaptic contacts (Gray’s type I) was almost equal to that of the labeled terminals containing pleomorphic vesicles and making symmetric synaptic contacts (Gray’s type II) on the CT motoneurons. The labeled axosomatic terminals were mostly Gray’s type II on the PCA-A motoneurons, while the majority of them were Gray’s type I on the PCA-B motoneurons. These results indicate that the laryngeal CT and PCA motoneurons receive a few direct excitatory and inhibitory inputs from the neurons in the NTS. Accepted: 2 June 2000     

Recordings from the facial nucleus in the rat: signs of abnormal facial muscle response

Summary Three monkeys with complete ablations of temporal-lobe limbic structures and three unoperated controls were compared in an automated testing apparatus for their ability to remember pictures presented between 1 and 180 seconds previously, as well as to learn picture discriminations in which successive trials with a given pair were separated by either 20 seconds or 24 hours. The operated animals were not impaired in picture discrimination learning under either condition and they were not impaired in picture recognition memory up to about 10 seconds. At 10 seconds and beyond, however, the operated animals showed rapid deterioration of picture memory. The results demonstrate that the limbic system's selective contribution to learning and retention uncovered initially with objects applies equally to pictures, this contribution being essential for recognition memory but not for discrimination habits. The results demonstrate further that, as in humans, temporal-lobe limbic structures are essential for recognition only when the retention test exceeds the immediate memory span of a few seconds.     

Changes in expression of prosaposin in the rat facial nerve nucleus after facial nerve transection

Prosaposin is the precursor of saposins A, B, C and D, which are activators of sphingolipid hydrolases. In addition, unprocessed prosaposin functions as a neurotrophic factor in the central and peripheral nervous systems by acting to prevent neuronal apoptosis, to elongate neurites and to facilitate myelination. In this study, the expression pattern of prosaposin in the facial nerve nucleus after facial nerve transection was examined by immunohistochemistry and in situ hybridization. Prosaposin immunoreactivity in the neurons on the operated side facial nerve nucleus showed a biphasic pattern: it was significantly increased on day 3 after transection, decreased dramatically on day 7, started to increase gradually on day 14 and reached another peak on day 21 after transection. Significant increases in the levels of prosaposin mRNA were identified in the neurons on the operated side, suggesting that prosaposin was synthesized vigorously by the neurons themselves in the case of facial nerve transection. The diverse changes in prosaposin immunoreactivity during the process of facial nerve regeneration may reflect the diverse neurotrophic activities of prosaposin in facial motoneurons.     

Microglial motility in the rat facial nucleus following peripheral axotomy

Microglial motility was studied in living mammalian brain tissue using infrared gradient contrast microscopy in combination with video contrast enhancement and time lapse video recording. The infrared gradient contrast allows the visualization of living cells up to a depth of 60 m in brain slices, in regions where cell bodies remain largely uninjured by the tissue preparation and are visible in their natural environment. In contrast to other techniques, including confocal microscopy, this procedure does not require any staining or labeling of cell membranes and thus guarantees the investigation of tissue which has not been altered, apart from during preparation. Microglial cells are activated and increase in number in the facial nucleus following peripheral axotomy. Thus we established the preparation of longitudinal rat brainstem slices containing the axotomized facial nucleus as a source of activated microglial cells. During prolonged video time lapse recordings, two different types of microglial cell motility could be observed. Microglial cells which had accumulated at the surface of the slice remained stationary but showed activity of the cell soma, developing pseudopods of different shape and size which undulated and which were used for phagocytosis of cell debris. Microglial phagocytosis of bacteria could be documented for the first time in situ. In contrast, ameboid microglia which did not display pseudopods but showed migratory capacity, could be observed exclusively in the depth of the tissue. Some of these cells maintained a close contact to neurons and appeared to move along their dendrites, a finding that may be relevant to the role of microglia in synaptic stripping, the displacement of synapses following axotomy. This approach provides a valuable opportunity to investigate the interactions between activated microglial cells and the surrounding cellular and extracellular structures in the absence of staining or labeling, thus opening a wide field for the analysis of the cellular mechanisms involved in numerous pathologies of the CNS.     

Denervation causes changes in electrophysiological properties in rat phrenic motoneurons

Thirty-nine male adult rats were divided into a control group and a denervation group that had been subjected to phrenicotomy 4 weeks earlier. Electrophysiological membrane properties (input resistance and rheobase) of phrenic motoneurons were measured from intracellular recordings made with glass microelectrodes. Under anesthetized and artificially ventilated conditions, the recorded motoneurons were divided into recruited (spike discharge) and non-recruited (depolarization only) types. There was a significant inverse relationship between the rheobase and input resistance in the control rats, but not in the denervated rats. In the control rats, the mean value of rheobase in the non-recruited motoneurons was significantly higher than that in the recruited motoneurons. In denervated rats, however, the mean value of rheobase in the recruited motoneurons was identical to that in the non-recruited motoneurons. The results indicated that phrenicotomy induced a de-differentiation of electrophysiological properties of the phrenic motoneurons, and that these changes might be restricted to the motoneurons innervating fast-twitch, low fatigue resistance muscle fibers.     

Synchronized discharge of taste neurons recorded simultaneously in rat parabrachial nucleus

1. Cross-correlation analysis was made in the taste-sensitive neuron pairs recorded simultaneously from the parabrachial nucleus (PBN) of rats. Three indexes were adopted to evaluate the activities of the taste neurons; namely, 1) spike response density (RD value), which is the net spike density to stimulation with the four basic tastes; 2) the frequency of correlated discharges (FC value in spikes per second), which was determined by measuring the area of the peak appearing in the cross-correlogram (CC) during application of the test fluids; and 3) the weight of correlated discharge (WC = FC/RD), which shows the relative importance of correlated discharges in the taste signals delivered by a component neuron of a given pair. 2. In 11 of 23 pairs, the CCs exhibited peaks during stimulation with tastants. These 11 pairs, which were recorded in the pontine taste area, were composed of 18 NaCl-best (most sensitive to NaCl) and 4 HCl-best neurons. In eight pairs, the best-stimulus of both of the component neurons was NaCl, and it was HCl in one pair (homo-type pairs). The remaining two pairs were composed of an NaCl-best and an HCl-best neuron (hetero-type pairs). 3. In eight homo-type pairs (7 NaCl-best pairs and 1 HCl-best pair), each pair exhibited the maximal FC value during stimulation with the best-stimulus of the component neurons (2.3 less than or equal to maximal FC less than or equal to 26.6 Hz). In the remaining three pairs, the maximal FC values were low (0.8-1.9 Hz).(ABSTRACT TRUNCATED AT 250 WORDS)     

Topography of the facial musculature within the facial (VII) motor nucleus of the neonatal rat

Summary WGA-HRP, HRP and fluorescent tracers were used to determine the representation of the facial muscles in the facial motor nuclear complex (FMNC) of the newborn rat. Tracer injections of the superficial cervical and anterior mandibular portions of platysma, the orbicularis oculi muscle, the nasolabial musculature and the posterior auricular musculature revealed an adultlike topographic organization across FMNC subnuclei. Tracer delivery to individual vibrissa follicle loci of the whiskerpad also demonstrated an adult-like musculotopic organization within the lateral subnucleus.     

面神经局部缺血对面神经及面神经核的影响

目的　探讨面神经局部缺血对面神经及面神经核的影响,为临床腮腺切除术提供参考。方法选用家兔,采用同体对照的方法,模拟人腮腺切除手术。实验侧于手术显微镜下,游离面神经并破坏其外血管系,切除腮腺。术后家兔存活4周,观察以下指标：分别检测家兔实验侧和对照侧面神经颊支的传导速度、CMAP波幅和潜伏期;取双侧茎乳孔外面神经干,透射电镜下观察面神经超微结构的变化;取双侧面神经核,Western Blotting法检测面神经核乙酰胆碱转移酶（CHAT）表达的变化,PCR-ELISA法观察面神经核端粒酶活性的变化。 结果　实验侧面神经颊支的传导速度明显低于对照侧、潜伏期明显长于对照侧、波幅明显低于对照侧（P＜0.01,P＜0.05）。实验侧面神经超微结构发生明显变化,以轴索变性为主,包括轴索内微丝增生、断裂,线粒体肿胀、嵴断裂,变性轴索溶解等。实验侧面神经核CHAT的表达和端粒酶活性明显低于对照侧（P＜0.01,P＜0.05）。 结论　游离面神经破坏其外血管系切除腮腺,可导致面神经超微结构发生明显改变、面神经传导功能下降,进而导致面神经核神经元合成乙酰胆碱的含量下降、神经元凋亡增加;提示临床腮腺切除时,应尽可能保护面神经外血管系,以减少面瘫的发生。     

The facial nucleus of the rat: representation of facial muscles revealed by retrograde transport of horseradish peroxidase

The representation of facial muscle groups in the facial nucleus of rat was examined by retrograde transport of HRP. Motoneurons supplying muscle groups are arranged in longitudinal columns. Those supplying nasolabial muscles are located in the lateral and ventral intermediate segments, posterior auricular muscles in a medial column, platysma in an intermediate column; the lower lip and ocular muscles are in the ventral and dorsal segments respectively of the intermediate column. The posterior belly of the digastric muscle is supplied by motoneurons extending from the dorsal aspect of the facial nucleus to the caudal pole of the trigeminal motor nucleus.     

Effects of neurotensin on discharge rates of rat suprachiasmatic nucleus neurons in vitro

The neuropeptide neurotensin and two classes of its receptors, the neurotensin receptor-1 and 2, are present in the suprachiasmatic nucleus of the mammalian hypothalamus. The suprachiasmatic nucleus houses the mammalian central circadian pacemaker, but the effects of neurotensin on cellular activity in this circadian pacemaker are unknown. In this study, we examined the effects of neurotensin on the spontaneous discharge rate of rat SCN cells in an in vitro slice preparation. Neurotensin (1-10 microM) increased cell firing rate in approximately 50% of cells tested, while approximately 10% of suprachiasmatic cells tested showed a decrease in firing rate in response to neurotensin. These effects of neurotensin were not altered by the GABA receptor antagonist bicuculline (20 microM) or the glutamate receptor antagonists, D-aminophosphopentanoic acid (50 microM) and 6-cyano-7-nitroquinoxaline-2,3-dione (20 microM). The neurotensin receptor selective antagonists SR48692 and SR142948a (10 microM) failed to antagonise neurotensin responses in the majority of cells examined. Compounds that function as agonists selective for the neurotensin-receptor subtypes 1 and 2, JMV-510 and JMV-431 respectively, elicited neurotensin-like responses in approximately 90% of cells tested. Six out of seven cells tested responded to both JMV-510 and JMV-431. Neuropeptide Y (100nM) treatment of suprachiasmatic nucleus slices was found to elicit profound suppression of neuronal firing rate. Co-application of neurotensin with neuropeptide Y significantly (P<0.05) reduced the duration of the response, as compared to that elicited with neuropeptide Y alone. Together, these results demonstrate for the first time the actions of neurotensin in the suprachiasmatic nucleus and raise the possibility that this neuropeptide may play a role in modulating circadian pacemaker function.     

面神经损伤后面神经核中神经型钙黏附分子及胎盘型钙黏附分子的表达

背景：面神经周围性损伤后,首先涉及其中枢神经元轴突的逆行性反应,神经能否再生则取决于神经元胞体的存活及功能状态。目的：检测面神经损伤后,面神经核中神经型钙黏附分子和胎盘型钙黏附分子的表达变化。方法：将新西兰大白兔随机分为模型组(n=48)和对照组(n=8)。模型组兔建立右侧面神经压榨损伤模型。模型组分别于损伤后1,4,7,14,21,28 d各取8只兔进行检测。运用免疫组织化学SP法及实时定量PCR法检测兔右侧面神经核运动神经元中神经型钙黏附分子和胎盘型钙黏附分子蛋白及mRNA的表达水平。结果与结论：对照组兔右侧面神经核运动神经元中无神经型钙黏附分子或胎盘型钙黏附分子标记的阳性神经元。模型组兔右侧面神经核运动神经元中存在神经型钙黏附分子和胎盘型钙黏附分子阳性神经元,2种阳性神经元数量均在第14天时达到峰值。与对照组相比,模型组损伤后4-28 d兔面神经核中神经型钙黏附分子mRNA的表达水平明显增加,损伤后1 d时兔面神经核中胎盘型钙黏附分子mRNA的表达水平明显下降,损伤后7-28 d时兔面神经核中胎盘型钙黏附分子mRNA的表达水平明显增加。提示面神经损伤的早期即出现2种分子的阳性表达,其中胎盘型钙黏附分子的表达自神经损伤后一直存在,而神经型钙黏附分子表达时间相对较短。在面神经损伤时,面神经核中神经型钙黏附分子和胎盘型钙黏附分子均表达增加,说明面神经再生可能与黏附分子的高表达有关。中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程