Aflatoxin B1-induced changes of glutathione-S-transferase activity in the plasma and liver of the rat

Physiologically based toxicokinetics of serum aflatoxin B1-lysine adduct in F344 rats

Aflatoxin B(1)-lysine adduct (AFB-Lys) is a reliable biomarker for aflatoxin exposure; however, a systematic toxicokinetic evaluation has not been reported. In this study, male F344 rats were orally exposed to single, or repeated, doses of AFB(1) and the toxicokinetics of serum AFB-Lys that followed treatments were investigated. A single-dose of AFB(1) increased serum AFB-Lys levels rapidly peaking at 4h, followed by first-order elimination, through which the half-life was estimated to be 2.31 days. A physiologically based pharmacokinetic model showed that approximately 3.00-3.90% and 1.12-1.98% of the administered AFB(1) doses were converted to serum AFB-Lys adducts at 2h and 24h post treatment, respectively. Repeated AFB(1) exposure at 5-25 μg/kg body weight linearly increased serum AFB-Lys levels for 5 weeks in animals, resulting in a 1-1.5 times higher AFB-Lys level overall. This indicates the potential of this adduct as a reliable biomarker for repeated low dose exposure. Higher dose exposure at 75 μg/kg increased the level of AFB-Lys to a maximum at 2 weeks, followed by a gradual decrease to near plateau level up to 5 weeks. In conclusion, this study systematically evaluated the toxicokinetics of serum AFB-Lys adduct in F344 rats using a physiologically based pharmacokinetic model and robust statistical modeling analysis and provided a firm and clear understanding of the toxicokinetics of this biomarker.

Influence of aflatoxin B1 on mRNA levels of acute-phase proteins and oncoproteins in albino rat liver

Background: The effect of aflatoxin B1 (AFB1) administration on expression of genes coding for acute-phase proteins, and nuclear protooncogenes c-fos and c-jun, and alpha-fetoprotein gene has been studied in rats. Methods: AFB1 was administered to male Albino Oxford (AO) rats as a single intraperitoneal dose (1 mg/kg body weight). The expression of genes for albumin, cystein protease inhibitor, fibrinogen, haptoglobin, a1-acid glycoprotein and for c-Fos, c-Jun and alpha-fetoprotein in rat liver was measured by Northern hybridization. Results: The mild increase in the levels of mRNA for acute-phase proteins after AFB1 administration was observed during the first 24 hours. The exceptions were the mRNA levels in liver for cystein protease inhibitor, which were 50%, decreased as compared to the control values. In addition, mild increase of the expression of c-fos protooncogene with two peaks were noted at three (1.3 fold) and 72 hours (1.5 fold) after injection AFB1 to rats. The expression of nuclear protooncogene c-jun at 1 hour and 72 hour after acute poisoning was 2.6 fold and 3.7 fold increased as compared to control values, respectively. The mRNA levels in liver for the alpha-fetoprotein reached a maximum at 1 hour after AFB1 injection and it was 1.8 times higher than the levels in the livers of nontreated animals. Conclusion: Single administration of AFB1 induced increased transcription of c-jun and c-fos genes while typical acute-phase response was not found.

Phytic Acid Exposure Alters AflatoxinB1-induced Reproductive and Oxidative Toxicity in Albino Rats (Rattus norvegicus)

The increased use of feed in Egypt's aquaculture and animal industries raises concerns about the possible presence of mycotoxins in feedstuffs. The use of alternative medicine, such as botanicals and nutritional supplements, has become popular with inflammatory cases. The present study aimed to testify the role played by phytic acid (IP6) in enhancing the reproductive and oxidative toxicity induced in aflatoxinB1 (AFB1) treated white male albino rats (Rattus norvegicus) throughout treatment and withdrawal periods. One hundred and twenty white male albino rats were grouped into four groups. Group 1, was injected with 300 μg kg⁻¹ body wt of AFB1 once every 3 days for 15 days and left uninjected for another 15 days to study the withdrawal effect. Group 2, was injected with 300 μg kg⁻¹ body wt of AFB1 once every 3 days for 15 days and treated simultaneously with IP6 daily for another 15 days. Group 3, was treated daily with IP6 (40 mg kg⁻¹ body wt) for 15 days and with no treatment for other 15 days. Group 4, injected with equivalent volume of sterile phosphate buffer saline solution as a control group. Sera were taken at the experimental intervals and assayed for testosterone hormone, follicular-stimulating hormone (FSH) and luteinizing hormone (LH) to determine the toxicological impact of AFB1 and the possibility of amelioration by phytic acid on the reproductive performance of the studied animal. The effects of AFB1 treatment on the absolute and relative weight of testis as well as its histopathologic effect on the testis and the possibility of amelioration by IP6 treatment were evaluated. The activities of enzymatic and non-enzymatic anti-oxidants, in addition to lipid peroxidation were measured in the testis’ homogenate of AFB1-treated rats. A decrease in sex hormone levels, an increase in testicular lipid peroxidation product levels and a significant decrease in testicular glutathione content, catalase and total peroxidase and superoxide dismutase activities were recorded. The histopathologic alterations revealed a degeneration and highly mitotic division within the spermatogenic nuclei, in addition to some karyomegaly and nuclear pyknosis. It is concluded that the reduction in the toxicity of free radicals by phytic acid might be responsible for the protective influence observed.