Neonatal androgen injection changes open-field behavior of mice.

Newborn female mice of the C57BL/6J and BALB/cJ inbred strains and their reciprocal F1 hybrids were injected either with testosterone or with oil vehicle alone. Both the repeatablity and mean level of open-field activity scores over a 10-day test period increased in hormone-injected animals compared with controls. Increased activity due to hormonal treatment was greater in hybrid females than in inbred females. There was no consistent effect of hormonal treatment on open-field defecation.