Effet de lʹextrait de Ginkgo biloba (EGb 761) chez le rat sur un modèle expérimental dʹencéphalopathie aiguë après irradiation corporelle totale

SummaryPurpose ine the therapeutic effect of Ginkgo biloba extract (EGb 761) in an experimental model of acute encephalopathy following total body irradiation in rats. al and methods four-month-old rats received 4.5 Gy total body irradiation (TBI) at day 1 while 15 rats received sham irradiation. A behavioural study based on a conditioning test of negative reinforcement, the one-way avoidance test, was performed test, was performed after irradiation. Orally treatment was started one day (study A) or twenty two days (study B) after irradiation and repeated daily for twelve days. In the irradiated group, three subgroups were defined according to the treatment received: EGb 761 (50 mg/kg), EGb 761 (100 mg/kg), water. s ork comprised two consecutive studies. In study A (45 rats) the one-way avoidance test was administered daily from day 7 to day 14. In study B (45 rats) the behavioural test was performed from day 28 to day 35. Study A (three groups of 15 rats): following TBI, irradiated rats treated with water demonstrated a significant delay in a learning the one-way avoidance test in comparison with sham-irradiated rats (P < 0.0002) or irradiated rats treated with EGb 761 (50 mg/kg; P < 0.0017) or EGb 761 (100 mg/kg; P < 0.0002). The irradiated rats, treated with EGb 761 (50 or 100 mg/kg) did not differ from the sham- irradiated controls. Study B (three groups of 15 rats): the irradiated rats, treated with water or EGb 761 (50 or 100 mg/ kg) did not differ from the sham-irradiated controls. sion tudy indicates that a relatively low dose of total body irradiation induces a substantial acute learning dysfunction in the rat, which persists fourteen days after TBI. This effect is prevented by the administration of EGb 761 (50 or 100 mg/kg) started twenty-four hours after irradiation.