Daikohara Kiyotaka, Akanuma Shin-Ichi, Kawanishi Miyu, Tega Yuma, Hosoya Ken-Ichi
Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan.
Pharm Res. 2025 Jun 3. doi: 10.1007/s11095-025-03872-w.
This study aimed to determine in vivo alterations in the rat retinal distribution of a substrate for P-glycoprotein (P-gp), which restricts drug transport to the retina at the inner blood-retinal barrier (BRB), by peripheral administration of lipopolysaccharide (LPS), an inflammatory agent.
Using retinal capillaries isolated from rats 24 h after peripheral 5 mg/kg LPS administration, transport analyses with a fluorescent substrate of P-gp were performed. In vivo retinal distribution of [H]digoxin, a P-gp substrate, in the LPS-administered rats was evaluated after intravenous or intracarotid artery injection. The mRNA and protein expression levels of P-gp in the retinal capillaries were evaluated.
P-gp-mediated luminal transport of the fluorescent substrate was significantly attenuated in retinal capillaries of the LPS-administered rats. Moreover, in vivo retinal [H]digoxin distribution in LPS-injected rats was significantly greater than that in saline-injected rats. Since the retinal distribution of [H]D-mannitol, a paracellular transport marker, was not significantly altered in LPS-treated rats, it is suggested that in vivo elevation of retinal [H]digoxin distribution is caused by P-gp downregulation at the inner BRB, but not a change in paracellular transport in the barrier. In retinal capillaries isolated from LPS-administered rats, expression analyses of P-gp mRNAs and protein indicated a reduction in its expression on the luminal membrane of the inner BRB.
Our study demonstrated that in vivo retinal distribution of P-gp substrates was elevated in LPS-administered rats via a decrease in the function and expression of P-gp at the inner BRB.
本研究旨在通过外周给予炎症因子脂多糖（LPS），确定P-糖蛋白（P-gp）底物在大鼠视网膜分布的体内变化，P-gp在内侧血视网膜屏障（BRB）限制药物向视网膜的转运。
使用外周给予5mg/kg LPS 24小时后分离的大鼠视网膜毛细血管，用P-gp的荧光底物进行转运分析。在静脉或颈内动脉注射后，评估LPS给药大鼠体内P-gp底物[H]地高辛的视网膜分布。评估视网膜毛细血管中P-gp的mRNA和蛋白表达水平。
在LPS给药大鼠的视网膜毛细血管中，P-gp介导的荧光底物腔面转运显著减弱。此外，LPS注射大鼠体内视网膜[H]地高辛的分布明显高于生理盐水注射大鼠。由于旁细胞转运标记物[H]D-甘露醇的视网膜分布在LPS处理的大鼠中没有显著改变，提示体内视网膜[H]地高辛分布的升高是由内侧BRB处P-gp下调引起的，而不是屏障中旁细胞转运的改变。在从LPS给药大鼠分离的视网膜毛细血管中，P-gp mRNA和蛋白的表达分析表明其在内侧BRB腔面膜上的表达减少。
我们的研究表明，在LPS给药大鼠中，通过内侧BRB处P-gp功能和表达的降低，P-gp底物的体内视网膜分布升高。
