Studies of activated microglia and macrophages in lumbosacral spinal cord following an intraperitoneal injection of 6-aminonicotinamide into adult rats.
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). Neuronal 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.(ABSTRACT TRUNCATED AT 250 WORDS)
Kaur
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Department of Anatomy, Faculty of Medicine, National University of Singapore, Kent Ridge.
Yong
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Ling
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D015120:6-Aminonicotinamide / Q000633:toxicity*; D000818:Animals; D000911:Antibodies, Monoclonal; D001370:Axonal Transport; D002467:Cell Nucleus / Q000648:ultrastructure; D002843:Chromatin / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D006984:Hypertrophy; D007150:Immunohistochemistry; D008264:Macrophages / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D017628:Microglia / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D009469:Neuromuscular Junction / Q000648:ultrastructure; D009474:Neurons / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure
D000911:Antibodies, Monoclonal; D002843:Chromatin; D015120:6-Aminonicotinamide