Protective effects of naringenin eye drops on N-methylN-nitrosourea-induced photoreceptor cell death in rats

AIM:To investigate the effects of naringenin eye drops on N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell death in rats.METHODS:Photoreceptor cell death was induced by single intraperitoneal injection of MNU(60 mg/kg)in rats.Both eyes of all animals were instilled with one drop of vehicle,0.5% or 1.0% naringenin eye drops three times per day from 7d before to 17d after MNU injection.Effects of naringenin on MNU-induced photoreceptor cell death were evaluated by electrophysiological and histological analysis.RESULTS:Flash electroretinography (FERG)and oscillatory potentials (OPs) recordings showed that the vehicle control group had remarkable reduction of amplitudes and prolongation of latency times.FERG and OPs responses were significantly reversed in MNUinduced rats treated with 0.5%or 1.0% naringenin eye drops compared with the vehicle control.The retinal morphological results showed that naringenin dosedependently preserved the outer nuclear layer,outer retina and total retina.CONCLUSION:These results indicate that topical treatment with naringenin eye drops prevented retinal neurons from MNU-induced structural and functional damages.

Confirmation of N-(Nitrosomethyl) urea as a Nitrosourea Derived by Nitrosation of Fish Sauce

N-(nitrosomethyl ) urea (NMU ) was characterized in the carcinogenic nitrosated fish sauce (NFS) with high performance liquid chromatography (HPLC )- pholohydrolysis-pyrolysis-thermal en -ergy analysis recently. We used HPLC-electronic spray ionization-mass spectrometry and HPLC-diode array detection to confirm NMU in NFS furiher. It was observed that the corresponding chro-matographic fraction of NMU of NFS showed the same mass spectrum (m/z 64, 102, and 145) andultraviolet-absorbance (λ max = 230 nm) as those of authentic NMU. These results confirmed that thecomponent of NFS was NMU

Effect of 1, 25-Dihydroxyvitamin D_3 on Gastric Carcinogenesis Induced by N-Methyl-N'-nitro-N-nitrosoguanidine in Rats

The effect of 1, 25-dihydroxyvitamin D3 (1, 25 (OH)2D3) given in the post-initiation stage of gastric carcinogenesis induced by N-methyl-N-nitro-N-nitrosoguanidine (MNNG) was investigated in male Wistar rats. Gastric carcinogenesis in rats was induced by administration of MNNG (150 mg·L-1) in drinking water. Four weeks after MNNG exposure, the rats were switched to the diet containing 1, 25 (OH)2D3 (2. 5 μg·kg-1 and 5. 0 μg·kg-1) and maintained on the diet. Animals were killed at week 16 and week 32 for immunohistochemical and histopathological studies. At week 16, the proliferating cell nuclear antingen (PCNA) labeling index in epithelium from the glandular stomach of rats that received 1, 25 (OH)2D3 (5.0 μg·kg-1) in combination with MNNG (150 mg·L-1) were significantly higher when compared with the rats receiving MNNG alone. Supplementation of 1, 25 (OH)2D3 (5. 0 μg·kg-1) in the rats' diet caused a dramatic increase in carcinoma incidence, and the number of individual cancer foci in the glandular stomach of rats receiving MNNG at week 32. It was concluded that certain dose of 1, 25 (OH)2D3 enhanced gastric carcinogenesis induced by MNNG in rats.

1,3-Bis(2-chloroethyl)-1-nitrosourea enhances the inhibitory effect of Resveratrol on 5-fluorouracil sensitive/resistant colon cancer cells

AIM:To study the mechanism of 5-fluorouracil(5-FU)resistance in colon cancer cells and to develop strategies for overcoming such resistance by combination treatment.METHODS:We established and characterized a 5-FU resistance(5-FU-R)cell line derived from continuous exposure(25μmol/L)to 5-FU for 20 wk in 5-FU sensitive HCT-116 cells.The proliferation and expression of different representative apoptosis and anti-apoptosis markers in 5-FU sensitive and 5-FU resistance cells were measured by the MTT assay and by Western blotting,respectively,after treatment with Resveratrol(Res)and/or 1,3-Bis(2-chloroethyl)-1-nitrosourea(BCNU).Apoptosis and cell cycle arrest was measured by 4',6'-diamidino-2-phenylindole hydrochloride staining and fluorescence-activated cell sorting analysis,respectively.The extent of DNA damage was measured by the Comet assay.We measured the visible changes in the DNA damage/repair cascade by Western blotting.RESULTS:The widely used chemotherapeutic agents BCNU and Res decreased the growth of 5-FU sensitive HCT-116 cells in a dose dependent manner.Combined application of BCNU and Res caused more apoptosis in5-FU sensitive cells in comparison to individual treatment.In addition,the combined application of BCNU and Res caused a significant decrease of major DNA base excision repair components in 5-FU sensitive cells.We established a 5-FU resistance cell line(5-FU-R)from 5-FU-sensitive HCT-116(mismatch repair deficient)cells that was not resistant to other chemotherapeutic agents(e.g.,BCNU,Res)except 5-FU.The 5-FU resistance of 5-FU-R cells was assessed by exposure to increasing concentrations of 5-FU followed by the MTT assay.There was no significant cell death noted in5-FU-R cells in comparison to 5-FU sensitive cells after5-FU treatment.This resistant cell line overexpressed anti-apoptotic[e.g.,AKT,nuclear factorκB,FLICE-like inhibitory protein),DNA repair(e.g.,DNA polymerase beta(POL-β),DNA polymerase eta(POLH),protein Flap endonuclease 1(FEN1),DNA damage-binding protein 2(DDB2)]and 5-FU-resistance proteins(thymidylate synthase)but under expressed pro-apoptotic proteins(e.g.,DAB2,CK1)in comparison to the parental cells.Increased genotoxicity and apoptosis were observed in resistant cells after combined application of BCNU and Res in comparison to untreated or parental cells.BCNU increased the sensitivity to Res of 5-FU resistant cells compared with parental cells.Fifty percent cell death were noted in parental cells when 18μmol/L of Res was associated with fixed concentration(20μmol/L)of BCNU,but a much lower concentration of Res(8μmol/L)was needed to achieve the same effect in 5-FU resistant cells.Interestingly,increased levels of adenomatous polyposis coli and decreased levels POL-β,POLH,FEN1 and DDB2 were noted after the same combined treatment in resistant cells.CONCLUSION:BCNU combined with Res exerts a synergistic effect that may prove useful for the treatment of colon cancer and to overcome drug resistance.

Suppression of <i>N</i>-Methyl-<i>N</i>-Nitrosourea-Induced Retinal Damage in Mice by Oligonol, an Oligomerized Polyphenol Formulation

Oligonol is a lychee fruit-derived functional food that contains oligomerized polyphenol compounds. Oligonol exhibits a number of beneficial biological effects, primarily due to its antioxidant activity. Retinitis pigmentosa (RP) is an inherited chronic degenerative disease affecting retinal photoreceptor cells. There is currently no effective therapy capable of stopping or reversing the progression of the disease. In RP, apoptosis of photoreceptor cells resulting from oxidative damage is considered to be the final common pathway. In this report, we present an evaluation of the suppressive activity of Oligonol against N-methyl-N-nitrosourea (MNU)-induced retinal damage in mice, which is a commonly used animal model of RP. Both intraperitoneal and oral administration of Oligonol reduced the loss of photoreceptor cells 7 days after MNU injection, as evaluated by histological staining. Photoreceptor cells derived from MNU-treated mice exhibited increased TUNEL-positive staining, suggesting increased DNA fragmentation, a hallmark of apoptosis. Oligonol treatment reduced the number of TUNEL-positive cells. Additionally, Oligonol suppressed MNU-induced retinal production of 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative stress. Moreover, Oligonol attenuated the MNU-induced decrease in the visual activity of mice, as evaluated by the visual cliff test. Oligonol, therefore, effectively suppresses NMU-induced retinal degeneration.

In vitro release of 1,3-bis(2-chloroethyl)-1-nitrosourea sustained-release microspheres and the distribution in rat brain tissues

BACKGROUND: The implantation of released chemotherapeutic drugs, which takes biodegradable polymer as vector, into the tumor site can get high concentration and release the drug for a long time, it can directly act on the tumor cells, and reduce the general toxicity. OBJECTIVE: To explore the in vitro and in vivo course of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) sustained-release from BCNU-loaded polylactide (PLA) microspheres (MS) and location in rat brain tissue. DESIGN: A repetitive measurement. SETTING:Central Pharmacy, General Hospital of Chinese People’s Armed Police Forces. MATERIALS: Thirty male SD rats were used. PLA (Mr5000, batch number: KSL8377) was produced by Wako Pure Chemical Inc.,Ltd. (Japan); BCNU (batch number: 021121) by Tianjin Jinyao Amino Acid Co., Ltd.; BCNU-PLA-MS was prepared by the method of solvent evaporation and pressed into tablets (10 mg/tablet). High-performance liquid chromatography (HPLC) Agilent 1100 (USA); LS9800 liquid-scintillation radiometric apparatus (Beckman). Chromatographic conditions: Elite Hypersil ODS2 C18 chromatographic column (5 μm, 4.6 mm×150 mm); Mobile phase: methanol: water (50:50), flow rate was 1.0 mL per minute, wave length of ultraviolet detection was 237 nm, and the inlet amount of samples was 10 μL. METHODS: The experiments were carried out in the experimental animal center of the General Hospital of Chinese Armed Police from May 2004 to July 2005. ① In vitro BCNU-PLA-MS release test: BCNU-PLA-MS was prepared by the method of solvent evaporation, then placed in 0.1 mol/L phosphate buffered solution (PBS, pH 7.4, 37 ℃), part of MS were taken out at 1, 2, 3, 7, 10 and 15 days respectively, and the rest amount of BCNU in MS was determined by HPLC, then the curve of BCNU-PLA-MS release was drawn. ②In vivo BCNU-PLA-MS release and distribution test: The rats were anesthetized, then BCNU-PLA-MS were implanted to the site 1 mm inferior to the cortex of frontal lobe. Five rats were killed postoperatively at 4 hours, 1, 2, 3, 7 and 15 days, the residual MS was removed from the brain tissue. The rest amount of BCNU was determined with HLPC, and the curve of BCNU-PLA-MS release was drawn as compared with the amount of BCNU in the implanted tablets. Besides, brain tissues (1 g) at the implanted side and the contralateral one were obtained respectively, blood sample (0.5 mL) was also collected, 3H-BCNU was counted radioactively in radioactive liquid flash solution. The distributions of BCNU-PLA-MS in normal rat brain tissue and serum were detected. The analysis of variance was applied to compare the intergroup differences of the measurement data. MAIN OUTCOME MEASURES: ① Characteristics of BCNU-PLA-MS release in phosphate buffered solution (PBS) and rat brain tissue; ② Distributions of BCNU-PLA-MS in normal rat brain tissue and serum. RESULTS: ① Release of BCNU-PLA-MS in PBS and rat brain tissue: The BCNU released from BCNU-PLA-MS could be sustained for over 2 weeks both in PBS and brain tissue. In PBS, the released rate of BCNU was over 15% at 24 hours, nearly 50% at 72 hours and over 90% at 15 days. In brain tissue, the released rate was 8% at 4 hours, 16% at 24 hours, 60% at 72 hours, respectively, and BCNU could be sustained released for over 15 days. ② Distributions of BCNU-PLA-MS in normal rat brain tissue and serum: The concentrations of BCNU in the ipsilateral brain tissue were 6 to 70 times higher than those in the contralateral one. The concentrations of BCNU in the ipsilateral brain tissue were obviously higher than those in serum and contralateral brain tissue (F =103.47, P < 0.01). CONCLUSION: BCNU-PLA-MS can increase the drug concentration in targeted brain tissue, decrease that in the non-targeted brain tissue, reduce general toxic and side effects, and have good releasing function.

INHIBITORY EFFECT OF GLYCYRRHIZA URALENSIS FISH AND CHELIDONIUM MAJUS L ON GASTROCARCINOGENESIS . INDUCED BY N-METHYL-N' -NITRO-N-NITROSOGUANIDINE

In order to investigate the antagonistic effect of Glycyrrhlza Uralensis Fish (GUF) and Chelidonium maJus L (CML) on gastrccarcinogenesls Induced by MNNG in Wastar rats, we treated the rats with MNNG alone (group 1) and with MNNG plus GUF and CML (group 2 and 3) respectively. The Incidence of Infiltrating adenocarcinoma of the glandular stomach and duodenum in group 2 was significantly lower than that in group 1 (26.7% vs. 67.8%). The differentiation and aggresslvenees of carcinomas occured in group 2 were much better and mild than those in group 1. Present study also demonstrated that the Inhibitory effect of CML on proliferation of human stomach carcinoma cell line MGC-803 was very remarkable; in addition, GUF and CML were able to antagonise the mutagenlc activation of MNNG. These results suggest that GUF and CML may be empoyed In prevention of gastric carcinoma.

An experimental study on N-ethyl-N-nitrosourea-induced rat brain gliomas

Rat brain gliomas were induced by transplacental and subcutaneous administration of synthesized Nethyl-N-nitrosourea(EVU, 60 mg/kg body weight) in the late gestational and 3-day Wistar rats respectively, observed until the end of 12th month after administration.The incidences of tumor formation were 73. 2% and 68.3% (those of gliomas were 65. 9% and 63. 4%) respectively. Histologically, the main types were mixed oligodendro-astrocytomas and oligodendrogliomas, with the characteristics of being microfocal, multifocal and mixed, in presence with focal and/or diffuse proliferation of glial cells. The results showed that these glioma models induced by the synthesized ENU were successful and stable, serving a fine approach to further study of the initiation,growth and differentiation of gliomas. The significance of proliferation of glioblasts in the oncogenesis of ENU-induced gliomas was discussed in this report.

非促分裂haFGF对MNU所致大鼠视网膜损伤的保护作用

目的 研究非促分裂haFGF(nm haFGF)对N 甲基 N 亚硝脲 (MNU)所致大鼠视网膜损伤的保护作用及其作用机制。方法 通过ipMNU(60mg·kg-1 )复制大鼠视网膜损伤模型, 0和 12h后,玻璃体腔内注射不同剂量nm haFGF。24h和 7d后,测量周边视网膜总厚度和外视网膜厚度、光感受器细胞凋亡指数及视网膜Bcl 2和Bax蛋白表达水平。结果 MNU作用 24h后,nm haFGF组周边视网膜的凋亡指数显著降低 (P<0 01); 7d后,nm haFGF组周边视网膜光感受器细胞数明显增多,且周边视网膜总厚度和外视网膜厚度增加 (P<0 01);不同剂量nm haFGF可调节Bcl 2和Bax蛋白表达水平。结论 nm haFGF能部分抑制MNU引起的SD大鼠视网膜损伤,其作用机制可能与上调Bcl 2和下调Bax蛋白表达水平有关。

N-甲基-N-亚硝脲诱导的视网膜变性大鼠模型的形态学和功能改变

目的:观察N-甲基-N-亚硝脲(N-m ethyl-N-n itrosourea,MNU)对SD大鼠视网膜光感受器细胞的毒性作用。方法:出生后50 d的SD大鼠84只,随机抽取4只作为正常对照组,余下80只分为4组,每组20只,分别按体质量一次性腹腔注射MNU 80、60、40和30 mg/kg。各组每次4只分别于12 h、24 h、48 h、72 h、120 h行右眼闪光视网膜电图检查(ERG),并于造模后1 d、2 d、3 d、5 d、7 d处死动物,取眼球做组织学检查。结果:1)显示正常对照组的大鼠ERG波形清晰,a、b波振幅正常。MNU 80、60、40和30 mg/kg剂量组a波消失时间分别为3 h、12 h、24 h、120 h;b波消失时间分别为12 h、24 h、72 h、168 h。2)形态学检查测到正常组大鼠中心视网膜的外视网膜厚度为(98.4±1.8)μm。MNU处理后5 d和7 d,80、60、40和30 mg/kg剂量组外视网膜厚度分别为0μm、(9.5±2.3)μm、(42.8±2.7)μm、(71.3±2.4)μm和0μm、0μm、(20.8±2.5)μm、(62.9±2.0)μm,其损伤程度和剂量及时间成正比。结论:MNU可选择性地诱导视网膜光感受器细胞发生凋亡,该作用呈剂量和时间依赖性。

灵芝孢子油对N-甲基-N-亚硝酸脲诱导的大鼠视网膜损伤中Caspase-3表达的影响

目的观察灵芝孢子油(ganoderma spore oil,GSO)对N-甲基-N亚硝酸脲(N-methyl-N-nitrosourea,MNU)诱导的视网膜外核层细胞损伤的作用及对Caspase-3时空表达的影响。方法50d♀SD大鼠随机分为正常对照(NC)组、MNU造模(MNU)组、二十二碳六烯酸处理(DHA)组和灵芝孢子油处理(GSO)组。各组分别于MNU造模前0h及造模后1d、3d、7d、10d处死大鼠取材,采用RT-PCR、免疫荧光技术检测视网膜中Caspase-3表达和分布的变化,TUNEL法检测视网膜细胞凋亡情况。结果①RT-PCR检测:与NC组比较,MNU组1d、3d、7d视网膜Caspase-3表达增强(P<0.01);GSO组和DHA组1d、3d低于MNU组(P<0.01),1dGSO组表达较DHA组低(P<0.01)。②免疫荧光检测:在3d,GSO组和DHA组Caspase-3表达水平低于MNU组,GSO组较DHA组稍弱。③TUNEL法检测:NC组在视网膜各层均未发现凋亡细胞,MNU造模后可见外核层细胞凋亡。GSO组和DHA组在1d、3d外核层细胞凋亡百分率少于对应的MNU组(P<0.01),3d GSO组低于DHA组(P<0.01)。结论灵芝孢子油可能通过下调视网膜Caspase-3的表达,阻抑MNU诱导的视网膜外核层光感受器细胞凋亡的作用。

N-甲基亚硝基脲诱导胸腺淋巴瘤病理形态学及超微结构研究

本研究探讨N-甲基亚硝基脲(MNU)诱导的小鼠胸腺淋巴瘤的肿瘤细胞起源及分型。应用光学显微镜、透射电子显微镜和免疫组织化学方法,对诱发肿瘤进行观察。结果表明,光学显微镜下胸腺结构破坏,代之以弥漫分布的中等大小的淋巴样肿瘤细胞。免疫组织化学检测显示,瘤细胞表达CD3和TdT。超微结构观察显示,瘤细胞表面无突起,核形相对规则或伴有扭曲核,胞质内细胞器极少。结论:MNU诱导的所有肿瘤为胸腺T淋巴母细胞淋巴瘤。

腹腔注射MNU对大鼠视网膜结构与功能的影响

目的 探讨N 甲基 N 亚硝脲 (N methyl N nitrosourea,MNU)对大鼠视网膜的毒性作用。方法 生后 5 0d的雌性SD鼠 76只 ,随机抽取 4只为正常对照组 ,余 72只等分为 3组 ,分别按体重一次性腹腔注射MNU 5 0、4 0、30mg·kg-1。各组每次 4只分别于6、12、2 4、4 8h ,3、5d行闪光视网膜电图 (ERG)检查 ,并于造模 1、2、3、5、7、10d全麻后处死动物 ,取眼球做病理切片。结果 MNU 5 0、4 0、30mg·kg-1剂量组ERGa波消失时间分别为 6、12h ,3d ,b波消失时间分别是 12、2 4h ,5d。HE染色显示 :以中周部视网膜为观察对象 ,MNU 30mg·kg-1组第 3天开始出现外颗粒层结构改变 ,第 10天光感受器细胞显著减少 ,但未消失 ;MNU 4 0和 5 0mg·kg-1组第 1天即出现外颗粒层排列紊乱 ,外颗粒层消失时间前者在第 10天 ,后者在第 5天。所有模型切片结果 ,其神经节细胞层、内颗粒层以及色素上皮层与正常组相比均未见明显差异。结论 MNU能选择性地损伤视网膜光感受器细胞。

MNU诱导的大白鼠膀胱肿瘤模型的建立及病理学动态观察

目的观察N-甲基亚硝基脲（MNU）诱发SD大鼠膀胱癌模型的建立及病理学动态过程。方法MNU大鼠膀胱灌注每2周1次，每次2mg，共4次。随机观察实验第3、6、9、12、14周膀胱黏膜的改变，并在9、12和10周膀胱灌注^125I-UdR后行SPECT平面显像。结果膀胱灌注3周出现不典型增生，6周有原位癌改变，9周膀胱内有明显癌性肿块，12～14周膀胱内均出现乳头状癌或浸润性癌，9周的致癌率100．0％，组织学改变及病理学特征与人膀胱癌十分相似。SPECT显像见^125I-UdR膀胱灌注3d后诱癌组大鼠膀胱区放射性浓集。结论MNU灌注诱导大鼠膀胱癌模型为一理想的动物模型。致癌过程经历不典型增生、乳头状瘤形成和癌变动态过程。

小鼠胸腺淋巴瘤动物模型的建立

本研究通过腹腔注射N-甲基亚硝基脲(MNU)建立小鼠胸腺淋巴瘤动物模型。第0、8周2次给C57BL/6小鼠腹腔注射MNU诱导液50mg/kg体重注射后观察动物一般情况;第22周处死全部小鼠,解剖检查胸腺肿瘤的发生及其他脏器情况。结果表明:第22周时67.5%(27/40)实验小鼠产生胸腺淋巴瘤。不同性别对成瘤率影响无明显差异。结论:腹腔分次注射MNU可以诱导小鼠建立胸腺淋巴瘤动物模型,其生物学行为与人类相似。

金钠多、灯盏花素对N-甲基-N-亚硝脲诱导SD大鼠视网膜变性的保护作用

目的 观察金钠多 (Gin)、灯盏花素 (Bre)对N 甲基 N 亚硝脲 (MNU)诱导SD大鼠视网膜变性的保护作用及机制。方法 雌性SD大鼠随机分为正常对照组、模型组、Gin组和Bre组。其中Gin又分大剂量和中剂量组 ,Bre分大剂量、中剂量和小剂量组。于生后 47d开始腹腔注射给药 ,每日 1次 ,连续给药 4d和 10d ,并于生后 50d腹腔注射MNU 60mg/kg。在MNU处理 2 4h和 7d后处死动物 ,取眼球。通过视网膜形态学分析测量周边视网膜的总厚度 ,TUNEL试剂盒检测光感受器细胞凋亡。结果 MNU处理 7d后 ,模型组周边视网膜的总厚度为 3 6μm ,Gin组和Bre组分别为 44、3 7、58、43和 3 9μm。MNU处理 2 4h后 ,模型组周边视网膜的光感受器细胞凋亡指数为 (3 8 0± 3 6) % ,Gin组和Bre组分别为 (2 6 3± 2 7) %、(3 7 4± 2 9) %、(19 4± 1 9) %、(2 8 0± 3 0 ) %和 (3 6 9± 2 1) %。结论 Gin和Bre对MNU引起的周边视网膜损伤有一定的保护作用 ,呈剂量依赖性 ,其作用机制是通过抑制光感受器细胞发生凋亡。

银杏苦内酯B对N-甲基-N-亚硝脲诱导的大鼠视网膜细胞凋亡的抑制作用

目的:探讨银杏苦内酯B(GB)对N-甲基-N-亚硝脲(MNU)诱导的大鼠视网膜变性的影响及其机制。方法:建立大鼠视网膜变性模型,应用TUNEL法检测光感受器细胞凋亡,RT-PCR法和免疫组织化学法分别检测MNU作用后不同时间大鼠视网膜中bcl-2和bax mRNA和蛋白的表达。结果:GB治疗组外核层细胞凋亡指数显著低于模型组(P<0.01)。MNU作用后12 h、1 d、2 d、3 d和5 d,bcl-2/bax mRNA模型组为0.36、0.15、0.29、0.42和0.64,GB治疗组为0.98、0.92、0.53、0.45和0.68,显著高于模型组(P<0.01)。GB治疗组Bcl-2蛋白在MNU给药后1 d表达最强,2 d阳性表达下降,3 d后阳性表达消失,模型组未见视网膜Bcl-2阳性表达;GB治疗组Bax蛋白表达显著低于模型组(P<0.01)。结论:银杏苦内酯B能抑制MNU诱导的视网膜光感受器细胞凋亡,可能与上调Bcl-2的表达量,提高Bcl-2/Bax比值有关。

川芎嗪对N-甲基-N-亚硝基脲致光感受器细胞损伤的保护作用及其机制

目的探讨川芎嗪对N-甲基-N-亚硝基脲(NmethylNnitrosourea,MNU)致大鼠视网膜损伤的作用。方法大鼠生后47d,腹腔注射不同剂量的川芎嗪注射液;50d注射MNU60mg·kg-1。测量视网膜总厚度;TUNEL和RTPCR法分别检测细胞凋亡、cjun和cfos的表达。结果川芎嗪注射液可剂量依赖性地增加周边视网膜总厚度和降低凋亡指数,并抑制MNU诱导的即早基因表达。结论川芎嗪通过下调基因c-jun和c-fos的表达,抑制光感受器细胞凋亡,从而部分保护MNU引起的视网膜损伤。

N-甲基-N-亚硝脲诱导的大鼠视网膜感光细胞损伤模型中Müller细胞增殖和细胞因子分泌的变化

目的:建立N-甲基-N-亚硝脲(N-methyl-N nitrosourea,MNU)损伤视网膜的模型,研究视网膜神经元凋亡对Müller细胞生物学特性的影响及神经营养因子的表达变化。方法:腹腔注射MNU建立视网膜损伤模型,免疫荧光染色方法研究感光细胞缺失对Müller细胞的生物学特性的影响,并检测主要神经营养因子表达的变化。结果:TUNEL法显示,腹腔注射MNU后2 d,视网膜外核层细胞凋亡现象明显。核增殖抗原(PCNA)及细胞周期素CyclinD_1的表达明显增高。与此同时,Müller细胞也开始表达神经干细胞抗原巢蛋白(nestin);RT-PCR显示胰岛素样生长因子(IGF),碱性成纤维细胞生长因子(bFGF)和肝细胞生长因子(HGF)mRNA的表达均升高。结论:在视网膜受到损伤时,Müller细胞增殖、去分化呈现出干细胞的特性。而视网膜中IGF、bFGF和HGF等细胞因子的表达明显增高,提示视网膜损伤后可能通过大量分泌细胞生长因子,促进Müller细胞的增殖。

大鼠视网膜变性中药保护作用的实验研究

目的观察金钠多(Ginaton,Gin)和葛根素(Puerarin,Pue)对N-甲基-N-亚硝脲(N-methyl-N-nitrosorea,MNU)诱导SD大鼠视网膜变性的保护作用及机制。方法雌性SD大鼠随机分为正常对照组、模型组、Gin大剂量和中剂量组、Pue大剂量和中剂量组。于生后47d开始腹腔注射给药,每日1次。并于生后50d,模型组和各药物处理组的大鼠腹腔注射MNU60mg·kg-1,正常对照组腹腔注射生理盐水。在MNU或生理盐水处理后不同时间处死动物,取眼球。视网膜形态学分析测量周边视网膜总厚度,TUNEL试剂盒检测感受器细胞凋亡。结果MNU处理7d后,模型纽周边视网膜总厚度为36μm,Gin组(大剂量和中剂量)和Pue组(大剂量和中剂量)分别为(44±2)μm,(37±2)μm,(46±2)μm,(35±2)μm。MNU处理24h后,模型组周边视网膜光感受细胞凋亡指数为(38.0±3.6)%,Gin大剂量组、中剂量组、Pue大剂量组和中剂量组分别为(26.3±2.7)%,(37.4±2.9)%,(25.4±3.0)%,(39.0±2.5)%.结论Gin和Pue对MNU引起周边视网膜损伤有一定的保护作用,呈剂量依赖性,其作用机制是通过抑制光感受器细胞发生凋亡。但二者对中心视网膜均无保护作用。