The restrictive role of chondroitin sulfate moieties on the lateral migration of trigeminal motor neurons during hindbrain development in rats

Abstract

Chondroitin sulfate (CS) proteoglycans are the most abundant proteoglycans in the mammalian central nervous system. They can influence neurite outgrowth, formation of neuronal nuclei, establishment of boundaries for axonal growth and neural plasticity both in development and in nerve regeneration. In this work, we aim to find if the CS moieties influence the migration of cranial motor neurons in developing embryos of Sprague Dawley rats. Immunostaining with CS56 showed change in localization of the CS epitope in hindbrains during embryonic day (E) 11.5-E15.5. At E11.5, CS56-immunopositivity was detected in rhombomere boundaries and from E13.5 onwards, as two longitudinal strips along the floor plate. The embryonic hindbrains were treated with chondroitinase ABC (ChaseABC) for 1 day in vitro (DIV) and then immunostained for Isl-1 to locate cranial motor neurons. The effectiveness of ChaseABC treatment was confirmed by the loss of CS56-immunopositivity in conjunction with the development of immunopositivities for stub-sensitive antibodies 2B6 and 3B3. The migration pathway of facial motor neurons in ChaseABC-treated hindbrains was similar to that in controls for all stages studied. However, the trigeminal motor neurons in ChaseABC-treated embryos indicated further migration in the lateral direction than in controls as early as E11.5+1DIV. These results suggest a restrictive role of CS moieties of proteoglycans on the early lateral migration of trigeminal motor neurons in rat.