Expression of hyaluronidase-4 in a rat spinal cord hemisection model.

Abstract

Study DesignExamination of hyaluronidase-4 (Hyal-4) expression in a rat spinal cord hemisection model.PurposeTo determine the status of Hyal-4 expression after hemisection of the spinal cord, and the relationship between its expression and that of chondroitin sulfate proteoglycans (CSPGs).Overview of LiteratureCSPGs are expressed at the site of spinal cord injury and inhibit axon regeneration. Administration of exogenous chrondroitinase ABC (ChABC), derived from bacteria, digested CSPGs and promoted axonal regrowth. Using a rat hemisection model, we have demonstrated peak CSPGs levels at by 3 weeks after injury but then decreased spontaneously. Could there be an endogenous enzyme similar to ChABC in the spinal cord? It has been suggested that Hyal-4 is involved in CSPG degradation.MethodsA rat hemisection model was prepared and spinal cord frozen sections were prepared at 4 days and 1, 2, 3, 4, 5, and 6 weeks post-cordotomy and stained for CSPGs and Hyal-4 and subjected to Western blotting.ResultsCSPGs appeared at the injury site at 4 days after hemisection, reached a peak after 3 weeks, and then decreased. Hyal-4 was observed around the injury site from 4 days after cordotomy and increased until after 5-6 weeks. Double staining showed Hyal-4 around CSPGs. Western blotting identified a band corresponding to Hyal-4 from 4 days after hemisection.ConclusionsHyal-4 was expressed in a rat hemisection model in areas surrounding CSPGs, and as its peak was delayed compared with that of CSPGs. These results suggest the involvement of Hyal-4 in the digestion of CSPGs.