烟碱乙酰胆碱受体显像剂2-[~(18)F]-A-85380的合成及大鼠脑磷屏显像

通过18F标记前体Me3N+-Boc-A-85380·CF3SO-3,合成了烟碱乙酰胆碱受体显像剂2-18 F]-A-85380,并探讨该显像剂在大鼠脑内的分布。采用取代法以Me3N+-Boc-A-85380·CF3SO-3为反应前体,在含氮芳香环的2位用18F进行标记,合成nAChRs显像剂2-18F]-A-85380;以聚酰胺薄膜为支持介质、生理盐水为展开剂,测定标记物的标记率和放化纯度;SD大鼠4只尾静脉注射0.5mL(1.48MBq)2-18F]-A-85380,分别在5、60、120、180min时用多聚甲醛灌流固定,取出大脑做冠状位切片,将切片与磷屏在专用暗盒内曝光30min,取出磷屏进行扫描显影。结果表明:2-18 F]-A-85380的标记率达93%,其放化纯在标记后2、4、6h均大于90%。磷屏显像结果显示:注药后60min时磷屏所受辐射最强,所得图像光强度大于5min、120min和180min的;丘脑分布最多、皮质次之、小脑及脑干分布较少。

Radiosynthesis of 2-[18 F]-A-85380 and Phosphor Screen Imaging on Rats

To investigate the radiosynthesis of 2-［¹⁸F］-A-85380 and its biodistribution in rat’s brain, 2-［¹⁸F］-A-85380 was synthesized with Me₃N⁺-Boc-A-85380?CF₃SO^-₃ as precursor. The radiolabeled compound was characterized by polymide TLC, in which the substratum of saline was used as developing agent. SD rats were sacrificed at 5, 60, 120 and 180 min after tail vein injection of 0.5 mL （1.48 MBq） freshly prepared 2-［¹⁸F］-A-85380. The heads were cut off and the brains were taken integrallty, then cut into slices and exposured with phosphor for 30 min, after that the phosphor was put into scan system and the digital images were obtained. The labeling yield of 2-［¹⁸F］-A-85380 is 93% and its radiochemical purity are exceeded 90% at 2, 4 and 6 h. Phosphor screen imaging show that the phosphor screen receives the highest radioactivity at 60 min after injection. The intensity of image is denser than that of 5, 120, 180 min. Accumulated radioactivity is greatest in thalamus, intermediate in the cortex, fewer in cerebellum and brainstem.