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: 6186589
• 负责人: LASZLO PROKAI
• 金额: $ 23.18万
• 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/6186589
• 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.

促甲状腺激素释放激素（TRH）类似物提供了对中枢神经系统的各种疾病（主要与由于运动神经元疾病、阿尔茨海默病、电休克疗法等引起的胆碱能功能减退相关）的潜在治疗。 该项目的主要目标是开发和评估化学输送系统，通过化学-酶法将中枢活性类似物靶向中枢神经系统（CNS）。 由于共价连接的亲脂性官能团（1，4-二氢胡芦巴基和亲脂性部分），“包装”肽通过被动转运穿过BBB，并且一旦进入CNS，转化为保留在靶位点的离子胡芦巴基衍生物。然后，通过顺序代谢获得生物活性肽。 新的脑靶向系统将基于系统地修饰先导化合物（[Leu 2]TRH）来设计和合成，以改善类似物在脑中的螯合和/或增强生物活性肽的递送后稳定性。 这些修改将允许降低全身给药剂量，并且还允许增加实验或治疗剂在CNS中的停留时间。 我们的假设是CNS螯合的功效可以通过使用α-羟基甘氨酸经由肽酰氨基乙醇酸裂解酶（PGL，EC 4.3.2.5）作用实现羧基末端酰胺化来改善，因为在保护酯功能的酯酶裂解后酶促生物活化的速率更高。 其中羧基末端脯氨酰胺被L-哌啶酸取代或氨基末端焦氨酰胺残基被非天然部分取代的类似物也将被掺入适当的靶向系统中。 设计和开发将得到理论计算的支持。 将测试新设计的类似物与脑TRH受体的结合，以比较它们与先导化合物的内在活性。 体外稳定性和代谢实验将解决优化和实际开发问题。 脑组织中的稳定性研究将解决肽活化和/或切割的速率、位点和程度，以探测CNS螯合中的关键步骤。 体内分布和代谢研究将评估在脑中转运和隔离TRH类似物的策略的功效。 我们将研究脑递送的药代动力学，预测的前体的“锁定”，以及合成的靶向系统的胃肠外给药后生物活性肽的释放。 将通过体内脑微透析研究（其中将测定治疗引起的乙酰胆碱水平变化）对脑给药类似物的作用进行比较药效学评价。最终，将在动物身上进行药理学实验，以调查该方法治疗与胆碱能功能丧失相关的疾病的潜力。 戊巴比妥诱导的睡眠的拮抗作用将被用作评估脑靶向化合物的急性作用的一般范例。还将通过适当的方法或研究设计解决行为观察、剂量依赖性和作用持续时间。