Abstract
Abstract: :
Purpose: To study the influence of nonsteroidal anti-inflammatory drugs (NSAIDs) on proteolytic activity in the mouse lens in organ culture and to examine possible morphological changes indicative of cataract induction. Methods: Mouse lenses were incubated in Earle’s balanced salt solution for 24 hours prior to addition of indomethacin or diclofenac at 0.5, 5, or 50 µM. The lenses were exposed to the NSAIDs from 1 to 12 days. Clarity of the lenses was studied every day. The proteolytic assay was performed on a microtiter plate using a fluorogenic substrate, Suc-Leu-Leu-Val-Tyr-AMC (LLVY-AMC) (50 µM) suitable for the calpain and proteasome proteolytic systems. The preparation was assayed at regular intervals for degradation of the substrate during 24 hours. Morphology of the lenses was studied after the experiment by light microscopy. Results: Opacification of the lenses appeared at day 8 at 50µM and at day 12 at 5µM NSAID concentration for indomethacin as well as for diclofenac. However, the indomethacin-incubated lenses expressed a more severe turbidity than diclofenac-incubated ones. Following an initial decrease in proteolysis (day 1-3), incubation with indomethacin resulted in increased proteolytic activity (4-12 days) of calpain and/or the proteasome. Lenses exposed to diclofenac exhibited increased degradation of LLVY as compared to control lenses during the whole incubation period. Morphological examination of the lenses exposed to NSAIDs showed swelling of outer cortical fibres at 0.5 µM. Higher concentrations presented major morphological changes, such as disrupted epithelial cells and swollen, partly globulized cortical fibres. Conclusion: The role of NSAIDs in cataract formation is still unclear; previous data has indicated a cataractogenic as well as a potential protective effect of NSAIDs against cataract formation. Our study demonstrates proteolytic disturbances in the calpain and proteasome system after NSAID administration and also morphological changes. Further studies are required to evaluate NSAID as a potential cataractogenic risk factor.
Keywords: cataract • proteolysis • microscopy: light/fluorescence/immunohistochem