Impulsive choice induced in rats by lesions of the nucleus accumbens core

Impulsive choice is exemplified by choosing a small or poor reward that is available immediately, in preference to a larger but delayed reward. Impulsive choice contributes to drug addiction, attention-deficit/hyperactivity disorder, mania, and personality disorders, but its neuroanatomical basis is unclear. Here, we show that selective lesions of the nucleus accumbens core induce persistent impulsive choice in rats. In contrast, damage to two of its afferents, the anterior cingulate cortex and medial prefrontal cortex, had no effect on this capacity. Thus, dysfunction of the nucleus accumbens core may be a key element in the neuropathology of impulsivity.     

Cardiovascular responses of the chicken to seasonal and induced temperature changes

Blood pressure and cardiac output decline as ambient temperature rises in birds acclimatized to both seasonal- and induced-temperature changes, in contrast to the response usually observed in unacclimatized mammals. The decline in chickens is due to a lowered vascular resistance and blood volume. These circulatory adjustments may be related to the fact that excess heat in birds is dissipated through the respiratory system rather than through the skin.     

Cretinism in rats: enduring behavioral deficit induced by tricyanoaminopropene

Rats reared on diets containing tricyanoaminopropene, the antithyroid compound that stimulates RNA synthesis, showed a deficit in performance on automated closed-field maze tests many weeks after discontinuation of the drug. The rats were also tested while still receiving the drug, and performance deficits were indicated in tests of Y-maze reversal and manual closed-field maze performance; rats treated with the drug and with thiouracil behaved in a highly similar fashion on several tasks. No evidence of facilitation by tricyanoaminopropene appeared in any of the eight learning situations used. Exposure to tricyanoaminopropene before and after birth, at doses sufficient to produce anatomical cretinism, apparently induces an enduring behavioral deficit which is similar to that of neonatal thyroidectomy-induced cretinism in rats and which parallels the mental retardation associated with human cretinism.     

Cardiac sympathetic nerve activity: changes induced by ouabain and propranolol

A study of the effects of ouabain and propranolol on the spontaneous activity in the preganglionic sympathetic nerves to the cat heart showed that ouabain can produce both an inhibition and a stimulation of the spontaneous activity in sympathetic nerves. The inhibition appears to be reflex in nature and is not present when the buffer nerves are sectioned. The stimulation is correlated with the development of cardiac arrhythmias and is antagonized by propranolol.     

Oxygen affinity in red cells: changes induced in vivo by propranolol

Propranolol, a blocking agent for the beta adrenergic receptor, produces a redistribution of 2,3-diphosphoglycerate in the red cell. At concentrations of 3.3 x10(-5)M, 2,3-diphosphoglycerate in the red cell membrane becomes unbound in vitro. The administration of propranolol to hunmns produces similar changes and results in a decrease in the affinity of hemoglobin for oxygen.     

低温诱导下烤烟花芽分化与IAA分解代谢相关酶的变化规律

研究了吉烟9号6叶龄烟苗在低温诱导下花芽生长发育进程,同时分析了花芽分化过程中IAA分解代谢相关酶的变化规律.结果表明,低温处理的烟株表现为植株矮小,叶数锐减,叶片小;在现蕾期上,低温处理比CK提早4d左右;解剖花芽观察可知,低温处理比CK花芽分化进程早3～5 d.在花芽分化进程中,CK和低温处理IAAO活性变化规律基本相同,均呈先下降后上升趋势,在移栽后44 d均达到最低值,且低温处理的酶活性略高;低温处理与CK的POD活性均呈先上升后下降的趋势,只是酶活性达到高峰的时间有所不同,分别为移栽后44和51d.总之,吉烟9号花芽开始分化到现蕾期大约需要15d左右.     

Addiction liability of albino rats: breeding for quantitive differences in morphine drinking

Selective breeding produced two strains of rats that differ in their susceptibility to morphine addiction. Inbreeding the more susceptible rats in an unselected population produced susceptible offspring; inbreeding resistant rats produced resistant offspring. Further selection and inbreeding increased the strain difference in the F(2) and F(3) generations. The F(3) generation also differed in their susceptibility to alcohol addiction.     

Permeability of a nuclear membrane: changes during normal development and changes induced by growth hormone

The ion permeability of the nuclear membrane envelope of salivary gland cells (of the midge Chironomus thummi) undergoes changes during development. Following the early fourth instar stage, permeability falls to about one-fifth of its base value over a period of 3 to 5 days of development of the animal, and then rises again over the next 2 to 4 days. The falling phase of the change can be reproduced within 1 hour by injections of the growth hormone ecdyson.     

Electrocardiogram monitoring: computerized detection of ventricular changes induced by drugs

Cardiac arrhythmia was induced in mice by the injection of ouabain, lidocaine, and diphenylhydantoin. Temporal spreading of ventricular electrocardiographic complexes is shown consistently to follow injection of a cardioactive drug and to precede rhythm disturbances. A computerized monitoring technique based on temporal spreading and waveform distortion should find wide clinical and experimental application.     

Oxygen affinity and electrolyte distribution of human blood: changes induced by propranolol

Propranolol causes a massive leakage of potassium ions from red cells, which results in an alteration of the Gibbs-Donnan equilibrium across the red cell membrane. According to such a mechanism, the presence of propranolol significantly increases the hydrogen ion activity of the interior of the red cell, causing a decreased oxygen affinity of hemoglobin according to the classical Bohr effect. No release of 2,3-diphosphoglycerate which may be bound to the membrane is thus necessary to explain the effect of propranolol on the oxygen dissociation curve of blood.     

Iron in synthetic quartz: heat and radiation induced changes

As part of a study of the possible changes in silicate material on the lunar surface produced by solar radiation, effects of ionizing radiation, of heating, and of heating followed by ionizing radiation on iron-doped synthetic quartzes have been studied as models. The optical changes are mainly related to valence changes in ferric or ferrous ions.     

Regulation of keystone predation by small changes in ocean temperature

Key species interactions that are sensitive to temperature may act as leverage points through which small changes in climate could generate large changes in natural communities. Field and laboratory experiments showed that a slight decrease in water temperature dramatically reduced the effects of a keystone predator, the sea star Pisaster ochraceus, on its principal prey. Ongoing changes in patterns of cold water upwelling, associated with El Nino events and longer term geophysical changes, may thus have far-reaching impacts on the composition and diversity of these rocky intertidal communities.     

TMV侵染番茄引起的细胞结构变化及细胞程序化死亡

为研究植物系统反应过程中出现的细胞程序化死亡(PCD)现象，用烟草花叶病毒(TMV)接种番茄叶片，光镜和电镜观察到茎尖顶端细胞出现：PCD特征：线粒体嵴数目减少直至双层膜破毁、前质体基粒扭曲变形、细胞核畸形、核染色质浓缩并边缘化、细胞质和液泡中出现大量环状片层及酚类物质、多泡体出现、细胞壁膨胀扭曲、叶肉细胞的叶绿体基粒和基质片层结构破坏。试验表明：TMV侵染番茄引起的系统反应过程中有：PCD发生；茎尖细胞发生的PCD现象类似于动物细胞中细胞质的细胞死亡。     

高温诱导叶用莴苣抽薹过程中细胞形态的变化

[目的]分析高温处理条件下叶用莴苣抽薹过程中花芽、花茎细胞学和茎的形态变化.[方法]以叶用莴苣(Lactuca sativeL.)“G-B30”,“G-B31”为材料,对两个易抽薹品种的花芽和茎的分化过程进行细胞学观察,并结合茎的快速伸长时期确定叶用莴苣的抽薹期.[结果]随着高温处理时间的延长,两个易抽薹品种的茎尖生长点由尖锐的锐角变为半球形,生长锥逐渐加宽变平,且都是在高温处理第4天时茎尖生长点就开始出现由圆锥形变扁平;花茎高温处理第8天细胞排列出现规律性,与常温8d处理相比差异显著;在8～20 d时花茎伸长迅速.[结论]通过观察花芽和花茎分化的情况,并结合花茎的形态变化判断,综合可知“G-B30”,“G-B31”在高温处理第8天开始抽薹.     

超氧化物歧化酶与苏云金芽胞杆菌高温诱导产黑色素相关

为探讨苏云金芽胞杆菌高温诱导产黑色素机制,利用含mini-Tn10转座子载体pIC333构建苏云金芽胞杆菌油松亚种4CA1,随机插入突变体库,以寻找相关调控基因。通过高温诱导筛选得到1株在42℃产黑色素减弱的菌株;克隆得到mini-Tn10中断基因的部分序列,通过测序及同源性比对分析,确定中断基因为超氧化物歧化酶基因sodA2。     

环磷酞胺复制中老年男性雄激素部分 缺乏综合征大鼠模型的研究

〔摘要〕目的应用环磷酞胺复制中老年男性雄激素部分缺乏综合征的大鼠模型建立〔方法取20只大鼠随机 分为2组:正常组,模型组〔分别于造模前、造模后1d、造模后30 d观察大鼠一般情况、体质量、悬尾实验和强迫游 泳实验时间以及辜丸指数,放射免疫法测定各组造模前后血清1"1'' , FT水平,免疫组化法测定各组大鼠辜丸间质细 胞stAR蛋白平均灰度值,并进行统计分析〔结果与正常组比较,模型组大鼠悬尾实验时间延长,差异具有统计学意 义(P<0.01),强迫游泳实验时间缩短,差异具有统计学意义(P<0.01) ,血清1"1'' , FT水平、stAR蛋白平均灰度值均显著 升高,差异具有统计学意义(P<0.05、结论环磷酞胺造成的大鼠血清1"1'' , FT水平卜降,行为学改变的反辜丸组织退 行性变.基木类似PADAM模型、     

Compulsive sexual activity induced by p-chlorophenylalanine in normal and pinealectomized male rats

p-Chlorophenylalanine depletes brain serotonin and induces longlasting sexual excitation in male rats. The effect of p-chlorophenylalanine is potentiated by pargyline. Administration of 5-hydroxytryptophan to rats treated with p-chlorophenylalanine plus pargyline blocks the sexual excitation. p-Chlorophenylalanine also elicits sexual excitation in pinealectomized rats; this effect is not mediated by the lack of indole hormones in the pineal but may be the consequence of depletion of 5-hydroxytryptophan in the brain and the resulting imbalance between 5-hydroxytryptophan and catecholamine activity in the central nervous system.