The Effects of Rat Selection and Reproduction on Learning Ability in the Offspring

Abstract

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 × bright, bright×dull, dull×bright, dull×dull, resulted in a significant increase in the number of dull offspring of dull×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 classifiy them as bright or dull.