Chondroitin sulfate proteoglycan distribution in the primate optic nerve head

To evaluate the presence and distribution of chondroitin and dermatan sulfate-containing proteoglycans in normal human and monkey optic nerve heads by light microscopic immunohistochemistry.

Monoclonal antibodies specific for glycosaminoglycan attachment sites remaining after incubation of tissues with chondroitinase ABC and ACII were used to detect proteoglycans containing unsulfated chondroitin (OS), chondroitin-4 and/or dermatan sulfate (4S), and chondroitin-6 sulfate (6S) glycosaminoglycans.

4S antibody labeling after chondroitinase ABC was heavily and evenly distributed within the peripapillary sclera and in the core of laminar beams and optic nerve septa. Preincubation with chondroitinase AC, which exposes only chondroitin sulfate attachment sites, diminished labeling intensity in the lamina cribrosa and sclera and almost completely eliminated it in the retrolaminar optic nerve septa. In contrast, 6S antibodies demonstrated a more intermittent linear distribution throughout the laminar beams and optic nerve septa. No qualitative differences were seen between human and monkey optic nerve heads.

Chondroitin and dermatan sulfate-containing proteoglycans exist throughout the support tissues of the optic nerve head. The specific distribution patterns demonstrated by these monoclonal antibodies, and, in particular, the unique confinement of one of them to the lamina, indicate the presence of different core proteins or different functional glycosaminoglycan side chains that may influence the behavior of the lamina cribrosa.