Stimulatory effects of benzene on rabbit liver and kidney microsomal cytochrome P-450 dependent drug metabolizing enzymes

Ameliorative Effects of Quercetin and Metformin and Their Combination Against Experimental Endometriosis in Rats

Endometriosis, as the leading cause of infertility, is attributed to oxidative stress, inflammation, and autophagy dysregulation. This study was conducted to evaluate the effect of quercetin and metformin, alone or in combination, on the ectopic and eutopic endometrial tissues in a rat model of endometriosis. We divided 60 female rats into 6 groups, including SH, Endo, Endo + Oil, Endo + Q, Endo + M, and Endo + Q + M. The last five groups underwent a surgery, so that we could induce endometriosis, and after 4 weeks, daily treatment began, lasting for a month. Subsequently, the size and histoarchitecture of the endometrial implants, serum levels of 17β-estradiol, progesterone and tumor necrosis factor (TNF)-α, and markers of oxidative stress and autophagy were assessed utilizing ELISA and gene expression analysis. Our results shed light to the fact that serum TNF-α and 17β-estradiol levels significantly increased in endometriosis rats. Moreover, NADPH: quinone oxidoreductase (NQO1) enzyme activity and gene expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and autophagy markers significantly decreased; meanwhile, mammalian target of rapamycin (mTOR) gene expression increased in the ectopic endometrial tissues, as compared with eutopic ones. Surprisingly, our results demonstrated that the treatment in which we applied the combination of quercetin and metformin significantly reversed these changes and had a pronounced effect on the endometrial implant size and gene expression levels of mTOR and autophagy markers in ectopic endometrium. The findings of the present study suggest that quercetin, metformin, and their combination were of potential therapeutic effects on the rat model of endometriosis.

The effect of co-administration of berberine, resveratrol, and glibenclamide on xenobiotic metabolizing enzyme activities in diabetic rat liver

It is possible to use plant-derived antioxidant molecules in the form of dietary supplements. However, dietary supplement-drug interaction pattern has not been well defined for most of these products. The aim of this study was to determine the effects of berberine, resveratrol, and glibenclamide on xenobiotic metabolizing enzyme activities in diabetic rats. Streptozotocin was administered to create experimental diabetes. Resveratrol (5 mg/kg) (R), glibenclamide (5 mg/kg) (G), and berberine (10 mg/kg) (B) were administered individually or in combinations in DMSO by intraperitoneal administration route to the diabetic rats. DMSO was also given to non-diabetic control (C) and diabetic control (D) groups. Livers of rats were taken under anesthesia at the end of the treatment period (12 days). Ethoxyresorufin O-deethylase (EROD), pentoxyresorufin O-depentylase (PROD), aniline 4-hydroxylase (A4H), erythromycin N-demethylase (ERND), glutathione S-transferase (GST), catalase (CAT), and glutathione reductase (GR) activities were measured in microsomes and cytosols. In addition, histomorphological studies were also performed in the liver tissues. EROD activity of D+R was significantly higher than C and D+R+B. PROD activity of D+R was significantly higher than C, D, D+R+G, D+R+B, and D+R+B+ G. PROD activity of D+B was significantly higher than C and D+R+B. ERND activity of D+R was significantly higher than D+R+G and D+R+B. GST activity of D+R was significantly higher than D+R+G. CAT activity of D+B was significantly lower than C. It is clear that co-administration of resveratrol, berberine, and glibenclamide modifies some of the important xenobiotic metabolizing enzyme activities. Resveratrol and berberine have the potential to cause dietary supplement-drug interaction.

Modulation of xenobiotic metabolizing enzyme activities in rat liver by co-administration of morin, endosulfan, and 7,12-dimethylbenz[a]anthracene

Morin is a flavonoid which is present in many plants. Endosulfan and 7,12-dimethylbenz[a]anthracene (DMBA) are toxic chemicals that humans are exposed to in their daily lives. In this study, the protective role of morin was investigated in endosulfan and DMBA treated rats. Eight groups, each comprising seven 2.5-month-old adult male Wistar rats (weighing 170-255 g), were used. Endosulfan, morin, and DMBA were administered individually or in combinations, at 5 mg/kg body weight (bw) (three times/week), 25 mg/kg bw (three times/week), and 30 mg/kg bw (once/week for three weeks) via oral gavage, respectively. On day 54 of the administration period, the rats were killed. DMBA + endosulfan co-administration significantly increased CYP1A1-, CYP1A2-, CYP2E-, and GST-associated activities in the rats compared to the control. DMBA + endosulfan + morin significantly increased CYP1A1, CYP1A2, CYP3A, and GST associated activities in the rats relative to the control. Histopathological studies were performed to investigate protective effects of morin on liver damage. The results indicated that DMBA + endosulfan treatment induced liver damage, and morin reduced this damage. These findings suggest that CYP1A, CYP3A, and GST enzyme activities participate in the protective mechanism of morin against endosulfan and DMBA induced toxicity.

Inhibitory action of Epilobium hirsutum extract and its constituent ellagic acid on drug-metabolizing enzymes

Epilobium hirsutum (EH) is a medicinal plant for treating various diseases. Despite its wide usage, there is no available information about its potential influences on drug metabolism. The present study was undertaken to determine the in vivo effects of EH on hepatic CYP2B, CYP2C, CYP2D, and CYP3A enzymes that are primarily involved in drug metabolism. Male Wistar rats were injected intraperitoneally with EH water extract (EHWE) and ellagic acid (EA) at a daily dose of 37.5 and 20 mg/kg, respectively, for 9 days and hepatic drug-metabolizing enzymes were assessed at activity, protein and mRNA levels. Erythromycin N-demethylase activity was inhibited by 53 and 21 % in EHWE- and EA-treated rats, respectively. Benzphetamine N-demethylase and 7-benzyloxyresorufin-O-debenzylase activities were decreased by 53 and 43 %, and 57 and 57 % in EHWE-and EA-treated rats, respectively. Moreover, protein levels of CYP2B1, CYP2C6, CYP2D2, and CYP3A1 also decreased by 55, 15, 33, and 82 % as a result of EHWE treatment of rats, respectively. Similarly, CYP2B1, CYP2C6, CYP2D2, and CYP3A1 protein levels decreased by 62, 63, 49, and 37 % with EA treatment, respectively. qRT-PCR analyses also showed that mRNA levels of these enzymes were significantly inhibited with bothEHWE and EA treatments. In conclusion, inhibition of drug clearances leading to drug toxicity because of the lowered activity and expression of drug-metabolizing enzymes might be observed in the people who used EH as complementary herbal remedy that might be contributed by its EA content.

ATSDR evaluation of health effects of benzene and relevance to public health

As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites that have the greatest public health impact. These profiles comprehensively summarize toxicological and environmental information. This article constitutes the release of portions of the Toxicological Profile for Benzene. The primary purpose of this article is to provide public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective on the toxicology of benzene. It contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health.

The effect of benzene on the activity of adenosine deaminase in tissues of rats

Swiss Albino (Rat rattus norvegicus) rats were intraperitoneally injected with a 100 mg kg(-1) dosage of benzene, a toxic and carcinogenic agent widely used for industrial purposes. Changes in the adenosine deaminase (ADA) activity in the liver, kidney and serum of rats were investigated at 0, 2, 4, 8, 16, 32 and 64 h following injection. Serum physiological was administered to each control group. Enzyme activities were measured spectrophotometrically. Our purpose was to further investigations of some diseases caused by benzene, and present evidence of variations in the activity of ADA enzyme effected by benzene. While benzene caused significant inhibitions in ADA activity in the liver at 16 and 32 h and at 0.05 probability level, no significant inhibition or activation occurred at other test periods (hours). ADA activity did not present any significant variation in the kidneys. It was observed that ADA activity displayed similar patterns in the control groups. Comparisons of ADA activities in the two groups showed a statistically significant decrease between 4(th) and 64(th) hours (p< 0.05), demonstrating a direct correlation between benzene and its effects on ADA enzymes.

Effects of diabetes on rabbit kidney and lung CYP2E1 and CYP2B4 expression and drug metabolism and potentiation of carcinogenic activity of N-nitrosodimethylamine in kidney and lung

There are limited number of studies regarding the influence of diabetes on the regulation of cytochrome P450s and associated drug metabolizing enzyme activities especially in extrahepatic tissues such as kidney. However, there is almost no such study in lung. Alloxan-induced diabetes did not change CYP2B4 expression as measured with immunoblot analysis and associated enzyme, benzphetamine N-demethylase, activity in rabbit kidney and lung. Induction of cytochrome P4502E1 by diabetes was identified by immunochemical detection on Western blots in the lung and kidney microsomes of rabbits. In parallel to CYP2E1 induction, aniline 4-hydroxylase and p-nitrophenol hydroxylase activities were markedly increased in diabetic rabbit lung and kidney. CYP2B4 and CYP2E1 dependent drug metabolism did not show any tissue variation in diabetic rabbit. These findings are in contrast to those of rats, mice and hamster. The results of the present work, in combination with those of the previous work [Arinç, E., Arslan, S., Adali, O., 2005. Differential effects of diabetes on CYP2E1 and CYP2B4 proteins and associated drug metabolizing enzyme activities in rabbit liver. Arch. Toxicol. 79, 427-433], indicate the existence of species-dependent response of CYP-dependent drug metabolizing enzymes to diabetes. A procarcinogen and food contaminant, N-nitrosodimethylamine (NDMA), is converted to its carcinogenic form after it is activated with NDMA N-demethylase. In the current study, a statistically significant increase of liver, kidney and lung NDMA N-demethylase activity associated with CYP2E1 was shown in diabetic rabbit. Thus, it is expected that, the risk of nitrosamine induced carcinogenesis will be greater in liver, kidney and lung of the diabetic subjects.

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.

The effect of retinol on hepatic and renal drug-metabolising enzymes

Retinol pretreatment (75 mg/kg/day, 4 days) potentiated paracetamol-induced hepatotoxicity in BALB/c mice (alanine aminotransferase (ALT) activity; 2510+/-602 vs 1155+/-282 IU/l; retinol+paracetamol vs corn oil+paracetamol, respectively, P<0.05); however, this potentiation did not occur in the kidney, indicating an organ-specific response. Retinol treatment alone was not toxic in either organ, as indicated by ALT activity, blood urea nitrogen and creatinine. The potentiation effect could be mediated by retinol's induction of CYP450 isoforms relevant to paracetamol metabolism or through depletion of glutathione. Therefore, these parameters were investigated in both organs. Following retinol treatment, renal CYP2E1 and hepatic CYP1A2 and CYP2E1 catalytic activities and polypeptide levels were unchanged. However, retinol significantly decreased both the catalytic activity (0.23+/-0.03 vs 0.53+/-0.06 nmol/mg/min; retinol vs untreated, respectively, P<0.05) and polypeptide levels (58+/-0.6% of control) of hepatic CYP3A. Inhibition of renal CYP3A did not occur as catalytic activity and polypeptide levels were unchanged from control. Following retinol treatment, total reduced glutathione levels, in both organs, were not significantly different from control. Therefore, the potentiation of paracetamol-induced hepatotoxicity is independent of CYP450 and glutathione.

Species comparison of hepatic and pulmonary metabolism of benzene

Benzene is an occupational hazard and environmental toxicant found in cigarette smoke, gasoline, and the chemical industry. The major health concern associated with benzene exposure is leukemia. Studies using microsomal preparations from human, mouse, rabbit, and rat to determine species differences in the metabolism of benzene to phenol, hydroquinone and catechol, indicate that the rat is most similar, both quantitatively and qualitatively, to the human in pulmonary microsomal metabolism of benzene. With hepatic microsomes, rat is most similar to human in metabolite formation at the two lower concentrations examined (24 and 200 microM), while at the two higher concentrations (700 and 1000 microM) mouse is most similar in phenol formation. In all species, the enzyme system responsible for benzene metabolism approached saturation in hepatic microsomes but not in pulmonary microsomes. In pulmonary microsomes from mouse, rat, and human, phenol appeared to competitively inhibit benzene metabolism resulting in a greater proportion of phenol being converted to hydroquinone when the benzene concentration increased. The opposite effect was seen in hepatic microsomes. These findings support the hypothesis that the lung plays an important role in benzene metabolism, and therefore, toxicity.

Age-dependent changes in rat liver microsomal membrane structure and functions under benzene treatment

The influence of benzene on 3 and 24 months old rat liver microsomes was studied. Some structural and functional changes occur under benzene treatment in the cytochrome P-450 system which are more pronounced in 3 months old rat microsomes than in the 24 months ones. Glucose-6-phosphatase and glucose dehydrogenase activities indicate that 3 months old rat microsomal vesicles are more stable against benzene injury than those, of 24 months old ones. In vitro benzene hydroxylation activation by NADPH addition decreased disruptive xenobiotic's effect on 3 but not on 24 months old rat liver microsomal vesicles. This fact suggests that the rate of benzene hydroxylation is important for its membrane damaging action effect. Thus, age-related differences in xenobiotic action on liver microsomes could be related to the decrease of benzene metabolism rate with senescence.

Immunochemical and sub-structural characterization of sheep lung cytochrome P450LgM2

Sheep lung cytochrome P450LgM2 belonging to gene subfamily 2B, was obtained in highly purified form and antibodies against sheep lung cytochrome P450LgM2 were produced in rabbits by using the previously developed methods in our laboratory. Immunological and enzymatic studies showed that antibodies against lung cytochrome P450LgM2 inhibited benzphetamine N-demethylation, ethylmorphine N-demethylation and aniline 4-hydroxylation reactions in sheep lung microsomes about 99, 80 and 62%, respectively. Benzphetamine N-demethylation reaction in sheep lung microsomes was only catalyzed by cytochrome P450LgM2 isozyme while the other isozymes of P450 as well as P450LgM2 are also involved in the metabolism of ethylmorphine and aniline. Similar to lung microsomes, benzphetamine N-demethylase activity of the reconstituted systems containing purified sheep lung cytochrome P450LgM2 or phenobarbital (PB)-treated rabbit liver cytochrome P450LM2(2B4) was also inhibited by P450LgM2 antibodies about 95 and 82%, respectively. A 50% inhibitory effect of sheep P450LgM2 antibodies was also observed in ethylmorphine N-demethylase activity of the reconstituted system containing purified sheep lung cytochrome P450LgM2. SDS-PAGE peptide maps obtained following the partial proteolysis of purified sheep lung cytochrome P450LgM2 and PB-rabbit liver P450LM2(2B4) isozymes, using chymotrypsin and papain, were similar in general. However they showed some differences both qualitatively and quantitatively, suggesting that some differences exist among the amino acid sequences of sheep lung cytochrome P450LgM2 and rabbit liver cytochrome P4502B4.

In vivo effects of the anesthetic, benzocaine, on liver microsomal cytochrome P450 and mixed-function oxidase activities of gilthead seabream (Sparus aurata)

Gilthead seabreams were exposed to benzocaine, 4-aminobenzoic acid ethyl ester, 57 mg/l in sea water for 3 min, daily, for 2 or 3 consecutive days. The fish were killed 20 hr after the last treatment. Benzocaine treatment for 2 or 3 days resulted in 57% and 67% inhibition of liver microsomal aniline 4-hydroxylase and ethylmorphine N-demethylase activities, respectively. The total cytochrome P450 content of fish liver microsomes was unaltered following the 2-day benzocaine treatment. However, additional 3 min benzocaine treatment on day 3 reduced cytochrome P450 level by 50%. Benzocaine produced type II difference spectra with rabbit liver microsomes. Difference spectra of fish liver microsomes elicited by benzocaine were complex. The position of peak and intensity were greatly influenced by the concentration of benzocaine.

Effects of in vivo benzo(a)pyrene treatment on liver microsomal mixed-function oxidase activities of gilthead seabream (Sparus aurata)

Benzo(a)pyrene [B(a)P] treatment of gilthead seabream, 25 mg/kg, i.p. for 5 consecutive days, did not cause any significant changes in ethylmorphine N-demethylase and aniline 4-hydroxylase activities of liver microsomes. The same treatment did not alter the liver microsomal cytochrome b5 content, NADH-cytochrome b5 reductase and NADPH-cytochrome P450 reductase activities. However, benzo(a)pyrene treatment caused a 2-3-fold increase in 7-ethoxyresorufin O-deethylase (7-EROD) activity of gilthead seabream liver microsomes. Although, upon treatment, total cytochrome P450 content of liver microsomes increased about 1.7-fold in 1990 fall, no such increase was observed in spring 1991. However, a new cytochrome P450 with an apparent M(r) of 58,000 was observed on SDS-PAGE of liver microsomes obtained from benzo(a)pyrene treated gilthead seabream. Besides, in vitro addition of 0.2 x 10(-6) M benzo(a)pyrene to the incubation mixture inhibited 7-ethoxyresorufin O-deethylase activity by 93%. Gilthead seabream liver microsomal 4-ethoxyresorufin O-deethylase activity was characterized with respect to substrate concentration, amount of enzyme, type of buffer used, incubation period and temperature.