共查询到20条相似文献,搜索用时 156 毫秒
1.
近年来,在脑干呼吸核团的电生理研究方面所得到的实验根据,对传统的三级呼吸中枢的理论提出了某些质疑。本文从探讨三级呼吸中枢理论发展的过程中,发现其中有肯定的实验结论,也有条件控制不严的,不能成立的实验报告;又介绍了近年来的一些与三级中枢理论相矛盾的新的实验证据。对产生自动节律性的呼吸中枢的概念有必要重新进行思索和研讨。 相似文献
2.
(一)兔颈交感神经干的动作电位和膈神经发放有明显的同步关系,是为交感发放的呼吸性节律。改变呼吸中枢和血管运动中枢的兴奋状态后,交感发放的呼吸性节律也随着发生相应的变化,但切断缓冲神经不影响交感的呼吸性节律发放。(二)必须保留脑桥和延髓完整,交感发放才能表现出呼吸性节律。在脑桥水平切断脑干而动物发生长吸式呼吸时,交感发放的呼吸性节律消失。(三)本文讨论了交感神经和膈神经同步化发放的机制,认为呼吸中枢的兴奋过程使血管运动中枢的活动被周期性地“强化”。于是交感发放出现呼吸性节律。呼吸中枢对血管运动中枢的“强化”的程度,乃取决于这两个中枢的兴奋性的高低,这一过程可能是在脑桥和延髓的网状结构中进行的。 相似文献
3.
4.
生物钟现象是一种普遍存在于生物界细胞的内源节律性保持机制。生物钟机制的存在可以使生物体的代谢行为产生并维持以24 h为周期的昼夜节律,从而更好地适应于地球自转所产生的环境条件昼夜间节律性变化。蓝藻是目前生物钟分子机制研究中的模式生物,其依赖于k ai基因家族成员的核心生物钟调控模式已经被众多研究者详细阐明。蓝藻生物钟的核心振荡器是由蓝藻k aiA/B/C的编码产物来调控的,Kai蛋白的表达模式具有节律性。KaiC蛋白磷酸化状态的节律性循环及输入、输出途径相关组成蛋白的翻译后修饰状态节律性循环共同组成其反馈回路,负责维持生物钟节律性振荡的持续进行并与环境周期保持同步。传统的蓝藻生物钟分子机制模型认为,节律性表达基因翻译产物的转录/翻译负反馈抑制环是生物节律性维持和输出的关键。遗憾的是,在其它物种生物钟分子机制研究中未发现由kai基因家族成员同源基因组成的节律性标签,这表明以k aiA/B/C为核心振荡器的生物钟系统并不是一种跨物种保守的生物钟系统。近期,人们发现非转录/翻译依赖的振荡器(NTO)也具有成为生物节律性产生和维持的“源动力”的可能。过氧化物氧化还原酶(PRX)氧化还原状态节律性是第一种被报道的跨物种保守的NTO节律性标签,这也日渐成为蓝藻生物钟分子机制研究新的热点。 相似文献
5.
生物节律基因非编码RNA调控机制 总被引:1,自引:0,他引:1
节律性的振荡不仅存在于生物节律中枢也存在于外周器官、组织及细胞中,其产生依赖于节律基因的转录、转录后及翻译后水平调控。近几年,生物节律转录后水平调控机制研究成为热点。非编码RNA(ncRNAs)调控组分小RNA(microRNA)与长链非编码RNA(lncRNA)作为参与转录后调控的重要分子,已有研究表明microRNA与lncRNA调控节律基因mRNA与蛋白的相位及振幅。本文概述microRNA与lncRNA参与昼夜节律中枢与外周调控的研究进展,为生物节律转录后调控机制的进一步研究提供参考。 相似文献
6.
《现代生物医学进展》2014,(7):I0004-I0004
据《自然一遗传学》上的两项独立研究显示,在某些转移性乳腺癌病例中,负责编码雌激素受体的基因会发生变异。这意味着雌激素受体对抗药物或对某些转移性乳腺癌病例具有疗效。Sarat Chandarlapaty等人选取了36个对激素疗法产生抗性的转移性乳腺癌肿瘤,对其中的230种基因进行测序,在9个肿瘤中发现ESRl基因突变。他们分析了44个转移性乳腺癌肿瘤中的ESRl基因,发现其中5个肿瘤存在基因突变。 相似文献
7.
近日节律是生命体生理及行为变量遵循内源性的以接近1个太阳日的周期进行循环的生物过程,人体近日节律调控机制及其相关疾病研究已成为当前生物医学新兴领域和研究热点。过去二十年间,以生物钟基因及其相互作用环路为核心的一系列机制研究不断取得新的进展,初步形成了近日节律的分子模型,近年来,生物钟基因在染色体重塑、转录翻译调控、转录后修饰等多个层次的调控模式得到深入的研究。同时,近日节律失控与肿瘤、代谢紊乱等临床疾病的相关性及其影响机的转化研究日益增多,形成了新兴的时间医学。本文谨就近年来近日节律分子机制及其疾病相关研究的概况和最新进展做一总结。 相似文献
8.
近日节律是生物节律中最重要的一种。它是一种以近似24 h为周期的自主振荡器,普遍存在于生物界中。近日节律主要受生物钟基因的调控,在哺乳动物中已发现时钟基因(Clock)、周期基因(Period,Per)家族、隐花色素基因(Cryptochrome1,Cry)家族、Bmal1(Brain and muscle ARNT-like 1)在内的多种重要的生物钟基因。这些基因及其蛋白质产物构成的反馈调节环是生物钟运行的分子基础。研究表明,生物钟基因不仅仅在近日节律的中枢系统中存在表达,在外周组织中也存在表达。而且生物钟基因与哺乳动物生殖密切相关,提示可能在生殖领域中具有重要的调控作用。主要从几个关键生物钟基因的发现、在近日节律和非近日节律中的调节作用、以及与哺乳动物生殖的关系做一综述。 相似文献
9.
10.
非编码RNA(ncRNA)是生物体细胞内一类重要的调控分子,其介导的昼夜节律调控日益受到研究者的重视。本文主要以黑腹果蝇Drosophila melanogaster和哺乳动物的相关研究为背景,阐述了微小RNA(miRNA)和长链非编码RNA(lncRNA)对昼夜节律的调控。miRNA介导的昼夜节律调控包括:生物体内(尤其是钟神经元中)具有节律性表达的miRNA;输入系统和miRNA存在相互调控,这主要是通过光照这个授时因子起作用;miRNA可直接调控核心振荡器,还可以调控其他基因而间接影响到核心振荡器;miRNA对输出系统的调控主要集中在代谢取食节律、运动节律、睡眠节律等。昼夜节律可调控lncRNA的表达,同时lncRNA也可调控昼夜节律,且lncRNA对基因调控范围广,作用机制复杂,这些都具有广阔的研究前景。本文将有助于进一步深入研究ncRNA对昼夜节律的调控。 相似文献
11.
12.
Activity of neurons in the pre-Bötzinger complex (pre-BötC) within the mammalian brainstem drives the inspiratory phase of the respiratory rhythm. Experimental results have suggested that multiple bursting mechanisms based on a calcium-activated nonspecific cationic (CAN) current, a persistent sodium (NaP) current, and calcium dynamics may be incorporated within the pre-BötC. Previous modeling works have incorporated representations of some or all of these mechanisms. In this study, we consider a single-compartment model of a pre-BötC inspiratory neuron that encompasses particular aspects of all of these features. We present a novel mathematical analysis of the interaction of the corresponding rhythmic mechanisms arising in the model, including square-wave bursting and autonomous calcium oscillations, which requires treatment of a system of differential equations incorporating three slow variables. 相似文献
13.
C Borday C Vias S Autran M Thoby-Brisson J Champagnat G Fortin 《Journal of Physiology》2006,100(5-6):284-289
Studies of the sites and mechanisms involved in mammalian respiratory rhythm generation point to two clusters of rhythmic neurons forming a coupled oscillator network within the brainstem. The location of these oscillators, the pre-B?tzinger complex (preB?tC) at vagal level, and the para-facial respiratory group at facial level, probably result from regional patterning schemes specifying neural types in the hindbrain during embryogenesis. Here, we report evidence that the preB?tC oscillator (i) is first active at embryonic stages, (ii) originates in the post-otic hindbrain neural tube and (iii) requires the glutamate vesicular transporter 2 for rhythm generation. 相似文献
14.
C. Borday C. Vias S. Autran M. Thoby-Brisson J. Champagnat G. Fortin 《Journal of Physiology》2006,100(5-6):284
Studies of the sites and mechanisms involved in mammalian respiratory rhythm generation point to two clusters of rhythmic neurons forming a coupled oscillator network within the brainstem. The location of these oscillators, the pre-Bötzinger complex (preBötC) at vagal level, and the para-facial respiratory group at facial level, probably result from regional patterning schemes specifying neural types in the hindbrain during embryogenesis. Here, we report evidence that the preBötC oscillator (i) is first active at embryonic stages, (ii) originates in the post-otic hindbrain neural tube and (iii) requires the glutamate vesicular transporter 2 for rhythm generation. 相似文献
15.
Varoqueaux F Aramuni G Rawson RL Mohrmann R Missler M Gottmann K Zhang W Südhof TC Brose N 《Neuron》2006,51(6):741-754
Synaptogenesis, the generation and maturation of functional synapses between nerve cells, is an essential step in the development of neuronal networks in the brain. It is thought to be triggered by members of the neuroligin family of postsynaptic cell adhesion proteins, which may form transsynaptic contacts with presynaptic alpha- and beta-neurexins and have been implicated in the etiology of autism. We show that deletion mutant mice lacking neuroligin expression die shortly after birth due to respiratory failure. This respiratory failure is a consequence of reduced GABAergic/glycinergic and glutamatergic synaptic transmission and network activity in brainstem centers that control respiration. However, the density of synaptic contacts is not altered in neuroligin-deficient brains and cultured neurons. Our data show that neuroligins are required for proper synapse maturation and brain function, but not for the initial formation of synaptic contacts. 相似文献
16.
Acute role of the brain-derived neurotrophic factor (BDNF) on the respiratory neural network activity in mice in vitro 总被引:1,自引:0,他引:1
Julien Bouvier Sandra Autran Gilles Fortin Jean Champagnat Muriel Thoby-Brisson 《Journal of Physiology》2006,100(5-6):290-296
In humans, several pathologies are associated with disturbances of the respiratory control, some of them including alteration in the brain-derived neurotrophic factor (BDNF) signalling pathway. BDNF has long been known as a neurotrophic factor involved in survival, differentiation and maintenance of neuronal populations in the peripheral and central nervous system. More recently BDNF has also been discovered to be a potent neuromodulator with acute effects on neuronal excitability and synaptic plasticity. Animals deleted for the gene encoding BDNF exhibit respiratory alteration suggesting an important but yet undefined role of the neurotrophin in respiratory rhythmogenesis either by a trophic and/or an acute action. The possibility that BDNF might exert an acute regulatory role on the rhythmic activity of the respiratory generator of the pre-B?tzinger complex has been recently examined in newborn mice in vitro. Results obtained, reviewed in the present paper, will help getting insights in respiratory rhythm regulatory mechanisms that involve BDNF signalling. 相似文献
17.
Learned motor behaviors require descending forebrain control to be coordinated with midbrain and brainstem motor systems. In songbirds, such as the zebra finch, regular breathing is controlled by brainstem centers, but when the adult songbird begins to sing, its breathing becomes tightly coordinated with forebrain-controlled vocalizations. The periods of silence (gaps) between song syllables are typically filled with brief breaths, allowing the bird to sing uninterrupted for many seconds. While substantial progress has been made in identifying the brain areas and pathways involved in vocal and respiratory control, it is not understood how respiratory and vocal control is coordinated by forebrain motor circuits. Here we combine a recently developed technique for localized brain cooling, together with recordings of thoracic air sac pressure, to examine the role of cortical premotor nucleus HVC (proper name) in respiratory-vocal coordination. We found that HVC cooling, in addition to slowing all song timescales as previously reported, also increased the duration of expiratory pulses (EPs) and inspiratory pulses (IPs). Expiratory pulses, like song syllables, were stretched uniformly by HVC cooling, but most inspiratory pulses exhibited non-uniform stretch of pressure waveform such that the majority of stretch occurred late in the IP. Indeed, some IPs appeared to change duration by the earlier or later truncation of an underlying inspiratory event. These findings are consistent with the idea that during singing the temporal structure of EPs is under the direct control of forebrain circuits, whereas that of IPs can be strongly influenced by circuits downstream of HVC, likely in the brainstem. An analysis of the temporal jitter of respiratory and vocal structure suggests that IPs may be initiated by HVC at the end of each syllable and terminated by HVC immediately before the onset of the next syllable. 相似文献
18.
19.
Hedrick MS Chen AK Jessop KL 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2005,142(2):231-240
Nitric oxide (NO) is a unique chemical messenger that has been shown to play a role in the modulation of breathing in amphibians and other vertebrates. In the post-metamorphic tadpole and adult amphibian brainstem, NO, acting via the neuronal isoform of nitric oxide synthase (nNOS), is excitatory to the generation of lung burst activity. In this study, we examine the modulation of breathing by NO during development of the amphibian brainstem. Isolated brainstem preparations from pre-metamorphic and late-stage post-metamorphic tadpoles (Rana catesbeiana) were used to determine the role of NO in modulating central respiratory neural activity. Respiratory neural activity was monitored with suction electrodes recording extracellular activity of cranial nerve rootlets that innervate respiratory musculature. Brainstems were superfused with an artificial cerebrospinal fluid (aCSF) at 20-22 degrees C containing l-nitroarginine (l-NA; 1-10 mM), a non-selective NOS inhibitor. In pre-metamorphic tadpoles, l-NA increased fictive gill ventilation frequency and amplitude, and increased lung burst frequency. By contrast, l-NA applied to the post-metamorphic tadpole brainstem had little effect on fictive buccal activity, but significantly decreased lung burst frequency and the frequency of lung burst episodes. These data indicate that early in development, NO provides a tonic inhibitory input to gill and lung burst activity, but as development progresses, NO provides an excitatory input to lung ventilation. This changing role for NO coincides with the shift in importance in the different respiratory modes during development in amphibians; that is, pre-metamorphic tadpoles rely predominantly on gill ventilation whereas post-metamorphic tadpoles have lost the gills and are obligate air-breathers primarily using lungs for gas exchange. We hypothesize that NO provides a tonic input to the respiratory CPG during development and this changing role reflects the modulatory influence of NO on inhibitory or excitatory modulators or neurotransmitters involved in the generation of respiratory rhythm. 相似文献
20.
Surf1 gene mutations were detected as a main cause for Leigh syndrome (LS), also known as infantile subacute necrotizing encephalomyelopathy. This syndrome which is commonly associated with systemic cytochrome c oxidase (COX) deficiency manifests in early childhood and has an invariable poor prognosis. Progressive disturbances of the respiratory function, for which both the metabolic condition and necrotizing brainstem lesions contribute, belong to the major symptoms of LS. A constitutive knockout (KO) mouse for Surf1 enables invasive investigations of distinct aspects of LS. In the present study the respiratory function was analyzed applying an arterially perfused brainstem preparation. Compared to wild type (WT) preparations Surf1 KO preparations had a higher baseline respiratory frequency and abnormal responses to hypoxia and hypercapnia that involved both respiratory frequency and motor nerve discharge pattern. These data suggest that COX deficiency impairs peripheral and/or central chemoreceptor function. 相似文献