Brain Uptake of [13C] and [14C]Sucrose Quantified by Microdialysis and Whole Tissue Analysis in Mice
Brain Uptake of [13C] and [14C]Sucrose Quantified by Microdialysis and Whole Tissue Analysis in Mice
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DOI：
10.1124/dmd.118.082909
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发表时间：
2018-11-01
影响因子：
3.9
通讯作者：
Bickel, Ulrich
中科院分区：
文献类型：
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作者：
Alqahtani, Faleh;Chowdhury, Ekram Ahmed;Bickel, Ulrich
在小的亲水性药物样分子中，[C-14]蔗糖一直被认为是测定血脑屏障通透性的金标准。然而，我们最近在大鼠中发现，与蔗糖稳定同位素（C-13）的液相色谱-串联质谱分析相比，[C-14]蔗糖显著高估了脑组织浓度和蔗糖摄取量，为6至7倍。这种差异是由于[C-14]蔗糖示踪剂溶液中存在少量亲脂性杂质所致。在这里，我们使用颅内微透析来测量静脉推注给药后小鼠脑细胞外液（ECF）中两种蔗糖变体的浓度。两种标记物显示出相似的血浆曲线和ECF透析液浓度。然而，[C-14]蔗糖的总脑组织浓度和表观脑摄取清除率分别是[C-13]蔗糖的4.1倍和3.6倍。因此，具有较高渗透性的[C-14]蔗糖污染物可能被脑细胞隔离，这使得它们不可透析。可以得出结论，虽然测量的放射性高估了完整的蔗糖在脑组织中的浓度，ECF放射性微透析后是一个相对准确的反映完整的蔗糖后，系统管理的[C-14]蔗糖标记。
Among small, hydrophilic drug-like molecules, [C-14]sucrose has long been considered the gold standard for determination of blood-brain barrier permeability. However, we have recently shown in rats that, compared with liquid chromatography-tandem mass spectrometry analysis of stable isotope (C-13) of sucrose, [C-14]sucrose significantly overestimates the brain tissue concentration and uptake of sucrose by a factor of 6 to 7. This discrepancy is due to the presence of small quantities of lipophilic impurities in [C-14]sucrose tracer solutions. Here, we used intracranial microdialysis to measure concentrations of both sucrose variants in brain extracellular fluid (ECF) after intravenous bolus administration to mice. Both markers displayed similar plasma profiles and ECF dialysate concentrations. However, total brain tissue concentrations and apparent brain uptake clearance of [C-14]sucrose were 4.1- and 3.6-fold higher, respectively, than those of [C-13]sucrose. Therefore, the contaminants of [C-14]sucrose with higher permeability were likely sequestered by brain cells, which renders them nondialyzable. It is concluded that although measurement of radioactivity overestimates the concentrations of intact sucrose in the brain tissue, the ECF radioactivity after microdialysis is a relatively accurate reflection of intact sucrose after the systemic administration of the [C-14]sucrose marker.