The expression of neuronal nicotinic acetylcholine receptors (nAChRs) influenced by lipid peroxidation has been investigated. The results showed that exposure of PC12 cells to a free radical insult (FeSO 4 ) induced concentration-dependent increase in level of MDA (malondialdehyde), and a significant decline in MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide] reduction. In cultured cells exposed to FeSO 4 , a significant dose-dependent decrease in [ 3 H] epibatidine binding sites was detected and a significant reduction in B m a x value was observed in the high affinity epibatidine binding site. These results demonstrate that lipid peroxidation in cellular membranes can induce a reduction in numbers of neuronal nAChRs.