吡格列酮对肾小球系膜细胞ROS和p38MAPK的影响

目的观察吡格列酮(PIO)对高糖培养的肾小球系膜细胞(MCs)p38丝裂原活化蛋白激酶(p38MAPK)表达和活性氧(ROS)水平的影响,探讨PIO肾保护作用及机制。方法体外培养MCs,随机分为正常对照组(NG组)、高糖(HG组)及高糖+不同浓度吡格列酮组。应用流式细胞术检测细胞ROS水平,半定量RT-PCR测定MCs p38MAPK mRNA表达情况。结果与NG组比较,HG组细胞内ROS水平明显增加,p38MAPK mRNA表达增多(P<0.01);各PIO干预组上述变化明显受抑制(P<0.01或P<0.05),且呈剂量依赖性。结论吡格列酮可拮抗高糖诱导的MCs内ROS和p38MAPK高表达。     

高糖环境中吡格列酮对MC3T3-E1成骨细胞的作用及其机制

目的观察高糖环境下吡格列酮对MC3T3-E1成骨细胞的作用并探讨其可能机制。方法高糖(22.5 mmol·L~(-1))环境培养MC3T3-E1细胞,分为对照组,吡格列酮2.5、5、10μmol·L~(-1)组,干预24、48 h。检测细胞增殖活性、凋亡率、骨钙素和碱性磷酸酶(ALP)分泌水平,以及过氧化物酶体增殖物激活受体γ(PPARγ)、成骨因子runt相关基因2(Runx2)和骨形态蛋白2(BMP-2)mRNA的表达水平。并分析PPARγ、Runx2的表达与骨钙素、ALP、BMP-2的相关性。结果在相同干预时限,吡格列酮各组MC3T3-E1成骨细胞增殖活性、骨钙素和ALP的分泌水平、Runx2 mRNA和BMP-2 mRNA的表达均低于对照组,凋亡率和PPARγmRNA的表达高于对照组(P<0.05)。随吡格列酮浓度增加,细胞增殖活性、骨钙素和ALP的分泌、Runx2 mRNA和BMP-2 mRNA的表达均降低,而细胞凋亡率和PPARγmRNA的表达增高(P<0.05)。与干预24 h相比,干预48 h时相同浓度吡格列酮组细胞增殖活性,骨钙素和ALP的分泌水平,PPARγ、Runx2、BMP-2 mRNA的表达或无变化或略增加。结论高糖环境下吡格列酮对成骨细胞有损害作用,促进PPARγ表达、抑制Runx2的表达可能为其作用机制之一。     

阿卡波糖、二甲双胍、吡格列酮对非酒精性脂肪性肝病大鼠肝组织肿瘤坏死因子-α及细胞色素P4502E1的影响

目的观察阿卡波糖、二甲双胍、吡格列酮对非酒精性脂肪性肝病(NAFLD)大鼠肝脏中肿瘤坏死因子-α(TNF-α)、细胞色素P4502E1(CYP2E1)的影响。方法将SD大鼠随机分为正常对照组(普通饲料喂养)、非酒精性脂肪肝组(高脂饮食喂养)、阿卡波糖干预组[高脂饮食喂养加阿卡波糖100 mg/(kg.d)灌胃]、二甲双胍干预组[高脂饮食喂养加二甲双胍500 mg/kg.d)灌胃]、吡格列酮干预组[高脂饮食喂养加吡格列酮15 mg/(kg.d)灌胃]。饲养12周末处死大鼠,检测血清丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、碱性磷酸酶(ALP)活性以及总胆固醇(TC)、甘油三酯(TG)、游离脂肪酸(FFA)含量,测量空腹血糖(FBG)及胰岛素(FINS)水平,计算胰岛素抵抗指数(HOMA-IR);HE染色观察肝脏病理形态学的变化;Real time PCR和免疫组化法检测肝组织中TNF-α及CYP2E1 mRNA及蛋白表达的变化。结果 3种药物干预组均可降低ALT,AST,ALP活性(P<0.05),减少TC,TG,FFA含量(P<0.05),改善大鼠肝脏病理形态学改变,降低肝脏中TNF-α及CYP2E1 mRNA及蛋白的表达(P<0.01)。二甲双胍、吡格列酮两组间无显著差异(P>0.05),阿卡波糖组的作用明显低于前两者(P<0.01)。结论阿卡波糖、二甲双胍、吡格列酮均可减少TNF-α及CYP2E1的表达,改善非酒精性脂肪肝的病理变化,其中二甲双胍、吡格列酮作用相似,阿卡波糖作用较弱。     

吡格列酮对高胆固醇模型大鼠脂肪组织细胞中肿瘤坏死因子-α分泌及其mRNA表达的影响

目的:研究吡格列酮对高胆固醇模型大鼠脂肪组织细胞中肿瘤坏死因子-α(TNF-α)分泌及其mRNA表达的影响。方法:将30只高胆固醇饮食8周的大鼠随机分为高胆固醇组(n=15)和吡格列酮组(n=15),前者继续给予高胆固醇饮食,后者在此基础上加吡格列酮3mg.kg-1.d-1,连续4周;另设喂普通饲料12周的对照组(n=15)。处死大鼠并检测血脂、血清TNF-α水平及其mRNA表达等指标。另取正常脂肪细胞加入脂多糖和不同浓度的吡格列酮(0.1、1.0、10.0μmol.L-1)中,测定脂肪组织细胞中的TNF-α水平及其mRNA表达。结果:与高胆固醇组比较,吡格列酮组可明显降低血清TNF-α水平及减弱其mRNA表达,但对血糖和血脂水平几乎无影响。上述吡格列酮各浓度组可呈浓度依赖性抑制脂多糖诱导TNF-α分泌及其mRNA表达。结论:吡格列酮可降低高胆固醇模型大鼠血清和脂肪组织中TNF-α水平。     

吡格列酮对波动性高糖处理的人脐静脉内皮细胞脂联素受体表达的影响

目的探讨吡格列酮对波动性高糖处理的人脐静脉内皮细胞(HUVEC)脂联素受体(AdipoR1和AdipoR2)表达的影响。方法将HUVEC在波动性高糖培养液(5.5、20mmol.L-1每隔8h轮换1次)中培养5d后,随机分为阴性对照组、吡格列酮处理组(10、1与0.1μmol.L-1)和阳性对照组。应用实时定量PCR方法检测脂联素受体mRNA表达的改变。结果与波动性高糖组比较,吡格列酮处理后HU-VECAdipoR1表达增高。当吡格列酮浓度增至1μmol.L-1以上时,AdipoR1mRNA表达增加呈现差异。各组细胞Adi-poR2表达量间差别无显著性。结论AdipoR1很可能是胰岛素增敏剂吡格列酮改善内皮胰岛素敏感性的作用机制之     

Effect of Pioglitazone on Expression of Chemerin,Cmklr1 and Tumor Necrosis Factor-alpha mRNA in Liver of Diabetic Rat Model

目的:观察噻唑烷二酮类药物对糖尿病大鼠肝脏chemerin、cmklr1及肿瘤坏死因子(TNF)-α mRNA表达的影响.方法:雄性SD大鼠随机分为正常组、糖尿病组与吡格列酮组,尾静脉注射链脲佐菌素制作糖尿病大鼠模型,造模成功后吡格列酮组每天按15 mg/kg经胃灌药,连续给药8周.第8周末处死大鼠留取肝脏组织.采用实时定量PCR法检测大鼠肝脏chemerin、cmklr1及TNF-α mRNA的表达水平.结果:糖尿病组肝脏chemerin表达低于正常组及吡格列酮组,差异均有统计学意义(均P＜0.017).3组间肝脏cmklr1表达差异无统计学意义.糖尿病组肝脏TNF-α表达较正常组升高(P＜0.017),吡格列酮组较糖尿病组有所降低,但差异无统计学意义.结论:糖尿病大鼠肝脏TNF-α表达增高,吡格列酮可能通过上调chemerin的表达而改善肝脏的胰岛素敏感性.     

吡格列酮对糖尿病大鼠心肌缺血再灌注损伤的影响

目的 观察糖尿病大鼠心肌缺血再灌注(MIR)时细胞间黏附分子-1(ICAM-1)和自由基代谢的变化及吡格列酮对其的影响,探讨糖尿病大鼠MIR损伤的机制.方法 制作糖尿病大鼠模型,4周后作MIR模型.糖尿病大鼠30只分为假手术对照(sham)组,MIR组和吡格列酮组.免疫组织化学法检测心肌ICAM-1蛋白表达.检测血清、心肌组织超氧化物酶(SOD)、丙二醛(MDA)、谷胱甘肽-过氧化物酶(GSH-PX)及心肌线粒体Na ,K -ATP酶、Mg2 -ATP酶、Ca2 -ATP酶活性.结果 与sham组相比,MIR组心肌线粒体Na ,K -ATP酶、Mg2 -ATP酶、Ca2 -ATP酶活性明显下降(P＜0.05),血清SOD明显降低(P＜0.01),心肌SOD和血清、心肌GSH-PX明显降低(P＜0.05),血清、心肌MDA明显升高(P＜0.05),心肌ICAM-1蛋白表达明显升高(P＜0.01).用吡格列酮4周后线粒体Na ,K -ATP酶、Mg2 -ATP酶、Ca2 -ATP酶活性高于MIR组(P＜0.05),血清、心肌SOD和GSH-PX水平高于MIR组(P＜0.05),心肌MDA低于MIR组(P＜0.01),心肌ICAM-1蛋白表达低于MIR组(P＜0.05).结论 吡格列酮可减轻糖尿病心肌缺血再灌注损伤.     

川芎嗪对高糖诱导后人腹膜间皮细胞血管内皮生长因子表达的影响

目的研究川芎嗪对体外培养的人腹膜间皮细胞在高糖刺激下血管内皮生长因子(VEGF)表达的影响。方法体外培养人腹膜间皮细胞,分为5组(每组设3个样本):正常对照组(完全培养液)、高糖对照组(2.5%葡萄糖)和高糖(2.5%葡萄糖)加川芎嗪(浓度依次为10,20,40 mg/L)组。采用半定量逆转录聚合酶链反应(RT-PCR)法检测细胞内VEGF mRNA的表达;酶联免疫吸附测定法(ELISA)检测细胞上清液中VEGF的蛋白质水平,用二喹啉甲酸蛋白检测法测定细胞中蛋白质含量,用以校正ELISA结果。结果川芎嗪能显著降低高糖所致的人腹膜间皮细胞VEGF的表达(P<0.01);两者在蛋白质和基因水平均呈量效关系。结论川芎嗪可以减少高糖刺激下人腹膜间皮细胞VEGF的表达,从而达到延缓腹透相关性腹膜纤维化的发生和发展。     

利拉鲁肽对高糖培养的H9c2心肌细胞氧化应激和内质网应激的影响

摘 要 目的：探讨利拉鲁肽对高糖培养的H9c2心肌细胞氧化应激和内质网应激的影响。方法: 在H9c2细胞的高糖培养液中加入利拉鲁肽（LIRA）、活性氧簇分子（ROS）清除药N-乙酰半胱氨酸（NAC）处理24 h,用流式细胞术检测细胞的ROS水平,用Western blot的方法检测H9c2细胞内质网应激标志蛋白葡萄糖调节蛋白78（GRP78）和C/EBP 同源蛋白（CHOP）的表达水平。结果:与正常糖对照组比较,高糖组细胞内的ROS含量、GRP78和CHOP的蛋白表达水平显著上升（P<0.01）。与高糖组比较,利拉鲁肽显著抑制了细胞内的ROS产生（P<0.01）,降低了GRP78和CHOP的蛋白表达水平（P<0.05）。结论:利拉鲁肽能抑制高糖培养的H9c2细胞的氧化应激和内质网应激水平。     

吡格列酮对2型糖尿病患者血清C反应蛋白和肿瘤坏死因子-α的影响

目的:观察吡格列酮治疗对2型糖尿病(T2DM)患者血清炎症因子C-反应蛋白(CRP)及肿瘤坏死因子-α(TNF-α)水平的影响.方法:采用随机、双盲法将2型糖尿病患者90例分为对照组和吡格列酮组,对照组联合应用磺脲类和双胍类药物,吡格列酮组每天加服吡格列酮15 mg治疗12周,分别检测两组治疗前后空腹血糖(FPG)、2 h血糖(2 hPG)、糖化血红蛋白(HbAlc)、血清CRP、TNF-α水平,评估治疗前后胰岛素抵抗(IR)变化.结果:对照组糖化血红蛋白(HbAlc)显著下降(P＜0.01),其他指标无显著变化;吡格列酮组治疗后FPG、2hPG、HbAlc、IR显著降低(P＜0.01),血清CRP、TNF-α水平治疗后显著下降(P＜0.01),与对照组比较差异有极显著性(P＜0.01).结论:吡格列酮治疗T2DM能改善胰岛素抵抗、降低血糖,具有明显的抗炎作用.     

Salviae radix root extract inhibits immunoglobulin E-mediated allergic reaction.

We investigated the effects of the aqueous extract of Salviae radix root (SRRAE) on immediate allergic reactions. SRRAE inhibited by 72.7% passive cutaneous anaphylaxis activated by anti-dinitrophenyl (DNP) immunoglobulin E (IgE). SRRAE dose dependently inhibited histamine release and tumor necrosis factor-alpha production from the rat peritoneal mast cells (RPMCs) by anti-DNP IgE. However, SRRAE showed no significant inhibitory effect on compound 48/80-induced systemic allergic reaction and histamine release from RPMCs. The level of cAMP in RPMCs, when SRRAE was added, significantly increased compared with that of a normal control. These results indicate that SRRAE may contain compounds with actions that inhibit anti-DNP IgE-induced mast cell degranulation in rats.     

Effect of Poncirus fructus on stem cell factor-induced mast cell migration.

Mast cell hyperplasia can be causally related with chronic inflammation. Stem cell factor (SCF), the ligand of the c-kit protooncogene product, is a major regulator and chemoattractant of mast cells. Poncirus fructus (PF) has been used against allergic diseases for generations in South Korea. PF (1 mg ml(-1)) significantly inhibited the SCF-induced migration of rat peritoneal mast cells (RPMCs). RPMCs exposed to SCF (50 ng ml(-1)) resulted in a drastic shape change with a polarized morphology while the cells exposed to PF (1 mg ml(-1)) remained resting, with little or no shape alteration. The drastic morphological alteration and distribution of polymerized actin were blocked by pretreatment with PF. In addition, PF inhibited both TNF-alpha and IL-6 secretion from RPMCs stimulated with SCF. Our findings provide evidence that PF inhibits chemotactic response and inflammatory cytokines secretion to SCF in mast cells.     

Effects of methyl p-hydroxybenzoate (methyl paraben) on Ca2+ concentration and histamine release in rat peritoneal mast cells

1 Mechanisms of methyl p-hydroxybenzoate (methyl paraben) action in allergic reactions were investigated by measuring the intracellular Ca(2+) concentration ([Ca(2+)](i)) and histamine release in rat peritoneal mast cells (RPMCs). 2 In the presence or absence of extracellular Ca(2+), methyl paraben (0.1-10 mM) increased [Ca(2+)](i), in a concentration-dependent manner. Under both the conditions, methyl paraben alone did not evoke histamine release. 3 In RPMCs pretreated with a protein kinase C (PKC) activator (phorbol 12-myristate 13-acetate (PMA) 3 and 10 nM), methyl paraben (0.3-3 mM) induced histamine release. However, a high concentration (10 mM) of the agent did not increase the histamine release. 4 U73122 (0.1 and 0.5 micro M), an inhibitor of phospholipase C (PLC), significantly inhibited the methyl paraben-induced histamine release in PMA-pretreated RPMCs. U73343 (0.5 micro M), an inactive analogue of U73122, did not inhibit the histamine release caused by methyl paraben. 5 In Ca(2+)-free solution, PLC inhibitors (U73122 0.1 and 0.5 micro M, D609 1-10 micro M) inhibited the methyl paraben-induced increase in [Ca(2+)](i), whereas U73343 (0.5 micro M) did not. 6 Xestospongin C (2-20 micro M) and 2 aminoethoxydiphenyl borate (30 and 100 micro M), blockers of the inositol 1,4,5-trisphosphate (IP(3)) receptor, inhibited the methyl paraben-induced increase in [Ca(2+)](i) in Ca(2+)-free solution. 7 In conclusion, methyl paraben causes an increase in [Ca(2+)](i), which may be due to release of Ca(2+) from storage sites by IP(3) via activation of PLC in RPMCs. In addition, methyl paraben possibly has some inhibitory effects on histamine release via unknown mechanisms.     

IL-37 is protective in allergic contact dermatitis through mast cell inhibition

Allergic contact dermatitis (ACD), characterized predominantly by erythema, vesiculation, and pruritus, is a T cell-mediated skin inflammatory condition. Among immune cells involved in ACD, mast cells (MCs) play an essential role in its pathogenesis. As an inhibitor of proinflammatory IL-1 family members, interleukin 37 (IL-37) has been shown to ameliorate inflammatory responses in various allergic diseases. In this study, we assessed the immunomodulatory effect of IL-37 on allergic inflammation using a 2,4-dinitrofluorobenzene (DNFB)-induced ACD rat model and isolated rat peritoneal mast cells (RPMCs). Systematic application of IL-37 significantly relieved ear swelling, reduced inflammatory cell infiltration, decreased inflammatory cytokine production (TNF-α, IL-1β, IFN-γ, and IL-13), inhibited MC recruitment, lowered IgE levels, and reduced IL-33 production in the local ear tissues with DNFB challenge. Additionally, RPMCs isolated from ACD rats with IL-37 intervention showed downregulation of IL-6, TNF-α, IL-13, and MCP-1 production following IL-33 stimulation, and reduction of β-hexosaminidase and histamine release under DNP-IgE/HSA treatment. Moreover, IL-37 treatment also significantly restrained NF-κB activation and P38 phosphorylation in ACD RPMCs. SIS3, a specific Smad3 inhibitor, abolished the suppressive effects of IL-37 on MC-mediated allergic inflammation, suggesting the participation of Smad3 in the anti-ACD effect of IL-37. These findings indicated that IL-37 protects against IL-33-regulated MC inflammatory responses via inhibition of NF-κB and P38 MAPK activation accompanying the regulation of Smad3 in rats with ACD.     

β‐eudesmol suppresses allergic reactions via inhibiting mast cell degranulation

The regulatory effect of β‐eudesmol, which is an active constituent of Pyeongwee‐San (KMP6), is evaluated for allergic reactions induced by mast cell degranulation. Phorbol 12‐myristate 13‐acetate (PMA) plus calcium ionophore A23187‐stimulated human mast cell line, HMC‐1 cells, and compound 48/80‐stimulated rat peritoneal mast cells (RPMCs) are used as the in vitro models; mice models of systemic anaphylaxis, ear swelling, and IgE‐dependent passive cutaneous anaphylaxis (PCA) are used as the in vivo allergic models. The results demonstrate that β‐eudesmol suppressed the histamine and tryptase releases from the PMA plus calcium ionophore A23187‐stimulated HMC‐1 cells. β‐eudesmol inhibits the expression and activity of histidine decarboxylase in the activated HMC‐1 cells. In addition, β‐eudesmol inhibits the levels of histamine and tryptase released from the compound 48/80‐stimulated RPMCs. Furthermore, β‐eudesmol decreases the intracellular calcium level in the activated RPMCs. β‐eudesmol also decreases the compound 48/80‐induced mortality and ear swelling response. β‐eudesmol suppresses the serum levels of histamine, IgE, interleukin (IL)‐1β, IL‐4, IL‐5, IL‐6, IL‐13, and vascular endothelial growth factor (VEGF) under PCA mice as well as PCA reactions. Therefore, the results from this study indicate the potential of β‐eudesmol as an anti‐allergic drug with respect to its pharmacological properties against mast cell‐mediated allergic reactions.     

The regulatory effect of SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-l]benzenesulfonamide) on stem cell factor induced migration of mast cells

SC-236, (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-]benzenesulfonamide; C(16)H(11)ClF(3)N(3)O(2)S), is a highly selective cyclooxygenase (COX)-2 inhibitor. Recently, there have been reports that SC-236 protects against cartilage damage in addition to reducing inflammation and pain in osteoarthritis. However, the mechanism involved in the inflammatory allergic reaction has not been examined. Mast cells accumulation can be related to inflammatory conditions, including allergic rhinitis, asthma, and rheumatoid arthritis. The aim of the present study is to investigate the effects of SC-236 on stem cell factor (SCF)-induced migration, morphological alteration, and cytokine production of rat peritoneal mast cells (RPMCs). We observed that SCF significantly induced the migration and morphological alteration. The ability of SCF to enhance migration and morphological alteration was abolished by treatment with SC-236. In addition, production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and vascular endothelial growth factor (VEGF) production induced by SCF was significantly inhibited by treatment with SC-236. Previous work has demonstrated that SCF-induced migration and cytokine production of mast cells require p38 MAPK activation. We also showed that SC-236 suppresses the SCF-induced p38 MAPK activation in RPMCs. These data suggest that SC-236 inhibits migration and cytokine production through suppression of p38 MAPK activation. These results provided new insight into the pharmacological actions of SC-236 and its potential therapeutic role in the treatment of inflammatory allergic diseases.     

RBL-2H3细胞不适合用于类过敏模型的建立

目的考察RBL-2H3细胞是否适用于建立类过敏反应模型。方法用荧光定量聚合酶链反应考察RBL-2H3细胞上Mas相关G蛋白偶联受体(Mas-related G protein cou-pled receptor,Mrgpr)B2的表达情况;用显微镜观察和MTS法考察Compound 48/80对RBL-2H3细胞活力的影响;测定不同浓度Compound 48/80刺激RBL-2H3细胞脱颗粒释放的β-己糖胺酶含量,对比RBL-2H3细胞、人肥大细胞系LAD2和大鼠腹腔肥大细胞(rat peritoneal mast cells,RPMCs)对Compound 48/80响应性的差异。结果RBL-2H3细胞可表达MrgprB2受体。Compound 48/80能剂量依赖性地诱导RBL-2H3细胞释放β-己糖胺酶,但在高剂量(≥20 mg·L^-1)时对RBL-2H3的细胞活力产生明显影响,此时释放的β-己糖胺酶应当是由于其细胞毒作用引起细胞破裂所致。同在无毒剂量(10 mg·L^-1)的Compound 48/80刺激下,LAD2和RPMCs的响应性良好,β-己糖胺酶释放量分别为空白对照的15.02倍和16.05倍,而RBL-2H3细胞仅为空白对照的2.35倍。结论RBL-2H3细胞对Compound 48/80的响应性差,表明其并不适用于建立类过敏反应模型。     

Involvement of reactive oxygen species in angiotensin II-induced vasoconstriction

In recent years it has been shown that angiotensin II (Ang II) stimulates formation of reactive oxygen species (ROS), presumably by activation of NAD(P)H oxidase. This ROS formation has been primarily associated with cellular growth regulation by Ang II. The objective of the present study was to investigate whether these ROS contribute to Ang II-induced vasoconstriction. Experiments were performed in isolated rat thoracic aorta. Concentration response curves were constructed for Ang II in the absence and presence of the NAD(P)H oxidase inhibitor DPI, and ROS scavengers catalase and EUK-8. Inhibition of NAD(P)H oxidase as well as scavenging of ROS, decreased the contractile response to Ang II. Administration of NADPH, a substrate for NAD(P)H oxidase, produced vasoconstriction that proved to be sensitive for DPI, catalase, and EUK-8. Exposure of the vessels to exogenous ROS, induced by electrolysis of the organ bath medium, also resulted in a contractile response that was decreased by ROS scavenging. The results suggest that ROS play a role in Ang II-induced vasoconstriction via the activation of NAD(P)H oxidase.     

Effect of polychlorinated biphenyls on production of reactive oxygen species (ROS) in rat synaptosomes

In this paper the effect of polychlorinated biphenyls (PCBs) on the production of reactive oxygen species (ROS) in rat synaptosomes is elucidated. The effect of methylmercury (MeHg) on rat synaptosomes was included as a positive control since several studies have investigated the ability of this substance to produce ROS. The exposure of the synaptosomes to the congener 2,2-dichlorobiphenyl (2, 2'-DCB; 12.5 microM) produced a linear increase in the formation of 2',7'-dichlorofluorescein (DCF) as a measure for the production of ROS. The congeners 2,2'-DCB (12.5 microM) and 3,3'-DCB (12.5 microM) stimulated, as expression of ROS production, a significant increase in DCF formation formation compared to the control. The congeners 2-chlorobiphenyl (2-CB) and 2,2',6-trichlorobiphenyl (2,2,6'-TCB) were active at 50 microM, whereas 2,2',4,4',5,5'-hexachlorobiphenyl (2,2',4,4',5,5'-HCB), 4,4'-DCB and 2,2',6,6'-tetrachlorobiphenyl (2, 2',6,6'-TeCB) were not active at this concentration. The increased formation of ROS in response to 2,2'-DCB and MeHg in the synaptosomes was dependent on extracellular Ca(2+). A phospholipase C inhibitor, U73122, was shown to significantly decrease the ROS formation induced by 2,2'-DCB, but did not reduce the ROS formation induced by MeHg. Ethanol (1%), a phospholipase D modulator, reduced the ROS formation induced by MeHg and by 2,2'-DCB by 33 and 52%, respectively. Wortmannin (25 nM), an inhibitor of phosphatidylinositol 3-kinase, completely inhibited the ROS formation induced by MeHg and 2,2'-DCB. It appears that the ROS-stimulating PCBs are the same congeners found to be neuroactive in other types of study. Phospholipase C and D and phosphatidylinositol 3-kinase seem to be involved in the intracellular signalling system that leads to ROS formation during PCB exposure.