NEUROBIOLOGY OF ENDOMORPHINS IN SPINAL DORSAL HORN

脊髓背角内啡肽的神经生物学

• 批准号: 6330625
• 负责人: Nae J Dun
• 金额: $ 18.56万
• 依托单位: EAST TENNESSEE STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-12-01 至 2002-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6330625
• 关键词: C fiber; G protein; biological signal transduction; calcium channel blockers; calcium flux; dorsal horn; electrophysiology; endogenous opioid; heat stimulus; immunocytochemistry; laboratory rat; mechanical pressure; membrane potentials; naloxone; naltrexone; neuropeptide receptor; opioid receptor; organ culture; pain; pertussis toxin; potassium channel; somatic afferent nerve; substance P; tachykinin; voltage /patch clamp

Substantia gelatinosa (SG) neurons in the spinal cord are the principal site of termination of primary afferents, many of which innervate nociceptors. Endogenous opiates or synthetic compounds are thought to produce their anti-nociceptors. Endogenous opiates or synthetic compounds are thought to produce their anti-nociception by interacting with subtypes of opiate receptors on SG neurons. Two recently isolated tetrapeptides endomorphin (Endo) 1 and 2 are believed to be the endogenous ligand for the mu-subtype of opioid receptors. Preliminary results showed endomorphin-like immunoreactivity (Endo-LI) subtype of opioid receptors. Preliminary results showed that endomorphin-like immunoreactivity (Endo-LI) is localized to dense networks of nerve fibers in the superficial layers of the rat dorsal horn. Thus, the rat dorsal horn offers a unique opportunity to test the hypothesis that Endo-1/Endo-2 is released endogenously and that it may modulate the activity of SG neurons. Two major issues will be addressed. First, release of endogenous of endogenous endomorphins will be evaluated in anesthetized rats in vivo or isolated rat spinal cords in vitro by the radioactive microprobe techniques. Electrical stimulation of afferent fibers of painful stimulus to the hindpaw will be employed to evaluate whether or not endomorphin release is altered under these conditions. Second, whole-cell patch recording techniques will be used to study the cellular action and the signal transduction mechanism underlying the action of Endo on single SG neurons in rat transverse spinal cord slices. Our preliminary results show that Endo inhibits the activity of SG neurons by hyperpolarizing the membrane and/or attenuating synaptic transmission. In this proposal, the pre- and post-synaptic actions of Endo will be evaluated electrophysiologically and pharmacologically. The subtype(s) of K+ channels that may underlie the hyperpolarizing action of Endo will be examined. Similarly, the subtype(s) of Ca2+ and/or K+ channels coupled to the presynaptic opiate receptor that may mediate the synaptic depressant action of Endo will be evaluated. The long term goal of this project is to improve our current understanding of the site and mechanism of action of this new class of opioid peptides on dorsal horn neurons, with the aim toward developing a novel class of opiate compounds with therapeutic potentials.

脊髓中的明质（SG）神经元是主要传入的主要部位，其中许多神经伤害感受器。内源性阿片类药物或合成化合物被认为会产生其抗伤心者。内源性阿片类药物或合成化合物被认为通过与SG神经元上鸦片受体的亚型相互作用来产生其抗吸引力。据信，最近有两个分离的四肽内啡吗啡（Endo）1和2是阿片受体的MU囊型的内源配体。初步结果显示阿片类药物受体的内胚蛋白样免疫反应性（ENDO-LI）亚型。初步结果表明，内胚蛋白样免疫反应性（Endo-LI）位于大鼠背角表层层中神经纤维的致密网络。因此，大鼠背角提供了一个独特的机会来测试内源性释放eNDO-1/endo-2的假设，并且可能调节SG神经元的活性。将解决两个主要问题。首先，将通过放射性微探针技术在体内或分离的大鼠脊髓中的麻醉大鼠或分离的大鼠脊髓中释放内源性内源性内吗啡。将采用对后爪刺激的传入纤维的电刺激，以评估在这些条件下的内啡肽释放是否改变。其次，全细胞贴片记录技术将用于研究细胞作用和信号转导机制，该机制在大鼠横向脊髓切片中内托对单个SG神经元作用的作用。 我们的初步结果表明，通过使膜超极化和/或衰减突触传播的超极化来抑制SG神经元的活性。在此提案中，将在电生理学和药理学上评估内托的前后突触后作用。将检查可能构成内托超极化作用的K+通道的亚型。类似地，将评估Ca2+和/或K+通道的亚型与突触前的阿片受体结合，可能会评估可能介导ENDO的突触抑制作用的作用。该项目的长期目标是提高我们对这种新的阿片类肽在背角神经元上的现场的理解和作用机理，旨在开发具有治疗潜力的新型阿片类化合物。