C57BL/6J mice show greater amphetamine-induced locomotor activation and dopamine efflux in the striatum than 129S2/SvHsd mice.

Inbred strains of mice have served as valuable models for studying genetic susceptibility to drug addiction, an alternative to genetically modified mouse models. This is the first study comparing amphetamine (AMPH) effects on locomotor stimulation and dopamine efflux between two inbred strains of mice C57BL/6J and 129S2/SvHsd, frequently used as background strains for production of genetically engineered mice. There were no significant differences in basal locomotor activity and basal dopamine levels between the two strains. However, C57BL/6J mice showed greater AMPH-stimulated locomotor activity and AMPH-induced striatal dopamine efflux than 129S2/SvHsd mice. The differential AMPH effects could not be explained by differences in presynaptic dopamine components such as surface and total dopamine transporter (DAT) expression levels, striatal dopamine contents, and DAT activity. C57BL/6J and 129S2/SvHsd mice are excellent models for future identification of genetic, molecular, and behavioral components related to individual vulnerability to AMPH addiction. This study emphasizes the importance of mouse strain selections in the production of genetically modified mice for investigating phenotypes and mechanisms of psychostimulants.