心理应激对大白鼠自由基损伤的影响

本研究将动物分为实验模型５天、１０天、２０天组及对照组,并检测各组动物上述组中的ＬＰＯ、ＳＯＤ、ＣＡＤ水平进行了分析;研究因噪音诱发的心理应激反应时大白鼠脑、肝、肺、心、肾组织自由基损伤情况及防御酶的活性变化;结果发现：在心理应激反应条件下,动物各组织的因自由基反应而使ＬＰＯ含量升高、防御酶ＳＯＤ、ＣＡＤ活性下降,表明：１．心理应激可以诱发动物体内产生大量的自由基,并对脑、肝、肺、心、肾组织产生影     

肝脏缺血预处理研究中的哲学思考

1　预处理研究与原型启示1 1　预处理发展史1 986年 ,Ｍｕｒｒｙ等首次报道结扎犬冠状动脉 5ｍｉｎ,再灌注 1 0ｍｉｎ ,重复进行 4次 ,不仅未产生累加性缺血损伤 ,反而可以减轻随后 45ｍｉｎ缺血所致的心肌损伤 ,他们将心脏遭受短暂缺血后能耐受随后较长时间缺血损伤的现象称为缺血预处理 (ｉｓ ｃｈｅｍｉｃｐｒｅｃｏｎｄｉｔｉｏｎｉｎｇ ,ＩＰＣ) [1] 。该现象已在不同种属动物与临床病人以及不同的实验模型 (在体心脏、离体心脏、培养的心肌细胞)、心脏以外组织器官(如肝、小肠、大脑、视网膜 )得到证实[2 ] 。整体动物进行肝脏缺血预…     

自由基在癫痫发生及其治疗中的研究现状与进展

癫痫是一组包括许多不同症状的综合征,其主要特征是对反复出现的无明显诱因的发作的易感性。无论动物实验还是临床观察均表明癫痫时伴有活跃的自由基反应,自由基与癫痫的发生发展有着密切的联系。清除自由基,阻断自由基反应无疑为癫痫的治疗开辟了新的途径。本文就自由基在癫痫发生及其治疗中的研究现状与进展作一概述。目前应用自由基清除剂治疗癫痫尚处于临床试验阶段,但我们可以预见,进一步探索癫痫发生的自由基病理机制,开发有效清除自由基的药物具有广阔的前景,并将为人类最终战胜癫痫提供有力的帮助。     

自由基在癫痫发生及其治疗中的研究现状与进展

癫痫是一组包括许多不同症状的综合征,其主要特征是对反复出现的无明显诱因的发作的易感性.无论动物实验还是临床观察均表明癫痫时伴有活跃的自由基反应,自由基与癫痫的发生发展有着密切的联系.清除自由基,阻断自由基反应无疑为癫痫的治疗开辟了新的途径.本文就自由基在癫痫发生及其治疗中的研究现状与进展作一概述.目前应用自由基清除剂治疗癫痫尚处于临床试验阶段,但我们可以预见,进一步探索癫痫发生的自由基病理机制,开发有效清除自由基的药物具有广阔的前景,并将为人类最终战胜癫痫提供有力的帮助.     

长期职业性稳态噪声暴露对工人诱发脑电图影响的计算机分析

一、引言噪声作为一种公害来说,不仅为世界所公认,而且受到各国的普遍的重视。这不仅是由于近年城市噪声有逐年上升的趋势,更重要的是由于噪声对人体造成多方面的危害,其中包括使人烦噪,干扰睡眠、工作和休息,导致耳聋,引起流产,影响消化系统和内分泌系统等等。然而人们最为关心的还是噪声对脑功能的危害。稳态噪声对人脑功能的危害,国内外都作过大量的研究,不过其中多数是以主诉症状的     

自由基在神经外科手术时脑保护中的意义

神经外科手术中脑内自由基(主要是氧自由基)产生增加,脂质过氧化反应增强,造成细胞结构和功能上的继发性损伤。自由基在继发性损伤中的具体机制尚未完全清楚,可能与缺血级联反应、缺血再灌注和细胞凋亡有关。术中采取措施清除自由基以及减少自由基的产生将有助于保护损伤的脑组织。     

自由基在神经外科手术时脑保护中的意义

神经外科手术中脑内自由基(主要是氧自由基)产生增加,脂质过氧化反应增强,造成细胞结构和功能上的继发性损伤.自由基在继发性损伤中的具体机制尚未完全清楚,可能与缺血级联反应、缺血再灌注和细胞凋亡有关.术中采取措施清除自由基以及减少自由基的产生将有助于保护损伤的脑组织.     

铁路运输噪声对周边环境的影响及防范措施

随着我国城市范围的不断扩张,铁路沿线正逐渐由市郊转变为市区,这导致铁路噪声污染对人们生活的影响日益加剧,而即便是位于郊外的铁路,其对动物正常繁衍作息的干扰也是不可忽视的。基于此,文章将简要探讨铁路运输噪声对环境的负面影响,并针对这些影响给出处理对策。     

工业噪声对人体瞬时记忆和注意的影响(Ⅱ)

噪声引起神经系统功能紊乱是对人体危害的一个重要方面。我们曾报道过噪声发生器产生的强噪声明显影响小白鼠脑的发育及条件反射的建立。俞大乾等的研究说明,短期连续噪声对小白鼠的记忆有直接影响。由于记忆和注意测验成绩可以作为人脑功能状态的重要指标;因此,我们抽取南京织布厂等十个工厂的232名工人进行了测查,结果说明强度为95分贝以上的稳态噪声长期积累性的暴露对人体的瞬时记忆和注意均有明显的危害,表现为记忆能力差;注意集中短暂。     

大白鼠脑双侧内嗅区损伤在攻击、自卫行为和开阔场地活动上的作用

本工作使用36只成年雌性大白鼠,随意分成三组,第一组11只动物接受双侧内嗅区损伤的手术,第二组11只动物作为手术对照,第三组14只动物不作手术,为正常对照。 本工作由两个同时进行的实验组成。(1)观察动物对训练棒的攻击和自卫行为反应,分别计算术前和术后每只动物出现强反应的百分比。(2)开阔场地测试,记录动物在10分钟内走过的方格数,并观察其活动方式。实验结果表明,损伤后,攻击行为、自卫行为的强反应比例和方格数都比术前有显著增加(P<0.001;<0.01;<0.001)。损伤后的动物在两个实验上都有“冻结”、蜷伏、理毛和洗脸等动作的明显减少。在第一个实验中还发现,动物会表现出被训练棒出现的新异视觉刺激强烈吸引的异常现象。分析这些结果,可以了解,大白鼠内嗅区的主要功能之一可能与形成恐惧性情绪因素有关,并因而促进动物活动中的止动反应。在行使这些功能的过程中,视觉因素可能存在着微弱的影响。     

A conditioned reinforcer maintained by temporal association with the termination of shock

Two experiments were conducted to determine whether a stimulus can be established as a positive conditioned reinforcer by associating it with the termination of shock, but without training the animal to make any response in its presence. In the first, six rats were conditioned to press a bar to terminate shock on a variable ratio schedule; white noise was then substituted as the immediate consequence, with the shock terminating 30 sec after the last press in its presence. It was found that the rate of pressing in the absence of noise depended on the contingency between the pressing and the noise. The second experiment sought to determine whether the difference in rates before and after the onset of the noise was due to the reinforcement of prior responding by the onset of the noise or to the suppression of subsequent responding by differential reinforcement of competing behavior. Six more rats were trained in the same manner, but with shock terminating 30 sec after the onset of the noise, regardless of what the animal did in its presence. Again the rate was higher before the onset of the noise, indicating that pressing was indeed maintained by the noise as a conditioned reinforcer.     

Effects of neonatal handling on play behavior and fear towards a predator odor in juvenile rats (Rattus norvegicus)

The effects of brief daily separation, also known as "handling," during the first 2 weeks of life on play behavior and fearfulness toward a predatory odor were assessed in juvenile rats. Handled rats were more playful than nonhandled control rats, and while handling had no effect on the direct response of these rats toward a predatory odor, handled rats did not exhibit a conditioned suppression of play when tested later in the same context where they had been exposed to the predatory odor. Handled rats were still wary of the environment in that they continued to show a heightened level of risk assessment behavior. These data suggest that early postnatal experiences may play a significant role in determining how an animal deals with predatory threats later in life.     

恐惧发生与预防的实验研究：──Ⅰ、强烈噪音下恐具行为的动物模型

通过不同方法对ＳＤ型大鼠分四组进行实验处理,观察比较大鼠的行为,发现：在突然的高强度噪音条件下,大鼠出现恐惧的行为反应;强刺激组大鼠恐惧行为较控制组明显增多,行为的唤醒适应能力异常,并存在显著的个体差异;噪音脱敏训练对提高大鼠在高强噪音条件下的应激能力、减少恐惧具有良好的促进作用;在脱敏训练中尤以逐渐递增噪音强度、刺激时间与平均分配实验日结合的方法效果最为显著。     

The effect of vibrato on the recognition of masked vowels

Five experiments on the identifiability of synthetic vowels masked by wideband sounds are reported. In each experiment, identification thresholds (signal/masker ratios, in decibels) were measured for two versions of four vowels: a vibrated version, in which FO varied sinusoidally around 100 Hz; and a steady version, in which F0 was fixed at 100 Hz. The first three experiments were performed on naive subjects. Experiment 1 showed that for maskers consisting of bursts of pink noise, vibrato had no effect on thresholds. In Experiment 2, where the maskers were periodic pulse trains with an F0 randomly varied between 120 and 140 Hz from trial to trial, vibrato slightly improved thresholds when the sound pressure level of the maskers was 40 dB, but had no effect for 65-dB maskers. In Experiment 3, vibrated rather than steady pulse trains were used as maskers; when these maskers were at 40 dB, the vibrated versions of the vowels were slightly less identifiable than their steady versions; but, as in Experiment 2, vibrato had no effect when the maskers were at 65 dB. Experiment 4 showed that the unmasking effect of vibrato found in Experiment 2 disappeared in subjects trained in the identification task. Finally, Experiment 5 indicated that in trained listeners, vibrato had no influence on identification performance even when the maskers and the vowels had synchronous onsets and offsets. We conclude that vibrating a vowel masked by a wideband sound can affect its identification threshold, but only for tonal maskers and in untrained listeners. This effect of vibrato should probably be considered as a Gestalt phenomenon originating from central auditory mechanisms.     

A nonobtrusive heart rate telemetry system for rats

A harness for recording heart rate (HR) from unrestrained rats and an inexpensive FM transmitter for broadcasting high-resolution EKGs are described. The harness, which employs surface electrodes rather than skin pins or implanted electrodes, is especially valuable for recording HR over extended periods of time. Because it is comparatively free of noise generated by the animal’s activity, the system is applicable to a wide range of experimental conditions. Sample HRs obtained from three strains of rats while engaging in different behavioral categories are presented.     

No control,no drive: how noise may undermine conservation behavior in a commons dilemma

Sometimes people may no longer engage in conservational behavior (e.g., to reduce emissions) because their attempts to do so have been thwarted by “negative noise”, or external forces that may cause otherwise cooperative intentions to translate into non‐cooperative action (e.g., strikes prevented to commute by public transport rather than by car). The purpose of the present research is to examine whether experiences with negative noise in a commons dilemma may undermine conservational motivation and behavior, even in a subsequent commons dilemma that is free of noise. Participants first interacted in a commons dilemma task—with noise versus without noise—in which the common pool was sustained versus deteriorating. Afterwards, participants were involved in an identical second task in the same pool size condition but noise‐free for everybody. Consistent with hypotheses, participants who faced noise and a deteriorating resource in the first task exhibited lower levels of conservation in the second task than did participants who were always acting free of noise. This pattern was mediated by a reduced motivation to preserve the common pool, suggesting that the experience of noise in combination with a decline in collective resources may especially undermine cooperative motivation and behavior. Copyright © 2007 John Wiley & Sons, Ltd.     

WITHIN‐SESSION TRANSITIONS IN CHOICE: A STRUCTURAL AND QUANTITATIVE ANALYSIS

The present study used within‐session transitions between two concurrent schedules to evaluate choice in transition. Eight female Long‐Evans rats were trained to respond under concurrent schedules of reinforcement during experimental sessions that lasted 22 hr. The generalized matching equation was used to model steady‐state behavior at the end of each session, while transitional behavior that emerged following the change in reinforcement schedules was modeled using a logistic equation. The generalized matching and logistic equations were appropriate models for behavior generated during single‐session transitions. A local analysis of behavior on the two response alternatives during acquisition was used to determine the source of preference as revealed in response ratios. The number of “low‐response” visits, those containing three to five responses, remained stable. Preference ratios largely reflected a sharp increase in the number of visits with long response bouts on the rich alternative and a decrease in the number of such visits to the leaner alternative.     

Control of responding by sounds of different quality: an evolutionary analysis.

Two experiments investigated the acquisition of discriminations between two acoustic stimuli of different quality (noise bursts vs. a 2-kHz pulsed signal) when features of the everyday environment were incorporated into the experiments. In Experiment 1, rats were trained, using food, to press a lever. Throughout all sessions, 5-s trials of noise bursts (the random stimulus) were presented, after variable intertrial intervals, through a remote speaker mounted outside the experimental enclosure. The noise burst occurred randomly with respect to reinforcement of lever pressing and had no programmed relationship to the animal's behavior. When lever pressing was established, the 2-kHz signal was presented through a speaker adjacent to the response lever according to a different set of variable intertrial intervals. A response in the presence of the 2-kHz signal terminated the trial and was reinforced. The 2-kHz signal acquired control of responding within the first few trials, whereas the random stimulus exerted no control of responding. In Experiment 2, rats were trained to press the lever in the presence of the 2-kHz signal presented through the adjacent speaker on a variable intertrial interval. After 14 sessions, 5-s trials of noise bursts (random stimulus) were presented through the remote speaker on the second variable intertrial interval. The random stimulus initially elicited exploratory behavior, which then rapidly declined. Subsequently, the random stimulus exerted no or weak control of responding. The introduction of the random stimulus had no effect on responding in the presence of the adjacent stimulus. In Experiments 3 and 4 the random stimulus was presented through the adjacent speaker, and the stimulus correlated with reinforcement was presented through the remote speaker. In both experiments, there was persistent control of responding by the random stimulus and slow development of control by the stimulus correlated with reinforcement. In Experiment 5, both stimuli were presented through the adjacent speaker. There was persistent control of responding by the random stimulus.     

The effects of d-amphetamine on the temporal control of operant responding in rats during a preshock stimulus.

The operant behavior of six rats was maintained by a random-interval schedule of reinforcement. Three-minute periods of noise were superimposed on this behavior, each period ending with the delivery of an unavoidable shock. Overall rates of responding were generally lower during the periods of noise than in its absence (conditioned suppression). These suppressed response rates also exhibited temporal patterning, with responding becoming less frequent as each noise period progressed. The effects of d-amphetamine on this behavioral baseline were then assessed. In four animals the relative response rates during the noise and in its absence suggested that the drug produced a dose-related decrease in the amount of conditioned suppression. However, this effect was often due to a decrease in the rates of responding in the absence of the preshock stimulus, rather than to an increase in response rates during the stimulus. Temporal patterning in response rates during the preshock stimulus was abolished, an effect that was interpreted in terms of rate-dependent effect of d-amphetamine. This study thus extends rate-dependent analyses of the effects of amphetamines to the patterns of operant behavior that occur during a preshock stimulus, and which have been discussed in terms of the disrupting effects of anxiety on operant behavior.