探针药物法测定大黄对大鼠肝细胞色素CYP2E1酶的影响

目的用探针药物法测定大黄对大鼠肝细胞色素CYP2E1酶的影响。方法将SD舍大鼠随机分组,给药组予大黄灌胃,以生理盐水组为空白对照,尾静脉给予CYP2E1探针药物氯唑沙宗,HPLC法检测体内药动学参数来评价各组的CYP2E1酶活性。结果氯唑沙宗代谢符合二室模型,给药组t1/2β（1．18±0．28）h、AUC（20．09±12．11）mg·h·L^-1、V（c）（0．30±0．21）L、CL（s）（0．94＋0．59）L·h^-1,对照组t1/2β（1．49±0．14）h、AUC（38．87±8．35）mg·h·L^-1、V（c）（0．21±0．06）L、CL（s）（0．12±0．02）L·h^-1.结论大黄对大鼠肝细胞色素CYP2E1有诱导作用。     

细胞色素P4502E1的研究进展

ＣＹＰ２Ｅ１在药物和人们经常接触的溶剂与环境污染物的代谢中具有重要作用。本文综述ＣＹＰ２Ｅ１的结构特点、基因、底物和探药以及影响其活性的主要因素。     

山楂对正常大鼠肝脏CYP2E1活性的影响

目的:探讨山楂对大鼠肝脏CYP2E1活性的影响,为山楂的药食同源应用提供依据.方法:实验分为正常对照组、山楂高剂量组和山楂低剂量组,给予山楂水提取液14天后,抽取肝微粒体酶,利用高效液相色谱检测CYP2E1代谢低物的能力.结果:山楂高剂量和低剂量组均能显著抑制CYP2E1的活性.结论:山楂是一种良好的药食同源的中药,能通过抑制CYP2E1活性对机体起保护作用.     

雷公藤多苷片对大鼠药物代谢酶CYP2E1和CYP3A4活性的影响

目的:研究雷公藤多苷片对大鼠CYP450亚型酶CYP2E1和CYP3A4活性的影响方法:16只Wistar大鼠随机分成2组,每组8只,实验组给予雷公藤多苷片(1 mg·kg^-1·d^-1,ig,qd),对照组给予同体积的纤维素钠空白溶剂,连续给药10d后同时静脉给予探针药物氯唑沙宗(5 mg·kg^-1)和咪达唑仑(2 mg·kg^-1)。HPLC法测定两个探针药物的血药浓度,计算其药物动力学参数,评价CYP450亚型酶CYP2E1和CYP3A4的活性。结果:与对照组比较,实验组的氯唑沙宗主要药物动力学参数无明显变化（P>0.05）,而咪达唑仑的CL和AUC较对照组差异有统计学意义（P<0.05）。结论:雷公藤多苷片对大鼠的CYP2E1酶活性无明显影响,对CYP3A4酶活性有一定的抑制作用。     

甘草与海藻 大戟 芫花配伍对大鼠肝脏CYP2E1酶活性及mRNA表达的影响

目的研究甘草与海藻、大戟、芫花合用对CYP2E1酶活性的影响及在mRNA水平的调控作用。方法采用高效液相色谱法测定CYP2E1活性;采用反转录聚合酶链反应(RT-PCR)评价药物对CYP2E1 mRNA水平的影响。结果甘草单用能明显诱导CYP2E1酶活性,与海藻、大戟、芫花合用后对CYP2E1酶活性的诱导作用没有甘草单用明显。CYP2E1 mRNA水平基本与酶活性水平相平行。结论甘草与海藻、大戟、芫花合用后诱导CYP2E1酶活性,酶活性变化可能主要通过影响基因转录来实现。     

黄葵胶囊对大鼠CYP450酶的影响

目的：研究黄葵胶囊对大鼠CYP1A2、CYP2E1、CYP3A4活性的影响。方法：14只大鼠随机均分成临床等效剂量组和高剂量组,连续2周灌胃给予黄葵胶囊（临床等效剂量组,0.75 g/kg;高剂量组,2 g/kg）前后,均同时灌胃给予3个探针底物（茶碱,30 mg/kg;氨苯砜,20 mg/kg;氯唑沙宗,50 mg/kg）,采血测定。用HPLC法同时测定大鼠体内各探针的血药浓度,DAS1.0软件计算药动学参数,并以配对t检验对两组大鼠前后两轮主要药动学参数进行差异性比较。结果：临床等效剂量组大鼠给药后,与给药前相比,茶碱、氨苯砜和氯唑沙宗的药动学参数无统计学变化（P〉0.05）;高剂量组大鼠给药后,氨苯砜的AUC0-24h与给药前相比,有降低趋势（P〈0.05）,是给药前的0.63倍;氯唑沙宗的AUC0-24h与给药前相比,有升高趋势（P〈0.05）,是给药前的1.75倍。结论：临床等效剂量黄葵胶囊对大鼠CYP1A2、CYP3A4、CYP2E1活性均无显著影响;而高剂量黄葵胶囊对大鼠CYP3A4有弱诱导作用,对CYP2E1有弱抑制作用。     

丹参-红花药对配伍前后对大鼠肝药酶亚型CYP1A2、CYP2E1和CYP3A4活性的影响

目的 研究丹参、红花药对配伍前后对大鼠肝药酶亚型CYP1A2、CYP2E1和CYP3A4活性的影响。方法 分别选用咖啡因、氯唑沙宗和咪达唑仑作为CYP1A2、CYP2E1和CYP3A4的探针药物。将大鼠随机分为4组,即空白对照组、丹参（1.2 g生药/kg）组、红花（0.4 g生药/kg）组、丹参（1.2 g生药/kg）+红花（0.4 g生药/kg）组,按上述剂量ig给药7 d。于末次给药后30 min,尾iv探针药物咖啡因、氯唑沙宗和咪达唑仑溶液,在不同的时间点取血进行检测;以甲硝唑为内标,采用HPLC法检测探针药物咖啡因、氯唑沙宗和咪达唑仑的量,评价各药物组对大鼠CYP3A4、CYP2E1和CYP1A2活性的影响。结果 与空白对照组比较,丹参组咖啡因、氯唑沙宗和咪达唑仑的清除率（CL）有所增强,曲线下面积（AUC）减少,其半衰期（t_1/2）有减少趋势,但差异均不显著;红花组咖啡因和氯唑沙宗的CL有所降低,但差异不显著,咪达唑仑的CL显著降低（P<0.01）,氯唑沙宗的AUC增加,但差异不显著,咖啡因和咪达唑仑的AUC明显增加（P<0.05、0.01）;丹参+红花组咖啡因和氯唑沙宗的CL明显降低（P<0.05）,曲线下面积（AUC）明显增加（P<0.05）,其t_1/2有延长趋势,但差异不显著。结论 丹参、红花配伍后对CYP450亚型CYP1A2和CYP2E1有抑制作用,这可能是丹参、红花配伍协同增效的作用机制之一。     

慢性间断性低氧对大鼠肝脏CYP3A_2和CYP2E_1的影响

目的:观察慢性间断性低氧对大鼠肝脏CYP3A2和CYP2E1的影响。方法:♂SD大鼠随机分为对照组和实验组,实验组分别低氧3、7、14、28d。采用酶法测定血清丙氨酸氨基转移酶(ALT)和天冬氨酸氨基转移酶(AST)活性,分光光度法测定大鼠肝微粒体红霉素N-脱甲基酶(ERD)、苯胺羟化酶(ANH)活性,半定量逆转录聚合酶链式反应(RT-PCR)检测大鼠肝脏细胞色素P4503A2、2E1的mRNA表达水平。结果:慢性间断性低氧对血清ALT和AST活性无明显影响;低氧7d后,大鼠肘脏ERD和ANH活性明显升高,28d时诱导率分别为155.5%和42.2%;同时CYP3A2和CYP2E1mRNA的表达水平也分别增加了220.5%和102.8%。结论:慢性间断性低氧能显著增加大鼠肝脏ERD(CYP4503A2)和ANH(CYP2E1)活性,其机制可能与其在转录水平上提高肝脏CYP4503A2和CYP2E1的基因表达水平有关。     

复方银杏叶胶囊对肝损伤大鼠CYP2E1、CYP3A4的影响

目的研究复方银杏叶胶囊(CGB)对酒精性肝损伤大鼠CYP2E1、CYP3A4活性的影响。方法正常组和酒精性肝损伤模型组均以CGB[(250 mg/(kg.d)]灌胃,分别在灌胃CGB前及灌胃1周后,灌胃探针药氯唑沙宗(50 mg/kg)及氨苯砜(20 mg/kg),于探针药灌后24 h内不同时间点采血,测定各探针药血药浓度。结果灌胃CGB前,模型组氯唑沙宗和氨苯砜的AUC0-24、Cmax均显著低于正常组(P<0.05或P<0.01)。灌胃CGB后,模型组氯唑沙宗和氨苯砜的AUC0-24、Cmax均较灌胃前显著升高(P<0.05或P<0.01);且氯唑沙宗的t1/2灌胃CGB后明显高于灌胃前(P<0.05)。结论 CGB能够明显抑制酒精性肝损伤大鼠CYP2E1、CYP3A4酶活性。     

Comparison of chlorzoxazone one-sample methods to estimate CYP2E1 activity in humans

Objective Comparison of a one-sample with a multi-sample method (the metabolic fractional clearance) to estimate CYP2E1 activity in humans.Methods Healthy, male Caucasians (n=19) were included. The multi-sample fractional clearance (Cl_fe) of chlorzoxazone was compared with one-time-point clearance estimation (Cl_est) at 3, 4, 5 and 6 h. Furthermore, the metabolite/drug ratios (MRs) estimated from one-time-point samples at 1, 2, 3, 4, 5 and 6 h were compared with Cl_fe.Results The concordance between Cl_est and Cl_fe was highest at 6 h. The minimal mean prediction error (MPE) of Cl_est as a percentage of actual mean Cl_fe was –4.2% at 6 h. Furthermore, regarding Cl_fe, there was a negligible difference (P=0.56) of bias between Cl_est at 3 h (MPE=–8.9%) and 6 h (MPE=–4.2%). The best concordance between MR and Cl_fe was found at 3 h (r=0.74; P<0.001).Conclusion All three single-dose-sample estimates, Cl_est at 3 h or 6 h, and MR at 3 h, can serve as reliable markers of CYP2E1 activity. The one-sample clearance method is an accurate, renal function-independent measure of the intrinsic activity; it is simple to use and easily applicable to humans.     

Differential effects of diabetes on CYP2E1 and CYP2B4 proteins and associated drug metabolizing enzyme activities in rabbit liver

The effects of diabetes on cytochrome P450 (CYP)-dependent drug metabolizing enzymes are yet to be clarified. The most widely used animals in these studies have been rats, and information on the effects of diabetes on rabbit liver drug metabolizing enzymes have been unavailable until now. In this study, for the first time, a significant induction of liver CYP2E1 is demonstrated via immunoblot analysis in alloxan-induced rabbits. The CYP2E1 content of diabetic microsomes was highly correlated with the activities of liver aniline 4-hydroxylase (r=0.82, p<0.05), and p-nitrophenol hydroxylase (r=0.86, p<0.01), and diabetes increased the activities of the enzymes associated with CYP2E1. The activities of aniline 4-hydroxylase and p-nitrophenol hydroxylase were significantly increased by 1.7 and 1.8-fold, respectively compared to those of control rabbits. In marked contrast, diabetes had no effect on the protein levels of CYP2B4 as determined by immunoblotting and on benzphetamine N-demethylase activity, which is known to be specifically metabolized by CYP2B4 in rabbit liver. The present study demonstrates that diabetes increases the activities of CYP2E1 and associated enzymes but does not change the activity levels of CYP2B4 and associated enzymes in diabetic rabbits. These findings are in contrast to those of mice, hamsters and rats, and that suggest the presence of species-dependent responses of CYP-dependent drug metabolizing enzymes to diabetes.An account of this work was presented at the 19th European Workshop on Drug Metabolism, DMW-2004, in Antalya, Turkey, on 3–8 October 2004     

Effect of piperine on CYP2E1 enzyme activity of chlorzoxazone in healthy volunteers

1.?The purpose of the present study was to investigate the effect of piperine (PIP) on CYP2E1 enzyme activity and pharmacokinetics of chlorzoxazone (CHZ) in healthy volunteers.

2.?An open-label, two period, sequential study was conducted in 12 healthy volunteers. A single dose of PIP 20?mg was administered daily for 10 days during treatment phase. A single dose of CHZ 250?mg was administered during control and after treatment phases under fasting conditions. The blood samples were collected at predetermined time intervals after CHZ dosing and analyzed by HPLC.

3.?Treatment with PIP significantly enhanced maximum plasma concentration (C_max) (3.14–4.96?μg/mL)_, area under the curve (AUC) (10.46–17.78?μg h/mL), half life (T_1/2) (1.26–1.82?h) and significantly decreased elimination rate constant (K_el) (0.57–0.41?h?^??¹), apparent oral clearance (CL/F) (24.76–13.65?L/h) of CHZ when compared to control. In addition, treatment with PIP significantly decreased C_max (0.22–0.15?μg/mL), AUC (0.94–0.68?μg h/mL), T_1/2 (2.54–1.68?h) and significantly increased K_el (0.32–0.43?h?^??¹) of 6-hydroxychlorzoxazone (6-OHCHZ) as compared to control. Furthermore, treatment with PIP significantly decreased metabolite to parent (6-OHCHZ/CHZ) ratios of C_max, AUC, T_1/2 and significantly increased K_el ratio of 6-OHCHZ/CHZ, which indicate the decreased formation of CHZ to 6-OHCHZ.

4.?The results suggest that altered pharmacokinetics of CHZ might be attributed to PIP mediated inhibition of CYP2E1 enzyme, which indicate significant pharmacokinetic interaction present between PIP and CHZ. The inhibition of CYP2E1 by PIP may represent a novel therapeutic benefit for minimizing ethanol induced CYP2E1 enzyme activity and results in reduced hepatotoxicity of ethanol.     

慢性间断性低氧对大鼠肝脏CYP3A_2和CYP2E_1的影响研究

目的研究慢性间断性低氧对大鼠肝脏CYP3A2和CYP2E1的影响。方法将大鼠随机分为对照组、低氧3d组、低氧7d组、低氧14d组、低氧28d组,低氧处理结束24h后,常规腹腔注射麻醉,摘取眼球血液2ml制备血清,并测定丙氨酸氨基转移酶(ALT)、天门冬酸氨基转移酶(AST)、红霉素N-脱甲基酶(ERD)、苯胺羟化酶(ANH)活性;取新鲜肝组织以制备微粒体和提取核糖核酸(RNA),并以RT-PCR进行基因片段扩增以检测大鼠肝脏细胞色素CYP3A2、CYP2E1的mRNA表达水平。结果慢性间断性低氧对血清ALT、AST活性无明显影响;低氧7d后,大鼠肝脏ERD、ANH活性明显升高,28d时诱导率分别为155.5%、42.2%;同时,CYP3A2、CYP2E1mRNA的表达水平也分别增加了220.5%、102.8%。结论慢性间断性低氧能显著增加大鼠肝脏ERD、ANH活性,其机制可能与其在转录水平上提高肝脏CYP3A2和CYP2E1的基因表达水平有关。     

In vivo CYP2E1 phenotyping as a new potential biomarker of occupational and experimental exposure to benzene

Assessing CYP2E1 phenotype in vivo may be important to predict individual susceptibility to those chemicals, including benzene, which are metabolically activated by this isoenzyme. Chlorzoxazone (CHZ), a specific CYP2E1 substrate, is readily hydroxylated to 6-OH-chlorzoxazone (6-OH-CHZ) by liver CYP2E1 and the metabolic ratio 6-OH-CHZ/CHZ in serum (MR) is a specific and sensitive biomarker of CYP2E1 activity in vivo in humans. We used this MR as a potential biomarker of effect in benzene-treated rats and, also, in humans occupationally exposed to low levels of benzene. Male Sprague-Dawley rats (375–400 g b.w.) were treated i.p. for 3 days with either a 0.5 ml solution of benzene (5 mmol/kg b.w.) in corn oil, or 0.5 ml corn oil alone. Twenty-four hours after the last injection, a polyethylene glycol (PEG) solution of CHZ (20 mg/kg b.w.) was injected i.p. in both treated and control animals. After 2, 5, 10, 15, 20, 30, 45, 60, 90, 120, 180, and 240 min from injection, 0.2 ml blood was taken from the tip tail and stored at −20 °C until analysis. A modified reverse phase HPLC method using a 5 μm Ultrasphere C18 column equipped with a direct-connection ODS guard column, was used to measure CHZ and its metabolite 6-OH-CHZ in serum. No statistically significant difference in the MR was observed, at any sampling time, between benzene-treated and control rats. The concentration-versus-time area under the curve (AUC), however, was lower (p < 0.05, Mann–Whitney test), whereas the systemic clearance was higher (p < 0.05) in treated than in control rats. Eleven petrochemical workers occupationally exposed to low levels of airborne benzene (mean ± SD, 25.0 ± 24.4 μg/m³) and 13 non-exposed controls from the same factory (mean ± SD, 6.7 ± 4.0 μg/m³) signed an informed consent form and were administered 500 mg CHZ p.o. Two hours later a venous blood sample was taken for CHZ and 6-OH-CHZ measurements. Despite exposed subjects showed significantly higher levels of t,t-MA and S-PMA, two biomarkers of exposure to benzene, than non-exposed workers, no difference in the MR mean values ± SD was found between exposed (0.59 ± 0.29) and non-exposed (0.57 ± 0.23) subjects. So, benzene was found to modify CHZ disposition, but not CYP2E1 phenotype in benzene-treated rats, nor in workers exposed to benzene, probably due to the levels of exposure being too low.     

Induction of CYP1A1 and CYP2E1 in rat liver by histamine: binding and kinetic studies

Histamine (HA) may bind to cytochrome P450 (CYP450) in rat liver microsomes. The CYP450-HA complex seems to regulate some cellular processes such as proliferation. In the present work, it is shown that HA increases the activity and protein level of CYP1A1 and CYP2E1, in vivo. CYP1A1 is associated with polycyclic aromatic hydrocarbon-mediated carcinogenesis and CYP2E1 with liver damage by oxidative stress. Studies of enzyme kinetics and binding with rat liver microsomes and supersomes were carried out to determine whether HA is a substrate of CYP1A1 and/or CYP2E1. The lack of NADPH oxidation in the presence of HA showed that it is not a substrate for CYP1A1. Activity measurements using the O-dealkylation of ethoxyresorufin indicated that HA is a mixed-type inhibitor of CYP1A1 in both microsomes and supersomes. On the other hand, HA induced a significant NADPH oxidation catalyzed by CYP2E1 supersomes, strongly suggesting that HA is a substrate for this isoform. Furthermore, HA is consumed in the presence of CYP2E1-induced microsomes and supersomes, as determined by o-phtalaldehyde complexes with HA by HPLC. The present findings may contribute to understand better the physiological function of CYP450 in relation with inflammation and other physiological processes in which HA may have a relevant role.     

淫羊藿苷对小鼠肝微粒体细胞色素P450酶及其亚型CYP2E1活性的影响

目的 研究淫羊藿苷对小鼠肝脏微粒体细胞色素P450(CYP)总酶含量及其亚型CYP2E1、CYP3A和CYP1A1活性的影响.方法 给予小鼠ig淫羊藿苷(50、100、200 mg·kg-1·d-1),3d后钙沉淀法制备肝细胞微粒体,UV法测定肝微粒体CYP的含量及其亚型CYP2E1与CYP3A的活性;荧光分光光度法测定肝微粒体CYP1A1的活性.结果 高剂量淫羊藿苷可降低小鼠肝脏微粒体CYP的含量(约54%)、抑制CYP2E1的活性(抑制率为53.1%),对CYP3A和CYP1A1的活性无影响.结论 大剂量淫羊藿苷可降低小鼠肝脏微粒体CYP的总含量,并抑制其亚型CYP2E1的活性.     

Undernutrition during hyperoxic exposure induces CYP2E1 in rat liver

Induction of cytochrome P450 2E1 (CYP2E1) has been shown to occur through two distinct mechanisms. The first is seen by treatment of rats with acetone, pyrazole, and 4-methyl-pyrazole, which induces CYP2E1 protein without affecting the mRNA level. The second is observed in starvation, diabetes, and obesity, in which an increase of CYP2E1 protein is associated with an increase of the CYP2E1 mRNA. It has been reported by (Tindberg and Ingelman-Sundberg 1989) that hyperoxic exposure (95% O₂) induced a several-fold increase of CYP2E1 protein in both the liver and lung of exposed rats without affecting the level of CYP2E1 mRNA. During the course of our previous study which demonstrated hyperoxia-induced specific pretranslational induction of CYP1A1/2 in the liver and CYP1A1 in the lung, we observed a progressive increase of hepatic CYP2E1 mRNA in animals of the hyperoxia group. Hyperoxia is accompanied by some degree of starvation and our earlier experiments were conducted with rats of significantly greater body weight than those used by Tindberg and Ingelman-Sundberg (260 vs 150 g). Thus we reevaluated the changes of CYP2E1 in the current study with the use of food-restricted control, and by utilizing rats of comparable weight (∼150 g) to that utilized by Tindberg and Ingelman-Sundberg. The results obtained in the present study showed that there was a significant increase in the levels of hepatic CYP2E1 mRNA, protein, and p-nitrophenol hydroxylase activity in the food-restricted control group compared to the untreated controls. Rats from the hyperoxia group also demonstrated a similar increase of these three parameters in their livers but showed no significant difference compared with the results of the food-restricted control group. Rats weighing ∼260 g were also examined with similar food restriction and hyperoxia, and the results were essentially similar to those obtained with the younger rats. The lungs of rats from food-restricted control and hyperoxia groups showed no increase of any of the CYP2E1 parameters. The results obtained in the current study, therefore, indicate that hyperoxia has no effect on CYP2E1 expression in both the liver and lung. Increased CYP2E1 mRNA, protein, and p-nitrophenol hydroxylase activity seen in the liver of rats, but not in the lungs, are consistent with the notion that undernutrition during hyperoxia is the underlying mechanism for this induction. Received: 29 April 1997 / Accepted: 11 June 1997     

醉酒人群CYP2E1基因多态性研究

目的:通过对醉酒人群的CYP2E1基因的检测,获得该基因遗传多态性数据,及其在醉酒人群中的分布。方法:采用聚合酶链式反应-限制性片段长度多态性(PCR-RFLP)技术,检测CYP2E1基因在154例醉酒样本的等位基因、基因型、基因频率。结果:CYP2E1基因在154例醉酒样本中共检出两种等位基因:等位基因c1和c2,观察到3种基因型c1/c1、c1/c2和c2/c2,基因型频率分别是68.8%、29.2%和1.9%。结论:对醉酒人群的CYP2E1基因的检测实验结果与本课题组先前的研究结果(酒依赖和健康对照组CYP2E1基因多态性)做统计分析。统计结果提示:醉酒人群的CYP2E1基因分布和酒依赖组没有差别,而与健康人群的CYP2E1基因分布存在差异,并且差异有统计学意义(P<0.05)。本研究用饮酒量分组与基因型分组,做统计分析,结果没有统计学意义。