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Monica Alves, Lilian E. Silva, Ana C. Dias, Carolina M. Módulo, Leonardo T. Malki, Eduardo M. Rocha; Dry Eye And Oxidative Stress: The Role Of Peroxidases And Hidrogen Peroxide In Rat Lacrimal Gland. Invest. Ophthalmol. Vis. Sci. 2012;53(14):629.
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Dry eye (DE) physiopathology has been linked to oxidative stress and peroxidases have been used as biomarkers of lacrimal gland (LG) function. The aims of this study are (1) to identify and distinguish the members of peroxidase superfamily in rat LG of both genders and in response to Diabetes Mellitus (DM) induction and insulin treatment and (2) to evaluate the impact of H2O2 injection in LG.
Wistar rats LG were homogenized and evaluated by Western blot (WB) to compare the expression of glutathione peroxidase-3 (GPX3), lactoperoxidase (LPO) and lactoferrin. We evaluated according to gender and in response to DM induction and treatment. Total peroxidase activity was also compared among the groups after protein normalization. H2O2 injection (1 and 5 uM) in LG was evalauted after 7 days in regard to tear secretion, ocular surface and histology of cornea and LG .
Western blot analysis had shown that GPX3, LPO and lactoferrin proteins were expressed in rats LG. GPX3 had similar expression in male and female rats (p=0.80) while LPO and lactoferrin were slightly increased in males (p=0.38 and p=0.14 respectively). After DM induction GPX3 was increased (p=0.17) and LPO and lactoferrin diminished as observed after insulin treatment (p=0.14 and p=0.07). Total peroxidase activity was equal according to gender (p=0.79) and was decreased in DM rats and raised with insulin treatment (p=0.05). H2O2 single injection did not affect tears secretion, ocular surface integrity or LG histology.
The present work reveals that peroxidases are expressed in LG, however our interventions to challenge its behavior did not affect significantly its activity, expression or tissues integrity. In face of these results we concluded that peroxidases are not usefull as biomarkers of DE.
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