Abstract
Purpose: :
To study the protective effects of 0.1% brimonidine tartrate on ARPE-19 and Müller Cells (MIO-M1) exposed to hydroquinone (HQ), one of the toxic components of cigarette smoke.
Methods: :
ARPE-19 and MIO-M1 cells were initially pre-treated for 6 hours with one of four different concentrations of 0.1% brimonidine tartrate ophthalmic solution 0.1%, (1/2 x, 1x, 5x,10x ). The clinical dose (1x) is defined as the amount of drug in 0.1 ml of 0.1% brimonidine if injected into the 4ml human vitreous. After 6 hours of brimonidine pre-treatment, cells were exposed to 100 µM HQ for 24 hours while brimonidine was still present. Cell viability (CV) was measured by a trypan blue dye exclusion assay. JC-1assay was performed to evaluate the mitochondrial membrane potential (ΔΨm).
Results: :
CV for ARPE-19 cells treated with 100µM HQ alone was 27.92±0.65. ARPE-19 cells pre-treated with brimonidine showed statistically significant improvement in CV at all doses: 1/2X (46.07±0.89; P<0.0001), 1X (46.07±0.084; P<0.0001), 5X (76.02±1.18; P<0.0001); and 10X (77.8±1.05; P<0.0001)., CV for MIO-M1 showed a similar significant increase in CV at all doses compared to 100 µM HQ alone: 63,67±0.6(P<0.0001), 67.23±0.49 (P<0.0001), 67.7±0.81(P<0.0001), and 78.27±0.62(P<0.0001) for 1/2X, 1X, 5X, and 10X respectively. ΔΨm of ARPE19 showed statistically significant improvements with brimodine pre-treatment at all doses but MIO-M1 cells showed a significant improvement only at 5X ad 10X doses. ARPE-19 cells showed ΔΨm of 4.825±0.58(P<0.0033), 4.913±0.41(P<0.0008), 5.665±(P<0.0001) and 7.818(P<0.0001) for 1/2X, 1X, 5X, and 10X respectively compared to 100µM HQ alone 4.383±0.74. MIO-M1 cells showed ΔΨm of 4.705±0.72(P>0.67), 4.880±0.30(P>0.06), 5.665±0.465(P<0.0001) and 7.785±0.31(P<0.0001) for 1/2X, 1X, 5X, and 10X respectively compared to 100µM HQ alone 4.634±1.07.
Conclusions: :
Brimonidine 0.1% exerts an in vitro protective effect against HQ induced toxicity on human retinal pigment epithelial (ARPE-19) and Müller (MIO-M1) cells
Keywords: drug toxicity/drug effects • retinal culture • neuroprotection