Abstract WP160: Conivaptan (Combined Vasopressin Receptor Antagonism) Attenuates Cerebral Edema Following Ischemic Stroke in Rodent Model

Abstract

Objective: To study the potential role of Conivaptan on cerebral edema, infarct volume, neurological deficit and survival. Introduction: Although vasopressin has a significant detrimental role in stroke-related cerebral edema, the effect of mixed vasopressin antagonism in stroke has not been well studied. We studied the effects of conivaptan on the course of cerebral edema, severity of neurological deficit, infarct volume, aquaporin-4 (AQP4) protein levels and survival after experimental stroke. Methods: Animals were randomized to receive either conivaptan or vehicle after reperfusion of experimental middle cerebral artery occlusion. The severity of neurological deficit, edema, and infarct volume assessments were performed by an investigator blinded to group assignment. All assessments were performed at either 12h or 24h and Western blot was subsequently used to investigate AQP4 levels. Results: At 12h, conivaptan-treated mice (n=16) had 6.64±6.50% ipsilateral hemispheric enlargement compared to 16.55±7.05% in control mice (n=16, p=0.0003). Similarly, at 24h, conivaptan-treated mice (n=12) had 6.81±4.63% ipsilateral hemispheric enlargement in comparison to 13.93±5.43% in control mice (n=12, p=0.0023). At 24h, the conivaptan-treated mice had lower neurological deficits in comparison to control (p=0.04). There was no significant effect of conivaptan on infarct size or AQP4 levels in comparison to vehicle, naïve and sham group. Conclusions: The present study highlights the role of mixed vasopressin receptor antagonism in reducing cerebral edema secondary to brain ischemia. This data suggests the possibility of developing vasopressin antagonism as a new adjuvant in treatment of stroke-related brain edema.