Influence of Dioxin and Metal-Contaminated Sediment on Phase I and II Biotransformation Enzymes in Silver Crucian Carp

Several biochemical responses were measured in silver crucian carp (Carassius auratus gibelio) after exposure to sediments obtained from contaminated Ya-Er Lake, No. 1 pond, and an unpolluted reference site, Honglian Lake. After 1 week of exposure, a significant induction of the phase I biotransformation enzyme (ethoxylresorufin-o-deethylase, EROD) was found (83-fold of control), whereas the phase II biotransformation enzyme (glutathione S-transferase, GST) exhibited a slight, but significant induction (1.4-fold of control) after 4 weeks of exposure. The level of cellular glutathione in the liver was also slightly elevated after 4 weeks of exposure. The delayed response of GST to the contaminants indicates that the phase I and phase II biotransformation enzymes are regulated differently in fish. The results suggest that EROD is a sensitive bioindicator to assess the toxicity of dioxin-contamined sediment in the laboratory.     

Maternal drug abuse and human term placental xenobiotic and steroid metabolizing enzymes in vitro

We evaluated the impact of maternal drug abuse at term on human placental cytochrome P450 (CYP)-mediated (Phase I) xenobiotic and steroid-metabolizing activities [aromatase, 7-ethoxyresorufin O-deethylase (EROD), 7-ethoxycoumarin O-deethylase (ECOD), pyrene 1-hydroxylase (P1OH), and testosterone hydroxylase], and androstenedione-forming isomerase, NADPH quinone oxidoreductase (Phase II), UDP-glucuronosyltransferase (UGT), and glutathione S-transferase (GST) activities in vitro. Overall, the formation of androstenedione, P1OH, and testosterone hydroxylase was statistically significant between control and drug-abusing subjects; we observed no significant differences in any other of the phase I and II activities. In placentas from drug-abusing mothers, we found significant correlations between ECOD and P1OH activities (p < 0. 001), but not between ECOD and aromatase or P1OH and EROD activities; we also found significant correlations between blood cotinine and UGT activities (p < 0.01). In contrast, in controls (mothers who did not abuse drugs but did smoke cigarettes), the P1OH activity correlated with ECOD, EROD (p < 0.001), and testosterone hydroxylase (p < 0.001) activities. Our results (wider variation in ECOD activity among tissue from drug-abusing mothers and the significant correlation between P1OH and ECOD activities, but not with aromatase or EROD activities) indicate that maternal drug abuse results in an additive effect in enhancing placental xenobiotic metabolizing enzymes when the mother also smokes cigarettes; this may be due to enhancing a "silent" CYP form, or a new placental CYP form may be activated. The change in the steroid metabolism profile in vitro suggests that maternal drug abuse may alter normal hormonal homeostasis during pregnancy.     

Using Semipermeable Membrane Devices, Bioassays, and Chemical Analysis for Evaluation of Bioavailable Polycyclic Aromatic Hydrocarbons in Water

Meiliang Bay is a sublake of Taihu Lake and has been polluted by domestic and industrial effluents. As part of a comprehensive risk assessment project in this region, semipermeable membrane devices (SPMDs) were applied to evaluate the levels and potential toxic potency of polycyclic aromatic hydrocarbons (PAHs) in lakewater, in combination with chemical analysis and in vitro bioassay using H4IIE rat hepatoma cells. In addition, induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity, in crucian carp (Carassius auratus), caged in the vicinity of SPMD sampling sites was also used as a biomarker of exposure to PAHs and related chemicals. The caged crucian carp accumulated similar PAH profile patterns (p < 0.001) but at lower levels compared with SPMDs on a wet-weight basis. Total concentrations of PAHs in crucian carp muscle tissues ranged from 35.6 to 69.1 ng/g after the 32-day exposure, whereas total PAHs in SPMDs ranged from 716.9 to 1007.8 ng/g. Dialysates from SPMDs exposed to Meiliang Bay water caused marked EROD activity in H4IIE cells. Toxic potency of dialysates expressed as bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ) ranged from 3.8 to 6.2 pg TCDD-EQ/g SPMD for 32-day exposure samples. A linear correlation of total amount of PAHs and in vitro TCDD-EQ of SPMD dialysates yielded an R ² of 0.82. Empirical evidence suggests that aryl hydrocarbon receptor-active PAHs can account for about 42–56% of the potency observed. Significant induction of liver EROD activity was also observed in crucian carp caged alongside SPMDs and there was a good correlation between the results of EROD assays in vivo and in vitro (R ² = 0.62, p = 0.02). It is, therefore, suggested that the SPMD technique in connection with chemical analysis and specific in vitro bioassays might be a valuable tool to assess the levels and effects of bioavailable hydrophobic pollutants in water.     

钱塘江水环境内分泌干扰物污染的研究

目的考查钱塘江水环境内分泌干扰物的污染情况。方法选择钱塘江7个代表性采样点,包括衢州樟潭、淳安街口(对照点位)、建德将军岩和严东关、桐庐、富阳、袁浦,对野生鲫鱼血清卵黄蛋白原(VTG)含量和肝7-乙氧基试卤灵-O-脱乙基酶(EROD)酶活性,以及鱼样肌肉中的有机磷、有机氯和拟除虫菊酯类农药含量进行检测,并选择4个点位进行水质化学分析。结果樟潭、将军岩、富阳和袁浦点位野生鲫鱼EROD酶活性[分别为(23.51±4.17)、(16.79±7.39)、(18.74±5.16)和(18.65±8.86)nmol.g-1 pro.min-1)]显著高于对照组(7.84±2.42nmol.g-1 pro.min-1)。野生鲫鱼VTG含量樟潭、桐庐、富阳、袁浦点位[分别为(1.536±0.521)、(16.404±13.579)、(19.672±16.354)和(17.079±18.397)μg/ml]明显高于对照点位[(0.400±0.099)μg/ml]。总有机磷含量桐庐>严东关>袁浦>富阳>樟潭>街口>将军岩,苯硫磷在桐庐和严东关野生鲫鱼肌肉中含量特别高,分别达到2695.64和611.96μg/kg。总有机氯含量桐庐>袁浦>严东关>富阳>樟潭>街口>将军岩,三氯杀螨砜在桐庐野生鲫鱼肌肉中含量特别高,达3962.17μg/kg。拟虫菊酯类农药含量桐庐>严东关>袁浦>樟潭>街口>富阳>将军岩。α-胺菊酯和α-苯醚菊酯在桐庐和严东关野生鲫鱼肌肉中含量较高(前者分别达到371.54和239.62,后者分别达到416.23和189.15μg/kg)。结论钱塘江水环境中樟潭、桐庐、富阳、袁浦这些点位水体受到较高内分泌干扰物的污染,与工业污染相比,这些点位的农药污染对雌激素效应的贡献可能更大。樟潭、将军岩、富阳、袁浦这些点位受到明显的有机污染物污染。水质化学性检测和鱼EROD酶活性的检测结果与实际有机物污染一致。以樟潭为代表的点位芳香烃污染水平较高可能导致环境污染的雌激素效应被低估。     

铅对接触男工性激素的影响

为评价铅接触对下丘脑-垂体-性腺轴的影响,选取健康男性工人189人,其中接触男工97名(血铅2.12±1.39μmol/L),非接触男工92名(血铅1.10±0.56μmol/L),以放射免疫法测定其血浆睾酮及血清LH、FSH。接触组工人平均血浆睾酮浓度为561.12ng/dl,明显低于对照组的725.29ng/dl(P<0.01)而血清LH水平则明显高于对照组工人,前者为19.17mIU/ml,后者为15.19mIU/ml(P<0.05);两组工人血清FSH含量无显著性差异,分别为12.21和11.03mIU/ml(P>0.05)。多元逐步回归分析表明,血清LH及血浆睾酮水平的改变与接触者的工龄明显相关,其次与吸烟也有一定关系。提示男工接触铅后可影响下丘脑-垂体-睾丸轴内分泌功能,引起血浆睾酮及血清LH浓度的改变。     

Long-term exposure effects in vitellogenin, sex hormones, and biotransformation enzymes in female carp in relation to a sewage treatment works

In the present study, the estrogenic response in the reproductive cycle of female carp, Cyprinus carpio, in relation to a sewage treatment works (STWs) was measured as: alterations in plasmatic and hepatic vitellogenin (VTG) content, plasma levels of testosterone (T) and estradiol (E2), and effects on key enzymes of phases I and II biotransformation, ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST). Low plasma VTG content in females collected 4 km downstream of an effluent discharge suggested possible estrogenic disturbances; however, hepatic VTG content and sex hormone levels did not mirror this. In fact, E2 and T largely fluctuated among fish, with individual variations even greater than among sampling stations or periods. This suggests that at moderately polluted sites, biological variations of female carp and genetic particularities are prevalent. Hepatic biotransformation enzymes, such as EROD, increased with increasing water temperature while, in contrast, GST was maximal at the lowest water temperature.     

Evaluation of the Interactive Effects of Lead,Zinc and Benzo(k)fluoranthene on Crucian Carp,Carassius carassius,Using a Multiple Biomarker Approach

The aim of this study was to evaluate the interactive effects of the metals lead (Pb) and zinc (Zn) and the polycyclic aromatic hydrocarbon benzo(k)fluoranthene (BkF) on crucian carp (Carassius carassius). To this end, various biomarkers in the fish [7-ethoxyresorufin-O-deethylase (EROD); superoxide dismutase (SOD); malondialdehyde (MDA) and metallothioneins (MT)] were measured after 96 h of exposure. When compared to either treatment with Pb and Zn mixtures or BkF-only treatment, the treatment with BkF combined with Pb and Zn resulted in lower responses of EROD and MT synthesis activity, and higher SOD and MDA increases. These results indicated that the co-exposure of metals and polycyclic aromatic hydrocarbons may cause more severe oxidative stress on fish. However, the effect of these interactions on EROD and MT may lead to an underestimation of the actual exposure in the field and thereby should be carefully considered.     

3,4-dichloroaniline-induced oxidative stress in liver of crucian carp (Carassius auratus)

3,4-dichloroaniline (DCA) and its analogs are widely used as chemical intermediates in the synthesis of herbicides, azo dyes, and pharmaceuticals. They bring danger to growth, development, and propagation of aquatic organisms. The purpose of this study was to show DCA-induced oxidative stress response in liver of crucian carp (Carassius auratus). Superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), nitric oxide (NO), and NO synthase (NOS) in liver were measured in crucian carp after exposure to DCA solution (0.2, 0.4, and 0.8 mg/L, respectively) for 15 days and compared with the control. DCA significantly induced SOD activity and enhanced MDA concentration in liver of crucian carp. Compared with the control, GSH and NO concentrations decreased and NOS activity was inhibited in crucian carp liver 15 days after DCA treatment. The data suggested that DCA-induced free radical generation and antioxidant depletion, and caused oxidative stress and lipid peroxidation in liver of crucian carp.     

Crucian carp (Carassius carassius) VTG monoclonal antibody: development and application

The vitellogenin (VTG) in fish has been used as an important biomarker for monitoring endocrine disrupting compounds (EDCs). This paper reports the development of a new monoclonal antibody (McAb) against the VTG of crucian carp (Carassius carassius). The McAb has a molecular weight of 149.4 kDa (heavy chain: 53.1 kDa; light chain: 21.6 kDa), and double diffusion indicated that it belongs to the IgG1 subclass. The titer is 10(5)-10(6) and the affinity constant (K(aff)) is 7.0 x 10(8)L/mol, showing the high specificity and sensitivity of the antibody. The established sandwich ELISA was sensitive with a detection limit of VTG 0.98 ng/mL. The cross-reactivity of antibody was detected in cyprinids such as rare minnow, zebrafish, and carp. This ELISA was used to detect the variation of VTG in crucian carp exposed to secondary effluent and reclaimed water from the Gaobeidian sewage treatment plant (SRP). The VTG induction in secondary effluent was higher than that in reclaimed effluent and the VTG levels in juvenile crucian carp increased with increasing exposure time. The VTG concentration in male fish from downstream of the Gaobeidian STP was 88.62+/-827.73 microg/mL, while that from a control site was undetectable.     

拟除虫菊酯对大鼠脑组织及肝脏生物转化酶的影响

目的 实验研究溴氰菊酯（ＤＭ）和氯菊酯（ＰＭ）对大鼠脑组织及肝脏某些生物转化酶的影响。方法 应用荧光分光光度法、二硝基苯肼比色法和Ｈａｂｉｇ法检测７－乙氧基试卤灵－Ｏ－脱乙基酶９ＥＲＯＤ０、Ｂ型单胺氧化酶９ＭＡＯＢ）和谷胱甘肽Ｓ－转移酶（ＧＳＴ）活力。结果 整体实验中，ＤＭ染毒动物肝脏ＥＲＯＤ、ＭＡＯＢ活力分别下降了４７．９４％和２２．７６％；脑组织和肝脏ＧＳＴ活力分别增加了２２．２０％和３９．５     

温石棉对A549细胞细胞色素P4501A1和谷胱甘肽S转移酶活性的影响

目的：探讨温石棉对体外培养细胞中外源性化合物代谢酶活性的影响。方法：采用不同剂量的UICC温石棉（UC）和国产茫崖温石棉（MC）分别作用于A549细胞,测A549细胞中细胞色素P4501A1（CYPA1）和谷胱甘肽S转移酶（GST）活性,并用苯并（a)芘对酶活性进行诱导,再测定温石棉对2种酶诱导活性的影响。结果：UC与A549细胞作用24h,乙氧基异酚恶唑－O－去乙基酶（EROD）活性随剂量增加呈缓慢递趋势,200mg/L UC可使EROD活性升高40％,但200mg/L UC作用48h则使其活性下降32％,提示UC对A549细胞EROD活性的影响呈现低剂量短时间诱导,而高剂量长时间抑制的趋势,MC对EROD活性的影响呈现多向性,无论作用24h还是48h,25mg/L UC作用48h则使其活性下降32％,提示UC对A549细胞EROD活性的影响呈现低剂量短时间诱导,而高剂量长时间抑制的趋势,MC对EROD活性的影响呈现多向性,无论作用24h还是48h,25mg/L的MC诱导作用最强（分别为对照组的1．86和1．28倍）,但随MC剂量增大和作用时间延长,EROD活性也随之下降,最低仅为对照组的35％,UC作用对GST的影响不明显,最高仅使GST活性升高20％,MC在25mg/L时驿GST的诱导最强,为对照组的1．4倍,但随着剂量的增加,对GST活性的上诱导转为抑制,200mg/L时GST活性下降了18．7％,先用温石棉与A549细胞作用24h,再加入苯并(a)芘对酶活性进行诱导,发现无论是UC还是MC,均未对苯并(a)芘诱导的EROD活性产生明显影响。但200mg/L的UC和100mg/L的MC均可增加GST的诱导活性。结论：不同剂量温石析对EROD和GST活性表现出不同的效应,其原因可能与2种温石棉的物理化学特性及表面活性有关。     

阿维菌素对几种淡水水生动物的急性毒性作用

目的 探讨阿维菌素对几种水生动物的急性毒性作用,为制订阿维菌素对淡水水生动物安全浓度的阈值提供参考依据.方法 采用换液法对蚤状潘、异育银鲫鱼种(鱼苗)、食蚊鱼、鲢鱼苗、青虾、幼蟹、圆田螺进行急性毒性实验,蚤状溞染毒48 h,其余水生动物染毒96 h.将每种实验动物495尾(只)随机分为11个组,分别为9个浓度组、1个空白对照组和1个乙醇(助溶剂)组,每组15尾(只)实验动物.平行3次.观察并记录动物死亡数,并计算24、48、72和96h的半数致死浓度(median-lethal concentration,LC_(50))和安全浓度(safety concentration,SC).结果 实验期间,蚤状溞、异育银鲫鱼种(鱼苗)、食蚊鱼、鲢鱼苗、青虾、幼蟹、圆田螺的死亡率均随处理时间的延长和阿维菌素浓度的增大而升高.阿维菌素对蚤状溞48 h的LC_(50)和安全浓度分别为0.000 37和0.000 037 mg/L,对异育银鲫鱼苗和鱼种、食蚊鱼、鲢鱼苗、青虾、幼蟹、圆田螺96 h的LC_(50)分别为0.018、0.06、0.08、0.02、0.52、0.25、0.57 mg,L,安全浓度分别为0.001 8、0.006、0.008、0.002、0.052、0.025、0.057 mg/L.阿维菌素对7种淡水水生动物的毒性依次为:蚤状溞＞异育银鲫鱼苗＞鲢鱼苗＞异育银鲫鱼种＞食蚊鱼＞幼蟹＞青虾＞圆田螺.结论 阿维菌素对水生动物具有较强的毒性.     

Comparison of the uptake of polycyclic aromatic hydrocarbons and organochlorine pesticides by semipermeable membrane devices and caged fish (Carassius carassius) in Taihu Lake, China

Uptake of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) by triolein-containing semipermeable membrane devices (SPMDs) and by crucian carp (Carassius carassius) was studied in Taihu Lake, a shallow, freshwater lake in China. Crucian carp and SPMDs were deployed side by side for 32 d. The first-order uptake rate constants of individual PAHs and OCPs for the two matrices were calculated and compared to relate the amounts of chemicals accumulated by the matrices to dissolved water concentrations. On a wet-weight basis, total concentrations of PAHs and OCPs in crucian carp fillets averaged 49.5 and 13.6 ng/g, respectively, after the 32-d exposure, whereas concentrations in whole SPMDs averaged 716.9 and 62.3 ng/g, respectively. The uptake rate constants of PAHs and OCPs by SPMDs averaged seven- and fivefold higher, respectively, than those for crucian carp; however, the patterns of uptake rate constants derived from test chemical concentrations in the crucian carp and SPMDs were similar. Although equilibrium was not reached for some PAHs and OCPs during the 32-d exposure period, a reasonably good correlation between the concentration factors (CFs) and octanol/water partition coefficient (Kow) values of PAHs and OCPs in SPMDs (r = 0.86, p < 0.001) was observed when potential sorption to dissolved organic carbon was taken into account. Similar efforts to correlate the CFs and Kow values of PAHs and OCPs in crucian carp (r = 0.75, p < 0.001) were less successful, likely because of PAH metabolism by finfish. Overall, the present results suggest that SPMDs may serve as a surrogate for contaminant monitoring with fish in freshwater lake environments.     

Response of the freshwater Alga chlorella vulgaris to trichloroisocyanuric acid and ciprofloxacin

The effects of trichloroisocyanuric acid (TCCA) and ciprofloxacin (CPFX) on the freshwater alga Chlorella vulgaris were assessed by toxicity bioassays and by the values of biomarkers in phase I and phase II. The biomarkers included growth rate, concentration of chlorophyll a, activities of 7-ethoxyresorufin-O-dealkylases (EROD), glutathione S-transferase (GST), catalase (CAT), and total glutathione (GSH). Ciprofloxacin was a weaker growth inhibitor than TCCA but, at a concentration of greater than 12.5 mg/L, decreased the growth of C. vulgaris. Concentration of chlorophyll a showed a similar trend. The 96-h median effective concentration (EC50; i.e., 50% reduction in growth relative to the control) of CPFX was 20.6 mg/L. Trichloroisocyanuric acid was a strong growth inhibitor and, at concentrations of greater than 0.80 mg/L, caused 100% inhibition on 24-h exposure. The 96-h EC50 of TCCA was 0.313 mg/L. Ciprofloxacin and TCCA affected the phase I and phase II enzyme activities differently. On exposure to CPFX, both EROD and GSH decreased at low CPFX concentrations (<5.0 mg/L) and increased at high CPFX concentrations (>12.5 mg/L), and CAT and GST exhibited induction at low concentrations and inhibition at high concentrations. In TCCA exposure, GST activity was significantly stimulated, and GSH concentration was increased. Catalase activity increased only at TCCA concentrations of greater than 0.12 mg/L, and no change in EROD activity was observed.     

Responses of serum transaminases in Notopterus notopterus chronically exposed to phenolic compounds and their combinations

Specimens of Notopterus notopterus were exposed to sublethal concentrations (10, 15, and 20 times diluted 96-hr LC₅₀) of phenol (P), dinitrophenol (DNP), pentachlorophenol (PCP), and their three combinations—additive [(DNP + P)/PCP], antagonistic [(PCP + DNP)/P], and synergistic [(P + DNP)/PCP]—for 30 days and their effects on serum transaminases (SGOT and SGPT) were studied. Significant (P < 0.05, P < 0.01, P < 0.001) enzymatic alterations were observed after treatment. The maximum stimulation (127.76%) was observed in SGOT at the highest concentration of the (P + DNP)/PCP combination and the minimum stimulation (6.67%) was observed in SGPT at the 20 times dilution concentration of the (PCP + DNP)/P combination after 30 days. However, inhibition in enzyme activity at the lowest concentration of P, DNP, and the (PCP + DNP)/P combination was also occasionally observed.     

Evaluation of waterborne exposure to oil spill 5 years after an accident in Southern Brazil

Fish (Astyanax sp.) were exposed to water samples from the Arroio Saldanha, locality of an oil spill, and the Barigui River (upstream and downstream of the confluence of the river and Arroio Saldanha), Brazil. Histopathological and biochemical biomarkers, as acetylcholinesterase (AchE), ethoxyresorufin-O-deethylase (EROD), catalase (CAT), glutathione-S-transferase (GST) activities, lipid peroxidation (LPO) levels, and amounts of polynuclear aromatic hydrocarbon residues (PAHs) in bile were evaluated. PAHs, metals, and surfactants were investigated in the water samples. CAT and GST activities increased in the Arroio Saldanha sample, whereas CAT activity and LPO levels were increased in the upstream and downstream sites. The results suggested a toxic action of the free radicals and disturbance of the antioxidant defense mechanisms. However, the EROD and AchE activities were not affected. Histopathology studies showed severe lesions. The oil is still bioavailable to biota, moreover, other pollution sources continue to affect the water in the Barigui River.     

Effects of metals and detergents on biotransformation and detoxification enzymes of leaping mullet (Liza saliens)

In this study, feral leaping mullet (Liza saliens) liver microsomal 7-ethoxyresorufin O-deethylase (EROD), and cytosolic glutathione S-transferases (GSTs) activities were investigated using 7-ethoxyresorufin, 1-chloro-2,4-dinitrobenzene (CDNB), and ethacrynic acid (EA) as substrates, respectively. The average EROD activity was found as 1139+/-175 pmol resorufin/min/mg protein. The average GST activities towards CDNB and EA were found as 1364+/-41 and 140+/-19 nmol/min/mg protein, respectively. We have, then, investigated the in vitro effects of some metals and detergents on CYP1A and GST activities in leaping mullet liver. Leaping mullet liver microsomal EROD activity was significantly inhibited by Hg (0.1 mM), Ni (0.1 mM), Cd (0.1 mM), Cu (0.1 mM), Zn (0.1 mM), Sb (0.1 mM), Fe2+ (1 mM), Co (1 mM), Al (1 mM), and Fe3+ (1 mM), with the percent inhibition of 80, 80, 77, 75, 70, 69, 56, 53, 46, and 44, respectively. Similarly, conjugation of CDNB catalyzed by GST was inhibited significantly to lesser extend by Hg (0.1mM), Sb (0.1 mM), Cd (0.1 mM), Cu (0.1 mM), Zn (0.1 mM), Fe3+ (1 mM), Co (1 mM), and Fe2+ (1 mM), with the percent inhibition of 70, 69, 65, 61, 54, 51, 47, and 43, respectively. The degrees of inhibition observed on GST catalyzed EA conjugation by Hg (0.1 mM), Cd (0.1 mM), Sb (0.1 mM), Cu (0.1 mM), and Zn (0.1 mM) were 86, 78, 69, 51, and 42, respectively. In addition to metals, the effect of various detergents on leaping mullet liver EROD, GST-CDNB, and GST-EA activities were studied. It was found that ionic detergents strongly inhibited the EROD activity, whereas much less inhibitions were observed with GST catalyzed activities. Therefore, the CYP1A inhibition potencies of metals and detergents suggest that their contribution to the overall CYP1A induction in polycyclic aromatic hydrocarbons contaminated environmental samples has to be taken into account for better interpretation of environmental studies.     

Interactions of 2,4,6-trinitrotoluene (TNT) with xenobiotic biotransformation system in European eel Anguilla anguilla (Linnaeus, 1758)

The aim of the present study was to investigate the interaction of 2,4,6-trinitrotoluene (TNT) with liver biotransformation enzymes in European eel Anguilla anguilla (Linnaeus, 1758). Eels were exposed to 0.5, 1 and 2.5 mg/l nominal concentrations of TNT for 6 and 24 h. Modulation of CYP1A1, UDPGT and GST genes was investigated by real-time PCR. Total CYP450 content, NADPH cytochrome c reductase activity, CYP1A and CYP2B-like activities, such as EROD, MROD and BROD, as well as GST and UDPGT activities, were measured by biochemical assays. An in vitro study was performed on EROD in order to evaluate catalytic modulation by TNT. No modulation of the CYP1A1 gene or protein was observed in TNT-exposed eels. On the other hand, a significant decline of EROD and MROD activities was observed in vivo. An increase in NADPH cyt c reductase, and phase II enzymes (UDPGT and GST) were observed at both gene expression and activity levels. The overall results indicated that TNT is a potential competitive inhibitor of CYP1A activities. A TNT metabolic pathway involving NADPH cyt c reductase and phase II enzymes is also suggested.     

Gender-related differences in mouse hepatic ethanol metabolism

The effect of an acute oral load of 2 g ethanol/kg body weight was studied in a group of male and female 10-wk-old C3H/HeNCrj (C3H/He) mice to investigate gender change throughout differences of the hepatic ethanol metabolism of mice. The following parameters were measured in the serum from 0 h to 3 h after the start of the experiment: ethanol, acetaldehyde, and acetate. Their concentrations in the serum in female mice tended to show lower levels than in male mice. In female mice, the concentration of ethanol at 1 h and the concentration of acetate at 1 h, 2 h, and 3 h after ethanol administration showed significantly lower levels than in male mice. Ten-week-old male and female C3H/He mice were subcutaneously injected 50 microg/kg body weight beta-estradiol and 1.45 mmol/kg body weight testosterone propionate (testosterone) in olive oil, respectively, and changes in the activity of enzymes related to the hepatic ethanol metabolism of mice were examined at 24 h after the administration of sex hormones. The activity of the cytosolic alcohol dehydrogenase (ADH) and microsomal aniline hydroxylase (ANH) and the low Km, high Km and total aldehyde dehydrogenase (AlDH) activities in the mitochondrial, the cytosolic, and the microsomal fraction of the liver were higher. Moreover, the density of the band of CYP2E1 in the microsome in female mice was stronger than in male mice, and in the microsomal fraction of the liver, the total content of cytochrome P-450 (CYP) and ethoxyresorufin O-dealkylase (EROD) activity in male mice showed significantly higher values than in female mice. The density of the band of CYP2E1 and the three activities of AlDH in the hepatic mitochondrial fraction of male mice increased significantly under treatment with beta-estradiol. The three activities of AlDH of the cytosolic fraction of the liver in female mice significantly decreased under treatment with testosterone. The present findings suggested that in C3H/He mice livers, the rate of ethanol metabolism is faster in females than in males, and the enzymes related to ethanol metabolism are controlled by testosterone or beta-estradiol. It is suggested that ethanol and its metabolite disappear faster from the serum of female mice than from the serum of male mice because the activities of hepatic enzymes related to ethanol metabolism are higher in female mice than in male mice. C3H/He mice, hepatic ethanol metabolism, gender different, ADH, AlDH     

The combined effects of garlic oil and fish oil on the hepatic antioxidant and drug-metabolizing enzymes of rats

This present study was designed to investigate the combined modulatory effect of garlic oil (GO) and fish oil (FO) on the antioxidant and drug metabolism systems. Rats were fed either a low-maize oil (MO) diet (50 g MO/kg), high-MO diet (235 g MO/kg) or high-FO diet (205 g FO+ 30 g MO/kg) and received different doses of GO (0-200 mg/kg body weight) three times per week for 6 weeks. Fatty acid analysis showed that 20 : 5n-3 and 22 : 6n-3 were incorporated into serum lipid at the expense of 18 : 2n-6 and 20 : 4n-6 in rats fed the high-FO diet. GO dose-dependently increased hepatic glutathione S-transferase (GST), glutathione reductase, superoxide dismutase (SOD) and ethoxyresorufin O-deethylase (EROD) activities, but decreased glutathione peroxidase and N-nitrosodimethylamine demethylase (NDMAD) activities (P<0.05). With the exception of glutathione peroxidase, the activities of glutathione reductase, SOD, GST, EROD and NDMAD were modulated by the dietary fat. The high-FO group had greater SOD and EROD activity than either MO-fed group; it also had greater NDMAD activity than the low-MO group (P<0.05). GST activity was higher in rats fed high-FO or high-MO diets than rats fed the low-MO diet. Change in erythromycin demethylase activity, however, was not caused by either dietary fat or GO. Immunoblot assay showed that GO dose-dependently enhanced the protein level of the Ya, Yb1, Yc isoenzymes of GST and cytochrome P450 (CYP) 1A1 and 3A1, but GO suppressed CYP2E1 expression. Regardless of the dosage of GO, the high-FO diet increased CYP1A1, CYP3A1 and CYP2E1 levels compared with the high- and low-MO diets. Accompanying the changes observed in immunoblots, CYP1A1 and CYP3A1 mRNA levels were increased by GO in a dose-dependent manner and also increased additively in combination with FO feeding. These present results indicate that co-administration of GO and FO modulates the antioxidant and drug-metabolizing capacity of animals and that the effect of GO and FO on drug-metabolizing enzymes is additive.