CYTOTOXIC EFFECTS OF 4-HYDROXYNONENAL IN PC12 CELLS: INVOLVEMENT OF NEUROTRANSMITTER RECEPTORS

Effect of 4-hydroxynonenal (HNE) was studied on the sensitivity of various neurotransmitter receptors in PC-12 cells. Initially, cytotoxicity profiling of HNE was carried out using HNE concentrations 0.1-50mM for 30min to 24h. The endpoints selected were, trypan blue dye exclusion, MTT, LDH release and neutral red uptake (NRU) assays. Significant cytotoxic responses were observed by minimum 2h of exposure, except for HNE at 50mM, where cytotoxicity was exerted even at 90min. HNE concentrations 10-50mM were found to be cytotoxic, 2-5mM cytostatic and 0.1-1mM non-cytotoxic. Neurotransmitter receptors studies were carried out using specific radioligands with selected doses of HNE (1, 10, 25 and 50mM for 1-8h). 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 even at lh exposure with 25 and 50mM concentrations of HNE. Whereas, significant inhibition in binding of 3H-Spiperone to DA-D2 receptor was started at 4h of exposure and continued till 8h. Specific binding with 3H-Fluinitrazepam and 3H-Ketanserin was reached to saturation at dose of 50mM for 4h and onwards. PC-12 cells have shown particular vulnerability to cytotoxic concentrations of HNE. Experimental HNE exposure provides an intriguing model of toxicant-cell interactions, which likely involved receptors in FINE neurotoxicity, lead neurodegeneration.