ABSTRACT:Several cytochrome P450 (P450) enzymes have been identified in the heart, and their levels have been reported to be altered during cardiac hypertrophy. Moreover, there is a strong correlation between P450-mediated arachidonic acid metabolites and the pathogenesis of cardiac hypertrophy. Therefore, we investigated the effect of isoproterenol-induced cardiac hypertrophy on the expression of several P450 genes and their associated P450-derived metabolites of arachidonic acid. Cardiac hypertrophy was induced by seven daily i.p. injections of 5 mg/kg isoproterenol. Thereafter, the heart, lung, liver, and kidney were harvested, and the expression of different genes was determined by real-time polymerase chain reaction. Heart microsomal protein from control or isoproterenol treated rats was incubated with 50 M arachidonic acid, and arachidonic acid metabolites were determined by liquid chromatography-electron spray ionization-mass spectrometry. Our results show that isoproterenol treatment significantly increased the heart/body weight ratio and the hypertrophic markers. In addition, there was a significant induction of CYP1A1, CYP1B1, CYP4A3, and soluble epoxide hydrolase and a significant inhibition of CYP2C11 and CYP2E1 in the hypertrophied hearts as compared with the control. CYP1A1, CYP2E1, and CYP4A3 gene expression was induced in the kidney, and CYP4A3 was induced in the liver of isoproterenol-treated rats. Isoproterenol treatment significantly reduced 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acid formation and significantly increased their corresponding 8,9-, and 14,15-dihydroxyeicosatrienoic acid and the 20-hydroxyeicosatetraenoic acid metabolite. In conclusion, isoproterenol-induced cardiac hypertrophy alters arachidonic acid metabolism and its associated P450 enzymes, suggesting their role in the development and/or progression of cardiac hypertrophy.

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ABSTRACT:The use of doxorubicin (DOX) is limited by significant cardiotoxicity, nephrotoxicity, and hepatotoxicity. We have previously shown that DOX cardiotoxicity induces several cardiac cytochrome P450 (P450) enzymes with subsequent alteration in P450-mediated arachidonic acid metabolism. Therefore, in the current study, we investigated the effect of acute DOX toxicity on P450 expression and arachidonic acid metabolism in the kidney and liver of male Sprague-Dawley rats. Acute DOX toxicity was induced by a single intraperitoneal injection (15 mg/kg) of the drug. After 6 and 24 h, the kidneys and livers were harvested, and several P450 gene and protein expressions were determined by real-time polymerase chain reaction and Western blot analyses, respectively. Kidney and liver microsomal protein from control or DOX-treated rats was incubated with arachidonic acid, and its metabolites were determined by liquid chromatography-electron spray ionization-mass spectrometry. Our results showed that acute DOX toxicity caused an induction of CYP1B1 and CYP4A enzymes and an inhibition of CYP2B1 and CYP2C11 in both the kidney and liver. CYP2E1 was induced and soluble epoxide hydrolase (sEH) was inhibited in the kidney only. In addition, DOX toxicity caused a significant increase in epoxyeicosatrienoic acids formation in the kidney and a significant increase in 20-hydroxyeicosatetraenoic acid formation in both the kidney and the liver. In conclusion, acute DOX toxicity alters the expression of several P450 and sEH enzymes in an organ-specific manner. These changes can be attributed to DOXinduced inflammation and resulted in altered P450-mediated arachidonic acid metabolism.

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Background and purpose:There is a strong correlation between cytochrome P450 (P450)-dependent arachidonic acid metabolism and the pathogenesis of cardiac hypertrophy. Several aryl hydrocarbon receptor (AhR) ligands were found to alter P450-dependent arachidonic acid metabolism. Here, we have investigated the effect of 3-methylcholanthrene (3-MC) and benzo(a)pyrene (BaP), two AhR ligands, on the development of cardiac hypertrophy. Experimental approach: Male Sprague Dawley rats were injected (i.p.) daily with either 3-MC (10 mg·kg ) for 7 days. Then hearts were removed, and the heart to body weight ratio and the gene expression of the hypertrophic markers and P450 genes were determined. Levels of arachidonic acid metabolites were determined by liquid chromatography-electron spray ionization-mass spectrometry. Key results: Both 3-MC and BaP increased the heart to body weight ratio as well as the hypertrophic markers, atrial natriuretic peptide and brain natriuretic peptide. 3-MC and BaP treatment increased the gene expression of CYP1A1, CYP1B1, CYP2E1, CYP4F4, CYP4F5 and soluble epoxide hydrolase. Both 3-MC and BaP treatments increased the dihydroxyeicosatrienoic acids (DHETs) : epoxyeicosatrienoic acids (EETs) ratio and the 20-hydroxyeicosatetraenoic acid (20-HETE) : total EETs ratio. Treatment with benzo(e)pyrene, an isomer of BaP that is a poor ligand for the AhR, did not induce cardiac hypertrophy in rats, confirming the role of AhR in the development of cardiac hypertrophy. Treatment with the w-hydroxylase inhibitor, HET0016, significantly reversed BaP-induced cardiac hypertrophy. Conclusions and implications: 3-MC and BaP induce cardiac hypertrophy by increasing the ratio of DHETs : EETs and/or the ratio of 20-HETE : total EETs, through increasing soluble epoxide hydrolase activity.

Abstract. Cytochrome P450 (P450)-derived arachidonic acid (AA) metabolites serve pivotal physiological roles. Therefore, it is important to determine the dominant P450 AA monooxygenases in different organs. We investigated the P450 AA monooxygenases protein expression as well as regioselectivity, immunoinhibition, and kinetic profile of AA epoxygenation and hydroxylation in rat heart, lung, kidney, and liver. Thereafter, the predominant P450 epoxygenases and P450 hydroxylases in these organs were characterized. Microsomes from heart, lung, kidney, and liver were incubated with AA. The protein expression of CYP2B1/2, CYP2C11, CYP2C23, CYP2J3, CYP4A1/2/3, and CYP4Fs in the heart, lung, kidney, and liver were determined by Western blot analysis. The levels of AA metabolites were determined by liquid chromatography-electrospray ionization mass spectroscopy. This was followed by determination of regioselectivity, immunoinhibition effect, and the kinetic profile of AA metabolism. AA was metabolized to epoxyeicosatrienoic acids and 19-and 20-hydroxyeicosatetraenoic acid in the heart, lung, kidney, and liver but with varying metabolic activities and regioselectivity. Anti-P450 antibodies were found to differentially inhibit AA epoxygenation and hydroxylation in these organs. Our data suggest that the predominant epoxygenases are CYP2C11, CYP2B1, CYP2C23, and CYP2C11/CYP2C23 for the heart, lung, kidney, and liver, respectively. On the other hand, CYP4A1 is the major ω-hydroxylase in the heart and kidney; whereas CYP4A2 and/or CYP4F1/4 are probably the major hydroxlases in the lung and liver. These results provide important insights into the activities of P450 epoxygenases and P450 hydroxylases-mediated AA metabolism in different organs and their associated P450 protein levels.

Context: Cajanus cajan L. (Fabaceae), a food crop, is widely used in traditional medicine. Objectives: The phytochemical composition of C. cajan seeds and evaluation of the antiinflammatory, immunomodulatory, antinociceptive, and antioxidant activities were studied. Materials and methods: Unsaponifiable matter and fatty acids were analyzed by GC and GC/MS. The n-butanol fraction was chromatographed on polyamide column. The anti-inflammatory activity of hexane extract (200 and 400 mg/kg, p.o.) was evaluated using the carrageenan-induced rat paw edema at 1, 2, and 3 h. The serum tumor necrosis factor-a, interleukin-6, and immunoglobulin G levels were detected by ELISA. The hexane extract antinociceptive activity was determined by adopting the writhing test in mice. DPPH radical scavenging, total reduction capability, and inhibition of lipid peroxidation of butanol fraction were evaluated. Results and conclusion: Twenty-one unsaponifiable compounds (mainly phytol, 2,6-di-(t-butyl)-4-hydroxy-4-methyl-2,5-cyclohexadiene-1-one, b-sitosterol, stigmasterol, and campesterol), as well as 12 fatty acids (primarily 9,12-octadecadienoic and palmitic acids) were identified in hexane extract of C. cajan seeds. n-BuOH fraction contains quercetin-3-O-b-D-glucopyranoside, orientin, vitexin, quercetin, luteolin, apigenin, and isorhamnetin. For the first time, quercetin-3-O-b-D-glucopyranoside is isolated from C. cajan plant. The hexane extract (200 and 400 mg/kg) inhibited carrageenaninduced inflammation by 85 and 95%, respectively, 3 h post-carrageenan challenge. This was accompanied by an 11 and 20%, 8 and 13%, respectively, decrease of TNF-a and IL-6, as well as significant decrease in IgG serum levels. Moreover, hexane extract (200 and 400 mg/kg) decreased the number of writhings by 61 and 83%, respectively. The butanol fraction showed DPPH radical scavenging (inhibitory concentration (IC 50 ) value: 9.07 mg/ml). ARTICLE HISTORY

We recently demonstrated that benzo(a)pyrene (BaP) causes cardiac hypertrophy by altering arachidonic acid metabolism through the induction of the expression of CYP ω-hydroxylases and soluble epoxide hydrolase (sEH) enzymes. The inhibition of CYP ω-hydroxylase enzymes partially reversed the BaP-induced cardiac hypertrophy. Therefore, it is important to examine whether the inhibition of sEH also confers cardioprotection. For this purpose, male Sprague-Dawley rats were injected intraperitoneally daily with either the sEH inhibitor 1-(1-methanesulfonyl-piperidin-4-yl)-3-(4-trifluoromethoxy-phenyl)-urea (TUPS; 0.65 mg/kg), BaP (20 mg/kg), or the combination of BaP (20 mg/kg) and TUPS (0.65 mg/kg) for 7 days. Thereafter, the heart, liver, and kidney were harvested, and the heart to body weight ratio was measured. The expression of the hypertrophic markers, sEH, heme oxygenase-1, and CYP450 enzymes was determined. Our results demonstrate that BaP alone significantly induced the expression of sEH and CYP ω-hydroxylases in the heart, liver, and kidney tissues. Treatment with TUPS significantly reversed the BaP-mediated induction of the hypertrophic markers, completely prevented the increase in the heart to body weight ratio, and reduced the BaP-induced CYP1A1, CYP1B1, CYP4F4, and CYP4F5 genes in the heart. The current study demonstrates the cardioprotective effect of sEH inhibitor, TUPS, against BaP-induced cardiac hypertrophy and further confirms the role of sEH and CYP450 enzymes in the development of cardiac hypertrophy.