Resveratrol, a natural aryl hydrocarbon receptor antagonist, protects sperm from DNA damage and apoptosis caused by benzo(a)pyrene

Benzo(a)pyrene (BaP), an aryl hydrocarbon receptor (AhR) ligand present in cigarette smoke and car exhaust, is thought to have negative effects on mat e reproduction. We hypothesized that Bal? damages sperm through AhR activat ion, phase I enzyme induction, DNA adduct formation, and increased germ cel l apoptosis in the testis, and that resveratrol. a natural competitive inhi bitor of the AhR found in some red wines, could prevent the adverse effects of Bal? on sperm. Male Balb C mice were injected subcutaneously (s.c.) for 5 weeks with a range of Bal? doses (0.5 mg/kg to 50 mg/kg). Live sperm wer e obtained from the vas deferens, counted, and stained to measure annexin-V positive (apoptotic) cells. In a subsequent study, mice were injected for 5 weeks with corn oil (control), BaP (5 mg/kg/week), or BaP plus resveratro l (50 mg/kg/week) (n = 3 per group). Immunohistochemistry (IHC) was perform ed on testis sections for the determination of CYP1A1. BaP diol epoxide (BP DE) DNA adducts, and apoptosis and the results quantified by using the HSCO RE. a semiquantitative scoring system. Our results demonstrated that sperm counts after 5 weeks were inversely correlated to BaP dosage. BaP (0.5 to 5 mg/week) positively correlated with sperm apoptosis while higher doses inc reased sperm necrosis. CYP1A1 protein was observed mainly in interstitial c ells of some testis sections, but there was no significant induction by BaP . BPDE DNA adducts were induced in all components of the seminiferous tubul es by BaP and suppressed by resveratrol: median HSCORE (interquartile range ) control 61 (52-71.5); BaP 213 (192-248), P = 0.01 compared to control; Ba P plus resveratrol 83 (70-90). BaP significantly increased apoptosis, mainl y in spermatogonia: medain HSCORE (interquartile range) BaP 189 (161-223) v ersus control 83 (57-93), P < 0.01: and this effect was abrogated by resver atrol. Median HSCORE for BaP plus resveratrol was 112 (range 99-121). In su mmary, BaP caused increased sperm cell BPDE DNA adduct formation and apopto sis in the mouse. The natural AhR antagonist, resveratrol diminished BaP-in duced DNA adducts and apoptosis in seminiferous tubules. (C) 2001 Elsevier Science Inc. All rights reserved.