正常猫膈神经单纤维电活动特征

在麻醉猫和麻痹的切断迷走神经的清醒猫,观察了膈神经单纤维电活动特征。1.电活动类型:按膈神经单纤维放电与其总干放电的相位关系分为三种类型。(1)完全同步型,即单纤维放电与总干放电同时开始并同时停止,占76.9％。(2)部分同步型占15.4％,其中早期同步,即单纤维放电与总干放电同时开始,但提前终止,占1.9％,中期同步,即单纤维放电较总干放电开始晚,又提前终止,占5.8％,晚期同步,即单纤维放电较总干放电开始晚,但两者同时终止,占7.7％。(8)非同步型,即吸气相和呼气相都有放电,但呼气相时冲动频率较低,占7.7％。前两型为单纯的吸气性放电,共占92.3％。2.单纤维放电平均参数值:麻醉猫每次吸气发放11个冲动,其频率为21次/秒,清醒猫每次吸气发放18个冲动,其频率为34次/秒。结果表明:猫膈神经单纤维放电类型和文献上报导的直接记录膈神经运动神经元放电一致,即以单纯的吸气性放电为最多。     

Group I metabotropic glutamate receptor-dependent TRPC channel trafficking in hippocampal neurons

The group I metabotropic glutamate receptor agonist (S)-3,5-dihydroxyphenylglycine (DHPG) elicited two phases of synchronized neuronal (epileptiform) discharges in hippocampal slices: an initial phase of short duration discharges followed by a phase of prolonged discharges. We assessed the involvement of transient receptor potential canonical (TRPC) channels in these responses. Pre-treatment of hippocampal slices with TRPC channel blockers, 1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole hydrochloride (SKF96365) or 2-aminoethoxydiphenyl borate, did not affect the short epileptiform discharges but blocked the prolonged epileptiform discharges. SKF96365 suppressed ongoing DHPG-induced prolonged epileptiform discharges. Western blot analysis showed that the total TRPC4 or TRPC5 proteins in hippocampal slices were unchanged following DHPG. DHPG increased TRPC4 and TRPC5 in the cytoplasmic compartment and decreased these proteins in the plasma membrane. Translocation of TRPC4 and TRPC5 was suppressed when the epileptiform discharges were blocked by ionotropic glutamate receptor blockers. Translocation of TRPC4 and TRPC5 was also prevented in slices from phospholipase C (PLC) beta1 knockout mice, even when synchronized discharges were elicited by the convulsant 4-aminopyridine. The results suggest that TRPC channels are involved in generating DHPG-induced prolonged epileptiform discharges. This function of TRPC channels is associated with a neuronal activity- and PLCbeta1-dependent translocation of TRPC4 and TRPC5 proteins from the plasmalemma to the cytoplasmic compartment.     

束旁核、中央中核对皮层体感觉区伤害性反应单位的影响

实验在清醒麻痹的猫上进行。先用记录诱发电位的方法,证明大脑皮层第 I 体感觉区(SI区)同一部位可接受来自外周神经、丘脑束旁核(Pf)和中央中核(CM)的上传信号;然后在这一皮层部位寻找在强电流刺激腓总神经时出现伤害性反应的神经元。在所观察的24个单位中,有20个单位如果先给予 Pf 刺激,可看到上述伤害性反应明显增强,增强的百分率平均在90.0%以上;在这同一组皮层单位,如果预先刺激 CM,有21个单位的伤害性反应明显减弱,反应抑制都在-55.6%以上。Pf 刺激本身对所观察单位的自发放电影响不明显,但 CM 刺激可明显抑制它们的自发放电。     

刺激大鼠尾核对丘脑束旁核躯体-内脏会聚神经元放电的影响

实验记录大鼠丘脑束旁核躯体-内脏会聚(PfSV)神经元伤害性放电。观察刺激尾核(Cd)对 PfSV 神经元放电的影响。(1)Cd 对刺激内脏大神经诱发 PfSV 神经元伤害性放电有抑制作用(n=19)。(2)Cd 对刺激腓浅神经和内脏大神经诱发同一 PfSV 神经元伤害性放电均有抑制作用(n=11)。结果提示,躯体和内脏痛觉信息可会聚到丘脑束旁核同一神经元,Cd 可能不仅能抑制躯体痛也能抑制内脏痛。     

高频电刺激对大鼠海马脑片癫痫样放电特性影响的研究

本文采用电极阵列检测技术,在大鼠海马脑切片上诱导出稳定的癫痫样放电,分析、研究130 Hz的高频电刺激(high-frequency stimulation,HFS) CA3区时,海马切片在癫痫发作间期放电(inter-ictal discharges,IID)和发作期放电(ictal discharges,ID)的各项参数、癫痫样放电地起始位点、传播方向和传输速率以及各频段的功率谱密度.结果显示:高频电刺激可以有效地降低癫痫发作期的幅值、减少持续时间、增长潜伏时间、抑制癫痫样放电由IID向ID的转变等.提示高频电刺激抑制癫痫的作用机制是通过促进神经元之间的抑制性传输系统,并且抑制海马神经元之间的兴奋性连接,从而达到抑制效果.     

Pattern- and age-dependency of the antiepileptic effects induced by valproic acid in the rat hippocampus.

The effects induced by the antiepileptic drug valproic acid were studied in the CA3 subfield of in vitro hippocampal slices obtained from young (16- to 27-day-old) and adult (over 60-day-old) rats. Spontaneous epileptiform discharges were induced by the addition of the convulsant 4-aminopyridine to the medium. Valproic acid (0.5 mM) selectively blocked the ictal epileptiform discharges in slices obtained from young rats. Interictal epileptiform discharges disappeared during perfusion with higher doses of valproic acid (2 mM). This blockade of interictal epileptiform activity was not observed when valproic acid (0.5-5 mM) was tested in hippocampal slices from adult rats. Thus, in the hippocampus of young rats, 4-aminopyridine-induced ictal activity is more sensitive to valproic acid than are interictal discharges. Moreover, valproic acid is effective in controlling interictal discharges in the young, but not in the adult rat hippocampus.     

糖尿病痛过敏大鼠尾神经中传入单位对交感传出的反应

实验观察了刺激交感神经（sympathetic stimulation,SS）、静脉注射去甲肾上素（noradrenaline,NA）和酚妥拉明对糖尿病痛过敏大鼠尾神经中各种传入单位的影响。结果发现,糖尿病痛过敏大鼠的具有自发放电的C单位和Aδ单位在SS后放电频率增加,α－受体阻断剂能消除这些自发放电活动;在无自发放电的C单位和Aδ单位中,SS能使部分C单位和Aδ单位由静息状态转入活动状态;它虽不能诱发C－机械感受单位（C mechanical receptive unit,C-M）产生传入放电,但可诱发部分C－机械热单位（C mechano-heat unit,C-MH）和C－多型单位（C polymodal unit,C-Pol）的活动;SS还能使部分Aδ－机械单位（Aδ mechanical receptive unit,Aδ-M）和Aδ－机械热单位（Aδ mechano-heat unit,Aδ-MH）产生传入放电;它所诱发的C单位和Aδ单位反应的潜伏期不等,但不短于5s;SS不能引起糖尿病痛过敏大鼠Aβ机械感受性单位和对照组大鼠各类感受性单位产生新的传入活动。静脉注射NA可诱发糖尿病痛过敏大鼠的部分C单位和Aδ单位产生新的传入活动。结果提示,交感神经末梢释放的NA对糖尿病痛过敏大鼠C单位和Aδ单位的兴奋作用是糖尿病大鼠产生痛过敏和感觉异常的外周因素。     

Stability of the low-temperature states of high-pressure microwave discharges

Symmetric (planar, cylindrical, and spherical) models of microwave discharges in air are considered assuming that the deposited energy is removed via heat conduction. The characteristic features of spherical discharges are analyzed in detail, and the conditions for discharge stability are examined. It is shown that discharges in the low-temperature (unstable) state can be stabilized by varying the power of a feedback-controlled microwave source.     

外源性锌离子对大鼠海马切片癫痫样放电的起源、传播与频率特性的调节作用

本研究采用多电极记录技术,在离体条件下研究外源性锌离子(Zn2+)对无镁人工脑脊液诱导的Sprague-Dawley大鼠海马切片癫痫样放电的起源、传播与频率特性的调节作用。结果表明:1μmol/L和100μmol/L的Zn2+作用于海马切片,不改变海马切片上癫痫样放电的起始位置,但能够降低癫痫样放电顺行和逆行两个方向的传播速度,并改变癫痫样放电不同频率范围成分所占的比例。以上结果提示,1μmol/L和100μmol/L的Zn2+可以对海马切片上的癫痫样放电起到调节作用,减慢癫痫样放电在网络中的传播速度,同时,可能对神经元放电活动起到去同步化的作用。     

应用多电极记录技术研究海马切片癫痫样放电的起始点和传播方向

弄清癫痫样放电的起始位置和传播方向对研究癫痫机制及其临床治疗有重要意义．为了解决这一问题,应用微电极阵列对低镁人工脑脊液诱导的Sprague-Dawley (SD)大鼠海马切片的癫痫样放电进行记录．分别用癫痫样放电的两种成分：场电位和多单元信号来确定癫痫样放电的起始位置和传播方向．首先计算并比较了海马切片锥体细胞层位置电极记录的癫痫样放电场电位的起始时间,由起始时间的先后关系确定癫痫样放电在锥体细胞层的起始位置和传播方向．然后用整个切片上记录的癫痫样放电的多单元信号动作电位序列进行互相关分析,进一步确定了癫痫样放电在整个海马切片内的起始位置和传播方向．结果显示,CA3区的癫痫样放电具有比CA1区更高的幅度和更长的持续时间,表明CA3区有更高的兴奋性．对于记录到的同步癫痫样放电,CA3b区场电位和多单元信号均比CA3c和CA1区出现更早,起始位置和其随后位置之间的传播延　时与二者之间的距离成正相关．因此,在低镁模型的大鼠海马切片中,癫痫样放电起始于CA3b区并分别向CA3c和CA1区传播．     

Effects of PN 200-110 on penicillin-induced epileptic activity in the cerebral cortex of rats]

In experiments on freely moving Wistar rats it was shown that an intraperitoneal administration of PN 200-110 in a dose of 2 mg/kg in the period of steady epileptic activity (EpA) with regular generation of ictal discharges in penicillin--induced focus resulted in suppression of EpA in most animals. Antiepileptic effect of the drug was manifested by decreasing frequency appearance of ictal discharges and shortening of the epileptic focus existence time. Intraperitoneal administration (5 mg/kg) and intraventricular injection (10 nmol) of PN 200-110 20 min before the epileptic focus formation resulted in an increased latency period of appearance interictal discharges and decreased number of ictal discharges, and shortening of the existence time of epileptic focus.     

Electrostatic plasma turbulence and spitzer longitudinal conductivity in tokamaks

An analysis has revealed that there may be three radically different steady states of a tokamak plasma: (i) discharges in which the electron and ion transport can be described by neoclassical theory; (ii) discharges with the Spitzer longitudinal conductivity, neoclassical ion transport, and “anomalous” electron transport; and (iii) discharges in which the electron transport and ion transport are both “anomalous.” The dimensionless parameters responsible for the occurrence of the three types of discharges are determined. In accordance with the criteria derived for the achievement of different steady states, discharges of the second type are most typical of modern tokamaks and discharges of the third type can occur only if the turbulence is sufficiently strong. Discharges of the first type cannot occur in the range of the working parameters of present-day tokamaks and future tokamak reactors, but they can be ignited in a large class of magnetic confinement systems. The physical reason for the onset of different types of discharges is associated with the fact that turbulent fluctuations play very different roles in the dynamics of the ion and electron components of a finite-size magnetized plasma. The question of the self-consistency between the profiles is considered. A law is derived according to which the thermal diffusivity increases toward the plasma edge.     

去甲肾上腺素介导低氧引起家兔颈动脉体神经电活动增加

在30只家兔颈动脉体-窦神经(CSN)标本上, 记录了窦神经中39个对低氧反应敏感的化学感受性单位由去甲肾上腺素(NA)及其拮抗剂引起的反应。结果如下 (1)以低氧的改良台氏液(MTS)灌流标本时, 19个单位放电频率由0.13±0.06增至0.25±0.12 imp/s (P<0.001); (2)在灌流液中加入去甲肾上腺素(10     

Spontaneous unit activity in anterior (limbic) nuclei of rabbit thalamus

Spontaneous spike activity in three anterior (limbic) neurons of the thalamic nucleus was studied by means of extracellular recording during chronic experiments on anesthetized rabbits. Neurons of the anteroventral nucleus showed high mean rate (24.8±5.8 spikes/sec) and varying structure of spike discharges ("inactivating" bursts of discharges, modulations in delta- and theta-rhythms, and bursts of discharges with a spindle rhythm of 12–14 Hz). "Inactivating" bursts of discharges alternating with single discharges predominated in the activity of neurons of the anteromedial nucleus (mean rate 10.0±1.4 spikes/sec). Activity of the anterodorsal nucleus could be clearly distinguished by the predominance of high-frequency groups of spikes (mean group frequency 67±5 spikes/sec) with prolonged intervals between groups.Institute of Biological Physics, Academy of Sciences of the USSR, Puschino, Moscow Province. Translated from Neirofiziologiya, Vol. 17, No. 5, pp. 579–586, September–October, 1985.     

Effect of paleocerebellar cortex electrical stimulation on generalized penicillin-induced seizure activity in rats

It was shown that low-frequency electrical stimulation (ES) (10-12 Hz, 0.5 ms) of paleocerebellar cortex (nodulus, uvula) is followed by activation of spike discharges which were induced via i.p. administration of sodium benzilpenicillin salt to alert Wistar rats (300,000 IU/kg). The facilitation of ictal discharges generation was also seen in the course of such an ES. High-frequency (100-300 Hz, 0.25 ms) ES of the same structure was followed by suppression of spike discharges and prevented the ictal discharges precipitation. Antiseizure action was obvious under condition of relatively low level of epileptic activity generation. In the course of such ES the decreasing frequency and amplitude of spike discharges were noted during interstimuli periods. Besides, the life-span of seizure activity was shortened as well. The repeated paleocerebellar ES made after electrocoagulation of irritated tissue did not cause modulations of seizure activity.     

Correlation of the unit activity of the right and left lateral hypothalamus in food motivation

Correlation between activities of neurons in the right and left lateral hypothalamus of a rabbit recorded during quiet wakefulness, after 24-h food deprivation, and after satiation was studies by plotting cross- and autocorrelation histograms. A predominant order in correlated bilateral discharges of hypothalamic neurons was revealed in hungry animals: in a significantly greater number of cases (59%) the left-side discharges led the right-side ones with time delays to 200 ms (peaks at 30 and 160 ms). The opposite order of discharges was less common (21%). In the state of hunger, the probability of appearance of theta-range frequencies in correlated neuronal discharges increased (from 11 to 29%).     

ATP-敏感钾通道和内源性腺苷参与刺激蓝斑引起的脊髓抗痛作用

根据蓝斑刺激可以通过脊髓下行性去甲肾上腺素能纤维阻断由背角上传到束旁核神经元的伤害性放电的事实,本实验用脊髓鞘内给予相应工具药的方法,进一步分析了上述下行性抑制作用在脊髓背角中阻止伤害性传入信号向上传递的可能机制,结果发现：（1）鞘内注入ATP-敏感钾通道阻断剂格列苯脲或腺苷受体拮抗剂氨茶碱,均可以阻断或取消刺激蓝斑引起的对束旁核伤害性放电的抑制作用;（2）鞘内注入ATP-钾通道激动剂nic-orandil或腺苷受体激动剂5‘-N-ethylcarboxamido-adenosine(NECA）,都可抑制束旁核神经元的伤害性放电;（3）鞘内注入氨茶碱可阻断鞘内注入nicorandil引起的束旁核痛放电的抑制,再鞘内注入格列苯脲不能阻断鞘内注入NE-CA引致的束旁核痛放电的抑制。这些结果提示：（1）蓝斑刺激在脊髓背角中抑制痛信号的上传,要有ATP-敏感钾通道的激活和内源性腺苷的释放为中介;（2）ATP-敏感钾通道的激活发生在腺苷的释放之前。     

Significance of nipple discharge clinical patterns in the selection of cases for cytologic examination

The cytodiagnostic significance of the clinical patterns (types and sites) of nipple discharges was studied in 5,305 cytologically examined discharges from 3,687 women in a consecutive series of 50,181 self-referred women in whom 1,062 breast cancers were detected. The clinical patterns were correlated with cytologic and histologic results in both the whole series and in 119 biopsied cases, and the relative risk of association with breast cancer was calculated for each pattern. As a whole, aside from the pattern, cases with nipple discharges showed a higher relative risk (48.5) than did asymptomatic cases, but a bloody nipple discharge was by far more frequently associated with cancer than was any other pattern, being present in 70% of the cancer cases and in almost all cancer cases with suspicious cytologic findings in the discharge smear. The presence of a nipple discharge, being associated with a higher risk of breast cancer, is an indication for a careful physical examination; systematic cytologic examination should be limited only to bloody discharges. Since cancer is rare in cases with nonbloody discharges and is difficult to detect in cytologic smears of such discharges, systematic cytologic examination of all nipple discharges would not be cost-effective.     

Lidocaine suppresses subthreshold oscillations by inhibiting persistent Na(+) current in injured dorsal root ganglion neurons

The aim of this study was to determine the effect and mechanism of low concentration of lidocaine on subthreshold membrane potential oscillations (SMPO) and burst discharges in chronically compressed dorsal root ganglion (DRG) neurons. DRG neurons were isolated by enzymatic dissociation method. SMPO, burst discharges and single spike were elicited by whole cell patch-clamp technique in current clamp mode. Persistent Na(+) current (I(NaP)) and transient Na(+) current (I(NaT)) were elicited in voltage clamp mode. The results showed that SMPO was suppressed and burst discharges were eliminated by tetrodotoxin (TTX, 0.2 micromol/l) in current clamp mode, I(NaP) was blocked by 0.2 micromol/l TTX in voltage clamp mode. SMPO, burst discharges and I(NaP) were also suppressed by low concentration of lidocaine (10 micromol/l) respectively. However, single spike and I(NaT) could only be blocked by high concentration of lidocaine (5 mmol/l). From these results, it is suggested that I(NaP) mediates the generation of SMPO in injured DRG neurons. Low concentration of lidocaine (10 micromol/l) suppresses SMPO by selectively inhibiting I(NaP), but not I(NaT), in chronically compressed DRG neurons.     

Antidromic discharges of dorsal root afferents in the neonatal rat.

Presynaptic inhibition of primary afferents can be evoked from at least three sources in the adult animal: 1) by stimulation of several supraspinal structures; 2) by spinal reflex action from sensory inputs; or 3) by the activity of spinal locomotor networks. The depolarisation in the intraspinal afferent terminals which is due, at least partly, to the activation of GABA(A) receptors may be large enough to reach firing threshold and evoke action potentials that are antidromically conducted into peripheral nerves. Little is known about the development of presynaptic inhibition and its supraspinal control during ontogeny. This article, reviewing recent experiments performed on the in vitro brainstem/spinal cord preparation of the neonatal rat, demonstrates that a similar organisation is present, to some extent, in the new-born rat. A spontaneous activity consisting of antidromic discharges can be recorded from lumbar dorsal roots. The discharges are generated by the underlying afferent terminal depolarizations reaching firing threshold. The number of antidromic action potentials increases significantly in saline solution with chloride concentration reduced to 50% of control. Bath application of the GABA(A) receptor antagonist, bicuculline (5-10 microM) blocks the antidromic discharges almost completely. Dorsal root discharges are therefore triggered by chloride-dependent GABA(A) receptor-mediated mechanisms; 1) activation of descending pathways by stimulation delivered to the ventral funiculus (VF) of the spinal cord at the C1 level; 2) activation of sensory inputs by stimulation of a neighbouring dorsal root; or 3) pharmacological activation of the central pattern generators for locomotion evokes antidromic discharges in dorsal roots. VF stimulation also inhibited the response to dorsal root stimulation. The time course of this inhibition overlapped with that of the dorsal root discharge suggesting that part of the inhibition of the monosynaptic reflex may be exerted at a presynaptic level. The existence of GABA(A) receptor-independent mechanisms and the roles of the antidromic discharges in the neonatal rat are discussed.