Published online before print July 10, 2008, doi: 10.1161/STROKEAHA.107.506048
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(Stroke. 2008;39:2544.)
© 2008 American Heart Association, Inc.
Original Contributions |
Effectiveness of PSD95 Inhibitors in Permanent and Transient Focal Ischemia in the Rat
From the Toronto Western Hospital Research Institute (H.-S.S., Y.F., L.T., M.A., A.L., J.P.F., M.T.), Toronto, Ontario, Canada; the Departments of Physiology (H.-S.S., M.T.) and Surgery (M.T.), University of Toronto, Toronto, Ontario, Canada; the Departments of Biology (T.A.D.), Biomedical Sciences (T.A.D., P.B.B., R.A.T.), and Psychology (C.L.R.), University of Prince Edward Island, Charlottetown, PEI, Canada; the Programme in Brain and Behaviour (M.W.S.), Hospital for Sick Children, Toronto, Ontario, Canada; and the Brain Research Center and Department of Medicine (Y.L., Y.T.W.), Vancouver Hospital and Health Sciences Center, University of British Columbia, Vancouver, BC, Canada.
Correspondence to Michael Tymianski, MD, PhD, Toronto Western Hospital Research Institute, Suite 4W-435, 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8. E-mail mike.tymianski{at}uhn.on.ca
Background and Purpose— Postsynaptic density-95 inhibitors reduce ischemic brain damage without inhibiting excitatory neurotransmission, circumventing the negative consequences of glutamatergic inhibition. However, their efficacy in permanent ischemia and in providing permanent neuroprotection and neurobehavioral improvement in a practical therapeutic window is unproven. These were tested here under conditions that included fever, which is a common occurrence in clinical stroke.
Methods— Six studies were performed in unfasted Sprague-Dawley rats. Two involved permanent pial vessel occlusion in male and female rats. Two involved permanent middle cerebral artery occlusion, which induced severe hyperthermia, and 2 involved transient middle cerebral artery occlusion. Animals were treated with a single intravenous injection of postsynaptic density-95 inhibitors (Tat-NR2B9c[SDV] or Tat-NR2B9c[TDV]) 1 hour or 3 hours after stroke. Infarct volumes and neurobehavior were assessed in a blinded manner at 24 hours (pial vessel occlusion and permanent middle cerebral artery occlusion) or at 62 days (transient middle cerebral artery occlusion).
Results— Postsynaptic density-95 inhibitors dramatically reduced infarct size in male and female animals exposed to pial vessel occlusion (>50%), in hyperthermic animals with fever exceeding 39°C exposed to permanent middle cerebral artery occlusion (approximately 50%), and at 62 days poststroke in animals exposed to transient middle cerebral artery occlusion (approximately 80%). Effectiveness of postsynaptic density-95 inhibitors was achieved without the drugs affecting body temperature. In transient middle cerebral artery occlusion, a single dose of postsynaptic density-95 inhibitor given 3 hours after stroke onset permanently maintained reduced infarct size and improved neurobehavior.
Conclusions— Postsynaptic density-95 inhibitors administrated 3 hours after stroke onset reduced infarct volumes and improved long-term neurobehavioral functions in a wide therapeutic window. This raises the possibility that they may have future clinical usefulness.
Key Words: behavior • cerebral ischemia • hyperthermia • middle cerebral artery occlusion • N-methyl-D-aspartate receptor • postsynaptic density