MODULATION OF SPINAL CORD NEUROPLASTICITY BY OPIOIDS

申请者摘要：此申请是对科学家的请求 发展奖。这个奖项是为了让我的全职研究 阿片类药物对脊髓神经传递的调节作用 以及突触的可塑性。这些新的研究经验在 我的导师的指导和更多的顾问将会装备我 在技术和实践上都要快速前进，成为一名 独立研究人员。 长时程增强(LTP)，迄今为止研究最好的模型， 中枢神经系统内的突触可塑性，涉及一种看似永久性的 反复激活后神经元兴奋性增加 传入神经元，并被认为是细胞 学习的基础。最近的临床和行为证据表明 累积表明大致相同的活动依赖型突触 参与痛觉的神经系统可能会发生变化。 强烈的疼痛刺激可产生中枢敏化作用 对实验动物和人类都有进一步的有害刺激。 对这种致敏作用的行为药理学研究表明 与LTP的神经化学有许多相似之处，包括其 依赖于NMDA类谷氨酸受体的激活和 某些鸦片类药物对它的调节作用。这里提出的研究包括 一种体外脊髓切片制备方法的应用研究 初级传入背角突触的阿片类调制 已知的参与伤害性感受的脊髓区域 正在处理。这些研究直接源于我们在 海马区LTP的诱导可以被kappa阿片类药物阻断。首字母 用新生大鼠横断脊髓切片进行实验 重点关注应用Mu、kappa和Delta阿片类药物在 调制刺激诱发的两种神经兴奋在大脑皮层I层 这一区域的背角和依赖活动的塑料变化。这些 研究将首先使用单细胞外记录技术，并 将从体外制剂中受益，使其能够应用 作用部位激动剂和拮抗剂的已知浓度 并且能够容易地可视化记录电极位置。 阳性的细胞外发现将使用完整的 细胞电压钳技术研究突触后机制 行动。此外，倒退地将荧光标记从 吻部脊髓丘脑束病变将用于靶向特定的 推测是脊髓丘脑细胞的伤害性反应。的影响 内源性Mu、Delta和Kappa类阿片对脊髓神经传递的影响 然后还将评估突触的可塑性。最后，这些结果 在新生儿脊髓中的作用将与使用 一种成人脊髓切片制剂。因此，使用体外模型和 各种电生理技术，希望能为大家提供洞察 初级传入神经传递的神经化学机制探讨 和神经可塑性以及Mu、kappa和Delta阿片的不同作用 在成人和新生儿中采取行动调节这些机制。是这样的 信息可能最终导致更好的药物治疗手段 管理和/或预防某些急性和慢性疼痛状态。

APPLICANT'S ABSTRACT: This application is a request for a Scientist Development Award. This award is sought to enable my full time research on the modulatory effects of opiates on spinal cord neurotransmission and synaptic plasticity. These new research experiences under the tutelage of my preceptor and additional consultants will equip me technically and practically to move forward quickly to become an independent researcher. Long term potentiation (LTP), the best studied model, to date, of synaptic plasticity within the CNS, involves a seemingly permanent increase in neuronal excitation following repeated activation of afferent input to that neuron and is thought to be the cellular basis of learning. Recent clinical and behavioral evidence has accumulated suggesting that much the same activity- dependent synaptic changes can take place in neural systems involved in pain perception. Intense painful stimuli can produce a central sensitization to further noxious stimulation in both laboratory animals and man. Behavioral pharmacologic studies of this sensitization suggest numerous similarities to the neurochemistry of LTP, including its reliance on activation of the NMDA class of glutamate receptors and its modulation by certain opiates. The studies proposed here involve the utilization of an in vitro spinal cord slice preparation to study the opioid modulation of primary afferent dorsal horn synapses in regions of the spinal cord known to be involved in nociceptive processing. These studies stem directly from our findings in the hippocampus that LTP induction can be blocked by kappa opioids. Initial experiments using the neonatal rat transverse spinal cord slice will focus on the actions of applied mu, kappa, and delta opioids in modulating both stimulation-evoked neural excitation in lamina I of the dorsal horn and activity-dependent plastic changes in this area. These studies will use single cell extracellular recording techniques first and will benefit from the in vitro preparation in enabling application of known concentrations of agonists and antagonists to the site of action and in allowing easy visualization of the recording electrode position. Positive extracellular findings will be further evaluated using whole cell voltage clamp techniques to study post-synaptic mechanisms of action. Further, retrogradely transported fluorescent markers from rostral spinothalamic tract lesions will be used to target specific presumably nociceptive spinothalamic cell responses. The effects of endogenous mu, delta and kappa opioids on spinal neurotransmission and synaptic plasticity will then also be evaluated. Finally, these results in neonatal spinal cord will be compared and contrasted to studies using an adult spinal cord slice preparation. Thus, using an in vitro model and a variety of electrophysiological techniques, we hope to provide insight into the neurochemical mechanisms of primary afferent neurotransmission and neuroplasticity and how mu, kappa, and delta opiates differentially act to modulate these mechanisms in the adult and neonate. Such information may ultimately lead to better pharmacological means of managing and/or preventing certain acute and chronic pain states.