Institute of Drug Metabolism and Pharmaceutical Analysis, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China.
Zhejiang Provincial Key Laboratory of Geriatrics &Geriatrics Institute of Zhejiang Province, Zhejiang Hospital, 12 Lingyin Road, Hangzhou, Zhejiang Province 310013, China.
Sci Rep. 2016 Sep 15;6:33338. doi: 10.1038/srep33338.
Regulating main brain-uptake transporter of morphine may restrict its tolerance generation, then modify its antinociception. In this study, more than 2 fold higher intracellular uptake concentrations for morphine and morphine-6-glucuronide (M6G) were observed in stable expression cells, HEK293-hOATP2B1 than HEK293-MOCK. Specifically, the Km value of morphine to OATP2B1 (57.58 ± 8.90 μM) is 1.4-time more than that of M6G (80.31 ± 21.75 μM); Cyclosporine A (CsA), an inhibitor of OATP2B1, can inhibit their intracellular accumulations with IC50 = 3.90 ± 0.50 μM for morphine and IC50 = 6.04 ± 0.86 μM for M6G, respectively. To further investigate the role of OATP2B1 in morphine brain transport and tolerance, the novel nanoparticles of DGL-PEG/dermorphin capsulated siRNA (OATP2B1) were applied to deliver siRNA into mouse brain. Along with OATP2B1 depressed, a main reduction was found for each of morphine or M6G in cerebrums or epencephalons of acute morphine tolerance mice. Furthermore, calcium/calmodulin-dependent protein kinase IIα (CaMKIIα) in mouse prefrontal cortex (mPFC) underwent dephosphorylation at Thr286. In conclusion, OATP2B1 downregulation in mouse brain can suppress tolerance via blocking morphine and M6G brain transport. These findings might help to improve the pharmacological effects of morphine.
调节吗啡的主要脑摄取转运体可能会限制其耐受性的产生，从而改变其镇痛作用。在这项研究中，与 HEK293-MOCK 相比，稳定表达细胞 HEK293-hOATP2B1 中吗啡和吗啡-6-葡萄糖醛酸苷（M6G）的细胞内摄取浓度高出 2 倍以上。具体而言，吗啡对 OATP2B1 的 Km 值（57.58±8.90 μM）是 M6G 的 1.4 倍（80.31±21.75 μM）；环孢素 A（CsA）是 OATP2B1 的抑制剂，可分别以 IC50=3.90±0.50 μM 和 IC50=6.04±0.86 μM 抑制其细胞内积累。为了进一步研究 OATP2B1 在吗啡脑内转运和耐受中的作用，应用新型 DGL-PEG/ Dermorphin 包裹 siRNA（OATP2B1）纳米粒将 siRNA 递送至小鼠脑内。随着 OATP2B1 的下调，急性吗啡耐受小鼠大脑中的吗啡或 M6G 每种物质都出现了主要的减少。此外，小鼠前额叶皮质（mPFC）中的钙/钙调蛋白依赖性蛋白激酶 IIα（CaMKIIα）在 Thr286 处发生去磷酸化。综上所述，小鼠脑内 OATP2B1 的下调可通过阻断吗啡和 M6G 的脑内转运来抑制耐受。这些发现可能有助于改善吗啡的药理学效应。
