Post-weaning social isolation of rats leads to an abnormal gait

The purpose of this study was to further characterize the phenotype of rats that have experienced prolonged postweaning social isolation, a paradigm t hat produces changes relevant to neuropsychiatric disorders. At weaning, ma le Wistar rats from three litters were housed socially (n = 12) or in isola tion (n = 13) for 10 weeks. Isolated rats could see, hear and smell other r ats. A sophisticated analysis of gait revealed that the stride duration was increased in isolates (12%, P = 0.0024) as a result of increased stance du ration (18%, P = 0.0005), but there was no difference in vertical reaction force or velocity. Adrenal glands were heavier in isolates (19%, P = 0.0047 ). There was no difference in cross-sectional area of the brain or lateral ventricles anywhere along the anterior-posterior axis. All experiments and analysis were performed blind to housing condition. This is the first study to demonstrate that socially isolated rats have an abnormal gait. Further analysis, including pharmacological manipulation, is needed in order to und erstand the nature of the abnormality.