Influence of cytotoxic doses of 4-hydroxynonenal on selected neurotransmitter receptors in PC-12 cells

Abstract

Effect of 4-hydroxynonenal (HNE), a long-chain alpha, beta unsaturated aldehyde product, generated by the oxidation of ω-6 polyunsaturated fatty acids on the sensitivity of selected neurotransmitter receptors was studied in PC-12 cells. Cytotoxicity profiling was carried out at varying concentrations of HNE (0.1–50 μM) for 30 min to 24 h. Trypan blue dye exclusion, MTT, LDH release and neutral red uptake (NRU) assays were carried out to assess the cytotoxicity of HNE. Cytotoxic response was found to be significant at 2 h of exposure. Cytotoxicity of HNE at 50 μM was exerted even at 90 min. HNE 10–50 μM was found to be cytotoxic, whereas, 2–5 μM causes physiological stress only and 1–0.1 μM non-cytotoxic. Effect on dopamine, cholinergic, serotonin and benzodiazepine receptors was studied at varying concentrations of HNE (1, 10, 25 and 50 μM for 1–8 h). A significant decrease in binding of 3H-QNB, 3H-Fluinitrazepam and 3H-Ketanserin, known to label cholinergic (muscarinic), benzodiazepine and serotonin (5HT2A) receptors respectively was observed at 1 h exposure of PC-12 cells to HNE at 25 and 50 μM concentrations. The decrease in the binding of 3H-Spiperone, known to label dopamine (DA-D2) receptors was evident at 4h of exposure of PC-12 cells to HNE. The decrease in the binding with DA-D2 receptors continued till 8h. Effect on the binding of 3H-Fluinitrazepam and 3H-Ketanserin appeared to be maximum at 25 and 50 μM concentrations of HNE for 4 h and 8 h. The PC-12 cells appear to be vulnerable to cytotoxic concentrations of HNE. Experimental HNE exposure provides an intriguing model of toxicant–cell interactions involving neurotransmitter receptors in HNE neurotoxicity.