A study on topographical change of proteoglycans in human lumbar disc.

Proteoglycan aggregates, the binding of disc proteoglycan to hyaluronate, chondroitin sulfate chain length, hexosamine and amino acid compositions were measured in different regions of the L1/L2 and L4/L5 intervertebral discs from 3 spines aged 35, 49, and 60 years. The results were as follows: proteoglycan aggregates and the binding of disc proteoglycan to hyaluronate were shown to increase from the nucleus pulposus to the outer annulus, while only small differences were observed among the anterior, posterior and lateral regions in either the inner or the outer annulus within a given disc. Changes in chondroitin sulfate chain length were observed with aging. However, within a given disc, and furthermore, within a given spine, chondroitin sulfate chains were similar in length. Glucosamine/galactosamine molar ratios of disc proteoglycan were higher in the L1/L2 disc than the L4/L5 disc. Changes with age were also observed. Nevertheless, only minor differences among the anterior, posterior and lateral regions of the annulus fibrosus were found within a given disc. The amino acid compositions showed small differences when proteoglycans from various regions of a disc were compared. All of them had a high content of aspartic acid, threonine, serine, glutamic acid, proline and glycine. The results indicate that it seems there are only minor differences among the anterior, posterior and lateral regions of the annulus fibrosus in a number of the experimented parameters.