Magnesium sulfate attenuates increased blood-brain barrier permeability during insulin-induced hypoglycemia in rats

Can J Physiol Pharmacol. 2001 Sep;79(9):793-8.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Glucose / drug effects
  • Blood Glucose / metabolism
  • Blood-Brain Barrier / drug effects*
  • Capillary Permeability / drug effects*
  • Cerebrovascular Circulation / drug effects
  • Cerebrovascular Circulation / physiology
  • Evans Blue
  • Female
  • Hypoglycemia / chemically induced
  • Hypoglycemia / metabolism*
  • Insulin / administration & dosage
  • Magnesium Sulfate / blood
  • Magnesium Sulfate / pharmacology*
  • Rats
  • Rats, Wistar
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors

Substances

  • Blood Glucose
  • Insulin
  • Receptors, N-Methyl-D-Aspartate
  • Evans Blue
  • Magnesium Sulfate