Differential effects of nicotine and amphetamine on locomotor activity and maze exploration in two rat lines.

Separate groups of two different rat breeding lines, Roman High Avoidance (RHA/Verh.) and Roman Low Avoidance (RLA/Verh.), treated with either saline, nicotine (0.2 mg/kg), or amphetamine (0.4 mg/kg) were compared for exploratory efficiency and for exploratory locomotion by using two different mazes on alternate testing days. The RHA/Verh. rats generally showed more locomotion but less intermaze transfer of exploratory efficency than the RLA/Verh. rats. Nicotine did not alter exploratory efficiency but stimulated locomotor activity in the RHA/Verh. rats, while it did not significantly alter either category of behavior in the RLA/Verh. rats. Amphetamine stimulated locomotor activity in both rat lines but this stimulation was weaker in comparison with that of nicotine. In contrast to nicotine, amphetamine impaired exploratory efficiency in the RHA/Verh. rats. Like nicotine, amphetamine did not significantly affect exploratory efficiency in the RLA/Verh. rats. The results demonstrate that, when the two lines of rats are compared, there is a dissociation of the two categories of behavior and a further differentiation between nicotine and amphetamine effects.