Glucocorticoid-induced cataract of developing chick embryo as a screening model for anticataract agents

In order to develop an effective screening model for anticataract agents, we examined the age dependence of cataract induction by glucocorticoid in developing chick embryos. Hydrocortisone sodium succinate (0.25 mumol) was administered to chick embryos on day 15 (15-day-old) and cataract formation was examined 48 hr later. Administration earlier than on day 13 or later than on day 15 was a little or ineffective. These results indicate that the formation of glucocorticoid-induced cataract in developing chick embryos depends on developing stages. The embryos treated with hydrocortisone sodium succinate on day 15 decreased GSH amount in the lens, approximately 50% of the control in 48hr. However, the embryos treated at other ages, in which cataract was not induced, showed little or no decrease of GSH. The cataract formation in chick embryos appeared to depend on structure of steroid and was due to biological activities of glucocorticoids. Since cataract is easily produced in a reproducible manner with high incidence by glucocorticoid, our chick embryo model will be a valuable model system for screening anticataract agents.