The glycosaminoglycan (GAG) concentrations in cerebral cortices of two strains of cesarean-derived, barrier-raised rats were compared as functions of growth and senescence. The qualitative distribution of the GAG was similar in both strains of rats at all ages. The GAG present were hyaluronic acid, chondroitin 4(6)-sulfate, heparan sulfate and a non-uronic acid containing glycoconjugate which was partially degraded by endo-B-D-galactosidase (keratanase). The chondroitin 4(6)-sulfate was remarkably constant throughout the lifespan studied and similar in both strains of rats. A non-uronic acid containing component in the GAG fraction increased significantly to a peak at 4 months of age in the Fischer rat and at 6 months of age in the King rat, but subsequently declined to the pre-peak baseline level in senescence. A parallel rise and fall of sulfate and sialic acid in the GAG fraction was observed in both strains of rats. Our data suggest that the non-uronic acid containing component is a sulfated glycoprotein-like glycoconjugate similar to keratan sulfate. The glycoconjugate peak in the cerebral cortex may be associated with the rapid proliferation of glyco-protein-rich glial cells. The gradual decline in keratan sulfate with age may represent the gradual alteration of glial glycoconjugates.
ASJC Scopus subject areas
- Geriatrics and Gerontology