The mouse spot test: results with a new cross

Area of Science:

• Toxicology
• Genetics
• Animal models

Background:

• The mammalian spot test is a standard method for evaluating the mutagenicity of chemicals.
• The classical TxC57Bl/6 cross is commonly used but may not be optimal in terms of fertility and animal usage.
• There is a need for more efficient and sensitive animal models in toxicological research.

Purpose of the Study:

• To assess the fertility and sensitivity of a novel mouse cross for use in the mammalian spot test.
• To evaluate the potential of this new cross to reduce the number of experimental animals required.
• To compare the sensitivity of the new cross to established models using various chemical mutagens.

Main Methods:

• A new mouse cross was generated using male PDB (a/a b/b d/d p/p) and non-agouti female NMRI (a/a c/c) mice.
• Embryos from this cross are heterozygous at coat colour loci relevant to the spot test.
• Fertility was assessed by litter size and pregnancy rate; sensitivity was evaluated using ethylnitrosourea, procarbazine, isoniazid, cyclophosphamide, and 4-nitroquinoline oxide.

Main Results:

• The new cross exhibits good fertility, with typical litter sizes of 9-10.
• High pregnancy rates contribute to significant economies in animal numbers.
• The sensitivity of this cross to tested chemical mutagens compares favorably with published data from other models.

Conclusions:

• The novel PDB x NMRI mouse cross demonstrates high fertility and comparable sensitivity to established models for the mammalian spot test.
• This new cross has the potential to reduce the number of experimental animals used in toxicological studies.
• Further evaluation is recommended to confirm these preliminary findings and establish the cross as a viable alternative.