Effect of prostaglandin E 1 on the rat inner ear microvascular thrombosis

Abstract

1. 1. The effect of prostaglandin E 1 was investigated with a two-rat model of hearing disturbance and equilibrium dysfunction associated with inner ear microvascular thrombosis. 2. 2. The inner ear microvascular thrombosis was induced by photochemical reaction between Rose Bengal and transmural green light (540 nm). Photochemical reaction causes endothelial injury followed by platelet adhesion, aggregation, and formation of a platelet- and fibrin-rich thrombus. 3. 3. Under anesthesia, the cochlea or the vestibule was irradiated with green light to induce hearing disturbance or equilibrium dysfunction. 4. 4. In the hearing disturbance model, a compound cochlear nerve action potential was recorded by electrocochleography every minute after the beginning of photoirradiation in the presence of Rose Bengal. 5. 5. In the equilibrium dysfunction model, the photoirradiation was applied for 10 min after Rose Bengal administration. The behavior of rats was observed in the swimming test, and nystagmus was observed 24 hr after the end of photoirradiation. 6. 6. Prostaglandin E 1 significantly ( P<0.05) prolonged the time required to suppress the action potential. In the swimming test, 3 of the 6 animals treated with prostaglandin E 1 did not rotate about their longitudinal axes (equilibrium dysfunction) and the duration of well-balanced swimming was significantly prolonged ( P< .001). Prostaglandin E 1 significantly ( P<0.05) suppressed the appearance of nystagmus. 7. 7. In conclusion, prostaglandin E 1 potentially prevents hearing disturbance and equilibrium dysfunction due to inner ear microvascular disorders.