Related Experiment Video
Updated: Dec 29, 2025
Transgenic Rodent Assay for Quantifying Male Germ Cell Mutant Frequency
Published on: August 6, 2014
Mutant Frequency is not Increased in Mice Orally Exposed to Sodium Dichromate
Yasunobu Aoki1, Michiyo Matsumoto1, Michi Matsumoto1
1National Institute for Environmental Studies, Center for Health and Environmental Risk Research, Tsukuba, Japan.
Abstract:
The in vivo mutagenicity of hexavalent chromium in the small intestine, the target organ of tumorgenicity, was examined by means of a transgenic mouse gene mutation assay. Sodium dichromate dihydrate was administered orally in drinking water to male gpt delta mice at a dose of 85.7 or 257.4 mg/L for 28 days or at a dose of 8.6, 28.6 or 85.7 mg/L for 90 days. No significant increase in gpt mutant frequency relative to that in control mice was observed in the small intestine in either the 28- or 90-day study, whereas 28-day oral administration of potassium bromate, a positive control substance, increased mutant frequency.
Insights
Hexavalent chromium (Cr(VI)) did not show mutagenicity in the mouse small intestine after oral administration. This study found no increase in gene mutations, suggesting Cr(VI) is not mutagenic in this target organ.
Area of Science:
- Toxicology
- Genetics
- Environmental Health
Background:
- Hexavalent chromium (Cr(VI)) is a known carcinogen, with the small intestine as a target organ.
- Assessing the in vivo mutagenicity of Cr(VI) is crucial for understanding its carcinogenic mechanisms.
Purpose of the Study:
- To evaluate the in vivo mutagenicity of hexavalent chromium in the small intestine of male gpt delta mice.
- To determine if oral administration of sodium dichromate dihydrate induces gene mutations in the target organ.
Main Methods:
- Male gpt delta mice were orally administered sodium dichromate dihydrate (8.6–257.4 mg/L) for 28 or 90 days.
- The gpt gene mutation assay was used to measure mutant frequency in the small intestine.
- Potassium bromate served as a positive control.
Main Results:
- No significant increase in gpt mutant frequency was observed in the small intestine of mice exposed to hexavalent chromium for 28 or 90 days.
- Oral administration of potassium bromate significantly increased mutant frequency, validating the assay.
Conclusions:
- Hexavalent chromium did not demonstrate in vivo mutagenicity in the mouse small intestine under the tested conditions.
- These findings suggest that the mutagenic potential of Cr(VI) may not be the primary driver of its carcinogenicity in the small intestine.
