RS-100642-198, a novel sodium channel blocker, provides differential neuroprotection against hypoxia/hypoglycemia, veratridine or glutamate-mediated neurotoxicity in primary cultures of rat cerebellar neurons |
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Authors: | Jitendra R Dave Yu Lin Haresh S Ved Michael L Koenig Larry Clapp John Hunter Frank C Tortella |
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Institution: | (1) Neurorestoration Group, Wolfson CARD, King’s College London, London, SE1 9RT, UK; |
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Abstract: | The present study investigated the effects of RS-100642-198 (a novel sodium channel blocker), and two related compounds (mexiletine and QX-314), inin vitro models of neurotoxicity. Neurotoxicity was produced in primary cerebellar cultures using hypoxia/hypoglycemia (H/H), veratridine or glutamate where, in vehicle-treated neurons, 65%, 60% and 75% neuronal injury was measured, respectively. Dose-response neuroprotection experiments were carried out using concentrations ranging from 0.1-500 μM. All the sodium channel blockers were neuroprotective against H/H-induced injury, with each exhibiting similar potency and efficacy. However, against veratridine-induced neuronal injury only RS-100642-198 and mexiletine were 100% protective, whereas QX-314 neuroprotection was limited (i.e. only 54%). In contrast, RS 100642-198 and mexiletine had no effect against glutamate-induced injury, whereas QX-314 produced a consistent, but very limited (i.e. 25%), neuroprotection. Measurements of intraneuronal calcium (Ca2+];) mobilization revealed that glutamate caused immediate and sustained increases in Ca2+]i which were not affected by RS-100642-198 or mexiletine. However, both drugs decreased the initial amplitude and attenuated the sustained rise in Ca2+]i mobilization produced by veratridine or KC1 depolarization. QX-314 produced similar effects on glutamate-, veratridineor KC1-induced Ca2+]i dynamics, effectively decreasing the amplitude and delaying the initial spike in Ca2+]i, and attenuating the sustained increase in Ca2+]i mobilization. By using differentin vitro models of excitotoxicity, a heterogeneous profile of neuroprotective effects resulting from sodium channel blockade has been described for RS-100642-198 and related drugs, suggesting that selective blockade of neuronal sodium channels in pathological conditions may provide therapeutic neuroprotection against depolarization/excitotoxicity via inhibition of voltage-dependent Na+ channels. |
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