Inhibition of soluble epoxide hydrolase confers cardioprotection and prevents cardiac cytochrome P450 induction by benzo(a)pyrene.

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.