MOLECULAR STUDIES OF BAB--LONG DURATION ANESTHETIC

治疗慢性疼痛的一种有前途的新方法是使用 直接将麻醉剂递送到患者体内的持续释放方法， 导致长期区域麻醉的背根。这通常 包括将麻醉剂溶解在悬浮液中， 硬膜外腔麻醉剂从悬浮液中慢慢渗出 为感觉神经纤维提供持续的麻醉源 导致疼痛的延长缓解。1987年，Shulman/37报告说， 对氨基苯甲酸正丁酯（BAB），一种酯 苯甲酸衍生物，在终末产生持久镇痛 癌症患者可以持续几个月。临床上，很少 BAB治疗已经确定了有害的副作用。 令人惊讶的是，BAB产生的疼痛缓解与任何 运动功能丧失。这表明BAB的作用是 选择性靶向背根神经节的伤害感受神经元 （DRG）。虽然BAB作为一种持久的麻醉剂显示出很大的希望， 慢性疼痛的治疗，BAB在细胞水平上的作用 不知道。初步研究表明BAB选择性抑制 电压门控Na通道。至少有五种不同的钠成分 电流有助于DRG神经元的动作电位。这 异质性严重阻碍了对BAB进行更详细的研究 行动上为了消除这种模糊性，我们计划 进一步研究了BAB对表达于 培养细胞并通过膜片钳技术记录。我们的实验 将重点关注外周神经（PN 1，PN 3）和大脑（RBI，rBIIA）Na 已知在DRG中表达的通道。我们计划使用网站- 定向诱变以表征这些的BAB结合位点 神经元Na通道此外，我们计划将我们的研究与 克隆通道与数据从天然神经元通过使用反义 选择性抑制天然DRG表达的寡脱氧核苷酸 钠通道。我们建议的研究将使我们更好地了解 BAB作用的分子机制及其对伤害性感受的影响 DRG的神经元。

A promising new approach for the treatment of chronic pain is the use of sustained release methodologies that directly deliver anesthetics to the dorsal roots resulting in long-term regional anesthesia. This usually involves dissolving anesthetics in suspensions that are injected into our epidural space. The slow leeching of the anesthetics from the suspension provides a constant source of anesthetic to the sensory nerve fibers resulting in the prolong relief of pain. In 1987 Shulman/37 reported that the epidural administration of n-butyl-p-aminobenzoate (BAB), an ester derivative of benzoic acid, produce long lasting analgesia in terminally ill cancer patients that can last up to several months. Clinically, few deleterious side effects have been identified with BAB treatment. Surprisingly, the pain relief produced by BAB is not associated with any demonstratable loss in motor function. This suggests that BAB acts by selectively targeting nociceptive neurons of the dorsal root ganglion (DRG). Although BAB shows great promise as a long-lasting anesthetic for the treatment of chronic pain, the effects of BAB at the cellular level are not known. Preliminary studies indicate that BAB selectively inhibits voltage-gated Na channels. At least five different components of Na current contribute to the action potentials of DRG neurons. This heterogeneity has significantly hampered more detailed studies of BAB action. In an attempt to eliminate some of this ambiguity, we plan to further study the effects of BAB on cloned Na channels expressed in cultured cells and recorded by patch clamp techniques. Our experiments will focus on the peripheral nerve (PN1, PN3) and brain (RBI, rBIIA) Na channels that are known to be expressed in the DRG. We plan to use site- directed mutagenesis to characterize the BAB binding sites of these neuronal Na channels. In addition we plan to correlate our studies of cloned channels with data from native neurons by using antisense oligodeoxynucleotides to selectively suppress the expression of native DRG Na channels. Our proposed studies will provide a better understanding of the molecular mechanism of BAB action and its effects on the nociceptive neurons of the DRG.