EVALUATION OF NOVEL EPILEPSY TREATMENT APPROACHES

这个项目的总体目标是调查 癫痫的药物治疗策略 动物模型的药理学研究。研究仍在继续 神经活性类固醇在癫痫中的作用及其临床意义 在癫痫治疗中的可能用途。神经活性类固醇是 内源性类固醇激素(及其合成类似物) 通过直接作用于神经元，迅速改变神经元的兴奋性 膜离子通道，包括GABA-A和NMDA 感受器。在以前的报告期内，几个结构上相关的 神经活性类固醇被证明是有效的。 抗惊厥药在小鼠戊四氮(PTZ)惊厥试验中的应用 一种与它们增强能力有关的效果 GABA诱发的氯离子电流。此外，还表明， GABA增强型神经活性类固醇对糖尿病有很强的保护作用 癫痫持续状态模型。慢性治疗研究表明 与其他增强GABA的药物不同，耐受性不 发展到神经活性类固醇的抗惊厥活性， 支持它们在癫痫治疗中的潜在效用。其他内容 研究检测了黄体酮的抗惊厥活性。 目的是探索为什么癫痫发作频率的波动 常见于月经期间和怀孕后的女性。 黄体酮被证明是一种有效的抗惊厥药物 PTZ测试，这一活动进一步被证明是由于 孕酮(通过5α-羟基酶同工酶)转化为 GABA增强型神经活性类固醇别孕酮。这个 结果表明，神经活性类固醇可能在 随病情变化而加重的癫痫的治疗 月经周期中的孕酮水平(月经性癫痫) 并在怀孕后。在本报告所述期间，研究 对内源性的孕烯醇酮硫酸盐(PS)进行了研究 神经活性类固醇，此前已被证明具有拮抗作用 GABA-A受体介导的抑制性反应及增强作用 NMDA受体在体外介导的兴奋性反应。评估 类固醇作为癫痫敏感性调节剂在癫痫发作中的作用 小鼠侧脑室注射PS。PS 引发边缘、阵挛和强直性发作，进展到状态 癫痫。对PS诱导的癫痫发作和致死性的保护 是由GABA-A受体阳性的变构 调节剂氯硝西潘和别孕酮，以及NMDA 受体拮抗剂地佐西平和(R)-CPP。药理学 Profile提示PS的惊厥作用是由 主要通过其对GABA-A受体的影响，也 可能是通过对NMDA受体的影响。这些观察结果引发了 PS作为一种内源性调节因子的可能性 癫痫敏感度。

The overall goal of this project is to investigate strategies for the drug treatment of epilepsy through pharmacological studies in animal models. Research was continued evaluating the role of neuroactive steroids in epilepsy and their possible uses in epilepsy therapy. Neuroactive steroids are endogenous steroid hormones (and their synthetic analogs) that rapidly alter the excitability of neurons by direct actions on membrane ion channels, including the GABA-A and NMDA receptors. In prior reporting periods, several structurally-related neuroactive steroids were demonstrated to be potent anticonvulsants in the mouse pentylenetetrazol (PTZ) seizure test, an effect that was associate with their ability to potentiate GABA-evoked chloride currents. In addition, it was shown that GABA-potentiating neuroactive steroids are highly protective in models of status epilepticus. Chronic treatment studies indicated that unlike other GABA potentiating drugs tolerance does not develop to the anticonvulsant activity of neuroactive steroids, supporting their potential utility in seizure therapy. Additional studies have examined the anticonvulsant activity of progesterone with the aim of exploring why fluctuations in seizure frequency often occur in women during the menses and following pregnancy. Progesterone was demonstrated to be an effective anticonvulsant in the PTZ test, and this activity was further shown to be due to conversion of progesterone (via 5alpha-hydroxylase isoenzymes) to the GABA-potentiating neuroactive steroid allopregnanolone. The results suggest that neuroactive steroids could be of utility in the treatment of seizure exacerbations that occur with changing progesterone levels during the menstrual cycle (catamenial epilepsy) and following pregnancy. In the present reporting period, studies were conducted on pregnenolone sulfate (PS), an endogenous neuroactive steroid that has previously been shown to antagonize GABA-A-receptor-mediated inhibitory responses and potentiate NMDA receptor-mediated excitatory responses in vitro. To assess the actions of the steroid as a modulator of seizure susceptibility in vivo, PS was administered intracerebroventricularly in mice. PS elicited limbic, clonic and tonic seizures that progressed to status epilepticus. Protection against PS-induced seizures and lethality was conferred by the GABA-A receptor positive allosteric modulators clonazepam and allopregnanolone, and by the NMDA receptor antagonists dizocilpine and (R)-CPP. The pharmacological profile suggested that the convulsant actions of PS are mediated predominantly via its effects on GABA-A receptors, and also possibly by effects on NMDA receptors. These observations raise the possibility that PS may serve as an endogenous regulator of seizure susceptibility.