Intestinal lymphangiectasis and lipidosis in rats following subchronic exposure to indole-3-carbinol via oral gavage

To investigate the toxicity and carcinogenic potential of indole-3-carbinol (I3C), the National Toxicology Program has conducted 13-week subchronic studies in Fisher 344 rats and B6C3F1 mice, and chronic 2-year bioassays in Sprague-Dawley rats and B6C3F1 mice. While the chronic study results are not yet available, subchronic study results and short-term special evaluations of interim sacrifices in the 2-year rat bioassay are presented. F344 rats were orally gavaged ≤300 mg I3C/kg body weight 5 days a week for 13 weeks. Rats treated with ≥150 mg/kg demonstrated a dose-related dilation of lymphatics (lymphangiectasis) of the duodenum, jejunum, and mesenteric lymph nodes. Material within dilated lacteals stained positively for Oil Red O and Sudan Black, consistent with lipid. Electron microscopic evaluation confirmed extracellular lipid accumulation within the villar lamina propria, lacteals, and within villar macrophages. Analyses of hepatic and pulmonary CYP1A enzymes demonstrated dose-dependent I3C induction of CYP1A1 and 1A2. B6C3F1 mice orally gavaged ≤250 mg I3C/kg body weight did not demonstrate histopathological changes; however, hepatic CYP induction was similar to that in rats. The histopathologic changes of intestinal lymphangiectasis and lipidosis in this study share similarities with intestinal lymphangiectasia as observed in humans and dogs. However, the resultant clinical spectrum of protein-losing enteropathy was not present.     

PI3K/Akt信号通路及内质网应激在肝纤维化大鼠肝细胞凋亡中的作用

目的观察磷脂酰肌醇-3激酶/蛋白激酶(PI3K/Akt)信号通路及葡萄糖调节蛋白78(GRP78)、生长停滞及DNA损伤基因(CHOP/GADD153)在四氯化碳(CCl4)诱导的肝纤维化中的表达并探讨其可能的作用。方法将30只SD大鼠随机分为正常组、肝纤维化模型(皮下注射40%CCl4橄榄油溶液)4及8周组。HE染色法观察肝组织病理形态学;用real-time PCR技术检测肝脏内GRP78及CHOP mRNA的表达;用Western blot检测肝脏内PI3K/Akt信号通路中Akt1、磷酸化Akt1及内质网应激相关蛋白GRP78及CHOP的表达;用原位末端转移酶标记(TUNEL)检测细胞凋亡。结果与正常组大鼠比较,肝纤维化模型4及8周组大鼠肝脏内GRP78及CHOP mRNA和蛋白表达均明显升高(P0.05),而肝脏内Akt1和磷酸化Akt1蛋白的表达则较正常大鼠显著降低(P0.05);与正常组大鼠比较,肝纤维化模型4及8周组大鼠肝细胞凋亡显著升高(P0.05)。结论 PI3K/Akt信号通路及内质网应激可能在肝纤维化大鼠肝细胞凋亡中发挥了重要作用。     

Butyl hydroxytoluene (BHT)-induced oxidative stress: effects on serum lipids and cardiac energy metabolism in rats.

Recent lines of evidences indicate that several pathological conditions, as cardiovascular diseases, are associated with oxidative stress. In order to validate a butylated hydroxytoluene (BHT)-induced experimental model of oxidative stress in the cardiac tissue and serum lipids, 12 Wistar rats were divided into two groups, a control group and the BHT group, which received BHT i.p. twice a week (1500 mg/kg body weight) during 30 days. BHT group presented lower body weight gain and heart weight. BHT induced toxic effects on serum through increased triacylglycerols (TG), VLDL and LDL-cholesterol concentrations. The heart of BHT animals showed alteration of antioxidant defenses and increased concentrations of lipid hydroperoxides, indicating elevated lipoperoxidation. TG concentrations and lactate dehydrogenase activities were elevated in the cardiac muscle of BHT animals. Thus, long-term administration of BHT is capable to induce oxidative and metabolic alterations similarly to some pathological disorders, constituting an efficient experimental model to health scientific research.     

Involvement of oxidative stress in the mechanism of triptolide-induced acute nephrotoxicity in rats

Triptolide is one of the most widely used and one of the most potent Chinese traditional herbal medicines. However, side effects, especially nephrotoxicity, limit the use of triptolide. It has been reported that oxidative stress is involved in drug-induced nephrotoxicity. In the present study, we focused on observing triptolide-induced acute nephrotoxicity in rats and investigating whether or not oxidative stress is involved in the pathogenesis of this process. The results showed that a single large dose peritoneal injection of triptolide caused severe oxidative stress characterized by significant decreases of renal SOD and GSH-Px activities, as well as significant increase of renal MDA content and also led to severe impairment of renal structure and function characterized by injury of renal tubules observed in HE-stained and TUNEL-stained slides and increases of Cre and BUN concentrations in a short time. However, pretreatment with the antioxidant vitamin C significantly ameliorated triptolide-induced depletion in renal SOD and GSH-Px activities, caused marked normalization of renal MDA content and also blunt the impairment of renal tubules and renal function. These results suggest that triptolide induces oxidative stress via impairing the antioxidant system, and oxidative stress contributes, at least in part, to the mechanism of triptolide-induced acute nephrotoxicity.     

Involvement of oxidative stress in the rapid Akt1 regulating a JNK scaffold during ischemia in rat hippocampus

It has been well documented that the activation of Akt1 and JNK pathways are involved in the neuronal cell death in cerebral ischemia. In this study, we describe a novel interaction between Akt1 and JNK interacting protein 1 (JIP-1). We first detected the interaction of Akt1 and JIP-1 in hippocampus at various time points of ischemia. In the basal state, JIP-1 bind to Akt1, MLK3 at maximum while JIP-1 binds to JNK3 at minimum. Ischemia stimulus decreased the Akt1-JIP-1 interaction and concomitantly increased association between JIP-1 and JNK3. While MLK3 binding to JIP-1 decreased, similar to Akt1-JIP-1 interaction during ischemia. These results indicated that Akt1 interaction with JIP-1 inhibited JIP-1-mediated potentiation of JNK activity by decreasing JIP-1 binding to specific JNK pathway kinases. Akt1 binding to JIP-1 acts as a regulatory gate preventing JNK activation, which is opened under conditions ischemia injury. Administration of antioxidant N-acetylcysteine (NAC) can obviously affected the level of MLK3, JNK3 and Akt1 binding to JIP-1 and JNK3 activation in the hippocampus at 15min ischemia. The findings suggest that Akt1 regulating JNK scaffold and then regulating JNK activation were closely associated with reactive oxygen species (ROS) during cerebral ischemia.     

Ameliorating effect of phytoestrogens on CCl4-induced oxidative stress in the livers of male Wistar rats

Glutathione-S-transferases and glutathione play a key role in the detoxification of most toxic agents. In the present study, the protective effects, if any, of isoflavone phytoestrogens--genistein and daidzein on the carbon tetrachloride (CCl4) induced changes in the activity of alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutathione S transferase (GSH) and levels of glutathione (GSH) and thiobarbituric acid reactive substances (TBARS)-were studied. The activities of ALT and AST were assayed in the serum, whereas the activity of GST and levels of GSH and TBARS were determined in the livers of rats. The current study involved the division of animals into two main groups: (i) rats pretreated with genistein and daidzein for three days; and (ii) non-pretreated rats. In the pretreated group, rats received oral doses of genistein (7.9 micromol/kg body weight) and daidzein (7.9 micromol/kg body weight) for three consecutive days (once daily) followed by oral dose of CCl4 on the 4th and the 5th day concurrently with the phytoestrogens-genistein or daidzein. In the non-pretreated group animals received oral dose of CCl4 (1 ml/kg body weight) for two consecutive days along with the phytoestrogens-genistein or daidzein. Treatment of male rats with CCl4 significantly elevated the activity of ALT and AST in serum and levels of TBARS in the liver. On the other hand, CCl4 resulted in decreased activity of GST and lowered the GSH levels. Coadministration of genistein and daidzein with CCl4 could not restore the alterations in the activity of ALT and AST caused by CCl4 to normal control levels. However, repeated dose treatments with genistein and daidzein for three days prior to the administration of CCl4 restored such alterations to normal levels. Our results indicate that genistein is more effective than daidzein in counteracting the inhibition of GST activity caused by CCl4 and restoring it to normal levels. Genistein was also more effective than daidzein restoring the induced TBARS levels caused by CCl4 to normal control levels when rats were pretreated with the isoflavone orally for three days. It has been observed that the tested isoflavonoids were able to antagonize the toxic effects of CCl4. Such counteracting effects were more pronounced for genistein and when the phytoestrogens were administered as repeated doses prior CCl4 administration.     

PI3K/AKT信号通路在全肝缺血再灌注大鼠肺损伤中的作用

目的 探讨磷脂酰肌醇-3激酶（PI3K）/AKT通路在大鼠全肝缺血再灌注肺损伤中作用。方法 本实验分两部分。(1)36只大鼠分别于肝缺血前与再灌注后不同时点处死取肺。（2）12只大鼠分成Wortmannin组与模型对照组。分别应用Western blot、原位末端转移酶(TUNEL)法与免疫组化法检测肺AKT、磷酸化AKT（p-AKT）表达、细胞凋亡与增殖细胞核抗原（PCNA）表达。结果（1）与缺血前相比,缺血再灌注后肺细胞凋亡指数显著增高; p-AKT/AKT与PCNA阳性指数呈双相变化;肺病理改变严重。（2）p-AKT/AKT与PCNA阳性指数成正相关;与凋亡指数呈负相关。（3)与模型对照组相比,Wortmannin组p-AKT/AKT与PCNA阳性指数显著降低,细胞凋亡指数显著增高,病理改变加重。结论 PI3K/AKT通路可能通过抑制凋亡、促进增殖对全肝缺血再灌注肺损伤发挥保护作用。     

丝胶对2型糖尿病大鼠胰腺胰岛素PI3K-Akt信号通路的调节作用

目的探讨丝胶是否通过影响胰腺胰岛素PI3K-Akt信号通路发挥降血糖的作用。方法 36只雄性SD大鼠随机分为正常对照组、糖尿病模型组和丝胶治疗组,每组12只。采用高脂高糖饲料喂养联合链脲佐菌素(35mg/kg,2次,1次/d)连续腹腔注射法制作2型糖尿病大鼠模型,模型成功标准是空腹血糖≥11.1mmol/L。模型成功建立后,丝胶治疗组大鼠给予丝胶灌胃35d。采用ELISA法检测大鼠血清脂联素水平,Western blotting法和Real-time PCR法分别检测大鼠胰腺胰岛素受体(IR)、胰岛素受体底物-1(IRS-1)、磷脂酰肌醇-3-激酶(PI3K)和Akt蛋白和mRNA的表达情况。结果与糖尿病模型组比较,丝胶治疗组大鼠血清脂联素水平,胰腺IR、IRS-1、PI3K、Akt蛋白和mRNA的表达明显升高(P0.01,P0.05)。结论丝胶可通过上调糖尿病模型大鼠胰腺IR、IRS-1、PI3K和Akt的表达,改善糖尿病时胰腺胰岛素PI3K-Akt信号转导通路的异常,从而发挥降低血糖的作用。     

吲哚-3-甲醇对人肝癌细胞株SMMC-7721增殖和凋亡的影响

目的探讨吲哚-3-甲醇（13C）对人肝癌细胞株SMMC．7721的增殖和凋亡的影响。方法不同浓度的13C（100、150、200、250、300、350Ixmol／L）处理细胞48h后,显微镜下观察细胞生长状况;采用WST-1法检测细胞增殖情况,Hoehest33258染色、TUNEL染色检测细胞凋亡情况,Westernblot法检测凋亡相关蛋白。结果13C能够抑制SMMC．7721细胞增殖,诱导细胞凋亡,处理浓度在250μmol／L以下时,细胞生长变慢;处理浓度达到300μmol／L时,大量细胞凋亡。13C浓度高于200μmol／L时CytC、Cleavedcaspase．9和Cleavedcaspase．3蛋白表达明显增加,且随着13C浓度的增加三种蛋白的表达也明显增加。结论13C在体外实验条件下可抑制人肝癌细胞株SMMC．7721增殖并诱导其发生凋亡。     

Toll-like receptor 3 agonist poly(I:C)-induced antiviral response in human corneal epithelial cells

The objective of this study was to examine the expression of Toll-like receptor 3 (TLR3) by human corneal epithelial cells (HCECs) and to determine whether exposure to the TLR3 agonist polyinosinic-polycytidylic acid [poly(I:C)] induces an antiviral response in these cells. Fluorescence-activated cell sorter (FACS) analysis revealed TLR3 to be constitutively expressed and distributed intracellularly in HCECs. Stimulation of HCECs with the TLR3 agonist poly(I:C) induced the activation of nuclear factor (NF)-kappaB and production of the proinflammatory cytokine interleukin (IL)-6 and the chemokine IL-8. Upon exposure to poly(I:C), HCECs initiated a potent antiviral response resulting in an increase of interferon (IFN)-beta mRNA expression (7-fold). Poly(I:C) stimulation also up-regulated mRNA expression of the antiviral chemokine IFN-gamma inducible protein 10 (IP10), myxovirus resistance gene A and 2',5'-oligoadenylate synthetase (5-, 10- and 9-fold, respectively), and secretion of IP10. These responses were also induced by exogenously added type 1 IFNs, but could not be blocked by pretreatment of the cells with anti-TLR3 monoclonal antibody, suggesting that the receptor was not expressed on the cell surface. Furthermore, incubation of HCECs with an endosomal acidification inhibitor, chloroquine, markedly inhibited poly(I:C)-mediated IFN-beta expression in HCECs. These results suggest that corneal epithelial cells are important sentinels of the corneal innate immune system against viral infection, and that stimulation of TLR3 can induce the expression of key proinflammatory cytokines and chemokines and antiviral genes that help in the defence of the cornea against viral infection.     

Inhibition of the anti-apoptotic PI(3)K/Akt/Bad pathway by stress

The initiation of apoptosis often transpires in the presence of agents that regulate cell survival. This study evaluated the effects of stress-induced ceramide on the anti-apoptotic activity of the phosphoinositide-3 kinase [PI(3)K] pathway. PI(3)K activity is directly down-regulated by stress-induced ceramide in a dose-dependent manner with rapid kinetics and high specificity. Ceramide inhibition of PI(3)K is dependent on acid–sphingomyelinase. Down-regulation of PI(3)K by ceramide results in inhibition of the kinase Akt and decreased phosphorylation of the death effector Bad. Thus, ceramide levels could act as a general apoptotic rheostat controlling cell survival by regulating PI(3)K anti-apoptotic effector mechanisms.     

肌肽对糖尿病大鼠海马中氧化应激及NF-κB信号通路的影响

目的　探讨肌肽（Carnosine, CAR）对糖尿病大鼠认知功能及大鼠海马中氧化应激和NF-κB信号通路的影响。 方法　50只雄性SD大鼠,除外对照组（n=8）均给予高糖高脂饲料,腹腔注射STZ建立Ⅱ型糖尿病模型,随机分为糖尿病模型组和不同剂量的肌肽组（100、300和900 mg/kg）。给药56 d后,Morris水迷宫进行行为学测试;HE染色观察海马病理变化;应用试剂盒法检测海马中的超氧化物歧化酶（SOD）活性、丙二醛（MDA）含量;高效液相色谱法（HPLC）检测海马中谷胱甘肽（GSH）、肌肽的含量;Western Blot检测胞浆中TNF-α、IL-1β,胞核中NF-κB p65的表达。 结果　与糖尿病组相比,肌肽组可以明显改善糖尿病大鼠的学习记忆能力和海马神经细胞形态,提高糖尿病大鼠海马中SOD活性及GSH、肌肽的含量,降低MDA的含量,同时肌肽可以明显降低糖尿病大鼠海马胞核中NF-κB蛋白向核内转移,并下调下游炎症因子TNF-α、IL-1β蛋白的表达。 结论　肌肽改善糖尿病大鼠的认知功能障碍,其机制可能是通过抑制氧化应激反应,并减少NF-κB向核内转移、下调TNF-α、IL-1β的表达有关。     

血必净通过激活PI3K/Akt/mTOR信号通路减轻大鼠睾丸缺血再灌注损伤

目的:探究血必净对缺血再灌注(I/R)损伤大鼠睾丸的保护作用及其相关机制。方法:45只雄性SD大鼠随机分为对照组、模型组、血必净低剂量组、血必净高剂量组和地塞米松组(均n=9);除对照组大鼠外,其它各组大鼠构建睾丸扭转复位模型,术后低、高剂量组及地塞米松组大鼠分别腹腔注射0.5和2 mL·kg^-1·d^-1血必净及0.5 mL·kg^-1·d^-1地塞米松。用药第3、7和14天取各组大鼠左侧睾丸,采用HE染色观察各组大鼠睾丸组织病理学改变;生化检测各组大鼠睾丸组织中丙二醛(MDA)、超氧化物歧化酶(SOD)、内皮素1(ET-1)和一氧化氮(NO)水平,Western blot检测各组大鼠睾丸组织中细胞周期相关蛋白、细胞凋亡相关蛋白以及PI3K/Akt/mTOR信号通路相关蛋白的水平。结果:血必净可显著减轻I/R大鼠睾丸损伤,显著升高I/R大鼠睾丸组织中SOD活性,降低MDA、ET-1和NO的含量,抑制I/R损伤组织中的氧化应激,介导细胞周期和细胞凋亡相关因子的表达,并显著升高I/R大鼠睾丸中p-PI3K、...     

PI3K/Akt信号通路在脓毒症肾脏损伤诱导的自噬中的调节作用*

 目的：研究脓毒症造成肾脏损伤时的自噬情况以及磷脂酰肌醇3-激酶（PI3K）/蛋白激酶B(Akt)信号通路的调节作用。方法：对大鼠盲肠进行结扎与穿刺（CLP）,对肾脏组织切片进行HE染色,并测定血清尿素氮和肌酐。通过Western blotting定量分析CLP大鼠肾脏损伤发生后不同时点自噬相关分子微管相关蛋白轻链3（LC3）Ⅰ/Ⅱ、beclin-1和Akt蛋白磷酸化的表达情况;体外用LPS诱导人近端肾小管上皮细胞株HK-2发生自噬,检测不同浓度LPS和不同刺激时间自噬相关分子LC3Ⅰ/Ⅱ和Akt蛋白磷酸化的表达情况;进一步使用PI3K抑制剂、Akt抑制剂和LPS刺激HK-2细胞观察自噬相关蛋白的表达情况及细胞的凋亡水平。结果：同对照组相比,CLP大鼠显微镜下可见肾损伤的典型病理改变,血清尿素氮和肌酐均有上升。CLP肾脏损伤发生后,自噬相关蛋白LC3Ⅰ/Ⅱ、beclin-1含量及Akt磷酸化水平均有上升。LPS刺激HK-2细胞后,随着刺激浓度的增加,p-Akt(308)表达量逐渐提高,而LC3Ⅰ/Ⅱ及p-Akt(472)的表达量在10 mg/L LPS刺激组最高。随着刺激时间的延长,p-Akt(308)表达量逐渐提高;LC3Ⅰ/Ⅱ表达量同p-Akt(472)在刺激8 h时最高;使用PI3K抑制剂及Akt抑制剂后,LPS诱导的LC3表达显著下调,HK-2细胞凋亡明显增加。结论：CLP肾脏损伤发生时可以诱导自噬发生, PI3K／Akt信号通路在其中发挥重要调节作用。     

肌肽对糖尿病肾病大鼠氧化应激及NF-κB信号通路的影响

目的　探讨肌肽对糖尿病肾病（DN）大鼠肾组织的保护作用及其对氧化应激、NF-κB信号通路的影响。 方法　60只SPF级8周龄雄性SD大鼠，随机选取12只为对照组，其余予以高糖高脂饮食+链脲佐菌素腹腔注射建立糖尿病模型。注射链脲佐菌素3 d后，将符合糖尿病标准大鼠随机分为模型组、肌肽（100、300、900 mg/kg）组。肌肽各组分别灌胃100、300、900 mg/kg肌肽，每日1次。8周后，检测空腹血糖（FBG）、血清肌酐（Scr）、尿素氮（BUN）、24 h尿微量白蛋白（mAlb）。PAS染色法观察大鼠肾形态学变化；试剂盒检测肾组织的超氧化物歧化酶（SOD）、丙二醛（MDA）、谷胱甘肽（GSH）、谷胱甘肽过氧化物酶（GSH-Px）含量；免疫组织化学及Western blot检测肾组织P-NF-κB P65蛋白的表达。 结果　 DN大鼠建模成功。与模型组相比，肌肽组肾组织病理损伤明显减轻。肌肽各组大鼠mAlb、FBG、BUN水平下降，呈量-效依赖性关系（P<0.05），而SOD、GSH、GSH-Px的含量逐级升高，同时MDA和P-NF-κB P65含量减少。 结论　肌肽对DN模型大鼠肾组织具有保护作用，其机制可能与抑制氧化应激和NF-κB信号通路异常激活有关。     

Involvement of the PI3K/Akt pathway in myxoid/round cell liposarcoma

The molecular determinants involved in the progression of myxoid liposarcoma to increased cellularity/round cell change are poorly understood. We studied the PI3K/Akt pathway in myxoid and round cell liposarcomas using a tissue microarray composed of 165 tumors from 111 patients, and mutational analysis of PIK3CA in 44 cases. Activating PIK3CA mutations were found in 6/44 cases, 14%; mutations were more frequent in round cell vs myxoid tumors (5/15, 33% vs 1/29, 3%; P=0.013). Complete loss of PTEN, an alternative mechanism for PI3K/Akt activation, was found in 13/111 (12%) cases and was mutually exclusive with PIK3CA mutation. Strong IGF1R expression was demonstrated in 14/39 (36%) of round cell and 11/58 (19%) of myxoid tumors (P=0.062). Activation of the PI3K pathway was confirmed using immunohistochemical analysis for downstream targets phospho-S6 ribosomal protein and phospho-4EBP1. Phospho-4EBP1 was increased in round cell tumors compared with myxoid tumors (24/30, 80% vs 25/44, 57%; P=0.038) or tumors with treatment effect (10/24, 42%; P=0.02). Phospho-S6 was highly expressed in both myxoid and round cell tumors (29/47, 62% and 14/30, 47%, respectively; P=0.2). In tumors with PIK3CA mutation, any IGF1R expression, or loss of PTEN expression, phospho-4EBP1 was more frequently elevated compared with tumors without a known activating event in the PI3K pathway (55/72; 76% vs 3/8, 38%; P=0.033). These findings suggest that activation of the PI3K/Akt pathway via activating mutation of PIK3CA, loss of PTEN, or IGF1R expression have a role in round cell transformation. The PI3K/Akt pathway may therefore provide a therapeutic target in round cell liposarcoma.     

Properties of poly(I).poly(C)-induced mouse L cell interferon

Mouse interferon produced by L-929 cells after induction with poly(l) · poly(C) and DEAE-dextran can be separated into two molecular species, designated Mu IFN-α and Mu IFN-β on the basis of molecular weight and antigenic properties. We show here that Mu IFN-α and Mu IFN-β differ in antiviral activity on hamster and rat cells, stability, and pharmacokinetic character. The properties of both murine interferon species observed so far are in agreement with the idea that Mu IFN-α is the murine counterpart of human IFN-α and Mu IFN-β that of human IFN-β.