牛磺酸对大鼠亚硒酸钠性白内障昌状体中游离氨基酸含量的影响

目的：研究腹腔注射牛磺酸对大鼠亚硒酸钠性白内障晶状体中游离氨基酸含量的影响。方法：测定第一次射亚硒酸钠后及每日腹腔注射一次牛磺酸的大鼠的第2、5、9、14天，大鼠晶状体中游离氨基酸的含量。结果：除牛磺酸、天冬氨酸和羟脯氨酸的含量明显下降外，其它大部分氨基酸的含量显著升高，在诱发后的第5天最明显；腹腔注射牛磺酸可显著抑制上述变化。其作用在诱发后的第2天和第5天最明显，结论：腹腔注射牛磺酸可显著抑制亚硒酸钠引起的晶状体中游离氨基酸含量的变化。     

牛磺酸对大鼠自由基的清除作用及其对亚硒酸钠性白内障脂质过氧化的影响

目的 探讨牛磺酸对体外反应系统中的羟自由基和超氧阴离子自由基的清除作用;观察腹腔注射牛磺酸对大鼠亚硒酸钠性白内障晶状体中脂质过氧化的影响。方法 应用电子自旋顺磁共振技术,检测不同浓度的牛磺酸对羟自由基和超氧阴离子自由基的清除作用。在注射亚硒酸钠后第2、5、9和14天,分别测定正常组、亚硒酸钠组和牛磺酸组大鼠晶状体中的丙二醛（malondialdehyde,MDA)含量。结果 牛磺酸对羟自由基和超氧阴离子自由基具有明显的清除作用。大鼠注射亚硒酸钠后,其晶状体中MDA的含量较正常晶状体明显升高,并随着白内障病程的发展逐渐增加。牛磺酸组晶状体中MDA的含量始终低于亚硒酸钠组。结论 牛磺酸对羟自由基、超氧阴离子自由基具有明显的清除作用;对亚硒酸钠性白内障晶状体中的脂质过氧化反应具有明显的抑制作用。     

牛磺酸对亚硒酸钠性白内障抑制作用的实验研究

目的 研究牛磺酸对亚硒酸钠性白内障的抑制作用。方法 从注射亚硒酸钠前２天,给Ｗｉｓｔａｒ大鼠每日腹腔注射一定浓度的牛磺酸,定期用裂隙灯显微镜检查。结果 ０．５％的牛磺酸对晶体无明显的保护作用,而１％、２％和４％牛磺酸可显著延缓核混浊的发生和发展,２％和４％的牛磺酸还可延缓皮质混浊的发展。结论 牛磺酸对亚硒酸钠性白内障有明显的抑制作用,它的作用强度与剂量成正比。牛磺酸有可能成为一种抗亚硒酸钠性白内障     

晶状体上皮细胞凋亡与硒性白内障关系的实验研究

目的 探讨晶状体上皮细胞凋亡与亚硒酸钠诱发的硒性白内障形成的关系。方法 给ＳＤ大鼠注射亚硒酸钠后１，３，７天剥取日状体吓膜。用流式细胞仪（ＦＣＭ）计数晶状体上皮细胞凋亡百分率，ＤＮＡ片断凝胶电泳检测晶状体上皮细胞核提取物，并应用透射电镜观察晶状体上皮细胞凋亡的开矿学变化。结果 给药后第１天晶状体上皮细胞凋亡百分率即显著增高，第３天达高峰，以后逐渐下降。而晶状体混浊程度持续加重，给药后第７天形成典型     

牛磺酸抑制亚硒酸钠性白内障的FT拉曼及FT红外光谱分析

目的 探讨亚硒酸钠性白内障中晶状体蛋白成分和结构的变化以及牛磺酸对这些变化的抑制作用。方法 首次用傅里叶变换拉曼光谱和红外光谱同步研究牛磺酸抑制亚硒酸钠性白内障晶状体中一些基因伸缩振动的变化。结果 亚硒酸钠性白内障晶状体中巯基和色氨酸的伸缩振动明显降低，蛋白质分子一些基团的伸缩振动在白内障形成之初就发生明显改变，牛磺酸可抑制上述变化。结论 亚硒酸钠性白内障形成之初，晶状体蛋白中ＳＨ－（巯基）、ｔｒｐ－（色氨酸）、ｐｈｅ－（苯丙氨酸）和ＣＨ２－（亚甲基）等就受到损伤，牛磺酸可保护这些基团，这可能是牛磺酸抑制亚硒酸钠性白内障的机理。     

牛磺酸对链脲佐菌素-糖尿病性白内障干预机制初探

探讨不同浓度牛磺酸对链脲佐菌素(STZ)-糖尿病性白内障的干预机制。方法：100只雄性SD大鼠,随机平均分为5组,腹腔注射STZ溶液(55mg／kg体重)诱发糖尿病性白内障,牛磺酸治疗组大鼠每日腹腔注射1次牛磺酸(5mL／kg体重)。定期测定各组大鼠血糖浓度,实验结束时测定各组血清中甘油三酯等生化指标及胰岛素水平,用毛细管电泳仪检测房水及晶状体中牛磺酸含量。结果STZ组大鼠在诱发的第3周晶状体开始出现囊泡或轻度混浊,而牛磺酸明显抑制了牛磺酸治疗组早期白内障的发生。诱发的第4～12周,STZ组晶状体混浊度迅速加重,而4％或8％牛磺酸组则明显延缓了白内障的发生。4％和8％牛磺酸治疗组在STZ诱发的第4天、第4周、第8周(4％牛磺酸组)的血糖均显著低于STZ组,第12周牛磺酸治疗组与STZ组的血糖值无显著意义。4％牛磺酸组大鼠血清甘油三酯水平显著低于STZ组(P=0.004),8％牛磺酸组大鼠血清甘油三酯水平也明显低于STZ组(P=0.010)。8％牛磺酸治疗组大鼠的房水中牛磺酸浓度高于STZ组,差异有显著意义(P=0.036),其晶状体中牛磺酸浓度也高于STZ组,差异有非常显著意义(P=0.000)。结论牛磺酸对STZ．糖尿病性白内障的干预作用具有剂量依赖性,其干预机制不仅与其降低血糖、降低甘油三酯水平、改善脂质代谢有关,特别与其提高房水和晶状体中牛磺酸含量,使晶状体免受氧化损伤有重要关系。     

血-视网膜屏障的发育与大鼠硒性白内障形成的关系

目的:探讨大鼠硒性白内障形成是否与血-视网膜屏障的发育情况有关.方法:测定了不同年龄段大鼠晶状体中谷胱甘肽过氧化物酶(GPx)活性、丙二醛(MDA)水平以及眼球中的硒含量;并采用氢氧化镧[La(OH)3]示踪法观察不同年龄段血-视网膜屏障的发育情况.结果:开眼前幼鼠GPx的酶活性最高,之后随着年龄的增长而逐渐下降;出生第20 d大鼠视网膜色素上皮层的La(OH)3分布显著少于出生第11天龄幼鼠.对出生第9d大鼠注射亚硒酸钠(Na2SeO3)48h后,La(OH)3大量进入视网膜的内层,视网膜色素上皮层受到严重破坏;而注射相同剂量Na2 SeO3的18天龄大鼠在48h后,只有少量的La(OH)3进入.开眼前大鼠晶状体中MDA含量最高,开眼后下降显著;Se组是对照组的5倍.再者,大鼠眼中的La(OH)3分布与眼球中的硒含量、晶状体中的MDA水平的变化基本一致.结论:亚硒酸钠诱导形成的硒性白内障主要原因是幼鼠血-视网膜屏障发育不成熟,而不是抗氧化能力.     

两种实验白内障晶状体及血清多元素含量的动态变化

研究亚硒酸钠或半乳糖诱发大鼠白内障形成中晶状体和血清的Fe、Al、Zn、Cu、Mg、Ca 和P 含量的动态变化。结果发现,用两种因子诱发白内障后,Ca/P 比值明显升高;在亚硒酸钠诱发的白内障晶状体中Zn 和Ca 含量增加,Zn、Cu、Mg、Ca 和P 元素与半乳糖诱发的白内障发展有密切关系。结果证明,这些元素可能是白内障的继发因子。     

活体观察N-乙酰半胱氨酸防治白内障的实验研究

背景 亚硒酸钠诱导的白内障与年龄相关性白内障的形成机制具有一定的相似性,即氧化损伤,N-乙酰半胱氨酸(NAC)是一种有效的抗氧化剂,但其对白内障的预防和治疗作用研究尚少. 目的 观察NAC对亚硒酸钠诱导大鼠白内障的预防和治疗作用,为白内障的药物防治提供实验依据.方法 实验分为预防部分和治疗部分.选取SD大鼠60只,随机数字表法分为正常对照组1、正常对照组2、硒性白内障组、NAC白内障预防组、硒性白内障生理盐水组及NAC白内障治疗组,每组10只大鼠.采用3.46 mg/kg亚硒酸钠颈部皮下注射法制作硒性白内障模型,隔日1次,共3次.预防实验时在首次注射亚硒酸钠前30 min大鼠腹腔内注射2 mmol/L NAC,每日1次,共6次;治疗实验时,硒性白内障大鼠造模后1d腹腔内注射2 mmol/LNAC,每日1次,共1个月;硒性白内障生理盐水组以同样方法注射生理盐水.每周各组大鼠在裂隙灯下观察晶状体混浊程度并参考LOCSⅢ标准进行分级.各实验组大鼠最后一次注药后制备晶状体组织切片,光学显微镜下观察晶状体上皮细胞( LECs)的组织病理学改变,扫描电子显微镜下观察晶状体上皮超微结构的改变.采用免疫组织化学法观察亚硒酸钠对晶状体中caspase-3的影响;对各组大鼠晶状体组织中超氧化物歧化酶(SOD)、丙二醛(MDA)含量的变化进行生化测定.结果 实验后7d正常大鼠晶状体透明.硒性白内障组Ⅴ级晶状体混浊者有11只眼,NAC白内障预防组仅有Ⅱ级混浊8只眼和Ⅰ级混浊2只眼,差异有统计学意义(x2=40.000,P＜0.05).实验后30d,硒性白内障生理盐水组和NAC白内障治疗组Ⅳ～Ⅴ级晶状体混浊均为20只眼,差异无统计学意义(x2=0.153,P＞0.05).常规组织病理学检查表明,正常对照组LECs及晶状体纤维结构正常,硒性白内障组、硒性白内障生理盐水组和NAC白内障治疗组LECs与前囊部分分离,排列疏松紊乱,细胞膜破裂,细胞核呈椭圆形或长条形,晶状体纤维断裂,NAC白内障预防组晶状体结构破坏程度较轻.扫描电子显微镜下可见硒性白内障组、硒性白内障生理盐水组和NAC白内障治疗组晶状体前囊分层,外膜脱离,深层可见“变性球样小体”,纤维紊乱破碎,形成无结构的“水泥样”外观.硒性白内障组caspase-3和SOD的表达明显低于正常对照组,MDA的表达高于正常对照组,差异均有统计学意义(P＜0.05),而NAC白内障预防组caspase-3和SOD的表达明显高于硒性白内障组,差异均有统计学意义(P＜0.05).硒性白内障生理盐水组与NAC白内障治疗组caspase-3、SOD和MDA表达均明显低于正常对照组2,差异均有统计学意义(P＜0.05),而硒性白内障生理盐水组与NAC白内障治疗组比较,caspase-3、SOD和MDA表达的差异均无统计学意义(P＞0.05).结论 NAC可以提高晶状体组织中SOD的活性,减少MDA生成,降低caspase-3的活性,从而减轻晶状体的氧化损伤,对早期白内障的发生、发展有一定的延缓和预防作用,但对于已经形成的白内障无明显治疗作用.     

亚硒酸钠诱发大鼠白内障实验方法的改进

白内障是致盲的主要厩因之一,因此,深入探讨发病机理尤为重要,建立一个理想的白内障动物模型对研究白内障的发生,发展机制及防治的研究有着重要意义.许多因素都能诱发白内障,膳食中硒含量的过量与缺乏均对晶体有不利影响,含硒的无机物亚硒酸钠诱发大鼠白内障的实验方法可建立较为理想的动物模型。一些学者分别给大鼠乳鼠注射不同剂量的亚硒酸钠在两周左右时,可诱发大鼠出现间歇性核型或成熟期白内障,其诱发白内障的时间较长,(1,2,3)本实验旨在改进其方法,以小剂量隔日注射(共三次)的方法,     

Modelling cortical cataractogenesis 22: is in vitro reduction of damage in model diabetic rat cataract by taurine due to its antioxidant activity?

The protective effect of taurine in model in vitro diabetic cataract and the mechanism of this effect were investigated in isolated rat lenses. Isolated rat lenses were incubated in medium 199 in elevated glucose (55.6 m m) with taurine (5 m m). Taurine concentrations in the lenses were determined by amino acid analysis. Accumulative leakage of the intracellular enzyme lactate dehydrogenase (LDH) was used to estimate damage to the lens, as previously reported. In the clear lenses, prior to vacuole formation, after 1 or 2 days of incubation, the taurine and amino acids in lenses decreased progressively in concentration. In lenses incubated with 5 m m taurine, the level of taurine was increased towards that of control lenses. In taurine-treated lenses LDH leakage was significantly decreased, and lens clarity was maintained, similarly to that found previously for vitamin C and lipoic acid. To test whether taurine has similar antioxidant activity, we tested its ability to decrease luminol luminescence generated by (1) superoxide from hypoxanthine/xanthine oxidase and (2) peroxide from diluted glucose/glucose oxidase. For either superoxide or peroxide, the luminescence was decreased to zero, as a function of increasing taurine concentration, at 30 m m, approximately the physiological concentration of taurine in the lens. Spin trapping confirmed that taurine scavenged superoxide. This is consistent with a role for taurine as an important antioxidant protecting the lens against oxidative insults. Amino acids also had antioxidant activity in this assay, and as a group, when all activities were summed, their loss also contributed significantly to the antioxidant loss. Taken in conjunction with Wolff and Crabbe's observation of increased free radical generation by glucose auto-oxidation in diabetes, this suggests a push-pull mechanism for increased oxidative stress in diabetic cataract, involving both increased free radicals and decreased radical scavenging antioxidants.     

Biochemical changes in selenite cataract model measured by high-resolution MAS H NMR spectroscopy

PURPOSE: To correlate certain levels of lens opacification with high-resolution magic-angle spinning proton nuclear magnetic resonance (HR-MAS (1)H NMR) spectroscopy analysis of the biochemical changes in rat lenses in a selenite cataract model. METHODS: Selenite cataract was induced by injecting 13-day-old Sprague-Dawley rat pups with a single subcutaneous dose of sodium selenite (3.28 mg/kg in 0.9% sodium chloride solution). Lens opacification was observed using a photographic slit-lamp microscope at selected time-points 3, 6 and 9 days after selenite injection and was then graded (levels 0, 1 and 2). The animals were killed after the slit-lamp microscopy, lenses were removed and HR-MAS (1)H NMR spectra from intact lenses were obtained. Relative changes in metabolite concentrations were determined after comparison with matched lenses from untreated animals. RESULTS: Photographic slit-lamp microscopy revealed different stages of cataract in all animals treated with selenite. In the high quality HR-MAS (1)H NMR spectra of the lenses, more than 30 different metabolites were identified in each lens. With the exception of taurine, the concentrations of all amino acids showed a significant increase (p < 0.05) in the second level of cataract. By contrast, glutathione (GSH), succinate and phosphocholine concentrations were significantly reduced. CONCLUSIONS: For the first time, this study demonstrates the potential to correlate the level of lens opacification with the biochemical changes obtained with HR-MAS (1)H NMR spectroscopy analysis in a selenite cataract model.     

Ocimum sanctum modulates selenite-induced cataractogenic changes and prevents rat lens opacification

PURPOSE: To study the effect of Ocimum sanctum (OS) on selenite-induced morphological and biochemical changes in isolated rat lenses as well as on cataract incidence in rat pups. METHODS: Transparent rat lenses were divided into normal, selenite-only, and four treated groups. Selenite-only and treated group lenses were subjected to oxidative stress in vitro by incorporating sodium selenite (100 microM) in the culture medium. The effect of OS (70, 140, 280, and 560 microg/ml) was studied on the levels of reduced glutathione (GSH) and thiobarbituric acid reacting substances (TBARS) in selenite-challenged lenses. The lowest concentration of OS offering significant modulation on these two parameters was determined. Subsequently, the effect of prior and cotreatment with the lowest effective concentration of OS was studied on TBARS, GSH, and on lens antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GSHPx), catalase (CAT), and glutathione-S-transferase (GST). Changes in lens protein profiles under different incubation conditions were analyzed by SDS gel-electrophoresis. In vivo, cataract was induced by a single subcutaneous injection of sodium selenite (25 micromole/kg b.w.) to 9-day-old rat pups. The anticataract effect of OS (5 and 10 mg/kg b.w.) injected intraperitoneally 4 hr prior to selenite challenge was evaluated by the presence of lens nuclear opacity in rat pups on the 16th postnatal day. Insolubilization of lens proteins post-selenite injection was monitored for 4 days. RESULTS: The lenses in the selenite-only group developed cortical opacities in 24 hr. OS showed different degrees of positive modulation in selenite-induced morphological as well as biochemical changes. The lowest effective dose of OS that significantly modulated glutathione and thiobarbituric acid reacting substances was found to be 140 microg/ml. At this dose, a significant increase in antioxidant enzyme levels and preservation of normal lens protein profile was observed. OS at the dose of 70 microg/ml did not show any significant protection with respect to either morphology or biochemistry of lenses. In vivo, 5 and 10 mg/kg of OS reduced the incidence of selenite cataract by 20% and 60%, respectively, and prevented protein insolubilization as well. CONCLUSIONS: Aqueous extract of OS possesses potential anticataract activity against selenite-induced experimental cataractogenesis. The protective effect was supported by restoration of the antioxidant defense system and inhibition of protein insolubilization of rat lenses as well.     

Quantitative estimation of the relationship between amino acids and cataracts in rat lens]

The concentration of free amino acids and their related compounds has been determined in the lenses of ICR (f) strain rat and in the Wistar strain rat's lenses which were cultured with diethyl maleate. It was supposed that the decrease of cystathionine and the increase of serine in lenses of ICR with aging were related with development of senile cataracts. The increase of cystathionine in lenses cultured were suggested that synthesis of taurine is done by cystathionine pathway. Quantitative changes of amino acids were higher than normal of glutamine, glycine and aspartate in lenses cultured. It was supposed that the changes were the flow in lens from medium for synthesis of glutathione and glucose.     

Prevention of selenite-induced cataractogenesis in Wistar rats by the polyphenol, ellagic acid

The present study sought to evaluate the efficacy of the naturally-occurring polyphenol, ellagic acid, in preventing selenite-induced cataractogenesis. In the present study, Wistar rat pups were divided into 3 groups of 15 each. Group I (normal) rats received an intraperitoneal (i.p.) injection of normal saline on postpartum day 10; group II (cataract-untreated) rats received a single subcutaneous (s.c.) injection of sodium selenite (19 micromol/kg body weight) on postpartum day 10; group III (cataract-treated) pups received a single s.c. injection of sodium selenite on postpartum day 10 and intraperitoneal injections of ellagic acid (200mg/kg body weight) on postpartum days 9-14. At the end of the study period (30th postpartum day), slit-lamp examination of both eyes of each rat pup revealed no lenticular opacification (cataract stage 0) in all eyes of group I pups, definite nuclear cataracts (stages 4-6) in the eyes of all (100%) group II rat pups and no lenticular opacification in eight (53%) and mild lenticular opacification (cataract stages 1-3) in seven (47%) of group III rats (changes in group II vs group III, P<0.01). The mean activities of the antioxidant enzymes catalase, glutathione peroxidase, superoxide dismutase and glutathione-S-transferase were significantly lower in lenses of Group II rats than in Group I or Group III rat lenses. In addition, the mean levels of GSH in lenses and erythrocytes were also significantly lower in Group II rats than in Group I or Group III rats. Conversely, the mean concentration of MDA (an indicator of lipid peroxidation) in lenses and erythrocytes was found to be significantly higher in Group II rats than that in Group I or Group III rats. Also, the mean concentration of calcium was found to be significantly higher in lenses of Group II rats than in those of Group I and Group III rats. The results suggest that ellagic acid can prevent or retard experimental selenite-induced cataractogenesis in Wistar rats. This protective effect in rat lenses appears to occur by maintaining the antioxidant defense system and inhibition of lipid peroxidation.     

Biochemical changes associated with the development and reversal of galactose cataracts.

The rate of synthesis of glutathione (GSH) in lens extracts during cataract formation has been determined and found to be the same as that of extracts from normal lenses. It is concluded that unlike X-ray-induced cataracts the potential mechanism for GSH synthesis in galactose cataracts is unaffected. In addition, the levels of GSH, free amino acids, dulcitol, cations and the degree of hydration of the lens during the development and reversal of galactose cataract have been determined.Feeding of a normal diet even after the development of mature cataracts (20 days) leads to the disappearance of cortical opacities almost completely leaving an essentially clear lens with only a very fine pinhead nuclear opacity.The levels of GSH, taurine and other free amino acids, which fall rapidly dudring cataract formation, return to near normal values during the reversal phase even though the lenses are hydrated. In cnntrast to the near complete recovery of these constituents, sodium ion concentration remains four times higher than in the control lenses almost 4 weeks after diet reversal. The recovery of potassium ion during the same period is about 70% of controls. The continued hydration of the lenses during the reversal phase of cataract, despite the disappearance of dulcitol, is apparently related to the elevated sodium ion concentration.A possible explanation for the recovery of GSH and free amino acids in hydrated lenses has been suggested.     

Modelling cortical cataractogenesis 21: in diabetic rat lenses taurine supplementation partially reduces damage resulting from osmotic compensation leading to osmolyte loss and antioxidant depletion.

The concentration of taurine and the amino acids, glutathione, cysteine, ascorbate and ATP were determined in the lenses of rats made diabetic with streptozotocin. In the clear lenses, prior to vacuole formation after 1 or 2 weeks of diabetes, the increase in concentration of sorbitol and the total decrease of all these osmolytes were not significantly different. The major components of the osmolytes lost were taurine and amino acids, which together accounted for over 75% of the total osmolyte loss. Since glutathione, ascorbate, taurine and cysteine have been reported to have antioxidant activity, it appears that their loss may potentiate damage occurring as a result of free radicals generated by nonenzymic glycation by the Maillard reaction. Amino acids also lost as a result of the osmotic compensation, are estimated to be responsible for almost half of the antioxidant activity lost. To test this hypothesis, normal and streptozotocin diabetic female Wistar rats were given taurine at 0.05% or 0.10% (w/w) in the diet. This treatment resulted in small only marginally significant increases in serum taurine levels. At the end of 6 weeks the rats were examined for weight gain or loss and at the time of killing, blood was collected for measurement of serum glucose. gamma-Crystallin levels were determined in vitreous and aqueous humours using a radioimmunoassay. A lens from each rat was homogenized in 8 m guanidinium chloride for adenosine triphosphate (ATP) analysis. In normal rats, a small amount of gamma-crystallin was found in the vitreous humour, and an even smaller amount in the aqueous humour. Diabetes caused a 4- to 5-fold increase in the vitreous humour and a 4-fold increase in gamma-crystallin in the aqueous humour. Diabetes also led to a significant worsening in general body condition, loss of body weight, formation of cataracts, and decrease in lens ATP levels. Addition of taurine to the diet of diabetic animals resulted in a significant decrease of gamma-crystallin leakage into the vitreous but not the aqueous humour. Taurine had no effect on the lens ATP levels. Neither streptozotocin diabetes nor taurine in the diet appeared to affect the weight of the lenses.     

牛磺酸对糖尿病性白内障防治的实验研究

目的探讨牛磺酸对链脲佐菌素（ＳＴＺ）诱导的大鼠糖尿病性白内障的防治效果。方法１４０只ＳＤ大鼠随机分为６组，实验组通过口服、点眼、结膜下注射等途径补充牛磺酸，定期观察晶状体的变化，测定血糖及晶状体中山梨醇、超氧化物歧化酶（ＳＯＤ）、丙二醛（ＭＤＡ）含量并与对照组相比较。结果白内障时晶状体中山梨醇及ＭＤＡ含量显著增加，ＳＯＤ活力明显下降。各牛磺酸用药组晶状体中山梨醇含量无显著性改变，但ＳＯＤ活力明显增加，ＭＤＡ含量明显降低，白内障发生时间推迟，混浊程度减轻，全身应用牛磺酸还可以降低血糖。结论牛磺酸对ＳＴＺ诱导的糖尿病性白内障有一定的防治作用。