GLUCOCORTICOID-INDUCED CATARACT OF DEVELOPING CHICK-EMBRYO AS A SCREENING MODEL FOR ANTICATARACT AGENTS

In order to develop an effective screening model for anticataract agen ts, we examined the age dependence of cataract induction by glucocorti coid in developing chick embryos. Hydrocortisone sodium succinate (0.2 5 mu mol) was administered to chick embryos on day 15 (15-day-old) and cataract formation was examined 48 hr later. Administration earlier t han on day 13 or later than on day 15 was a little or ineffective. The se results indicate that the formation of glucocorticoid-induced catar act in developing chick embryos depends on developing stages. The embr yos treated with hydrocortisone sodium succinate on day 15 decreased G SH amount in the lens, approximately 50% of the control in 48hr. Howev er, the embryos treated at other ages, in which cataract was not induc ed, showed little or no decrease of GSH. The cataract formation in chi ck embryos appeared to depend on structure of steroid and was due to b iological activities of glucocorticoids. Since cataract is easily prod uced in a reproducible manner with high incidence by glucocorticoid, o ur chick embryo model will be a valuable model system for screening an ticataract agents.