Mifepristone blocks specific glucocorticoid receptor binding in rabbit iris-ciliary body
P. M. Munden and T. J. Schmidt
Department of Ophthalmology, University of Iowa Hospitals and Clinics, Iowa City 52242.
Mifepristone is a specific glucocorticoid receptor antagonist that has been
shown to lower intraocular pressure modestly when applied topically to
rabbit eyes. We evaluated the ability of mifepristone to block specific in
vitro glucocorticoid receptor binding of the labeled agonist triamcinolone
acetonide in cytosol isolated from rabbit iris-ciliary body tissue. A
500-fold molar excess of nonradioactive mifepristone completely blocked
specific binding of triamcinolone acetonide to glucocorticoid receptors in
the iris-ciliary body cytosol. Additionally, specific binding was blocked
in a dose-dependent fashion over a range of 0.005-fold to 500-fold molar
excess of mifepristone. Mifepristone's effect on intraocular pressure may
be due to its ability to antagonize glucocorticoid receptor-mediated
effects in ocular tissues.
