MODULATION OF SPINAL CORD NEUROPLASTICITY BY OPIOIDS

申请人摘要：本申请是对一名科学家的请求 发展奖。这个奖项旨在使我的全职研究 阿片类药物对脊髓神经传递的调节作用 和突触可塑性。 这些新的研究经验下， 导师的指导和其他顾问将使我 在技术上和实践上迅速前进，成为一个 独立研究员。 长时程增强（LTP）是迄今为止研究得最好的模型， 中枢神经系统内的突触可塑性，涉及一个看似永久的 重复激活后神经元兴奋增加 它被认为是细胞内 学习的基础。 最近的临床和行为证据表明， 这表明同样的活动依赖性突触 疼痛感知的神经系统会发生变化。 强烈的疼痛刺激可以产生中枢敏感性， 对实验室动物和人类造成进一步的有害刺激。 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， 通过某些鸦片制剂进行调节。 这里提出的研究涉及 利用离体脊髓片标本研究 阿片对大鼠初级传入背角突触调节 已知参与伤害感受的脊髓区域 处理.这些研究直接源于我们在 海马LTP诱导可被κ阿片类阻断。 初始 使用新生大鼠横断脊髓切片的实验将 重点关注应用的mu，kappa和delta阿片类药物在 调节刺激诱发的神经兴奋在板层I的 背角和活动依赖性的塑料变化在这方面。这些 研究将首先使用单细胞胞外记录技术， 将受益于体外制备， 作用部位的激动剂和拮抗剂的已知浓度 并且允许记录电极位置的容易可视化。 阳性细胞外结果将使用整体 细胞电压钳技术研究突触后机制 行动上此外，从细胞中逆行转运的荧光标记物 头侧脊髓丘脑束病变将用于靶向特定的 推测为伤害性脊髓丘脑细胞反应。的影响 内源性μ、δ和κ阿片类物质对脊髓神经传递的影响， 然后还将评估突触可塑性。最后，这些结果 在新生儿脊髓将进行比较和对比的研究， 成人脊髓切片制备。因此，使用体外模型和 各种电生理技术，我们希望提供洞察力， 初级传入神经传递的神经化学机制 和神经可塑性，以及mu，kappa和delta阿片类药物 在成人和新生儿中调节这些机制。等 信息可能最终导致更好的药理学手段， 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.