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Abstract #9848 Published in IGR 5-3
Altered peripheral sensitivity to glucocorticoids in primary open-angle glaucoma
Stokes J; Walker BR; Campbell JC; Seckl JR; O'Brien C; Andrew RInvestigative Ophthalmology and Visual Science 2003; 44: 5163-5167
PURPOSE: Increased levels of glucocorticoids are associated with raised intraocular pressure (IOP). The activity of glucocorticoids is regulated at a prereceptor level by 11β-hydroxysteroid dehydrogenases (11β-HSD). This study was an investigation of the central and peripheral sensitivity to glucocorticoids in patients with POAG or ocular hypertension (OHT) and the differential metabolism of glucocorticoids by 11β-HSDs. METHODS: Patients with POAG or OHT and normal control subjects were studied. Peripheral sensitivity to glucocorticoids was assessed as dermal blanching and central sensitivity by dexamethasone suppression testing. Daily production rates of glucocorticoids were determined by quantifying metabolites in 24-hour urine. Plasma cortisol levels were determined at baseline (9 am) and after an overnight low-dose dexamethasone suppression test. In a separate study, plasma and aqueous humor cortisol levels were determined in patients with POAG and normal subjects. RESULTS: Patients with POAG exhibited a greater cutaneous vasoconstrictor response to glucocorticoids than patients with OHT and normal subjects (20.7 ± 3.1 versus 8.5 ± 4.4 and 8.6 ± 4.5 arbitrary units, respectively; p < 0.05 in each case). Total glucocorticoid production rates were not different between groups, nor were total circulating cortisol levels before or after suppression of the hypothalamic-pituitary-adrenal axis by dexamethasone or concentrations in aqueous humor. The ratio of urinary cortisol to cortisone metabolites was elevated in POAG versus normal control and OHT (1.74 ± 0.13 versus 1.34 ± 0.11 and 1.32 ± 0.14; p < 0.05 in each case), indicating a change in the balance of 11β-HSDs, without a change in other metabolic pathways. CONCLUSIONS: Patients with POAG exhibit increased peripheral vascular sensitivity to glucocorticoids. Increased sensitivity of glucocorticoid receptors, may enhance local glucocorticoid action in the eye and exacerbate the adverse effects of glucocorticoids in this condition.
Dr. J. Stokes, Endocrinology Unit, School of Molecular and Clinical Medicine, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, UK. jst2121@aol.com
Classification:
9.4.1 Steroid-induced glaucoma (Part of: 9 Clinical forms of glaucomas > 9.4 Glaucomas associated with other ocular and systemic disorders)
