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目的:研究脑乙酰胆碱酯酶(AChE)活性的正电子断层扫描(PET)诊断显像剂[~(11)C]4-乙酰氧基-N-甲基哌啶([~(11)C] MP4A)在大鼠体内的摄取和分布。方法:正常雌性SD大鼠尾静脉注射[~(11)C]MP4A,按注射后5、15、25、35、45和60 min时间点分组后断头处死动物,迅速取血,分离脏器和脑(大脑皮质、小脑和脑干),用自动γ放射性计数仪计算经衰变校正后不同时间点各脏器放射性摄取率,以%ID/g表示。结果:一次剂量的[~(11)C]MP4A静脉注射后,血中5 min时%ID/g为(13.44±1.88),清除迅速,60 min时接近于基线水平;各脏器组织中%ID/g 15～25 min达到稳态;大脑皮质5 min%ID/g为(2.26±0.29)。脑内各区域的摄取在注射后15～25 min达到稳态。皮质的平均%ID/g>小脑,两者比值范围为1.13～2.08;60min时小脑、脑干和皮质的%ID/g与其最高峰相比分别下降了77%、80%和40%;皮质放射活性清除最慢。结论:[~(11)C]MP4A血中清除迅速。脑各区域摄取在短时达到稳态,提示[~(11)C]MP4A有较好的脂溶性,易透过血脑屏障;皮质摄取比小脑高但清除慢,表明[~(11)C]MP4A能更好反映皮质AChE活性,适合作为脑AChE活性的PET诊断显像剂。
Objective: To study the diagnostic value of positron emission tomography (~ 11 C) 4-acetoxy-N-methylpiperidine ([~ (11) C] MP4A) uptake and distribution in rats. Methods: The normal female SD rats were injected with [~ (11) C] MP4A into the tail vein, and the rats were sacrificed at 5, 15, 25, 35, 45 and 60 min after injection. And brain (cerebral cortex, cerebellum and brain stem). The radioactive uptake rate of each organ at different time points after decay correction was calculated by automatic γ radioactivity counter, expressed as% ID / g. Results: After a single dose of [~ (11) C] MP4A was injected intravenously, the percentage of% ID / g was (13.44 ± 1.88) at 5 min in the blood, cleared rapidly and approached the baseline at 60 min. ID / g 15 ~ 25 min reached steady state; 5 min% of cerebral cortex ID / g was (2.26 ± 0.29). Intake in various regions of the brain reaches steady state 15 to 25 minutes after injection. Cortical average% ID / g> cerebellum, the ratio between the two ranged from 1.13 to 2.08;% ID / g of cerebellum, brain stem and cortex decreased by 77%, 80% and 40% respectively at 60min; The slowest radioactivity removal. Conclusion: The blood of [~ (11) C] MP4A is cleared quickly. Steady state of brain uptake in a short period of time indicated that [~ (11) C] MP4A had better liposolubility and penetrated the blood-brain barrier. Cortical uptake was slower than that of the cerebellum, ] MP4A can better reflect the activity of cortical AChE and is suitable as PET diagnostic imaging agent for brain AChE activity.