Stilwell Geoff E, Saraswati Sudipta, Littleton J Troy, Chouinard Scott W
Cambria Biosciences, 8A Henshaw St., Woburn, MA 01801, USA.
Eur J Neurosci. 2006 Oct;24(8):2211-22. doi: 10.1111/j.1460-9568.2006.05075.x.
An important application of model organisms in neurological research has been to identify and characterise therapeutic approaches for epilepsy, a recurrent seizure disorder that affects > 1% of the human population. Proconvulsant-treated rodent models have been widely used for antiepileptic drug discovery and development, but are not suitable for high-throughput screening. To generate a genetically tractable model that would be suitable for large-scale, high-throughput screening for antiepileptic drug candidates, we characterized a Drosophila chemical treatment model using the GABA(A) receptor antagonist picrotoxin. This proconvulsant, delivered to Drosophila larvae via simple feeding methods suitable for automated screening, generated robust generalised seizures with lethality occurring at doses between 0.3 and 0.5 mg/mL. Electrophysiological analysis of CNS motor neuron output in picrotoxin-treated larvae revealed generalised seizures within minutes of drug exposure. At subthreshold doses for seizure induction, picrotoxin produced an increased frequency of motor neuron action potential bursting, indicating that CNS GABAergic transmission regulates patterned activity. Mutants in the Drosophila Rdl GABA(A) receptor are resistant to picrotoxin, confirming that seizure induction occurs via a conserved GABA(A) receptor pathway. To validate the usefulness of this model for in vivo drug screening, we identified several classes of neuroactive antiepileptic compounds in a pilot screen, including phenytoin and nifedipine, which can rescue the seizures and lethal neurotoxicity induced by picrotoxin. The well-defined actions of picrotoxin in Drosophila and the ease with which compounds can be assayed for antiseizure activity makes this genetically tractable model attractive for high-throughput in vivo screens to identify novel anticonvulsants and seizure susceptibility loci.
模式生物在神经学研究中的一个重要应用是识别和表征癫痫的治疗方法，癫痫是一种复发性发作性疾病，影响着超过1%的人类人口。经促惊厥剂处理的啮齿动物模型已被广泛用于抗癫痫药物的发现和开发，但不适用于高通量筛选。为了生成一个适合大规模、高通量筛选抗癫痫药物候选物的遗传易处理模型，我们使用GABA(A)受体拮抗剂印防己毒素对果蝇化学处理模型进行了表征。这种促惊厥剂通过适合自动筛选的简单喂食方法递送至果蝇幼虫，产生强烈的全身性癫痫发作，致死剂量在0.3至0.5 mg/mL之间。对经印防己毒素处理的幼虫的中枢神经系统运动神经元输出进行电生理分析发现，药物暴露后几分钟内出现全身性癫痫发作。在诱导癫痫发作的阈下剂量下，印防己毒素使运动神经元动作电位爆发的频率增加，表明中枢神经系统GABA能传递调节模式化活动。果蝇Rdl GABA(A)受体的突变体对印防己毒素具有抗性，证实癫痫发作是通过保守的GABA(A)受体途径发生的。为了验证该模型在体内药物筛选中的有用性，我们在初步筛选中鉴定了几类神经活性抗癫痫化合物，包括苯妥英和硝苯地平，它们可以挽救由印防己毒素诱导的癫痫发作和致死性神经毒性。印防己毒素在果蝇中的明确作用以及化合物抗癫痫活性检测的简便性，使得这个遗传易处理模型对于高通量体内筛选以识别新型抗惊厥剂和癫痫易感性位点具有吸引力。
