紫杉醇诱发神经痛中GABAB受体表达及MAPKs通路激活对中枢神经元递质释放的影响

It is quite common that paclitaxel, an antitumor agent, can induce neuropathic pain, but there are no effective treatments in clinical practice. The previous studies showed that there are down-regulation of GABAB receptors, up-regulation of p-CREB and increased glutamic acid neurotransmitter release in spinal cord dorsal horn neurons in rats with diabeteic neuropathic pain. It has been established that there are the same pathological changes and activation mechanism of MAPK pathway in paclitaxel and diabeteic induced neuropathic pain, but in paclitaxel-induced neuropathic pain, the effect of GABAB receptors expression and MAPKs pathway activatation on central neurotransmitter release is not clear. To explore the issue, by using selective GABAB receptors agonist and transcription factors antagonists, the study is to investigate the effect of paclitaxel on expression of GABAB receptors, activation of MAPKs pathway and expression of transcription factor in vitro, further to elucidate that NF-kB is the key target of mutual regulation of GABAB receptors and MAPKs pathway , and to explore the role of Ca2 + in this progress. Based on vitro experiments, by using model rats with paclitaxel-induced neuropatic pain and selective agonist/antagonist , this study is to explore the role of central GABAB receptors expression and MAPKs pathway activatation in neurotransmitter release in neurons of hippocampal and spinal cord dorsal horn in rats with paclitaxel-induced pain. This study is desiged to elucidate the pathogenesis in paclitaxel-induced neuropathic pain, and to provide new ideas for the further development of targeted medicines.

作为抗肿瘤药物，临床紫杉醇诱发神经病理痛很常见，目前尚无有效治疗方法。课题组前期研究表明糖尿病神经痛大鼠脊髓背角神经元GABAB受体表达下调、而p-CREB表达上调，谷氨酸释放增多。目前已证实紫杉醇与糖尿病诱发神经痛有相同病理改变及MAPKs通路激活机制，但紫杉醇诱发神经痛中GABAB受体表达变化及MAPKs通路激活对中枢神经元递质释放的影响尚不清楚。本研究利用选择性GABAB受体激动剂及各种转录因子抑制剂，体外水平研究紫杉醇对GABAB受体、MAPKs通路激活及转录因子表达的影响，阐明NF-kB作为关键靶点对GABAB受体与MAPKs通路调控机制，以及Ca2 +在其中的作用；在此基础上，利用紫杉醇诱发痛大鼠模型和选择性激动剂/抑制剂，探讨中枢GABAB受体表达变化及MAPK通路激活对海马/脊髓背角神经元递质释放的影响。该研究有助于阐明紫杉醇诱发痛的发生机制，为开发针对性药物提供新的思路。

作为抗肿瘤药物，临床紫杉醇诱发的神经病理痛很常见，目前尚无有效治疗方法。故本研究利用荧光标记激光共聚焦扫描显微镜、流式细胞、分子生物学和电生理等技术测定GABAB受体、核转录因子（NF-kB）及炎性因子（TNFα、IL-1β）等蛋白含量变化，（1）利用体外细胞培养技术，对紫杉醇影响海马神经元GABAB受体表达、MAPKs通路激活、二者间的调控机制及NF-kB在其中的作用进行了深入细致研究，结合受体阻断剂和转录因子抑制剂，发现了NF-kB是MAPKs通路激活调控GABAB受体的关键靶点，阐明了GABAB受体与MAPKs通路在氧化应激及促炎状态形成中的作用，为在体实验提供了理论基础。（2）通过制备紫杉醇诱发神经痛大鼠模型，率先发现了GABAB受体与MAPK通路相互调节机制，结合电生理技术，进一步证实了激活GABAB受体对神经元递质释放的影响。通过观察GABAB受体激动剂与NF-kB抑制剂联合应用的镇痛作用，证实了NF-kB在紫杉醇诱发神经痛大鼠神经免疫应激及炎症状态的形成中发挥关键作用，为化疗药对中枢神经元损伤提供了重要的理论依据。（3）从不同水平、不同角度阐明了GABAB受体与MAPKs通路在紫杉醇诱发神经痛中的作用，以及二者间相互调节对脊髓背角神经元兴奋性及递质释放的影响，为深入开发针对性药物提供新的思路。本研究不但发现了化疗药紫杉醇的中枢神经毒性，而且为其中枢损害的作用机制研究打开了新的领域，也为临床化疗药合理安全应用提供了可靠的理论依据。