Comparative distribution,pharmacokinetics and placental permeabilities of all-trans-retinoic acid, 13-cis-retinoic acid,all-trans-4-oxo-retinoic acid,retinyl acetate and 9-cis-retinal in hamsters

Pregnant hamsters were given a single oral dose (35 mol/kg) of all-trans-retinoic acid, 13-cis-retinoic acid, all-trans-4-oxo-retinoic acid, 9-cis-retinal or all-trans-retinyl acetate during the early primitive streak stage of development. The radioactivity associated with the acidic retinoids was distributed to all tissues sampled (including placenta and fetus), with the largest accumulation in the liver and the least accumulation in fat. Radioactivity from 9-cis-retinal or retinyl acetate concentrated in the liver and lung. The all-trans-retinoic acid was oxidized in vivo to all-trans-4-oxo-retinoic acid and isomerized to 13-cis-retinoic acid; 13-cis-retinoic acid was oxidized to 13-cis-4-oxo-retinoic acid and isomerized to all-trans-retinoic acid. No parent 9-cis-retinal or retinyl acetate could be detected in maternal plasma. Plasma concentrations of the parent acidic retinoids reached their maxima within 60 min and then followed exponential decay. Of all the retinoids examined here, 13-cis-retinoic acid showed the largest area under the plasma curve, the slowest clearance and the longest elimination t 1/2. Total plasma radioactivity, consisting of unidentified metabolites, remained elevated at 4 days after dosing. Maternal peak circulating concentrations of the parent retinoids, total radioactivity, plasma pharmacokinetic parameters or the total concentrations of residual radioactivity in fetal tissues could not be correlated with the differential teratogenic potencies of these retinoids.     

Retinoids induce Fas(CD95) ligand cell surface expression via RARgamma and nur77 in T cells

Cells from the CD4+ murine T hybridoma line IP-12-7 enter the apoptotic suicide program via the Fas ligand (FasL)/Fas-mediated pathway upon TCR stimulation. This stimulus regulates the sensitization of the Fas death pathway and the cell surface appearance of preformed FasL. The apoptosis is dependent on new mRNA and protein synthesis and involves up-regulation of nur77.Two groups of nuclear receptors for retinoic acids (RA) have been identified: retinoic acid receptors (RAR) and retinoid X receptors. IP-12-7 cells express RARalpha and RARgamma. Here we show that,in the IP-12-7 T cells, RA also induced the expression and DNA binding of nur77, and the cell surface appearance of FasL. The induction was mediated via RARgamma. Despite the induced expression of cell surface FasL, only two structurally related RARgamma-selective compounds, CD437 and CD2325, initiated apoptosis in these cells. The lack of apoptosis induction by natural RA was related to the inability of RARgamma to sensitize the Fas death-pathway. Cell surface FasL, however, was able to induce cell death in Fas-bearing target cells. Natural RA also induced the expression of FasL in phytohemagglutinin-activated peripheral murine T cells. It is proposed that therapeutically administered RA might induce apoptosis in Fas-sensitive cells via induction of FasL expression in activated Tcells.     

DMBA-induced tumors and their prevention by aromatic retinoid (Ro 10-9359)

Summary Both auricles of 21 domestic rabbits were painted with dimethylbenz-anthracene (DMBA). Eleven animals of this group were additionally fed aromatic retinoid (AR) by an esophageal tube. Two control animals were not treated at all.Eight or 9 weeks after the beginning of the study six of the seven remaining animals, which had only been painted with DMBA, developed a total of 25 keratoacanthoma-like tumors (KA). On the other hand, none of the seven animals left, which were painted with DMBA and fed AR showed any tumor by this time.The systemic effect of AR was studied in biopsies from the snout and the back. The epidermis of the snout showed mucous mataplasia by histochemical and electron-microscopic criteria, whereas the epidermis of the back was not significantly altered. The production of intra- and extracellular lamellated material indicated an additional effect of AR on epidermal lipid metabolism. The effect of AR in the prevention of DMBA-induced tumors was characterized by mucoid cytolysis and karyolysis.Supported by the Deutsche Forschungsgemeinschaft (Ma 674/3-2)     

维A类化合物4-APR抑制肿瘤侵袭、转移的作用

用体内外实验模型,研究了新维A类化合物4-乙酰胺苯基维A酸酯(4-APR)对肿瘤侵袭、转移的抑制作用。4-APR 43.3mg·kg^-1po即能减少小鼠Lewis肺癌的自发性肺转移瘤数。半体内实验证明4-APR10^-5mol·L^-1和10^-6mol·L^-1对B16-F10癌细胞的人工肺转移瘤数分别抑制67.9%和36.6%。体外实验显示,4-APR对B16-F10细胞侵袭重组基底膜的抑制率分别为54.2%和41.9%。     

维甲酸、三氧化二砷诱导NB4细胞TRAIL基因表达的研究

目的：研究全反式维甲酸(ATRA)或三氧化二砷(As2O3)诱导急性早幼粒细胞白血病(APL)NB4细胞肿瘤坏死因子相关的凋亡诱导配体(TRAIL)基因的表达及其治疗APL的机制。方法：采用RT—PCR检测TRAIL基因表达的变化。结果：10^-6mol／L的ATRA作用6h或10^-6mol／L的As2O3作用12h，即可诱导TRAIL基因表达。结论：ATRA或As2O3能诱导NB4细胞TRAIL基因表达，TRAIL基因可能以类似“旁分泌”的作用方式杀伤NB4细胞。诱导TRAIL基因介导的细胞凋亡可能是ATRA或As2O3治疗APL的机制之一。     

Retinyl palmitate reduces hepatic fibrosis in rats induced by dimethylnitrosamine or pig serum

Background/Aims: Lipid peroxidation has been found to be associated with Ito cell activation. Ito cells are the principal collagen-producing cells and the main storage sites of retinoids. However, the relationship between retinoids and hepatic fibrosis is complex. The aim of this study was to elucidate the role of retinoids as a fibrosuppressant: the effects of retinoids on hepatic fibrosis induced in rats by dimethylnitrosamine or pig serum, as well as on rat Ito cells in primary culture, were examined in order to assess the antioxidant activity of retinoids.Methods: Male Wistar rats were given a single injection of 40 mg/kg dimethylnitrosamine or 0.5 ml PS twice weekly for 10 weeks. In each model, rats were treated with retinyl palmitate for 2 weeks before hepatotoxin treatments or for the last 2 weeks of the treatments. The cumulative amount of retinyl palmitate administered in each experiment was 2, 10, or 20×10⁴ IU/rat.Results: Retinyl palmitate treatment before or after administration of dimethylnitrosamine or pig serum suppressed the induction of hepatic fibrosis, restored hepatic retinyl palmitate levels, prevented increases in hepatic levels of collagen and malondialdehyde, a product of lipid peroxidation, and prevented increases in deposition of type III collagen and the number of α-smooth muscle actin (α-SMA) positive-Ito cells in the liver. Retinyl palmitate supplementation resulted in a dose-dependent reduction of α-SMA expression and an oxidative burst in cultured Ito cells. In addition, retinyl palmitate inhibited Fe²⁺/adenosine 5′-diphosphate-induced lipid peroxidation in rat liver mitochondria and showed radical scavenging activity.Conclusions: These findings suggest that retinyl palmitate may suppress the induction of hepatic fibrosis, at least in part, by the inhibition of Ito cell activation through its antioxidant activity.     

RXR激动剂通过抑制PKC激活对抗高糖诱导的大鼠血管平滑肌细胞增殖

 目的:探讨视黄醇类X受体 (RXR)激动剂对高糖诱导的大鼠主动脉平滑肌细胞(RASMCs)增殖的影响及其作用机制。方法:体外组织块干涸法培养RASMCs,以25 mmol/L葡萄糖干预,模拟糖尿病患者体内环境,通过WST-1法检测细胞增殖活性,BrdU插入法测定细胞DNA合成,流式细胞术检测细胞周期进程。用免疫印迹杂交方法检测细胞周期蛋白依赖激酶2(CDK2)、细胞周期蛋白依赖激酶抑制物p27Kip1的蛋白表达及蛋白激酶C (PKC)的磷酸化水平。结果:(1) 在高糖环境(葡萄糖终浓度为25 mmol/L)下,RASMCs的增殖活性、DNA合成速率及其在细胞周期S期的分布比例均显著增加;(2) 高糖显著增加RASMCs内CDK2蛋白的表达,但明显降低p27Kip1的蛋白表达水平;(3) RXR天然配体9-顺式维甲酸(9-cis-RA)可显著抑制高糖诱导的RASMCs增殖活性增强、DNA合成加速及RASMCs在细胞周期S期分布比例的增加幅度,且具有浓度依赖性;10-7mol/L浓度的SR11237(RXR特异性配体)与等浓度的9-cis-RA具有相似的抑制效应;(4) 9-cis-RA 和SR11237均可显著抑制高糖诱导的CDK2蛋白表达水平的增加幅度,同时上调高糖环境下p27Kip1蛋白的表达;(5) PKC抑制剂(PKC inhibitor peptide, 20 μmol/L)显著抑制高糖环境下RASMCs的增殖活性和CDK2蛋白的表达,但明显增加高糖条件下p27Kip1蛋白的表达;(6) 9-cis-RA 和SR11237可抑制高糖诱导的PKC蛋白磷酸化。结论: PKC的活化参与了高糖诱导下RASMCs的增殖过程。RXR激动剂通过抑制PKC活化对抗高糖诱导的血管平滑肌细胞增殖。     

日本血吸虫视黄酸X受体2全长cDNA的克隆及初步分析

目的克隆编码日本血吸虫视黄酸X受体2(SjRXR2)蛋白的全长cDNA,并对其进行初步研究。方法利用cDNA末端快速扩增技术(RACE)获得SjRXR2蛋白全长编码cDNA。利用生物信息学技术,对基因结构进行初步分析。利用实时荧光定量(Real time)PCR技术对该基因在日本血吸虫不同时期虫体中的转录情况进行分析。应用在线抗体表位预测软件获得SjRXR2配体结合区抗原性较强的一个多肽序列,合成该多肽片段,并免疫小鼠制备抗血清。利用Western blot技术分析该蛋白在日本血吸虫中的表达。结果采用RACE技术成功获得了SjRXR2蛋白全长编码cDNA,总长度为5 960bp,其完整开放阅读框为4 308 bp,编码1 435个氨基酸,预测分子量为159 kDa。生物信息学分析表明该基因编码的蛋白质序列具有核受体家族2的典型结构域特征,且与曼氏血吸虫RXR2有较高的相似性。Real time PCR分析表明,该基因在21、42 d龄日本血吸虫虫体内有较高的转录水平。Western blot分析表明,小鼠SjRXR2多肽免疫血清可特异性识别日本血吸虫虫体150 kDa蛋白。结论成功获得了编码SjRXR2蛋白的全长cDNA,并制备了针对该蛋白的特异性多克隆抗体,为进一步研究该蛋白的功能奠定了基础。     

血管紧张素1-7对大鼠血脂及胆固醇逆转运相关因子表达的影响

目的 探讨血管紧张素1-7[Ang(1-7)]对大鼠血脂及胆固醇逆转运相关因子ATP结合盒转运子A1(ABCA1)、过氧化体增殖物激活型受体γ(PPARγ)、肝X受体α(LXRα)和视黄酸X受体α(RXRα)表达的影响.方法 将40只健康雄性SD大鼠随机分为正常对照组、高脂饲料组、Ang(1-7)组及Ang(1-7)+ A779组.通过植入式胶囊渗透压泵,经颈静脉插管持续给予Ang(1-7),28天后,检测各组大鼠血浆总胆固醇、甘油三酯、低密度脂蛋白胆固醇及高密度脂蛋白胆固醇水平,定量实时聚合酶链反应及Western blot检测各组大鼠动脉组织中ABCA1、PPARγ、LXRα、RXRα基因表达的变化.结果 与正常对照组比较,高脂饲料组大鼠总胆固醇、甘油三酯、低密度脂蛋白胆固醇均有所升高(P＜0.05),高密度脂蛋白胆固醇有所降低(P＜0.05);与高脂饲料组比较,Ang(1-7)组大鼠总胆固醇、甘油三酯、低密度脂蛋白胆固醇均有所降低(P＜0.05),高密度脂蛋白胆固醇有所升高(P＜0.05);与Ang(1-7)组比较,Ang(1-7) +A779组大鼠总胆固醇、甘油三酯、低密度脂蛋白胆固醇均有所升高(P＜0.05),高密度脂蛋白胆固醇有所降低(P＜0.05).与正常对照组比较,高脂饲料组大鼠ABCA1、PPARγ、LXRα、RXRα的mRNA和蛋白含量均有所降低(P＜0.05);与高脂饲料组比较,Ang(1-7)组大鼠ABCA1、PPARγ、LXRα、RXRα的mRNA和蛋白含量均有所升高(P＜0.05);与Ang(1-7)组比较,Ang(1-7)+ A779组大鼠ABCA1、PPARγ、LXRα、RXRα的mRNA和蛋白含量均有所降低(P＜0.05).结论 Ang(1-7)能够降低大鼠血浆中血脂水平,促进大鼠动脉组织中ABCA1、PPARγ、LXRα、RXRα的基因表达,对高脂血症有一定的治疗作用.     

视黄醇类核内受体α基因慢病毒表达载体构建

目的 通过构建大鼠视黄醇类核内受体-α(RXR-α)基因慢病毒表达载体,获得可供转染的滴度.方法 大鼠RXR-α基因序列进行聚合酶链反应(PCR)扩增,与经AgeI酶切后的pCC-FU-3FLAG载体连接产生慢病毒载体表达质粒pGC-fu-3flag-Rxra,转化DH5α,PCR筛选阳性克隆,片段长为411bp.测序并转入293T细胞Western blot鉴定,90 KDr处有特征条带.将pGC-fu-3flag-Rxra、pHelper 1.0、pHelper 2.0三质粒共转染293T细胞,包装成慢病毒,测病毒滴度,1.00E-04μl组和Control组的Ct值存在差异(2.775).结果 DNA测序及Western blot鉴定证实构建的大鼠RXR-α基因慢病毒表达载体pGC-fu-3flag-Rxra正确,浓缩慢病毒悬液滴度为2×108TU/ml.结论 成功构建携带大鼠RXR-α基因的重组慢病毒表达载体.