Histochemistry and Cell Biology

, Volume 105, Issue 1, pp 81–89

Induction of cytosolic NADPH-diaphorase/nitric oxide synthase in reactive microglia/macrophages after quinolinic acid lesions in the rat striatum: an electron and light microscopical study

  • Jaroslaw Calka
  • Gerald Wolf
  • Werner Schmidt
Original Paper

DOI: 10.1007/BF01450881

Cite this article as:
Calka, J., Wolf, G. & Schmidt, W. Histochem Cell Biol (1996) 105: 81. doi:10.1007/BF01450881

Abstract

Induction of nitric oxide synthase and increased production of nitric oxide in microglia may play a crucial role in neuronal damage and neurodegenerative disorders. In the present study we have used light and electron microscopical NADPH-diaphorase histochemistry as the visualization procedure for nitric oxide synthase to investigate the time-course and subcellular patterns of NADPH-diaphorase expression in microglia/macrophages of quinolinic acid-lesioned rat striatum. For light microscopy, NADPH-diaphorase histochemistry sections were stained with nitroblue tetrazolium, while for ultrastructural analysis the tetrazolium salt 2-(2′-benzothiazolyl)-5-styryl-3(4′-phthalhydrazidyl) tetrazolium chloride (BSPT) was applied. Light microscopical inspection revealed a progressively increasing number of positive cells with increasing intensity of NADPH-diaphorase staining in microglia/macrophages from day 1 after quinolinic acid injection onward. Electron microscopical examination revealed a membrane bound NADPH-diaphorase in quiescent microglia as well as in activated microglia/macrophages through all stages of the lesion studied. Predominantly membranes of the nuclear envelope and the endoplasmic reticulum were labeled with BSPT-formazan, while in advanced stages selective membrane portions of mitochondria, Golgi apparatus and plasmalemma were also stained. From day 5 onward after lesion induction, a very distinctive type of NADPH-diaphorase was observed, forming accumulations of electron-dense grains that were distributed differentially throughout cytoplasmic areas and phagocytic vacuoles. Dynamics of expression, unique cytosolic localization and occurrence exclusively in activated microglia/macrophages suggest that this particular NADPH-diaphorase activity probably reflects the inducible isoform of nitric oxide synthase, whereas the membrane-bound precipitate may represent the neuronal and/or the endothelial isoform of the enzyme.

Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • Jaroslaw Calka
    • 1
  • Gerald Wolf
    • 1
  • Werner Schmidt
    • 1
  1. 1.Institute of Medical NeurobiologyOtto von Guericke University of MagdeburgMagdeburgGermany
  2. 2.Department of Animal Anatomy, Veterinary FacultyAgricultural and Technical University of OlsztynOlsztynPoland