Proteoglycans (PG) are involved in the brain development as well as in the pathogenesis of age-related neurodegenerative disorders but underlying mechanism remains poorly understood. We showed that senescence-accelerated OXYS rats are suitable model of age-related cerebral dysfunctions. Here the content and composition of PG in the postnatal development and during behavioral decline were examined in the brain of OXYS and Wistar(control) rats at the ages of 1, 7, 14 days and 1, 2 and 14 months. Thereafter behavior in open field (OF) and elevated plus maze (EPM) was investigated. Data confirmed the absence of differences in the performance in tasks between Wistar and OXYS rats at the age of 1 month and showed faster age-related anxiety-like behavior decline in OXYS rats. The distribution of PG and the extent of their sulfation undergo dramatic and rapid changes in the brain during postnatal development both in Wistar and OXYS rats. Significant differences in these parameters appeared in the period of development of behavioral decline in OXYS rats. In contrast, no interstrain differences were revealed in the content and composition of PG in 14-month-old rats when behavior deteriorations are already developed. The results suggest that behavioral deterioration in OXYS rats occurs against the background of altered composition, quantity and glycosaminoglycans (GAG) sulfation.