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

Effect of 4-hydroxynonenal (HNE), a long-chain alpha, beta unsaturated aldehyde product, generated by the oxidation of omega-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 (0.1-50microM) for 30min to 24h. 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 2h of exposure. Cytotoxicity of HNE at 50microM was exerted even at 90min. HNE 10-50microM was found to be cytotoxic, whereas, 2-5microM causes physiological stress only and 1-0.1microM non-cytotoxic. Effect on dopamine, cholinergic, serotonin and benzodiazepine receptors was studied at varying concentrations of HNE (1, 10, 25 and 50microM for 1-8h). A significant decrease in binding of 3H-QNB, 3H-Fluinitrazepam and 3H-Ketanserin, known to label cholinergic (muscarinic), benzodiazepine and serotonin (5HT(2A)) receptors respectively was observed at 1h exposure of PC-12 cells to HNE at 25 and 50microM concentrations. The decrease in the binding of (3)H-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 (3)H-Fluinitrazepam and 3H-Ketanserin appeared to be maximum at 25 and 50microM concentrations of HNE for 4h and 8h. 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.