Ontogeny of activity in inbred and random-bred strains of mice: effects of scopolamine.

ABSTRACT

In Experiment 1, the activity of five inbred strains, A/J, BALB/c, C3H/HeJ, C57BL/6J, and DBA/2J, and two random-bred strains, Fullensdorf and Quackenbush, was observed at ages from 13 to 28 days. The C3H/HeJ, Fullensdorf, and Quackenbush strains exhibited a sharp increase in activity, to a peak at 17 days of age, followed by a decline at later ages. In contrast, the activity of the A/J, BALB/c, C57BL/6J, and DBA/2J mouse strains increased gradually, reaching a peak at 19 days of age. These mice displayed no decline in activity at later ages. In Experiment 2, mice from the five inbred strains and the Quackenbush strain were injected with either 0, 1.0, or 4.0 mg/kg of scopolamine before activity testing at 17, 21, or 28 days of age. Scopolamine had no effect on the activity of the various strains of mice at 17 or 21 days of age. At 28 days of age, the 4.0 mg/kg dose of scopolamine was associated with increased activity in all of the mouse strains.