^(99m)Tc complex conjugated to insulin: CNS radiopharmaceuticals design based on principles of blood-brain barrier transport vector  

作　　者：LIU Fei FAN Caiyun ZHANG Jinming WANG Wushang LIU Boli 

机构地区：[1]Department of Chemistry, Beijing Normal University, Beijing 100875, China

出　　处：《Chinese Science Bulletin》2005年第20期2297-2301,共5页

基　　金：This work was supported by the Na—tional Natural Science Foundation ofChina(Grant No.20471011).

摘　　要：Hydrophilic 99mTc-EC and nonlipophilic 99mTc- MAMA′-BA complexes, owing to the existing of intact blood-brain barrier (BBB) in vivo, cannot cross from blood to brain. Previous studies showed that insulin is selectively transported by receptor-mediated transcytosis through the brain capillary endothelial wall that makes up the BBB. In this paper, based on the characteristic of the insulin receptor enriched in brain capillary, the complexes of hydrophilic 99mTc-EC and nonlipophilic 99mTc-MAMA′-BA are conju- gated to insulin respectively. After purification, the radio- chemical purity of 99mTc-EC-insulin and 99mTc-MAMA′- BA-insulin was > 90% and the stability in vitro was good. Expectation for the special formulation can be internalized and endocytosed into the capillary membrane by the vec- tor-mediated brain delivery system, and transported 99mTc-labeled conjugate through the BBB in vivo, thus en- hancing brain uptake in mice. The biodistribution results of 99mTc-EC-insulin and 99mTc-MAMA′-BA-insulin in mice in- dicated that the brain uptake was higher than 99mTc-EC and 99mTc-MAMA′-BA to some extent. The ratios of brain uptake of 99mTc-EC-insulin to 99mTc-EC, 99mTc-MAMA′-BA-insulin to 99mTc-MAMA′-BA were 4―6 at 2 and 3 h post-injection respectively. In conclusion, the given results have illustrated a new way of brain uptake enhancing for nonlipophilic like complexes that have BBB delivery problems. It has a poten- tial value for the ongoing development of 99mTc-labeled ra- diopharmaceuticals for CNS receptors imaging.Hydrophilic ^99mTc-EC and nonlipophilic ^99mTc- MAMA＇-BA complexes, owing to the existing of intact blood-brain barrier （BBB） in vivo, cannot cross from blood to brain. Previous studies showed that insulin is selectively transported by receptor-mediated transcytosis through the brain capillary endothelial wall that makes up the BBB. In this paper, based on the characteristic of the insulin receptor enriched in brain capillary, the complexes of hydrophilic ^99mTc-EC and nonlipophilic ^99mTc-MAMA＇-BA are conjugated to insulin respectively. After purification, the radiochemical purity of ^99mTc-EC-insulin and ^99mTc-MAMA＇-BA-insulin was 〉 90% and the stability in vitro was good. Expectation for the special formulation can be internalized and endocytosed into the capillary membrane by the vector-mediated brain delivery system, and transported ^99mTc-labeled conjugate through the BBB in vivo, thus enhancing brain uptake in mice. The biodistribution results of ^99mTc-EC-insulin and ^99mTc-MAMA＇-BA-insulin in mice in- dicated that the brain uptake was higher than ^99mTc-EC and ^99mTc-MAMA＇-BA to some extent. The ratios of brain uptake of ^99mTc-EC-insulin to ^99mTc-EC, ^99mTc-MAMA＇-BA-insulin to ^99mTc-MAMA＇-BA were 4-6 at 2 and 3 h post-injection respectively. In conclusion, the given results have illustrated a new way of brain uptake enhancing for nonlipophilic like complexes that have BBB delivery problems. It has a potential value for the ongoing development of ^99mTc-labeled radiopharmaceuticals for CNS receptors imaging.

关 键 词：血脑屏障 BBB 生理功能 胰岛素 接受体 脑传输 

分 类 号：R331[医药卫生—人体生理学]