OBJECTIVETo investigate the susceptibility to carbon tetrachloride and benzene in offspring of expanded simple tandem repeats (ESTR) mutation mice exposed to formaldehyde (FA).

METHODSF5 and F10 offspring (200 mg/m3 x 2 hours) served as H group and ICR mice were used as control group (group C). The F5 and F10 offspring were exposed to 10 ml/kg carbon tetrachloride at the doses of 0.05%, 0.50% or 5.00% for 24 hours, respectively or 500 or 1000 mg/kg benzene for 24 hours, respectively by intraperitoneal injection. Serum alanine transaminase (ALT), aspartate transaminase (AST) and the hepatic superoxide dismutase (SOD) or malondialdehyde (MDA) were detected; also the hepatic pathological changes were observed under light microscope; the micronucleus in sternum bone marrow cells as the biomarker of benzene blood toxicity were measured.

RESULTSALT and AST activities in group C of F5 mice exposed to 0.50% and 5.00% CCl4, ALT in groups C and H of F10 mice exposed to 0.05%, 0.50%, 5.00% CCl4, AST in groups C and H of F10 mice exposed to 0.50% and 5.00% CCl4 were significantly higher than those in controls, respectively (P<0.05); as compared to the control, hepatic SOD activities in group C of F5 and F10 mice exposed to 0.50% and 5.00% CCl4, in group H of F5 mice exposed to 0.50% and 5.00% CCl4 and F10 mice exposed to 5.00% CCl4 were significantly reduced, respectively (P<0.05); however, MDA contents in group C of F10 mice exposed to 0.50% and 5.00% CCl4, in group H of F5 mice exposed to 0.05% and 0.50%, 5.00% CCl4 and F10 mice exposed to 0.50% and 5.00% CCl4 were significantly increased than those in control group, respectively (P<0.05). The susceptibility to CCl4 in ESTR mutation F5 mice exposed to FA was significantly higher than that in control F5 mice, but the susceptibility to CCl4 in ESTR mutation F10 mice exposed to FA was significantly lower than that in control F10 mice. The histopathological examination showed that the injury of hepatocytes in C and H groups significantly increased CCl4 doses, and the injury of hepatocytes in H group was higher than that in C group. The micronuclear rates in C and H group mice exposed to benzene(500 mg/kg C group, F5 and F10 mice; 1000 mg/kg C group, F5 and F10 mice; 500 mg/kg H group, F5 and F10 mice; 1000 mg/kg C group, F5 and F10 mice) were 5.88 per thousand +/- 4.55 per thousand, 8.25 per thousand +/- 2.06 per thousand, 7.50 per thousand +/- 6.99 per thousand, 10.67 per thousand +/- 1.16 per thousand, 7.88 per thousand +/- 3.09 per thousand, 9.20 per thousand +/- 1.30 per thousand, 9.63 per thousand +/- 4.34 per thousand and 13.33 per thousand +/- 2.08 per thousand, respectively, which were significantly higher than those (1.13 per thousand +/- 0.35 per thousand, 1.20 per thousand +/- 0.82 per thousand, 1.25 per thousand +/- 0.46 per thousand, 1.33 per thousand +/- 1.03 per thousand) in the solvent control group (P<0.05 or P<0.01).

CONCLUSIONFA could result in the change of susceptibility to CCl4 and benzene in offspring of ESTR mutation mice. ESTR mutation may be a biomarker of the susceptibility to chemicals, but the molecular mechanisms should be investigated in the future.