应激浓度皮质酮对大鼠海马神经元兴奋性氨基酸受体的快速作用

目的:研究大鼠应激浓度皮质酮对兴奋性谷氨酸受体——N-甲基-D-天冬氨酸(NMDA)受体的快速调控作用及其机制。方法:运用常规膜片钳技术,研究细胞外给予应激浓度皮质酮(CORT)对原代培养的大鼠海马神经元谷氨酸(Glu)和NMDA诱发电流(IGlu和INMDA)的快速作用,以及细胞内透析CORT对INMDA影响。结果:CORT (10 μmol／L)可快速、可逆地抑制大鼠海马神经元IGlu和INMDA;细胞外牛血清清蛋白耦联的皮质酮(CORT-BSA,10 μmol／L)有与CORT相似的作用;细胞内CORT(10 μmol／L)对INMDA的峰值无明显影响。结论:提示应激浓度 CORT对大鼠巾枢神经系统兴奋性突触传递过程有快速抑制作用,对谷氨酸受体(GluR)的作用主要是通过NMDA 受体实现的;该作用是通过细胞外快速膜机制产生的。

硫酸镁对气管插管时血流动力学和应激激素浓度的影响

目的:以脑电双频指数(BIS)作为麻醉深度监测指标,研究靶控输注丙泊酚时不同剂量的硫酸镁对气管插管时血流动力学和应激激素浓度变化的影响,以及对丙泊酚效应室靶浓度的影响。方法:60例择期手术病人随机分为C组、M1组和M2组,每组20例。以靶控输注丙泊酚行麻醉诱导(初始靶浓度为2μg/mL),M1组和M2组在气管插管前3min分别静脉推注硫酸镁15、25mg/kg;并根据BIS值变化调节3组丙泊酚靶浓度,使BIS值在45～55范围内。结果:C组的SBP、MBP在插管后即刻和1min较基础值明显升高(P<0.01),M1、M2组变化不明显(P>0.05)。C组血浆Cor浓度在插管后3min时明显上升(P<0.05),而M1、M2组呈下降趋势(P<0.05)。C组血浆A-Ⅱ浓度在插管后3、10min时明显上升(P<0.05),与M1组、M2组相比差异显著(P<0.05)。C组在插管后5、10min丙泊酚靶有效浓度显著高于M1组和M2组(P<0.01);M2组在同一时点低于M1组(P<O.O5)。结论:与15mg/kg硫酸镁组相比,25mg/kg硫酸镁组能更好地减轻气管插管引起的应激反应,并且明显降低丙泊酚TCI效应室靶浓度,减少丙泊酚用量。

右美托咪定对静脉全麻诱导时心率变异性、血流动力学及应激激素质量浓度的影响

目的 ：观察右美托咪定（dexmedetomidine,DEX）对静脉全麻诱导时心率变异性（heart rate variability,HRV）、血流动力学及应激激素质量浓度的影响。方法：选择择期行腹部手术的患者40例,年龄18-60岁,随机均分为两组：DEX组（D组）麻醉诱导前10 min开始予DEX 1μg/kg,微量泵10 min内静脉输注完毕;对照组（C组）：予同等剂量的生理盐水。分别在入室后10 min（Ta）、给药后10 min至麻醉诱导后（Tb）、气管插管后3 min（Tc）,各时间段均记录5 min心电信号;入室后10 min（T0）、给药后10 min（T1）、麻醉诱导后（T2）、气管插管后3 min（T3）,记录各时间点的心率（heart rate,HR）、收缩压（systolic pressure,SBP）、舒张压（diastolic pressure,DBP）;同步于各时点抽取静脉血7 m L,采用放免法测定血清皮质醇（cortisol,Cort）、去甲肾上腺素（norepinephrine,NE）和肾上腺素（epinephrine,E）的浓度。结果：与C组比较：T1-T3时D组SBP、DBP、HR及E、NE、Cort明显降低（P〈0.05）;D组Tb、Tc时低频指标显著下降（P〈0.05）,高频指标下降不明显。结论：术前予小剂量的DEX（1μg/kg）缓慢静注,能较好地抑制气管插管反应,HRV可定量反映静脉全麻诱导时DEX对自主神经功能的影响,可作为临床合理用药和麻醉监测的一种手段。

Tissue-specific bioaccumulation and oxidative stress responses in juvenile Japanese flounder (Paralichthys olivaceus) exposed to mercury

To understand mercury （Hg） toxicity in marine fish, we measured Hg accumulation in juvenile Japanese flounder （Paralichthys olivaceus） and assessed the effects on growth and antioxidant responses. After Hg exposure （control, 5, 40, and 160 gg/L Hg） for 28 d, fish growth was significantly reduced. The accumulation of Hg in fish was dose-dependent and tissue-specific, with the maximum accumulation in kidney and liver, followed by gills, hone, and muscle. Different antioxidants responded differently to Hg exposure to cope with the induction of lipid peroxidation （LPO）, which was also tissue-specific and dose- dependent. As Hg concentration increased, superoxide dismutase （SOD） and catalase （CAT） activities increased significantly, whereas glutathione S-transferase （GST） activity and glutathione （GSH） levels decreased significantly in the gills. SOD and glutathione peroxidase （GPx） activities and the GSH level increased significantly in the liver. SOD activity and GSH levels increased significantly, but CAT activity decreased significantly with an increase in Hg concentration in the kidney. LPO was induced significantly by elevated Hg in the gills and kidney but was least affected in the liver. Therefore, oxidative stress biomarkers in gills were more sensitive than those in the liver and kidney to Hg exposure. Thus, the gills have potential as bioindicators for evaluating Hg toxicity in juvenile flounder.

Oxidative stress responses of submerged macrophyte Vallisneria asiatica to different concentrations of cyanobacteria

In a 10-day aquarium experiment, this investigation examines macrophyte restoration in eutrophic Lake Taihu, the physiological effects of different plant biomass levels and of increasing natural cyanobacterial concentrations on a submerged macrophyte, Vallisneria asiatica. Cyanobacterial stress suppressed the superoxide dismutase （SOD） activity of the plant＇s leaves and induced the catalase （CAT） and peroxidase （POD） activities of its roots. The soluble protein content in V. asiatica decreased with an increase in natural cyanobacterial concentrations, whereas the malonaldehyde （MDA） increased significantly at chlorophyll a （Chl a） concentrations of 222 and 262 μg/L in water. V. asiatica adapted to the stress caused by cyanobacterial concentrations by adjusting its antioxidant defense system to remove the excessive reactive oxygen species when the algal Chl a concentration was 〉109 μg/L. Additionally, high biomass of V. asiatica （2 222 g FW/m^2） can inhibit the reproduction of cyanobacteria more significantly than low biomass （1 111 g FW/m^2）. High biomass of V. asiatica increased the oxidative stress in an individual plant when the initial Chl a concentration in the water reached 222 and 262 μg/L, as expressed by the increased MDA in leaves, compared with low biomass of K asiatica. This provides a basis for controlling cyanobacterial concentrations and V. asiatica biomass for the recovery of V. asiatica in eutrophic Lake Taihu.

Response of Populus x canescens (Populus tremula x alba) to high concentration of NaCl stress

Populus x canescens was cultivated on solid substrate and treated by salt （150 mM NaCl）. The growth parameters including new leaf formation, height increment, diameter at the base increment, fresh and dry mass of leaf, stem, coarse root, and fine root were determined. The nutrient elements in leaves of samples under salt stress and the control, and the chlorophyll fluorescence of plants separated dark and light, initial fluorescence （Fo）, and maximum fluorescence （Fro） were measured. Results showed that 150 mM NaCI treatment resulted in growth reduction of Populus x canescens. Nutrient element contents in the foliage of plants under salt stress were different from that of control. The foliar N-concentrations of plants under salt stress were not affected. Contents of Na under salt stress were 120 times as much as that under control. However, contents of S, K, P, Ca, Mg, Fe, Mn under salt stress were less than that under control. Salt stress caused damage in the PSII reaction centers, i.e. photo-inhibition couldn＇t be repaired under dark situation. The yield of chlorophyll fluorescence showed that several parameters associated with PSII functions, e.g. Fv/Fo, Fv/Fm were not influenced at the first stage of salt stress treatment. However, after a period of time, PSII functions were significantly inhibited, which led to the decrease of carbon assimilation. These results suggest that salt stress （150 mM NaCl） did not affect photosynthetic chlorophyll fluorescence of Populus x canescens immediately. After four day of salt stress, PSII reaction centres were seriously damaged during photo-inhibition.

Effect of Transport Time and Handling on Physiological Responses of Cattle

The objective of this work was to determine the effect of transport time （up to 11 hours） on animal welfare. 540 animals （cows, bulls and calves）, three transport times of 2, 4 to 6, and 10 to 11 hours, and two space allowances （2 m2 and 1.5 m2 per animal for cows and bulls; and 1.2 m2 and 0.8 m2 per animal for calves） were used for the experiment during transport from farms to the abattoir in Uppsala, Sweden. Measurements were made on five animals on each trip. Stress response parameters considered were cortisol, glucose, lactate, creatine kinase and heart rate. Blood samples were taken before and after transport. Heart rate sensors were mounted on the animals at least 30 minutes before loading and measurements were made continuously from farms to the abattoirs until stunning. The results of heart rate measurement indicated that loading, un-loading and forced movement in the stunning box were the most stressful events. However, the results of statistical analysis confirmed that transport time doesn＇t have significant effect （P 〈 0.05） on heart rate. Concentration level of cortisol increased by 10 folds during short transport. However, cortisol concentration decreased with an increase of transport times （P 〈 0.01）. Glucose concentrations increased with transport time in all animal categories （P ≤ 0.01）. Transport time has significant effect on concentration levels of glucose （P ≤ 0.01）, creatine kinase （P 〈 0.001） and lactate （P 〈 0.01） particularly after 6 hours journey time.