Observation of hepatotoxic effects of 2-n-pentylaminoacetamide (Milacemide) in rat liver by a combined in vivo/in vitro approach

Evaluation of chlorinated benz[a]anthracene on hepatic toxicity in rats and mutagenic activity in Salmonella typhimurium

Chlorinated benz[a]anthracenes (Cl-BaA) are halogenated aromatic compounds (typified by dioxins) found in the environment at relatively high concentrations. Fischer 344 rats were intragastrically administered 0, 1, or 10 mg of Cl-BaA or its parent compound benz[a]anthracene (BaA) per kg of body weight for 14 consecutive days. Both chemicals at 10 mg/kg/day inhibited the gain in body weight, and consequent increase in relative liver weight. Hepatic gene expression of cytochrome P450 (CYP) 1A1, 1A2, and 1B1 was significantly stimulated by administration of BaA (10 mg/kg/day) compared with the control. After administration of Cl-BaA, only the CYP1A2 gene was significantly induced, even at the lower dosage; CYP1A1 and 1B1 mRNA levels remained unchanged in Cl-BaA-treated rats compared with controls. To elucidate the role of such Cl-BaA exposure and induced CYPs at toxicity onset, we investigated the mutagenicity of BaA and Cl-BaA using Salmonella typhimurium TA98 and TA100. BaA and Cl-BaA at 10 μg/plate produced positive results in both strains in the presence of rat S-9. Incubation of Cl-BaA with recombinant rat CYP1A2 produced a significantly higher number of revertant colonies in TA98 and TA100 than in controls, but no such change was observed for BaA. In conclusion, BaA changes its own physiological and toxicological actions by its chlorination; (1) daily exposure to Cl-BaA selectively induces hepatic CYP1A2 in rats and (2) Cl-BaA induces frameshift mutations in the presence of CYP1A2, although BaA does not exert mutagenicity. This indicates that CYP1A2 may metabolize Cl-BaA to active forms.

Alterations in hepatic metabolism of adult male rats following exposure to hydroxyprogesterone during embryonic development

AIM

To investigate the effect of in utero exposure to hydroxyprogesterone (HP) on liver metabolism in adult male albino rats.

METHODS

Pregnant Wistar strain albino rats were exposed to supra-normal levels (10 mg/kg and 25 mg/kg) of HP on days 1, 7 and 14 of pregnancy. The male pups were maintained under controlled conditions and the rats were killed 90 days after birth. The liver tissue was immediately excised, weighed and used for biochemical assays.

RESULTS

The activity levels of succinate dehydrogenase (SDH), glutamate dehydrogenase (GDH), glucose-6-phosphate dehydrogenase (G-6-PDH), malate dehydrogenase (MDH) and aminotransaminases were significantly increased in the livers of rats exposed to HP during embryonic development. The lactate dehydrogenase (LDH) activity level was significantly decreased in the liver of experimental rats. Furthermore, there was a significant elevation of activity levels of antioxidant enzymes (glutathione S-transferase [GST] and catalase [CAT]) with an increased lipid peroxidation in the hepatic tissue of experimental rats compared with the control group.

CONCLUSION

The results of the present study suggest that there is an increase in the oxidative metabolism, antioxidative mechanism and levels of lipid peroxidation in rats exposed to HP during embryonic development. The increased aminotransaminase activities in these rats reveal tissue damage and disruption of mitochondrial integrity.