EMR照射对大鼠血脑屏障超微结构及通透性的影响

目的研究EMR照射对大鼠血脑屏障超微结构及通透性的影响。方法用硝酸镧示踪和电子显微镜观察EMR照射后大鼠血脑屏障通透性及超微结构的变化。结果EMR照射后,海马、皮层组织、下丘脑中硝酸镧颗粒从毛细血管中渗出,毛细血管紧密联结开放,毛细血管内皮中吞噬小体增加,可见镧颗粒沉积于组织间隙及神经细胞内膜上,神经细胞变性,但结构基本正常。结论EMR照射后大鼠血脑屏障通透性增大,但尚未对脑神经细胞结构的完整性造成损伤。     

电磁脉冲对大鼠血脑屏障通透性及紧密连接蛋白的影响

目的 研究电磁脉冲(electromagnetic pulse,EMP)辐照对大鼠血脑屏障通透性及血脑屏障紧密连接(tight junction,TJ)相关蚩白的影响.方法 66只健康成年雄性SD大鼠按体重随机分为假辐照组和辐照组.EMP辐照参数为:场强200 kV/m,脉宽7 ns,脉冲次数200,脉冲重复频率1 Hz.辐照后不同时间取材,用白蛋白免疫组织化学方法 观察EMP辐照后血脑屏障通透性的变化,免疫印迹法检测脑组织和脑微血管中TJ蚩白(occludin和ZO-1)的表达情况,免疫荧光方法 观察微血管紧密连接蛋白的分布情况.结果 免疫组织化学结果 显示,辐照后0.5 h即可见有白蛋白漏出的微血管,但数目较少,随辐照后时间延长,有白蛋门漏出的微血管数目逐渐增加,至辐照后3 h达到高峰,辐照后6 h时开始恢复,辐照后12 h基本恢复至对照水平;免疫印迹结果 显示,occludin蛋白水平与对照组相比无明显差异;ZO-1蛋白水平在辐照后1、3 h明显降低,并且免疫荧光结果 显示ZO-1在微血管上的分布亦发生了改变,由辐照前的连续分布变为断续分布.结论 EMP辐照后ZO-1蛋白水平和分布的改变可能是EMP致大鼠血脑屏障通透性增加的分子机制之一.     

电磁辐射对血脑屏障通透性的影响及其机制研究进展

血脑屏障(blood-brain-banjer,BBB)是存在于血液与脑组织之间的屏障结构,由脑微血管内皮细胞、基膜和星形胶质细胞足突组成.脑的毛细血管属连续型,毛细血管内皮细胞之间以紧密连接(tight junction,TJ)封闭,内皮外有基膜、周细胞以及星形胶质细胞突起的足突围绕.与机体其他部位的微血管相比,BBB的通透性极低,其目的是防止血液中的有害物质通过BBB而对神经元造成损伤,维持大脑微环境的相对稳定.     

乙酸铅及硫酸铝和甲醛暴露对大鼠不同脑区血脑屏障通透性的影响

目的定量评估乙酸铅、硫酸铝和甲醛暴露对大鼠不同脑区血脑屏障(blood-brain barrier,BBB)通透性的影响。方法设低(1/8 LD50)、中(1/4 LD50)、高剂量(1/2 LD50)和空白对照组(不作处理),采用腹腔注射染毒Wistar大鼠。于染毒后24、48和72 h采用伊文蓝(EB)比色法测定大鼠大脑皮质、皮质下及海马组织血脑屏障通透性。血脑屏障通透性以每毫克组织中EB的光密度值表示(OD/mg)。结果与对照组比较,低、中、高剂量乙酸铅(18.75、37.5和75.0 mg/kg)、硫酸铝(7.5、15.0和30.0 mg/kg)染毒后24、48和72 h大鼠大脑皮质、皮质下及海马组织血脑屏障通透性增高(P0.01)。各剂量甲醛染毒组(50.0、100.0和200.0 mg/kg)大鼠皮质下及海马组织血脑屏障通透性在所有观察时点均增高(P0.05),脑皮质血脑屏障通透性在第48和72小时增高(P0.05)。结论乙酸铅、硫酸铝和甲醛暴露能够引起大鼠大脑皮质、皮质下及海马组织的血脑屏障通透性增高,提示对上述脑区血脑屏障功能具有损伤性,较易侵入大脑甚至对中枢神经产生暴露和影响。     

采用能谱法研究铅对大鼠血脑屏障的通透性

目的研究铅从血液进入脑实质的可能机制,血管内皮细胞的连续层对铅的屏障作用。方法用电镜硝酸镧示踪和电子探针能量色散Ｘ射线分析观察大鼠饮用含铅水（１０和３０ｍｇ／Ｌ）３个月后,铅在大鼠脑皮质区毛细血管内、外侧不同细胞中的分布与血脑屏障通透性的变化。结果对照组与１０ｍｇ／Ｌ组血铅浓度虽有差异,但在毛细血管内皮细胞内表面的质膜中都只收集到了铅的Ｌα峰,在内皮细胞外侧的基膜,星形胶质细胞足板及神经细胞轴突中未出现任何铅峰,同时硝酸镧示踪也未显示血管通透性有变化。而在３０ｍｇ／Ｌ组,上述细胞部位均收集到了铅的Ｌα峰和Ｍα峰,同时在管腔较大的毛细血管的某些部位可见镧盐颗粒穿过内皮细胞间的缝隙到达基膜及周细胞。结论血管内皮细胞内表面的质膜是铅作用于脑的最初靶点,血管内皮细胞的连续层对铅有屏障作用,但该屏障作用非常弱,铅在内皮细胞内表面的质膜中积累稍多,便会损害内皮细胞间的紧密联结透至脑实质,与硝酸镧示踪的结果一致。     

Toxicity of bis (tri-n-butyltin) oxide on learning and development in the rat

The toxicity of bis (tri-n-butyltin) oxide (TBTO) was studied in THA rats. Doses of 0 (control), 10 or 15 mg/kg/day of TBTO were administered to adult rats for 12 consecutive days, and 0, 5 or 10 mg/kg/day was given to pregnant rats from day 6 to day 20 of gestation by gastric intubation. In the adult rat exposure experiment, the 15 mg/kg group showed slightly decreased body weight and spontaneous motor activity, and a low avoidance rate in the Sidman avoidance test in the early stage of administration. In the pregnant-rat exposure experiment, no effect of TBTO was seen in either the 5 mg/kg or 10 mg/kg groups in dams while all pups in the 10 mg/kg group died by postnatal day 3. Little effect of TBTO on body weight, pinna detachment, incisor eruption, eye opening, surface righting, cliff avoidance, pivoting, negative geotaxis and auditory startle was found in the 5 mg/kg pups. In the Sidman avoidance test, the avoidance rate of the 5 mg/kg pups was lower than that of control pups in the early stage of the session. In a water E-maze test, the swimming time to the goal and the number of errors were increased in the 5 mg/kg pups. In a reversal water E-maze test, increases of the swimming time to the goal and the number of errors made by the 5 mg/kg pups were marked. These results suggest that TBTO administration disrupts the learning acquisition of rats, and that the toxicity of TBTO is greater in prenatally exposed pups than in adult rats.     

Changes in permeability of the alveolar-capillary barrier in firefighters.

The effect on alveolar-capillary barrier permeability of chronic exposure to a smoke produced by the partial combusion of diesel oil, paraffin, and wood was examined. An index of permeability was determined from the rate of transfer from the lung into the blood of the hydrophilic, labelled chelate 99mTc diethylene triamine penta-acetate (MW 492 dalton). The results of this test were expressed as the half time clearance of the tracer from the lung into the blood (T1/2 LB). The study was carried out at the Royal Naval Firefighting School, HMS Excellent. Permeability index was measured on seven non-smoking naval firefighting instructors who had worked at the school for periods of longer than two and a half months. Tests of airway function and carbon monoxide transfer factor were performed on four of these seven instructors. The results of the permeability index showed a T1/2 LB of 26 min +/- 5 (SEM) which differed significantly from that of normal non-smokers. By contrast all other lung function tests had values within the predicted normal range.     

Anorectic effects of circulating cytokines: role of the vascular blood-brain barrier

Communication between the central nervous system and peripheral tissues is mediated in part by the ability of the blood-brain barrier (BBB) to transport peptides and regulatory proteins. Many cytokines with effects on appetite, including interleukins 1alpha, 1beta, and 6 and tumor necrosis factor-alpha, are transported across the BBB. Cytokines also can interact with the luminal surface of the brain endothelial cells, which constitute the BBB, to induce brain endothelial cells to release appetite-affecting substances into brain interstitial fluid. Leptin, a 16-kDa protein that binds to a cytokine receptor, is produced by fat cells and transported across the BBB by a saturable system to exert its anorectic effects. Transporter performance for appetite-related peptides and regulatory proteins can be altered by disease and under conditions associated with anorexia or obesity, a striking example being leptin transport in obesity. In mice with obesity of maturity, leptin transport is reduced by about two-thirds, showing that obesity involves a dysfunction of the BBB. That altered transport across the BBB of other substances related to feeding also might result in obesity or anorexia is a possibility that deserves investigation.     

孕酮对大鼠脑挫裂伤后水通道蛋白-4与血脑屏障通透性的影响

目的探讨孕酮减轻创伤性脑水肿的机制。方法建立雄性大鼠额叶脑挫裂伤模型并予孕酮干预治疗。免疫组织化学法检测脑组织星形胶质细胞AQP4表达的变化;伊文氏蓝法测定脑组织血脑屏障通透性的变化。结果经孕酮干预治疗,脑组织含水量在各时相点均下降（P〈0．05）。脑挫裂伤后24、72、120h时间段伤灶及其周边脑组织星形胶质细胞AQP4阳性细胞计数下降（P〈0．05）;伤后6h和24hEB含量明显下降（P〈0．01）。结论孕酮减轻创伤性脑水肿的作用,可能与它降低外伤后脑组织AQP4表达水平和减轻伤后早期血脑屏障通透性有关。     

Effect of bis(maltolato)oxovanadium (IV) (BMOV) on selenium nutritional status in diabetic streptozotocin rats

The role of V as a micronutrient, and its hypoglycaemic and toxicological activity, have yet to be completely established. The present study focuses on changes in the bioavailability and tissue distribution of Se in diabetic streptozotocin rats following treatment with V. The following four study groups were examined: control; diabetic (DM); diabetic treated with 1?mg V/d (DMV); diabetic treated with 3?mg V/d (DMVH). V was supplied in the drinking water as bis(maltolato)oxovanadium (IV). The experiment had a duration of 5 weeks. Se was measured in food, faeces, urine, serum, muscle, kidney, liver and spleen. Glucose and insulin serum were studied, together with glutathione peroxidase (GSH-Px), glutathione reductase (GR), glutathione transferase (GST) activity and malondialdehyde (MDA) levels in the liver. In the DM group, we recorded higher levels of food intake, Se absorbed, Se retained, Se content in the kidney, liver and spleen, GSH-Px and GST activity, in comparison with the control rats. In the DMV group, there was a significant decrease in food intake, Se absorbed, Se retained and Se content in the liver and spleen, and in GSH-Px and GST activity, while fasting glycaemia and MDA remained unchanged, in comparison with the DM group. In the DMVH group, there was a significant decrease in food intake, glycaemia, Se absorbed, Se retained, Se content in the kidney, liver and spleen, and in GSH-Px and GST activity, and increased MDA, in comparison with the DM and DMV groups. We conclude that under the experimental conditions described, the treatment with 3?mg V/d caused a tissue depletion of Se that compromised Se nutritional status and antioxidant defences in the tissues.