Preventive effects of quercetin against benzo[a]pyrene-induced DNA damages and pulmonary precancerous pathologic changes in mice.

The aim of this study was to investigate the preventive effects of quercetin against benzo[a]pyrene-induced blood lymphocyte DNA damages and pulmonary precancerous pathologic changes in mice, and to reveal the potential mechanism behind these effects. In this study, mice in quercetin-treated groups were given quercetin for 90 days. After one week of treatment, mice in the quercetin-treated groups and the positive control group received a single intraperitoneal dose of benzo[a]pyrene (100 mg/kg body weight). The results of single cell gel electrophoresis assay showed that the average lengths of the comet cell tail and DNA damage in the peripheral blood lymphocytes of mice induced by benzo[a]pyrene decreased significantly as a result of quercetin treatment dose-dependently. Light microscopic examination showed that the degrees of pulmonary precancerous pathologic changes in the quercetin-treated groups decreased significantly compared with those in the positive control group. Meanwhile, the cytochrome P4501A1-linked 7-ethoxyresorufin O-dealkylase activities in lung microsomes of mice decreased as the dose of quercetin increased. The results of this in vivo study revealed that quercetin had a significant preventive effect on benzo[a]pyrene-induced DNA damage, and had a potential chemopreventive effect on the carcinogenesis of lung cancer induced by benzo[a]pyrene. The mechanism of these effects of quercetin could be related to the inhibition of cytochrome P4501A1 activity.

[Effects of fenvalerate on reproductive and endocrine systems of male rats].

OBJECTIVES: To evaluate the impairment of fenvalerate on reproductive and endocrine systems and clarify the mechanism of action. METHODS: Different doses of fenvalerate (0, 2, 4, 12, 60 mg/kg) were orally treated to the adult male SD rats for 15 days and 30 days, respectively. The levels of serum follicle stimulating hormone(FSH), luteinizing hormone (LH), testosterone(T) and testis homogenate T were determined by radioimmunoassay(RIA). Besides, the activity of testicular marked enzymes such as acid phosphatases(ACP) and gamma-glutamyl transpeptidase(gamma-GT) were examined, and sperm head counts were measured to explain the changes of daily sperm production(Spr). RESULTS: In fifteen days, serum FSH levels markedly increased in rats exposed to fenvalerate of < or = 12 mg/kg groups(P < 0.01) and serum levels of LH increased in 12 mg/kg group(P < 0.01). In addition, T levels in testis homogenates decreased after treated with the doses of > or = 12 mg/kg groups compared with the control group(P < 0.01). In thirty days, serum contents of FSH were significantly elevated in the doses of > or = 12 mg/kg groups(P < 0.01) and homogenate levels of T were diminished in the low dose group(2.4 mg/kg) (P < 0.05). Activity of ACP increased in 12 mg/kg group after fifteen days(P < 0.05) and was restrained in the high dose group(60 mg/kg) in thirty days(P < 0.05), but the contents of gamma-GT were arrested with different doses dependently in the testis(P < 0.05). Fenvalerate caused dose-dependent reduction in sperm head counts and daily sperm production, which markedly reduced at the doses of > or = 12 mg/kg groups(P < 0.01). CONCLUSIONS: Fenvalerate has obvious reproductive toxicity on male rats and can change their serum and testis homogenate levels of sex hormone or activity of testicular marked enzymes, which may be correlated with the impairment of Sertoli cell and spermatogenic epithelium.