EVALUATION OF NOVEL EPILEPSY TREATMENT APPROACHES

本项目的总体目标是调查 癫痫的药物治疗策略 动物模型中的药理学研究。研究继续进行 评估神经活性类固醇在癫痫中的作用及其 可能用于癫痫治疗。神经活性类固醇为 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， 膜离子通道，包括GABA-A和NMDA 受体。在以往报告所述期间， 神经活性类固醇被证明是有效的 在小鼠戊四唑（PTZ）癫痫发作试验中的抗惊厥药， 这种效应与它们增强 GABA诱发的氯电流。此外，研究表明， GABA增强的神经活性类固醇在以下方面具有高度保护性： 癫痫持续状态模型长期治疗研究表明， 与其他GABA增强药物的耐受性不同， 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。额外 研究已经检测了孕酮的抗惊厥活性 目的是探索为什么癫痫发作频率的波动 通常发生在妇女月经期间和怀孕后。 Progesterone被证明是一种有效的抗惊厥药， PTZ测试，这种活性进一步表明是由于 孕酮的转化（通过5 α-羟化酶同工酶）， GABA增强神经活性类固醇别孕烯醇酮。的 结果表明，神经活性类固醇可能是有用的， 癫痫发作恶化的治疗 月经周期中的孕酮水平（月经性癫痫） 和怀孕后。在本报告所述期间，研究 对内源性硫酸双烯醇酮（PS）进行了研究。 神经活性类固醇，以前已被证明可以拮抗 GABA-A受体介导的抑制反应和增强 NMDA受体介导的体外兴奋性反应。评估 类固醇作为癫痫易感性调节剂的作用， 在体内，在小鼠脑室内施用PS。PS 诱发边缘系统、阵挛性和强直性癫痫发作， 癫痫对PS诱导的癫痫发作和致死性的保护 是由GABA-A受体阳性变构 调节剂氯硝西泮和别孕醇酮，以及NMDA 受体拮抗剂地佐环平和（R）-CPP。药理 特征表明，PS的惊厥作用是介导的， 主要通过其对GABA-A受体的作用， 可能是通过对NMDA受体的影响。这些意见提出 PS可能作为一种内源性调节因子， 癫痫易感性

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.