It is said that "almost makes difference": are different strains of nice the same?
Both inbred (A/J, AKR, Balb/c, C3H, C57BL/6, DBA/2, FVB) and outbred (Swiss Webster, CD-1) strains of mice are commonly used in in vivo and in vitro experiments. Behavioral and pharmacological comparisons of different strains of mice revealed high variability in a number of behavioral parameters and in sensitivity to pharmacological treatments. Between-strain differences were observed in sensitivity to antidepressant drugs, morphine, MK-801, kainate and amphetamine. There are both highly sensitive strains and strains resistant to action of drugs. Less often are observed opposite reactions to pharmacological treatments. The genetic background is, therefore, an important factor contributing to variability of results obtained in different laboratories using different strains of mice. This problem is important not only in behavioral pharmacology but also in in vitro experiments and in genetic engineering.