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|Title:||MINOCYCLINE AND INTRACEREBRAL HEMORRHAGE: MAXIMIZING NEUROPROTECTION IN CELL CULTURE AND IN MICE |
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|Authors/Affiliations:||1 Mengzhou Xue*; 1 Elena Mikliaeva; 1 V. Wee Yong; |
1 University of Calgary, AB, Canada
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|Content:||OBJECTIVES: The mechanisms of brain injury following intracerebral hemorrhage (ICH) involve inflammatory responses and neuronal death. Minocycline (MO), a semi-synthetic tetracycline, has anti-inflammatory and anti-apoptotic properties, and it provides histological protection in ICH and several neurological disorders, although contradictory results have also been noted. One reason for the controversy is the dose and route of administration used for minocycline after injury. We have tested the hypothesis that high doses of minocycline applied locally to the proximity of ICH would be more efficacious than lower doses or other routes of administration.|
MATERIALS AND METHODS: In tissue culture studies, human fetal neurons (HFN) were exposed to fresh human blood, and immunostaining for microtubule-associated protein-2 was used to examine neuronal survival. In in vivo studies, 10 Ál of autologous tail blood mixed with MO or saline was injected into the right striatum of CD-1 mice. Other mice received MO injected intracerebrally into the hematoma but treatment was initiated only 1 hour after ICH. ICH mice injected intraperitoneally with MO was used as a comparison group as this has been the means by which many studies have administered MO. 24 hours after ICH, brain sections were stained to quantify lesion areas, neuronal death, neutrophil infiltration and microglia/macrophages reaction in the brain adjacent to the hematoma. Other groups were used for behavioral tests at 2 to 14 days after ICH.
RESULTS: In culture, concentration-dependent neurotoxicity of whole blood was observed when HFN were exposed to blood (2.5 - 5 Ál of blood added to 100 Ál of culture medium). MO added 5 minutes before blood reduced the neurotoxicity of blood in culture and there was a concentration-dependent effect from 10 to 40 mg/ml of MO. In vivo, and 24 hours following ICH, we find that histopathological changes were significantly reduced by MO applied intracerebrally plus intraperitoneally compared to each separate administration alone. Moreover, the reduction of ICH-inflicted brain damage and neuronal death was achieved by MO in a concentration-dependent manner when this medication was applied intracerebrally. Behavioral tests including grid walking and open field over 14 days showed significant improvement in mice treated with MO applied intracerebrally plus intraperitoneally compared to intraperitoneal administration.
CONCLUSION: Minocycline reduced neurotoxicity of blood in cell culture in a concentration dependent manner and in mouse ICH model in a dose- and route- dependent manner. These results have relevance to the application of minocycline in humans to maximize recovery from certain neurological insults.
(This work was supported by Canadian Institutes of Health Research and Alberta Heritage foundation for Medical Research)
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