Microglia and macrophages are the major source of tumor necrosis factor in permanent middle cerebral artery occlusion in mice

J Cereb Blood Flow Metab. 2000 Jan;20(1):53-65. doi: 10.1097/00004647-200001000-00009.


The proinflammatory cytokine tumor necrosis factor (TNF) is known to be expressed in brain ischemia; however, its cellular and temporal appearance is not fully settled. In this study, nonradioactive in situ hybridization for murine TNF mRNA was performed on brain sections from adult C57x129 mice at 6 hours, 12 hours, 24 hours, 2 days, 5 days, or 10 days (six to eight mice per group) after induction of permanent focal cerebral ischemia. Cortical infarct volumes were estimated, and TNF mRNA-expressing cells were counted within the infarct and infarct border using Cast-Grid analysis. At 12 hours, a peak of 19.2 +/- 5.1 TNF mRNA-expressing cells/mm2 was counted, contrasting two to three times lower values at 6 and 24 hours (6.4 +/- 4.6 and 9.2 +/- 3.4 cells/mm2, respectively) and <2 cells/mm2 at 48 hours and later stages. The TNF mRNA-expressing cells were distributed along the entire rostrocaudal axis of the cortical infarcts and occasionally within the caudate putamen. At all time points, TNF mRNA colocalized with Mac-1-positive microglia/macrophages but not with Ly-6G (Gr-1)-positive polymorphonuclear leukocytes. Similarly, combined in situ hybridization for TNF mRNA and immunohistochemistry for glial fibrillary acidic protein at 12 and 24 hours revealed no TNF mRNA-expressing astrocytes at these time points. Translation of TNF mRNA into bioactive protein was demonstrated in the neocortex of C57B1/6 mice subjected to permanent middle cerebral artery occlusion. In summary, this study points to a time-restricted microglial/macrophage production of TNF in focal cerebral ischemia in mice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arterial Occlusive Diseases / complications
  • Arterial Occlusive Diseases / metabolism*
  • Brain Ischemia / complications
  • Cerebral Arteries*
  • Cerebral Infarction / etiology
  • Cerebral Infarction / metabolism
  • Cerebral Infarction / pathology
  • Macrophage-1 Antigen / metabolism
  • Macrophages / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Microglia / metabolism*
  • Neutrophils / pathology
  • RNA, Messenger / metabolism
  • Time Factors
  • Tissue Distribution
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism*


  • Macrophage-1 Antigen
  • RNA, Messenger
  • Tumor Necrosis Factor-alpha