In Vivo Neurochemical Imaging Studies

体内神经化学成像研究

• 批准号: 6104223
• 负责人: ALLEN R BRAUN
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON DEAFNESS AND OTHER COMMUNICATION DISORDERS
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6104223
• 关键词: Primates; Rodentias; adenylate cyclase; autoradiography; biological models; biological signal transduction; blood brain barrier; brain metabolism; chemical synthesis; fluorine; forskolin; model design /development; neurochemistry; neuropharmacology; positron emission tomography; radiochemistry; radionuclide imaging /scanning; radiotracer

To develop methods for in vivo imaging of CNS receptor and signal transduction mechanisms, radiolabeled ligands with appropriate SAR requirements are being produced and used to develop in vivo animal models, and will lead ultimately to studies in human subjects. Synthetic organic chemistry techniques are used to produce cold-labeled derivatives of candidate compounds to determine SAR in displacement assays using standard beta (C-14 or H-3) or gamma (I-125) emitting radioligands. If cold-labeled compounds retain activity, techniques are developed for rapid radiosynthesis. Positron (F-18, C-11, N-13) or single photon (I- 123, In-111, Tc-99m) emitting derivatives are used in initial in vivo studies to determine blood brain barrier penetration and in vivo activity; both autoradiographic and external imaging (high resolution small animal PET) techniques are used. Tracer kinetic (bolus or equilibrium) models have been developed in rodents and primates, and validated using activation and displacement techniques. A cold-fluorinated (fluoroethyl-carbamate) derivative of forskolin was previously synthesized, and high affinity (Kd < 40 nM), saturable binding to adenylyl cyclase demonstrated in vitro. A tritiated derivative of this compound has now been shown to cross the blood brain barrier in sufficient concentration (< 1% of injected dose/g) when administered in vivo to rodents to allow PET imaging when labeled with F-18. The tritiated compound accumulated in brain areas following in vivo infusion at a rate proportional to regional adenylyl cyclase concentration. The binding of the labeled forskolin to isoforms type II and V has additionally been shown to be sensitive to activation of the enzyme by Gs-alpha-GTP. These features will be capitalized upon to develop tracer kinetic models, ultimately permitting dynamic imaging of adenylyl cyclase activity in vivo using PET. Results of the above studies are being prepared for publication. F-18 labeling of the fluoroethyl-carbamate forskolin derivative has been successfully carried out and pilot PET studies in non-human primates are currently being analyzed. Further studies to determine how the binding of fluoroethyl-carbamate forskolin to the various cyclase isoforms might be similarly affected by calcium-calmodulin, PKC, and beta-gamma subunits of the G-protein complex are underway. Pilot studies evaluating voltage sensitive compounds for use in PET have been completed.

开发CNS体内成像的方法 受体和信号转导机制，放射性标记的配体 有了适当的SAR要求，正在生产并习惯 发展体内动物模型，并最终导致研究 人类主题。合成有机化学技术用于 生产候选化合物的冷标记衍生物 使用标准β（C-14或 H-3）或伽马（I-125）发射放射性物体。如果是冷标记的 化合物保留活性，开发了用于快速的技术 辐射合成。正电子（F-18，C-11，N-13）或单个光子（I-） 123，in-1111，tc-99m）发射衍生物用于初始体内 确定血脑屏障渗透和体内的研究 活动;放射自显影和外部成像（高 分辨率小动物宠物）技术。示踪剂动力学 （推注或平衡）模型已在啮齿动物和 灵长类动物，并使用激活和位移进行验证 技术。 冷氟（氟乙基 - 氨基甲酸酯）衍生物 先前合成了福斯科林的，高亲和力（kd <40 NM），与腺苷环酶的饱和结合在体外表现出。一个 现已显示，该化合物的衍生化衍生物已被证明 足够浓度的血脑屏障（<1％的注射 剂量/g）当体内给啮齿动物施用以允许宠物成像 用F-18标记时。累积的曲折化合物 体内输注后的大脑区域，与 区域腺苷酸环化酶浓度。标记的结合 Forskolin至II型同工型，V还显示为 通过GS-Alpha-GTP对酶的激活敏感。这些 功能将被大写以开发示踪动力学模型， 最终允许腺苷酸环化酶活性的动态成像 在体内使用宠物。上述研究的结果正在准备 出版。 F-18标记氟乙酯福克林 衍生物已成功进行，并在 目前正在分析非人类灵长类动物。进一步的研究 确定氟乙基 - 氨基甲酸酯Forskolin与 各种环化酶同工型可能会受到类似的影响 钙 - 钙调蛋白，PKC和β-gamma亚基 G蛋白复合物正在进行中。试点研究评估电压 用于宠物的敏感化合物已完成。