Department of Pharmacology & Therapeutics, University of Manitoba, 753 McDermot Ave., Winnipeg, Manitoba, R3E 0T6, Canada.
Pharm Res. 2011 Oct;28(10):2505-15. doi: 10.1007/s11095-011-0478-6. Epub 2011 May 20.
To examine functional activity of P-glycoprotein (P-gp) in the blood-brain barrier (BBB) using near infrared fluorescence (NIRF) imaging techniques.
Cellular accumulation and bi-directional permeability of the NIRF probe, rhodamine 800 (R800) was determined in MDCKMDR1 and MDCKwt monolayers under normal conditions and following P-gp inhibition with GF120918. Functional P-gp activity was also assessed in mice following administration of R800 alone and with GF230918. Quantitative analysis of R800 fluorescence in brain tissue and blood was measured ex-vivo using Odyssey Near Infrared imaging.
R800 accumulation was reduced in MDCKMDR1 compared to MDCKwt monolayers. Addition of GF120918, resulted in increased R800 accumulation in MDCKMDR1 monolayers. Permeability of R800 in MDCKMDR1 monolayers was significantly enhanced (4-fold) in the basolateral to apical direction under control conditions and was abolished following treatment with GF120918. With the exception of the choriod plexus, there was very little penetration of R800 into the brain under control conditions. Treatment of mice with GF120918 resulted in a nearly 4-fold increase in R800 fluorescence in the brain. In contrast, GF120918 had no effect on brain penetration of a vascular permeability marker.
In vitro studies demonstrate the P-gp transporter properties of the NIRF probe R800. Preliminary in vivo studies confirm the P-gp transporter liabilities of R800 and suggest this probe may be useful as a molecular imaging agent for examining P-gp activity in the BBB.
利用近红外荧光（NIRF）成像技术研究血脑屏障（BBB）中 P-糖蛋白（P-gp）的功能活性。
在正常条件下以及用 GF120918 抑制 P-gp 后，测定 NIRF 探针罗丹明 800（R800）在 MDCKMDR1 和 MDCKwt 单层细胞中的细胞积累和双向通透性。在用 R800 单独给药和用 GF230918 给药后，还在小鼠中评估了功能性 P-gp 活性。使用 Odyssey 近红外成像技术对脑组织和血液中的 R800 荧光进行定量分析。
与 MDCKwt 单层相比，R800 在 MDCKMDR1 中的积累减少。加入 GF120918 后，MDCKMDR1 单层中 R800 的积累增加。在对照条件下，R800 在 MDCKMDR1 单层中的渗透性显著增强（4 倍），并用 GF120918 处理后被消除。除脉络丛外，在对照条件下，R800 很少穿透进入大脑。用 GF120918 处理小鼠导致大脑中 R800 荧光增加近 4 倍。相比之下，GF120918 对血管通透性标志物进入大脑没有影响。
体外研究表明 NIRF 探针 R800 具有 P-gp 转运体特性。初步的体内研究证实了 R800 的 P-gp 转运体缺陷，并表明该探针可用作检查 BBB 中 P-gp 活性的分子成像剂。
