RETROGRADE TRANSPORT AND INTRANEURONAL FATE OF EXOGENOUS HORSERADISH PEROXIDASE IN THE NERVOUS SYSTEM

Abstract

Exogenous horseradish peroxidase (HRP, Type VI, Sigma) was applied as a marker for retrograde neuroanatomical tracing in the nigroneostriatal system and the sciatic nerve of adult rats. The retrograde transport and intraneuronal fate of HRP was examined with light and electron microscopy.In the nigroneostriatal system, the labeled neurons containing many brown granules in their perikarya were observed in the ipsilateral substantia nigra 3-4 hours after an injection of HRP, confirming the existence of a nigroneo-striatal pathway. Ultrastructually, these granules appear as multivesicular and lysosomal bodies in the perinuclear region.The labeled nerve cells of the spinal ganglia were also observed within 12 hours after the application of HRP in the sciatic nerve. The HRP positive brown granules had accumulated in the perinuclear region and were rapidly degraded by the lysosomal system disappearing 2 weeks after the injection.In instances of long periods of survival, characteristic lysosomal bodies which included crystals, crystalloid and laminar structures were found.