Changes in the structure of the agonistic behavior of mice produced by D-amphetamine.

The effects of three acute doses of D-amphetamine (0.25, 1.5 and 3 mg/kg) were studied in a model of isolation-induced aggression in male mice. An ethopharmacological analysis of the encounters was carried out, which studied the frequency, total and mean duration of different behavioral categories, including the temporal distribution of attacks and the duration of inter-attack intervals. The results show a reduction in the total and mean duration of the Attack category and an increase in motor activity manifested by longer durations, both total and mean, of Non Social Exploration and shorter Immobility. The temporal analysis of Attack revealed an increase in the number of very short (< 15 s) inter-attack intervals and a temporal redistribution of the attacks to later in the course of the social encounters. These results confirm for a complex behavior such as aggression, that D-amphetamine, even at low doses, favors a fragmentation and repetition of motor routines with a simultaneous reduction in the influence of environmental cues on the control of behavior.