An in vitro model of dorsal root ganglion (DRG) neurons to investigate the molecular mechanisms of oxaliplatin-induced peripheral neuropathy.

In our laboratory we characterized a cell model to study neuronal activity modulation and neuropathy. F11 is a hybrid cell line of rat dorsal root ganglion (DRG) neurons and mouse neuroblastoma N18TG-2 cells, which can be differentiated in mature DRG neurons through chemical agents. By maintaining for 14 days the cells in 1 % serum, the most physiological differentiating method, we obtained morphologically mature neurons which we characterized by immunocytochemistry methods and functional techniques. Electrophysiological recordings were performed by the patch-clamp technique in the whole-cell configuration, in the voltage- and current-clamp modes. The information we extracted from the experiments was represented by sodium and potassium current densities, resting membrane potential measurements, the generation of spontaneous or induced action potentials. Differentiated F11 cells showed increasing of sodium current density and of spontaneous electrical activity (78 % vs 29 % of undifferentiated cells), exhibited neuritic-like processes, and expressed neuronal markers. These data demonstrated that differentiated F11 cells are functional mature neurons. Moreover F11 differentiated cells responded to acetylcholine, capsaicin, glutamate and low pH, demonstrating the expression of typical receptors of sensory neurons and the formation of mature circuits with the release of excitatory neurotransmitters. Since F11 differentiated cells are a good model to study neuronal activity modulation, we have recently started studying the effects of oxaliplatin (OXA), an anti-cancer molecule known to cause peripheral neurotoxicity as the most common side effect. We tested the drug (7,5 µM for 24 h) on differentiated F11 cells to investigate the molecular targets of the neuropathic symptoms manifested in treated patients. Electrophysiological recordings showed effects of OXA on voltage-gated sodium channels, in particular a shift of both activation and inactivation properties. Moreover, we reported for the first time an effect of OXA on ERG (ether-à-go-go-related gene) potassium channel. These effects on both sodium and potassium channels could explain the membrane depolarization and the change in the electrical activity we recorded in OXA-treated cells, which seem to correspond with acute OXA induced peripheral neurotoxicit.