Abstract
Purpose: :
To study the in vitro effects of memantine, a neuroptotectant used in patients with Alzheimer’s disease and glaucoma, on human ARPE-19 and MIO-M1 cells exposed to hydroquinone (HQ), one of the toxic components of cigarette smoke
Methods: :
ARPE-19 and MIO-M1 cells were pretreated for 6 hours with 30µM of memantine and then exposed to 200µM, 100µM, 50µM and 25µM of HQ (dissolved in DMSO), while the memantine was still present. JC1 assay was performed to evaluate the mitochondrial membrane potential (ΔΨm). LDH production was measured by the LDH-Cytotoxicity Assay Kit II.
Results: :
The ΔΨm for ARPE-19 cells exposed to 200µM, 100µM, 50µM and 25µM of HQ was 3770±43.08, 4015±66.51, 5139±40.76 and 7475±94.06, respectively compared to the highest (200 µM) DMSO equivalent-treated cells (9097±76.06). Pretreatment with 30µM memantine resulted in an increased ΔΨm only at the 50 µM HQ dose, at the level of 6997±75.45 (p<0.0001). The values for memantine pretreated cultures plus 200µM, 100µM and 25µM HQ were 3777±23.23(p=0.8787), 4181±39.52(p =0.0573) and 7637±41.71(p =0.1461), respectively. ΔΨm for MIO-M1 treated cultures plus 200µM, 100µM, 50µM and 25µM HQ were 3275±81.50, 4527±61.49, 5625±57.80 and 7763±34.77, respectively compared to the highest (200 µM) DMSO equivalent -treated cells (9118±45.9). In the 50µM HQ dose, after memantine pretreatment the ΔΨm increased to 6695±34.03(p <0.0001 ). There were no statistically significant differences for the other HQ doses. LDH levels for ARPE-19 cells treated with 200µM, 100µM, 50µM and 25µM HQ were 5.50±0.25, 4.8±0.20, 4.16±0.06 and 2.0±0.10 . The LDH levels were decreased significantly after pretreated with memantine at 50 µM and 25 µM HQ doses to 2.233±0.08(p <0.0001) and 1.567±0.12(p< 0.0314). MIO-M1 cells treated with the same concentrations of HQ alone showed LDH levels of 6.20±0.11, 5.66±0.08, 5.35±0.13 and 2.06±0.03. The level of LDH decreased significantly after pretreatment with memantine only at the 25 µM HQ to 1.250±0.08 (p< 0.0007).
Conclusions: :
Memantine showed an in vitro protective effect against HQ induced toxicity by increasing the ΔΨm at 50µM HQ dose on both cell lines and decreasing LDH levels at 50µM and 25µM HQ doses in ARPE-19 cells and at the 25µM HQ dose on MIO-M1 cells.
Keywords: neuroprotection • retinal culture • Muller cells