DHA makes PNAS. PGNX.
Proc. Natl. Acad. Sci. USA, Vol. 98, Issue 20, 11720-11724, September 25, 2001
Neurobiology
Dehydroascorbic acid, a blood-brain barrier transportable form of vitamin C, mediates potent cerebroprotection in experimental stroke
Judy Huang*, David B. Agus,, Christopher J. Winfree*, Szilard Kiss*, William J. Mack*, Ryan A. McTaggart*, Tanvir F. Choudhri*, Louis J Kim*, J Mocco*, David J. Pinsky*, William D. Fox, Robert J. Israel§, Thomas A. Boyd§, David W. Golde, and E. Sander Connolly Jr.*,¶
* Department of Neurological Surgery, College of Physicians and Surgeons, Columbia University, 710 West 168th Street, New York, NY 10032; Program in Molecular Pharmacology and Therapeutics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021; and § Progenics Pharmaceuticals, Inc., 777 Old Saw Mill River Road, Tarrytown, NY 10591
Communicated by Samuel J. Danishefsky, Memorial Sloan-Kettering Cancer Center, New York, NY, June 27, 2001 (received for review January 11, 2001)
Neuronal injury in ischemic stroke is partly mediated by cytotoxic reactive oxygen species. Although the antioxidant ascorbic acid (AA) or vitamin C does not penetrate the blood-brain barrier (BBB), its oxidized form, dehydroascorbic acid (DHA), enters the brain by means of facilitative transport. We hypothesized that i.v. DHA would improve outcome after stroke because of its ability to cross the BBB and augment brain antioxidant levels. Reversible or permanent focal cerebral ischemia was created by intraluminal middle cerebral artery occlusion in mice treated with vehicle, AA, or DHA (40, 250, or 500 mg/kg), either before or after ischemia. Given before ischemia, DHA caused dose-dependent increases in postreperfusion cerebral blood flow, with reductions in neurological deficit and mortality. In reperfused cerebral ischemia, mean infarct volume was reduced from 53% and 59% in vehicle- and AA-treated animals, respectively, to 15% in 250 mg/kg DHA-treated animals (P < 0.05). Similar significant reductions occurred in nonreperfused cerebral ischemia. Delayed postischemic DHA administration after 15 min or 3 h also mediated improved outcomes. DHA (250 mg/kg or 500 mg/kg) administered at 3 h postischemia reduced infarct volume by 6- to 9-fold, to only 5% with the highest DHA dose (P < 0.05). In contrast, AA had no effect on infarct volumes, mortality, or neurological deficits. No differences in the incidence of intracerebral hemorrhage occurred. Unlike exogenous AA, DHA confers in vivo, dose-dependent neuroprotection in reperfused and nonreperfused cerebral ischemia at clinically relevant times. As a naturally occurring interconvertible form of AA with BBB permeability, DHA represents a promising pharmacological therapy for stroke based on its effects in this model of cerebral ischemia |
