Effect of methylprednisolone on the cerebrovascular permeability in the rat

The beneficial effect of a corticosteroid on membrane-stability was studied in rat brains with increased vascular permeability induced by an infusion of hypertonic solution via the carotid artery. Rats were divided into three groups: the first group (n=18) was presented with physiological saline, the second group (n=18) was administered 30 mg/kg of methylprednisolone (MPS), and the third group (n=18) 100 mg/kg of MPS intravenously. After endotracheal intubation under nitrous oxide-oxygen-halothane anesthesia, animals were immobilized with a muscle-relaxant and maintained under artificial ventilation. The neck was incised and the external carotid artery was ligated. Ten minutes after infusion of experimental solution, the internal carotid artery was cannulated via the common carotid artery and 2.5 ml of 1.4 M mannitol was infused over a period of 30-seconds, followed immediately by intravenous injection of Evans blue (EB). Twenty minutes later, the brain was fixed by perfusion of 5% glutaraldehyde and removed for observation of EB staining. Increased permeability was assessed in five grades, i.e., O, no staining; I, localized staining; II, light but extensive staining of the hemisphere; III, moderate staining; IV, deep staining. It was found that pretreatment with MPS significantly inhibited EB staining, but no significant difference was observed between pretreatment with 30 mg/kg and 100 mg/kg of MPS. We conclude that pretreatment with MPS prevents an increase in cerebrovascular peremability induced by hypertonic solution.