Histochemical and immunohistochemical studies of the effects of experimental anterior disc displacement on sulfated glycosaminoglycans, hyaluronic acid, and link protein of the rabbit craniomandibular joint

Abstract

Purpose: The purpose of this study was to determine the effects of surgically induced anterior disc displacement (ADD) on sulfated glycosaminoglycans (GAGs) such as keratan sulfate (KS), chondroitin-4-sulfate (C4S), and chondroitin-6-sulfate (C6S), hyaluronic acid (HA), and link protein (LP) of the rabbit craniomandibular joint (CMJ) using histochemical and immunohistochemical techniques.

Materials and methods: The right joint of 20 rabbits was exposed surgically, and all discal attachments were severed except for the posterior attachment. The disc was then repositioned anteriorly and sutured to the zygomatic arch. The left joint served as a sham-operated control. Ten additional joints were used as nonoperated controls. Deeply anesthetized rabbits were perfused with 2% buffered formalin 2 weeks (10 rabbits) or 6 weeks (10 rabbits) after surgery. Discs, bilaminar zones, condyles, and articular eminences were excised. Condyles and articular eminences were decalcified in ethylenediaminetetraacetic acid (EDTA). All tissues were sectioned at 10 microns in a cryostat. Sections were incubated with alcian blue and monoclonal antibodies directed against KS, C4S, C6S, HA, or LP. After incubation in the appropriate fluorescein isothiocyanate (FITC)-labeled secondary antibodies, tissue sections were studied under the fluorescence microscope.

Results: The results showed a reduction in alcian blue staining and KS, C4S, C6S, HA, and LP immunostaining in the disc and articular surfaces at 2 weeks after induction of ADD. This reduction was followed by an increase in their immunostaining at 6 weeks. Also, there was a progressive increase in alcian blue staining, and KS, C4S, C6S, and HA immunostaining in the bilaminar zone at 2 and 6 weeks.

Conclusion: It was concluded that surgical induction of ADD in the rabbit CMJ leads to alterations in KS, C4S, C6S, HA, and LP content, consistent with similar changes accompanying osteoarthritis of other synovial joints.