The effects of chloridazepoxide on avoidance performance of mice subjected to undernutrition or handling stress in early life.

This experiment compared the effects of (u) "early undernutrition" by rearing in large litters and (ii) an early handlin g stress, on avoidance learning in Swiss white mice. The two treatments, the first leading to permanent physical stunting and the second not, had similar and additive detrimental effects on avoidance performance. Treatment with the minor tranquillizer Chlordiazepoxide improved performance in all groups but had a proportionately greater effect on previously undernourished, handled mice. Thus the poor avoidance performace of mice reared in large litters appears to be largely independent of the growth stunting effect and more closely related to an elevated stress response produced by stress in early life.