A new test for social investigation in mice: effects of d-amphetamine.

A new automated device that concurrently records social investigatory responses and spontaneous motor activity is described and the effects of d-amphetamine are presented. The rectangular Plexiglas apparatus was divided into three compartments, separated from each other by wire mesh screens. A male mouse was placed into the center compartment and the amount of time spent investigating the two adjacent stimulus compartments was recorded using contact circuits. One stimulus compartment housed a female conspecific, while the other remained uninhabited and served as a control for nonsocial investigatory responses. A photo-cell bisected the center compartment and recorded motor activity. Doses of 0, 0.3, 1.0, and 3.0 mg/kg d-amphetamine administered to both sexually naive and sexually experienced male mice resulted in a dose-dependent decrease in investigation of both stimulus chambers, however social investigation was significantly affected at a lower dose. Both groups of males preferred the female to the uninhabited chamber at all but the highest dose of d-amphetamine, which abolished the preference. Locomotor activity for both inexperienced and experienced males increased with increasing doses of d-amphetamine.