One trial passive avoidance learning in neonatally hormone treated rats. Its relation with activity.

The performance in one trial passive avoidance learning and the degree of activity were determined in adulthood, from neonatal hormone treated and intact rats. Activity was measured in the same environmental conditions in which the learning test takes place, i.e., shuttle box unequally illuminated. The treated groups were androgenized females and castrated males. Intact groups were composed by normal males and females. Intact females showed more activity than intact males. Castrated males and androgenized females displayed a degree of activity similar to the normal females. This score was negatively correlated with the total time that each animal remained in the dark compartment of the box. In this respect the normal males showed greater dark preference than the other three groups, which had no differences among them. Similar results to that of dark preference were obtained in performance on one trial passive avoidance learning, that is, androgenization in females did not produce a significant effect in this test and castration in males decreased their performance. A linear correlation between activity and passive avoidance score could be established.