Studies of activated microglia and macrophages in lumbosacral spinal cord following an intraperitoneal injection of 6-amino-nicotinamide into adult rats

• Kaur, C. ^[1] ; Yong, E.S. ^[1] ; Ling, E. A. ^[1]
  1. [1] National University of Singapore

     National University of Singapore

     Singapur

     
• Localización: Histology and histopathology: cellular and molecular biology, ISSN-e 1699-5848, ISSN 0213-3911, Vol. 8, Nº. 4, 1993, págs. 699-707
• Idioma: inglés
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• Resumen

  • The anterior horns of the lumbosacral segment of the spinal cord in rats showed an extensive lesion following an intraperitoneal administration of 6-amino-nicotinamide (6-AN). Neurona1 chromatolysis was observed in some of the large efferent neurons 1-7 days after the injection of 6-AN. The capability in their uptake of fluorogold and its retrograde transport was comparable to those in the normal rats. Small neurons presumably internuncial cells underwent degeneration. 8 weeks after 6-AN injection, all the surviving neurons appeared normal. 1 day after 6-AN injection microglial cells appeared activated as evidenced by the hypertrophy and expansion of their processes. A large number of macrophages were observed in the lesioned site 7 days after the administration of 6-AN. The activated microglia and macrophages showed intense immunoreactivity with the monoclonal antibody OX-42. The immunoreactivity declined with time so that by 4 weeks after the injection of 6-AN very weak immunoreactivity was seen on some very branched cells. A similar pattern of immunoreactivity was observed with the monoclonal antibodies OX-18 and OX-6. It was concluded from this study that neuronal chromatolysis and neuronal degeneration induced the expression of CR3 receptors (marked by OX-42) and MHC encoded antigens (marked by OX-18 and OX-6) in activated microglia and macrophages. With time the immunoreactivity decreased so that by 4 weeks after the administration of 6-AN only faint immunoreactivity was observed on some branched cells. Concurrent with a possible down regulation of surface antigens was the restoration of the motor activity of the extremities of the animals which were severely paralyzed 4-7 days after 6-AN injection.