Mechanisms and Consequences of Locus Coeruleus Activation

描述（由申请人提供）：神经性疼痛反映了外周、脊髓和脊髓上结构的无数变化。有趣的是，尽管这种令人困惑的变化，许多批准的治疗神经性疼痛招募，增强，或模拟球脊髓抑制，包括吗啡，去甲肾上腺素（NA）再摄取抑制剂，可乐定。尽管临床研究表明神经性疼痛患者存在下行抑制的基线缺陷，但我们认为该通路的激活是几种有效和获批治疗方法的关键机制。加巴喷丁（GBP）常用于治疗神经病理性疼痛，但其镇痛机制尚不完全清楚。我们最近证明GBP激活蓝斑（LC）神经元通过神经元能信号和GBP在周围神经损伤的大鼠的抗过敏作用依赖于这种激活和随后的脊髓NA释放。本提案的目标是确定GBP调节谷氨酸释放以激活LC的机制，并确定GBP对LC神经元输入的机制是否适用于全局或特定于镇痛和不良反应（如嗜睡、注意力下降和记忆保持）的子集。首先，我们将研究GBP调制GABA调节突触前谷氨酸释放的LC突触体和微透析的机制。其次，我们将研究GBP调节独特的星形胶质细胞-神经元相互作用的LC，以增加细胞外谷氨酸，使用培养的星形胶质细胞和微透析的机制。最后，我们将管理GBP在LC和比较NA释放在脊髓，前额叶皮层，腹外侧视前区的下丘脑，背侧海马通过微透析测试是否GBP诱导激活LC是一个全球性的现象或选择性的控制疼痛，注意力，唤醒和记忆的投射。本实验不仅为了解GBP的镇痛机制提供了重要信息，而且为神经病理性疼痛的治疗提供了新的假说。

DESCRIPTION (provided by applicant): Neuropathic pain reflects a myriad of changes in the periphery, spinal cord, and supra-spinal structures. Interestingly, despite this baffling array of changes, many approved treatments for neuropathic pain recruit, augment, or mimic bulbospinal inhibition including morphine, noradrenaline (NA) re-uptake inhibitors, and clonidine. Although clinical studies suggest a baseline deficit of descending inhibition in patients with neuropathic pain, we believe that activation of this pathway is a key mechanism engaged by several effective and approved treatments. Gabapentin (GBP) is commonly used for treatment of neuropathic pain but its mechanisms for analgesia are not entirely known. We recently demonstrated GBP activates locus coeruleus (LC) neurons via glutamatergic signaling and that the anti-hypersensitivity effects of GBP in rats with peripheral nerve injury relies on this activation and subsequent spinal NA release. The goals of this proposal are to identify the mechanisms by which GBP regulates glutamate release to activate the LC and also to determine whether the mechanisms of GBP on input to LC neurons apply globally or specifically to subsets involved in analgesia and adverse effects such as somnolence, reduction of attention, and memory retention. Initially, we will examine mechanisms by which GBP modulates GABA regulation of pre-synaptic glutamate release in the LC using synaptosomes and microdialysis. Secondly, we will examine mechanisms by which GBP modulates the unique astroglial-neuronal interaction in the LC to increase extracellular glutamate, using cultured astrocytes and microdialysis. Lastly, we will administrate GBP in the LC and compare NA release in the spinal cord, prefrontal cortex, ventro-lateral preoptic area of the hypothalamus, and the dorsal hippocampus by using microdialysis to test whether GBP-induced activation in the LC is a global phenomenon or selective to projections controlling pain, attention, arousal and memory. The proposed experiments will not only provide important information for understanding analgesic mechanisms of GBP but also lead to novel hypothesis regarding the treatment of neuropathic pain.