Mouse and rat genotype choices.

There are advantages and disadvantages to all animal models for aging research. Investigators need to understand these issues, as well as the nature of each relevant model, to choose the best model for their research. There is no, "best" or "worst" model for aging research. Five genetically defined rodent models of potential utility in aging research are: (1) inbred strains and F1 hybrid mice and rats, (2) single gene mutations and other single locus effects, (3) congenic lines, (4) recombinant Inbred (RI) strains, and (5) genetically selected strains and stocks. Animals of each of these types are available for research, but only inbred and F1 hybrid mice and rats are commercially available as aged animals. A genetic understanding of the need for careful genetic definition and for the best available barriér-breeding facilities has improved the quality of aging research significantly in the last one decades.