猫扣带回前部内脏伤害感受神经元的膜电学特性

目的：研究猫扣带回前部内脏大神经刺激相关神经元的膜电生理特性,以便从神经元水平进一步了解大脑皮质内脏伤害感受的特性及机制,为痛觉理论“特异性学说”提供新的实验依据。方法：应用在体玻璃微电极细胞内电位记录技术及细胞内注入极化电流的方法,测量和计算神经元的膜电学参数。结果：将20只猫扣带回前部176个内脏大神经刺激相关神经元,分为内脏伤害(148个)和非伤害(28个)感受神经元。发现它们在膜电阻、时间常数、膜电容及I—V曲线等方面存在差异。注入去极化电流引发的放电幅值及频率也存在差异。结论：扣带回前部内脏伤害与非伤害感受神经元可能在细胞膜结构、细胞大小等形态学方面存有差别。     

三种蜘蛛粗毒对NG108—15细胞电压门控钠通道的抑制作用

利用小鼠神经细胞瘤×大鼠神经胶质细胞的杂交细胞NG108-15,通过全细胞记录(whole-cellrecording)模式的膜片钳技术,检验了虎纹捕鸟蛛(Selenocosmia huwena)、海南捕鸟蛛(Selenocosmia hainana)和广西大疣蛛(Macrothele guangxiasp)的粗毒对NG108-15细胞膜上电压门控TTX敏感型钠电流和延迟整流钾电流的作用.结果表明,三种蜘蛛粗毒对外向延迟整流钾电流没有明显作用,但对TTX敏感型的快钠电流表现出较强的抑制效应.抑制效应呈量效关系.三种粗毒抑制钠电流的EC     

青蒿素衍生物对Na+和K+通道的抑制及其与普鲁卡因作用的比较

抗疟新药青蒿素的某些含氮衍生物在动物实验中还显示中局部麻醉效应。本工作利用分化的ＮＣ１０８－１５细胞,在全细胞电压箝位下,比较了五种青蒿素 生物和普鲁卡因对电压门控钠流和延迟整汉钾流的作用。所观察的五种衍生物均部分可逆地和剂量依赖地抑制ＩＮａ,其中含芳香环的ＳＭ５４１作用最强,效应与普鲁卡因的相近。３００μｍｏｌ／Ｌ普卡因对ＩＫ只有微弱的抑制作用;而五种衍生物在相同浓度下均明显抑制ＩＫ,并加快它的     

Population genetic simulation: Benchmarking frameworks for non-standard models of natural selection

Population genetic simulation has emerged as a common tool for investigating increasingly complex evolutionary and demographic models. Software capable of handling high-level model complexity has recently been developed, and the advancement of tree sequence recording now allows simulations to merge the efficiency and genealogical insight of coalescent simulations with the flexibility of forward simulations. However, frameworks utilizing these features have not yet been compared and benchmarked. Here, we evaluate various simulation workflows using the coalescent simulator msprime and the forward simulator SLiM, to assess resource efficiency and determine an optimal simulation framework. Three aspects were evaluated: (1) the burn-in, to establish an equilibrium level of neutral diversity in the population; (2) the forward simulation, in which temporally fluctuating selection is acting; and (3) the final computation of summary statistics. We provide typical memory and computation time requirements for each step. We find that the fastest framework, a combination of coalescent and forward simulation with tree sequence recording, increases simulation speed by over twenty times compared to classical forward simulations without tree sequence recording, although it does require six times more memory. Overall, using efficient simulation workflows can lead to a substantial improvement when modelling complex evolutionary scenarios—although the optimal framework ultimately depends on the available computational resources.     

Effect of beta-endorphin on the thermal excitability of preoptic neurons in the unanesthetized rabbit

The opioid peptide, beta-endorphin (beta-E), will promote changes in body temperature when injected into the brain. It is possible that beta-E alters body temperature by affecting the activity of thermoregulatory neurons in the preoptic anterior hypothalamus (POAH). Single unit activity in the POAH was recorded in unanesthetized rabbits while radiant heat was applied to the dorsal skin. Beta-E was then microinjected into the POAH, and the peripheral heating was repeated. Seventy-seven percent of the POAH neurons were responsive to skin heating. Beta-E and equal excitatory and inhibitory effects on warm-excited and warm-inhibited neurons. Four of six warm-excited neurons were converted to warm-inhibited or unresponsive following beta-E injection. Six out of ten warm-inhibited neurons were converted to warm-excited or unresponsive by beta-E. Beta-E-induced shifts in thermal excitability of POAH neurons may be responsible for the ability of POAH injections of beta-E to elevate body temperature in the rabbit.     

Simultaneous Electrophysiological Recording and Calcium Imaging of Suprachiasmatic Nucleus Neurons

Simultaneous electrophysiological and fluorescent imaging recording methods were used to study the role of changes of membrane potential or current in regulating the intracellular calcium concentration. Changing environmental conditions, such as the light-dark cycle, can modify neuronal and neural network activity and the expression of a family of circadian clock genes within the suprachiasmatic nucleus (SCN), the location of the master circadian clock in the mammalian brain. Excitatory synaptic transmission leads to an increase in the postsynaptic Ca²⁺ concentration that is believed to activate the signaling pathways that shifts the rhythmic expression of circadian clock genes. Hypothalamic slices containing the SCN were patch clamped using microelectrodes filled with an internal solution containing the calcium indicator bis-fura-2. After a seal was formed between the microelectrode and the SCN neuronal membrane, the membrane was ruptured using gentle suction and the calcium probe diffused into the neuron filling both the soma and dendrites. Quantitative ratiometric measurements of the intracellular calcium concentration were recorded simultaneously with membrane potential or current. Using these methods it is possible to study the role of changes of the intracellular calcium concentration produced by synaptic activity and action potential firing of individual neurons. In this presentation we demonstrate the methods to simultaneously record electrophysiological activity along with intracellular calcium from individual SCN neurons maintained in brain slices.     

Monitoring of behavior using a video-recording system for recognition of Salmonella infection in experimentally infected growing pigs

Behavior is one of the most commonly used indicators of illness; however, few studies have investigated how different common diseases affect animal behavior. This experiment was conducted to investigate behavioral and clinical alterations in growing pigs experimentally infected with Salmonella spp. during a 4-week post-infection period. A total of 48 growing pigs were divided into one of the three treatment groups (1) control, (2) infection with Salmonella Typhimurium or (3) infection with Salmonella Enteritidis. Individual pigs’ behavior was recorded daily (0900 to 1100 and 1600 to 1800 h) using a video-recording system. Pigs in both infected groups had lower weight gain and feed intake during week 0 to 2 and 0 to 4 experimental period. Bacteriological data revealed that pigs in both infected groups persistently shed bacteria throughout the period of study. Oral infection of growing pigs with S. Typhimurium and S. Enteritidis significantly reduced the frequency of morning large (except week 1) and small movement throughout the study period. In the evening, significantly lowest frequency of movements were observed in the S. Enteritidis-infected group compared with the control. The standing and sitting frequency were significantly lower in both infected groups only at the morning of week 4. Infection with Salmonella spp. led to a significant reduction in the frequency and duration of morning eating and drinking throughout the experimental period, with the exception of 4^th week drinking duration. The lowest frequency of evening eating during week 1 and 4 was recorded in both infected groups; whereas, the duration differed only at week 1. The evening drinking frequency only tended to decrease in response to S. Typhimurium infection at week 1. This study shows that, pigs infected with Salmonella spp. had poor performance, shedding high levels of Salmonella with their feces and reduced feeding and drinking activity, which are adaptive responses to infection and may help caretakers to detect ill health.     

Octopamine modulates the sensitivity of silkmoth pheromone receptor neurons

Effects of octopamine and its antagonist epinastine on electrophysiological responses of receptor neurons of Antheraea polyphemus specialised to the pheromone components (E,Z)-6,11-hexadecadienyl acetate and (E,Z)-6,11-hexadecadienal were investigated. Injections of octopamine and epinastine into the moths had no effect on the transepithelial potential of the antennal-branch preparation nor on the spontaneous nerve impulse frequency in either type of receptor neuron. However, in the presence of continuous low-intensity pheromone stimulation, octopamine significantly increased the nerve impulse frequency in the acetate receptor neuron, but not in the aldehyde receptor neuron. Octopamine and epinastine had no significant effect on the receptor potential amplitudes elicited in both receptor neuron types by pheromone stimulation. However, the peak nerve impulse frequency in the response of both receptor neuron types to pheromone was significantly affected: decreased by epinastine and increased by octopamine over a broad range of pheromone concentrations. In control experiments, injection of physiological saline did not significantly alter the peak nerve impulse frequency. The effect of octopamine was established within 1 h after injection and persisted for about 4 h. The possibility of a direct action of octopamine on the nerve impulse generation by the receptor neurons is discussed. Accepted: 8 January 2000     

Floristic changes in the British Isles: comparison of techniques for assessing changes in frequency of plants with time

Botanical recording data are often used to assess changes in the frequencies of plant species over time, but are subject to marked variations in recording activity. We compare and evaluate some general methods that can be used to detect changes in species' frequencies taking into account the recording variations. Models for 15 species that have been studied in detail previously were compared using the numbers of individual records, sites, hectads, or vice-counties at different time scales (year, decade, moving averages, and pre-/post- specific dates), with or without correction for recording variation. The best methods had a correction for the amount of recording over time, summarized records by decade or moving average, and used an extrapolation between first and last records for sites or hectads. Increasing the geographical and temporal scales can decrease the influence of recording variations, but leads to a loss of sensitivity and under-estimates the true extent of change. The choice between sites and hectads will depend on the detail of the records available; cruder data sets should use the latter.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 279–301.     

尖吻蝮蛇毒对蟾蜍交感神经节细胞电活动的影响

用细胞内电位记录技术,以离体蟾蜍交感链为标本,观察了尖吻蝮蛇毒(AAV)的神经毒性作用。结果表明,该蛇毒(10-200μg/ml)对交感神经元的静息电位、膜电阻和膜电容没有显著的作用,对动作电位形状也无可测出的影响,但能使阈电位轻皮升高,即使神经元兴奋性稍降低。AAV(>25μg/ml)对胆碱能性的快兴奋性突触后电位有剂量依从性的,部分可逆性的抑制作用。其作用机制至少应部分归之于AAV对突触后膜上的N型胆碱能受体的阻断作用。本研究发现的AAV神经毒性作用可能有一定实践意义。