Dasilva J N, Crouzel C, Stulzaft O, Khalili-Varasteh M, Hantraye P
Service Hospitalier Frédéric Joliot, DRIPP, DSV, CEA, Orsay, France.
Int J Rad Appl Instrum B. 1992 Feb;19(2):167-73. doi: 10.1016/0883-2897(92)90004-i.
11,17 beta-Dihydroxy-6-methyl-17 alpha-(3-[18F]fluoro-prop-1- ynyl)androsta-1,4,6-trien-3-one [( 18F]RU 52461), an 18F-analog of RU 28362, was synthesized by bromide displacement with [18F]fluoride in 12-30% overall radiochemical yield (decay-corrected) within 140 min from end of bombardment (EOB). The specific activity was 900-1500 mCi/mumol (33.3-55.5 GBq/mumol) at the end of synthesis (EOS). Biodistribution studies indicated high adrenal and pituitary retention, and uniformly low uptake of [18F]RU 52461 in all other brain regions of the rat. Except for the pituitary, no specific receptor-mediated uptake of [18F]RU 52461 could be demonstrated using saturating doses of unlabeled RU 52461 in rat brain. While no change was observed throughout the brain areas in adrenalectomized rats and in animals coinjected with dexamethasone, when compared to controls. PET studies revealed extremely low levels of radioactivity in baboon brain. Therefore, [18F]RU 52461 does not appear to cross the blood-brain barrier, suggesting that this radiopharmaceutical is not suitable to visualize the brain glucocorticoid binding sites by PET.
11,17β-二羟基-6-甲基-17α-(3-[¹⁸F]氟丙-1-炔基)雄甾-1,4,6-三烯-3-酮([¹⁸F]RU 52461)，RU 28362的¹⁸F类似物，通过用[¹⁸F]氟化物进行溴置换反应合成，从轰击结束(EOB)起140分钟内，总放射化学产率(衰变校正)为12 - 30%。合成结束(EOS)时的比活度为900 - 1500 mCi/μmol(33.3 - 55.5 GBq/μmol)。生物分布研究表明，大鼠肾上腺和垂体摄取率高，而[¹⁸F]RU 52461在大鼠所有其他脑区的摄取均较低。除垂体外，在大鼠脑中使用未标记RU 52461的饱和剂量未能证明[¹⁸F]RU 52461有特异性受体介导的摄取。与对照组相比，在肾上腺切除的大鼠和同时注射地塞米松的动物的整个脑区均未观察到变化。PET研究显示狒狒脑中放射性水平极低。因此，[¹⁸F]RU 52461似乎不能穿过血脑屏障，这表明这种放射性药物不适用于通过PET可视化脑糖皮质激素结合位点。
