Abstract
Purpose: :
To assess the effects of exogenous and endogenous arachidonic acid (AA) and prostaglandins (PG) on the glutathione (GSH) levels in SV40–transformed human lens epithelial cells (HLEC; SRA01/04) and rabbit lens epithelial cells (RLEC; N/N1003A).
Methods: :
The intracellular concentration of reduced GSH was quantified spectrophotometrically by conversion of DTNB (5, 5’–dithiobis–2–nitrobenzoic acid) and the GSH concentration calculated (mM/mg protein).
Results: :
The GSH concentration in RLEC (3.1±0.87 mM/mg protein) was slightly higher than in HLEC (1.99±0.14 mM/mg protein). The intracellular concentrations of GSH in HLEC and RLEC were not affected by overnight incubation in medium containing 500 ng/ml PGA2, PGE2, PGF1 or PGF2. The GSH and protein concentrations in cultures of HLEC and RLEC increased up to 2–fold in a dose–dependent manner following overnight incubation with PGD2. Cytotoxicity induced by AA in HLEC and RLEC was dose–dependent and caspase–3 dependent. Notably, the cyclooxygenase/glutathione S–transferase (GST) inhibitors Ebselen increased while indomethacin had no effect on GSH in HLEC.
Conclusions: :
Our data suggest that increased GSH levels in human and rabbit lens cell was due to lens cell growth induced by exogenous PGD2. These results are consistent with the suggestion that exogenous PGD2 stimulates lens cell growth while exogenous AA induces lens cell death in vitro. The Ebselen induced increase in GSH suggests inhibition of GST in lens cells.
Keywords: eicosanoids • cataract • growth factors/growth factor receptors