BRAIN TARGETING OF THYROTROPIN RELEASING HORMONE ANALOGS

促甲状腺激素释放激素类似物的大脑靶向

• 批准号: 2908258
• 负责人: LASZLO PROKAI
• 金额: $ 23.55万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-05 至 2003-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2908258
• 关键词: acetylcholine; amidine lyase; bioimaging /biomedical imaging; biotransformation; blood brain barrier; brain metabolism; drug delivery systems; drug design /synthesis /production; drug screening /evaluation; enzyme activity; esterase; frontal lobe /cortex; hormone receptor; hypothalamus; injection /infusion; laboratory mouse; laboratory rat; microdialysis; neuronal transport; neuropharmacology; pentobarbital; peptide hormone analog; pharmacokinetics; radiotracer; receptor binding; thyrotropin releasing hormone

Thyrotropin-releasing hormone (TRH) analogues offer potential treatment of various maladies of the central nervous system (associated mainly with cholinergic hypofunction due to motorneuron diseases, Alzheimer's disease, electroconvulsive shock therapy, etc.). The main objective of the project is to develop and evaluate chemical delivery systems for targeting centrally active analogues into the central nervous system (CNS) by a chemical-enzymatic approach. Due to covalently attached lipophilic functional groups (a 1,4-dihydrotrigonellyl and a lipophilic moiety) a "packaged" peptide crosses the BBB by passive transport and, once in the CNS, converts to an ionic trigonellyl derivative that is retained at the target site. Then, the biologically active peptide is obtained by sequential metabolism. New brain-targeting systems will be designed and synthesized based on systematically modifying a lead compound ([Leu2]TRH) to improve sequestration of the analog in the brain and/or enhance post-delivery stability of the biologically active peptide. These modifications will allow for a decrease of the systemically administered dose and also for an increase in the residence time of the experimental or therapeutic agent in the CNS. Our hypothesis is that the efficacy of CNS-sequestration can be improved by using alpha-hydroxyglycine to achieve carboxy-terminal amidation via peptidylamidoglycolate lyase (PGL, EC 4.3.2.5) action because of the higher rate of enzymatic bioactivation after esterase cleavage of the protecting ester function. Analogues in which the carboxy-terminal prolinamide is replaced by L-pipecolic acid or the amino-terminal pyroglutaminyl residue is subtituted by an unnatural moiety will also be incorporated into appropriate targeting systems. The design and development will be supported by theoretical calculations. The newly designed analogs will be tested for binding to brain TRH receptors to compare their intrinsic activity with that of the lead compound. In vitro stability and metabolism experiments will address optimization and practical development. Stability studies in brain tissue will address rates, sites and extent of peptide activation and/or cleavage to probe crucial steps in the CNS-sequestration. In vivo distribution and metabolism studies will assess the efficacy of the strategy to transport and sequester the TRH analogs in the brain. We will examine pharmacokinetics of brain-delivery, "lock-in" of the predicted precursors, and the release of the biologically active peptide after parenteral administration of the synthesized targeting systems. Comparative pharmacodynamic evaluation of the effect of brain-delivered analogues will be addressed via in vivo cerebral microdialysis studies in which changes in acetylcholine levels due to treatment will be assayed. Ultimately, pharmacological experiments will be carried out in animals to survey the potential of the approach to treat maladies associated with the loss of cholinergic functions. The antagonism of pentobarbital-induced sleeping will be used as general paradigm to assess the acute effects of brain-targeted compounds. Behavioral observations, dose-dependence and duration of action will also be addressed by appropriate method or study designs.

甲状腺蛋白释放激素（TRH）类似物提供了中枢神经系统各种疾病的潜在治疗方法（主要与胆碱能功能低下有关，这是由于胆碱能疾病引起的疾病，阿尔茨海默氏病，静电性休克疗法等）。 该项目的主要目的是通过化学酶方法开发和评估用于将中心活动类似物（CNS）靶向中央活动的化学输送系统。 由于共同附着的亲脂性官能团（1,4-二氢三甲基甲基烷烷和亲脂性部分）“包装”的肽通过被动转运横穿BBB，并且在中枢神经系统中，将其转换为在目标位置保留的离子三角素衍生物。然后，通过顺序代谢获得生物活性肽。 将根据系统地修饰铅化合物（[LEU2] TRH）来设计和合成新的脑靶向系统，以改善大脑中的类似物的隔离和/或增强生物活性肽的递送后稳定性。 这些修饰将允许降低系统施用的剂量，并增加CNS实验或治疗剂的停留时间。 Our hypothesis is that the efficacy of CNS-sequestration can be improved by using alpha-hydroxyglycine to achieve carboxy-terminal amidation via peptidylamidoglycolate lyase (PGL, EC 4.3.2.5) action because of the higher rate of enzymatic bioactivation after esterase cleavage of the protecting ester function. 羧基末端五氧胺被L-二脂酸取代或氨基末端焦谷氨酰氨基蛋白基残基的类似物也将被非自然部分订立在适当的靶向系统中。 设计和开发将由理论计算支持。 新设计的类似物将进行测试，以与脑TRH受体结合，以将其内在活性与铅化合物的活性进行比较。 体外稳定性和代谢实验将解决优化和实际发展。 脑组织中的稳定性研究将解决肽激活和/或裂解的速率，位点和程度，以探测CNS序列中的关键步骤。 体内分布和代谢研究将评估运输和隔离大脑中TRH类似物的策略的功效。 我们将检查脑外生物术后肠胃外置换型靶向系统后的脑部传递，预测前体的“锁定”的药代动力学。 通过体内脑透析研究将解决对脑部分割类似物的影响的比较药效学评估，其中将分析乙酰胆碱水平的变化。最终，将在动物中进行药理学实验，以调查治疗与胆碱能功能丧失相关的疾病方法的潜力。 戊巴比妥诱导的睡眠的拮抗作用将用作一般范式，以评估靶向脑靶向化合物的急性作用。行为观察，剂量依赖性和作用持续时间也将通过适当的方法或研究设计来解决。