RESUMEN
Background Long-term administration of glucocorticoid drugs induces ocular hypertension in susceptible individuals probably.It has been verified that 1 1β-hydroxysteroid dehydrogenase type 1 (11β-HSD1),glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) can affect the generating of aqueous humor,but how they play the role in glucocorticoid-induced ocular hypertension is unclear.Objective This study was to investigate the relationship of expressions of 11β-HSD1 and steroids receptors in ciliary body and steroid-induced ocular hypertension.Methods Thirteen 12-16 week-old New Zealand albino rabbits were randomized to control group (5 rabbits) and experimental group (8 rabbits).Steroid-induced glaucoma models were induced by administration of subconjunctival injection of 5 mg dexamethasone solution(1 ml) and 0.5％ dexamethasone eye drops on alternate days in the left eyes for consecutive two months in the experimental group,and the equal volume of sterile normal saline solution was used in the same way in the control group.The successful criteria of model eyes was defined as rising of intraocular pressure (IOP) to ≥ 18 mmHg for over one week.Then,the animals were sacrificed by excessive anesthesia and the ciliary tissues were isolated for the assay of expressions of 1 1β-HSD1 protein by immunochemistry,and the expressions of 11β-HSD1 mRNA,GR mRNA and MR mRNA in ciliary body were semi-quantitatively detected by reverse transcription-PCR (RT-PCR).The experimental results were compared between the two groups.Results The IOP was normal in the first two weeks after administration of drugs,and no significant difference was found in IOP between the first week and the second week in the experimental group (q =0.469,P ＞0.05).From 3 through 5 weeks after injection,the IOP was gradually elevated,with the highest value of (18.87±0.77) mmHg in the fifth week.Significant differences were seen between the two groups at mentioned-above time points (q =10.535,20.353,28.681,all at P ＜ 0.01).11β-HSD1 protein was positively expressed in nonpigmented epithelial cells of ciliary tissue of rabbits in both groups,however,the expression intensity was weaker in the experimental group compared with the control group.The relative expressional values of MR mRNA,GR mRNA and 11β-HSD1 mRNA in the ciliary tissue were 2.22±0.78,0.64±0.11 and 0.47±0.16 in the experimental group,and those in the control group were 0.94±0.27,1.88±0.74 and 2.68±1.28,with significant differences between the two groups (t =6.070,P =0.004 ; t =5.170,P =0.007 ; t =5.540,P =0.005).Conclusions Corticosteroidinduced glaucoma probably is associated with the up-regulation of MR level and down-regulations of GR and 11β-HSD1 in ciliary body.