N-Acetylcysteine Impairs Survival of Luteal Cells Through Mitochondrial Dysfunction

N-acetylcysteine (NAG) is known as an antioxidant and used for mucus viscosity reduction. However, this drug prevents or induces cell death depending on the cell type. The response of steroidogenic luteal cells to NAC is unknown. Our data shows that NAG can behave as an antioxidant or prooxidant in dependency on the concentration and mitochondrial energization. NAG elevated the flowcytometric-measured portion of hypodiploid (dying) cells. This rise was completely abolished by aurintricarboxylic acid, an inhibitor of topoisomerase II. NAG increased the secretion of nitric oxide and cellular nitrotyrosine. An image analysis indicated that cells pretreated with NAG and loaded with DHR showed a fluorescent structure probably elicited by the oxidative product of DHR, rhodamine 123 that sequesters mitochondrially. Pretreating luteal cells with NAG or adding NAG directly to mitochondrial fractions followed by assessing the mitochondrial transmembrane potential difference (Delta psi) by the JC-1 technique demonstrated a marked decrease in Delta psi. A protonophore restored Delta psi and rotenone (an inhibitor of respiratory chain complex I) inhibited mitochondria] recovering. Thus, in steroidogenic luteal cells from healthy mature corpus luteum, NAG impairs cellular survival by interfering with mitochondrial metabolism. The protonophore-induced recovering of NAG-provoked decrease in 64 indicates that an ATP synthase-favored route of H+ re-entry to the matrix is essentially switched off by NAG while other respiratory chain complexes remain intact. These data may be important for therapeutic timing of treatments with NAG. (C) 2010 International Society for Advancement of Cytometry