Effects of dexamethasone, progesterone, and testosterone on IOP and GAGs in the rabbit eye

The effects of steroids on intraocular pressure and on aqueous outflow pathway (AOP) and adjacent anterior segment tissue glycosaminoglycans (GAGs) were studied in New Zealand Red rabbits treated for 4 wk with dexamethasone, hydroxymethyl-progesterone and methyl-testosterone. Only topical administration of dexamethasone resulted in a significant increase in intraocular pressure. The eyes were labeled in vitro for 1 hr with GAG precursors, [3H]-glucosamine and [35S]-sulfate, and maintained as whole organ cultures. The GAGs were biochemically isolated, fractionated by gel filtration chromatography and subjected to selective GAG degradative procedures. The total content of hyaluronic acid and chondroitin sulfate was analyzed by high performance liquid chromatography. In dexamethasone-treated eyes, the total content of hyaluronic acid was decreased in the AOP, although the specific activity of [3H]-glucosamine did not change. The total content of chondroitin sulfate was increased in the AOP and iris-ciliary body, while the specific activity of the [35S]-label was decreased in the AOP, iris-ciliary body, and sclera. The changes in the AOP GAGs in dexamethasone-treated eyes may be important factors for the development of dexamethasone-induced ocular hypertension in the rabbit.