[The effects of rat selection and reproduction on learning ability in the offspring].

We studied the effect of selective reproduction on rats purchased from a breeder, so as to detect learning impairments in their offspring. The parent rats selected for mating were categorized as bright or dull in terms of learning ability on the basis of a learning test in a water maze or passive avoidance response (PAR). Offspring were tested in the same way as the selected rats, with their responses being compared for each generation. 1. The matings, consisting of bright X bright, bright X dull, dull X bright, dull X dull, resulted in a significant increase in the number of dull offspring of dull X dull from parents selected by water maze or PAR learning test. 2. Bright or dull mothers selected by PAR learning were treated with chlorpromazine 6 mg/kg (2 times/day/s.c.) on the 13th day of gestation. Afterwards, a slight increase in dull offspring of dull parents was seen. 3. These results indicate that in order to evaluate the learning ability of F1 in a reproductive test, it is first necessary to check the reaction of the parents, purchased F0, and to classify them as bright or dull.