Short-term, preweaning treatment with tetracycline affects physical development and behavior in rats.

Tetracycline (TC) was administered indirectly to rat pups through maternal milk, giving mothers diluted TC solutions as a single source of drinking water, during 13-16 days of postnatal age (PND) in Experiment 1. In Experiment 2, using rats of a different strain, TC dose and its application period were reduced from 0.5 mg/ml to 0.25 mg/ml and from PND 13-16 to PND 13-15, respectively. In Experiment 3, TC was administered directly to the pups via stomach intubation during PND 13-16. The effects of these short-term treatments were tested in adulthood. Brain weight decreased, although no abnormal changes were found histologically in the cerebral cortex