Minocycline alleviates hypoxic-ischemic injury to developing oligodendrocytes in the neonatal rat brain.
The role of minocycline in preventing white matter injury, in particular the injury to developing oligodendrocytes was examined in a neonatal rat model of hypoxia-ischemia. Hypoxia-ischemia was achieved through bilateral carotid artery occlusion followed by exposure to hypoxia (8% oxygen) for 15 min in postnatal day 4 Sprague-Dawley rats. A sham operation was performed in control rats. Minocycline (45 mg/kg) or normal phosphate-buffered saline was administered intraperitoneally 12 h before and immediately after bilateral carotid artery occlusion+hypoxia and then every 24 h for 3 days. Nissl staining revealed pyknotic cells in the white matter area of the rat brain 1 and 5 days after hypoxia-ischemia. Hypoxia-ischemia insult also resulted in apoptotic oligodendrocyte cell death, loss of O4+ and O1+ oligodendrocyte immunoreactivity, and hypomyelination as indicated by decreased myelin basic protein immunostaining and by loss of mature oligodendrocytes in the rat brain. Minocycline significantly attenuated hypoxia-ischemia-induced brain injury. The protective effect of minocycline was associated with suppression of hypoxia-ischemia-induced microglial activation as indicated by the decreased number of activated microglia, which were also interleukin-1beta and inducible nitric oxide synthase expressing cells. The protective effect of minocycline was also linked with reduction in hypoxia-ischemia-induced oxidative and nitrosative stress as indicated by 4-hydroxynonenal and nitrotyrosine positive oligodendrocytes, respectively. The reduction in hypoxia-ischemia-induced oxidative stress was also evidenced by the decreases in the content of 8-isoprostane in the minocycline-treated hypoxia-ischemia rat brain as compared with that in the vehicle-treated hypoxia-ischemia rat brain. The overall results suggest that reduction in microglial activation may protect developing oligodendrocytes in the neonatal brain from hypoxia-ischemia injury.
Cai
Z
Z
Department of Pediatrics, Division of Newborn Medicine, University of Mississippi Medical Center, Jackson, 39216-4505, USA. zcai@ped.umsmed.edu
Lin
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S
Fan
L-W
LW
Pang
Y
Y
Rhodes
P G
PG
D000818:Animals; D000831:Animals, Newborn; D000954:Antigens, Surface / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D017536:Carotid Artery, Common; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D004195:Disease Models, Animal; D005609:Free Radicals / Q000378:metabolism; D005911:Gliosis / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control; D020925:Hypoxia-Ischemia, Brain / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D008026:Ligation; D017628:Microglia / Q000187:drug effects / Q000378:metabolism; D008911:Minocycline / Q000494:pharmacology* / Q000627:therapeutic use; D009410:Nerve Degeneration / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control; D009413:Nerve Fibers, Myelinated / Q000187:drug effects / Q000378:metabolism; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology / Q000627:therapeutic use; D009836:Oligodendroglia / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000187:drug effects / Q000378:metabolism; D016896:Treatment Outcome
D000954:Antigens, Surface; D015415:Biomarkers; D005609:Free Radicals; D018696:Neuroprotective Agents; D008911:Minocycline