Magnesium sulfate attenuates increased blood-brain barrier permeability during insulin-induced hypoglycemia in rats.
Magnesium probably protects brain tissue against the effects of cerebral ischemia, brain injury and stroke through its actions as a calcium antagonist and inhibitor of excitatory amino acids. The effects of magnesium sulfate on cerebrovascular permeability to a dye, Evans blue, were studied during insulin-induced hypoglycemia with hypothermia in rats. Hypoglycemia was induced by an intramuscular injection of insulin. After giving insulin, each animal received MgSO4 (270 mg/kg) ip, followed by a 27 mg/kg dose every 20 min for 2.5 h. Plasma glucose and Mg2+ levels of animals were measured. Magnesium concentrations increased in the serum following MgSO4 administration (6.05+/-0.57 vs. 2.58+/-0.14 mg/dL in the Mg2+ group, and 7.14+/-0.42 vs. 2.78+/-0.06 mg/dL in the insulin + Mg2+ group, P < 0.01). Plasma glucose levels decreased following hypoglycemia (4+/-0.66 vs. 118+/-2.23 mg/dL in the insulin group, and 7+/-1.59 vs. 118+/-4.84 mg/dL in the insulin + Mg2+ group, P < 0.01). Blood-brain barrier permeability to Evans blue considerably increased in hypoglycemic rats (P < 0.01). In contrast, blood-brain barrier permeability to Evans blue was significantly reduced in treatment of hypoglycemic rats with MgSO4 (P < 0.01). These results indicate that Mg2+ greatly reduced the passage of exogenous vascular tracer bound to albumin into the brain during hypoglycemia with hypothermia. Mg2+ could have protective effects on blood-brain barrier permeability against insulin-induced hypoglycemia.
Kaya
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Istanbul Faculty of Medicine, Department of Physiology, University of Istanbul, Capa, Turkey. mehkaya@istanbul.edu.tr
Küçük
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Kalayci
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Cimen
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Gürses
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Elmas
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Arican
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D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000187:drug effects*; D002199:Capillary Permeability / Q000187:drug effects*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology; D005070:Evans Blue; D005260:Female; D007003:Hypoglycemia / Q000139:chemically induced / Q000378:metabolism*; D007328:Insulin / Q000008:administration & dosage; D008278:Magnesium Sulfate / Q000097:blood / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors
D001786:Blood Glucose; D007328:Insulin; D016194:Receptors, N-Methyl-D-Aspartate; D005070:Evans Blue; D008278:Magnesium Sulfate