Mutation Research/Genetic Toxicology and Environmental Mutagenesis
Anticlastogenic effects of Ginkgo biloba extract (EGb 761) and some of its constituents in irradiated rats
Introduction
Chromosomal aberrations resulting from ionizing radiation are well documented. While a large body of evidence supports a direct effect of ionizing radiation on the chromosomes of exposed cells, several observations suggest indirect radiation effects due to the presence of plasma factors able of inducing chromosomal aberrations in unexposed cells. Such chromosomal breakage or clastogenic factors (CF) were first described in the plasma of patients, who had been irradiated accidentally [1]or therapeutically [2]. They were also observed in A-bomb survivors, where they persisted for many years after irradiation [3]. In a previous study, we reported that clastogenic activity was present in the plasma of Chernobyl accident recovery workers [4]and in children exposed to radiation as the consequence of this disaster [5]. We were also able to show that the damaging effects of these CF can be inhibited in vitro and in vivo by treatment with an extract from Ginkgo biloba leaves (EGb761) 6, 7. In the present study, we tried to determine which component of this extract was responsible for the protective effects. For this purpose, we choose an animal model, previously shown to respond to X-rays with CF formation [8].
Section snippets
Animals
Male Wistars rats (IFFA CREDO, Les Oncins France), 3 months of age were used for this study. They weighed approximately 400 g when they were irradiated.
Radiation exposure
Whole body irradiation was administered by a telecobalt unit to deliver a dose of 4.5 Gy in one fraction using two parallel opposed equally weighted lateral fields (8×8 cm at source axis distance, 80 cm).
Blood samples were taken on day 22 and 44 after irradiation and immediately centrifuged for plasma preparation. During the 3-week period
Results and discussion
The present study confirms the findings of Faguet et al. [8], who reported that the plasma of irradiated rats has clastogenic properties in cultures set up with blood of unexposed rats. The clastogenic activity was demonstrable immediately after irradiation, diminished therafter, but remained significantly increased until the end of their study period (10 weeks).
We studied a group of 14 animals at day 8 after irradiation and noted clastogenic activity in all samples, with a mean ACS of
Acknowledgements
We are grateful to Professor F. Baillet and the Department of Radiotherapy, La Pitié-Salpétrière Hospital, Paris, where the animals were irradiated.
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