Temporal, regional, and cell-specific changes of iNOS expression after intrastriatal microinjection of interferon gamma and bacterial lipopolysaccharide

• Published in: Journal of chemical neuroanatomy 2000-04, Vol.18 (4), p.167-179
• Main Authors: Heneka, Michael T., Dumitrescu, Lucia, Löschmann, Peter-A., Wüllner, Ulrich, Klockgether, Thomas
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic Agents - pharmacology; Astrocytes; Astrocytes - chemistry; Astrocytes - drug effects; Astrocytes - enzymology; Corpus Callosum - cytology; Corpus Striatum - cytology; ED1; Glial fibrillary acidic protein; Glial Fibrillary Acidic Protein - analysis; In Situ Nick-End Labeling; In vivo; Inducible nitric oxide synthase; Interferon-gamma - pharmacology; Lipopolysaccharides - pharmacology; Male; Microglia; Microglia - chemistry; Microglia - drug effects; Microglia - enzymology; Microinjections; Neuritis - enzymology; Nitric oxide; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type II; Rats; Rats, Wistar; Tyrosine - analogs & derivatives; Tyrosine - analysis
• ISSN: 0891-0618; 1873-6300
• DOI: 10.1016/S0891-0618(00)00041-7

Here we study expression of the inducible isoform of nitric oxide synthases after intrastriatal microinjection of interferon-γ and bacterial lipopolysaccharide in the rat at different time points to detect time- and localisation-dependent changes of iNOS expression. Three different areas in the striatum and the corpus callosum were evaluated. Antibodies against the glial fibrillary acidic protein and the microglia/brain macrophage epitope ED1 were used to detect colocalisation of inducible nitric oxide synthase with astrocytes or activated microglia/brain macrophages, respectively. Inducible nitric oxide synthase-positive cells occured first in intravascular and perivascular cells at 4 h. Perivascular and parenchymal inducible nitric oxide synthase expression increased up to 24 h in the striatum, whereas in the corpus callosum inducible nitric oxide synthase expression was maximal after 16 h. Inducible nitric oxide synthase was still present in perivascular cells 7 days after immunostimulation. At all time points, inducible nitric oxide synthase was predominantly detected in ED1-positive microglia/brain. Nitrotyrosine immunohistochemistry was performed to detect NO-mediated nitration of proteins at all time points. Nitrotyrosine-positive neurons and microglial cells were detected from 24 h until 7 days after immunostimulation and were absent in controls. Detailed knowledge of the changes in the time course and cellular source of inducible nitric oxide synthase expression following brain immunostimulation provide a basis for establishing treatment strategies and windows of therapeutic intervention during neuroinflammation.