Analysis of glucose levels during glucocorticoid-induced cataract formation in chick embryos

When 15-day-old developing chick embryos were administered hydrocortisone hemisuccinate sodium (HC; 0.25 mumol/egg), the content of glucose in the lens markedly increased from around 6 hr, and reached about 25-30-fold above the matched control at 24-48 hr. Thereafter, the glucose level declined and returned to the control level by 100 hr. The profile of lenticular glucose levels was similar to that of the appearance and disappearance of lens opacification. Prednisolone, as well as HC, produced cataract and the elevation of glucose in the lenses. Cortexolone and cortisone, which have weak or negligible glucocorticoid activity in developing chick embryo, could neither produce cataract nor the elevation of glucose in the lenses. An attempt was made to find similarity between this glucocorticoid-induced cataract and sugar cataract known in mammals. In both control and HC-induced cataract (stage IV-V) obtained 48 hr after HC administration, sorbitol, fructose, and glycosylation of protein could not be detected. Dehydration was observed in HC-induced cataractous lens. These data demonstrate that the glycosylation of lenticular protein and the accumulation of polyol were not involved in glucocorticoid-induced cataract formation in developing chick embryos. These results suggest a relationship between the elevation of glucose and cataract formation. However, when cataract formation was blocked by ascorbic acid treatment, the glucose level remained high. Therefore, any relationship between glucose level and cataract may be complex or indirect.