Mäenpää Hanna, Mannerström Marika, Toimela Tarja, Salminen Lotta, Saransaari Pirjo, Tähti Hanna
Medical School, University of Tampere, Finland.
Pharmacol Toxicol. 2002 Sep;91(3):116-22. doi: 10.1034/j.1600-0773.2002.910305.x.
The systemic drugs chloroquine and tamoxifen have caused retinal defects in human eye. The aim of our study was to investigate the effects of the amphiphilic drug tamoxifen, of its homologue toremifene, and of chloroquine on the glutamate uptake in retinal pigment epithelial (RPE) cells. Cultured human RPE cell line D407 and pig RPE cells were used in the study. Glutamate uptake was characterised and the glutamate transporters of pig RPE cells and the human RPE cell line D407 were compared to each other. The uptake of glutamate was studied using L-[3H]glutamate as a tracer. The radioactivity in the solubilised RPE was measured with a liquid scintillation counter. In the uptake experiments, the cells were exposed to the test drugs, to the selected glutamate receptor antagonists, and to the glutamate transporter inhibitors. Both RPE cell types exhibited a high-affinity transport system for glutamate. The glutamate transporter in RPE exhibited features characteristic of the uptake systems of neurotransmitters. The transport was Na+-dependent, and L- and D-aspartate were transported into the cell by the same transporter. Chloroquine had no effect on glutamate uptake, but tamoxifen and toremifene decreased the glutamate uptake of RPE cells dose-dependently both in pig RPE cells and in human RPE cell line. The IC50 values of tamoxifen and toremifene were lower for pig RPE cells, compared to the human RPE cell line D407. The glutamate uptake was a sensitive target for the effects of tamoxifen and toremifene, and disturbances in this function could be considered as one of the possible mechanisms of retinal defects.
全身性药物氯喹和他莫昔芬已导致人类眼部出现视网膜缺陷。我们研究的目的是调查两亲性药物他莫昔芬、其同系物托瑞米芬以及氯喹对视网膜色素上皮（RPE）细胞谷氨酸摄取的影响。本研究使用了培养的人RPE细胞系D407和猪RPE细胞。对谷氨酸摄取进行了表征，并比较了猪RPE细胞和人RPE细胞系D407的谷氨酸转运体。使用L-[3H]谷氨酸作为示踪剂研究谷氨酸摄取。用液体闪烁计数器测量溶解的RPE中的放射性。在摄取实验中，将细胞暴露于受试药物、选定的谷氨酸受体拮抗剂以及谷氨酸转运体抑制剂。两种RPE细胞类型均表现出对谷氨酸的高亲和力转运系统。RPE中的谷氨酸转运体表现出神经递质摄取系统的特征。该转运依赖于Na+，L-天冬氨酸和D-天冬氨酸通过同一转运体转运进入细胞。氯喹对谷氨酸摄取无影响，但他莫昔芬和托瑞米芬在猪RPE细胞和人RPE细胞系中均剂量依赖性地降低RPE细胞的谷氨酸摄取。与人类RPE细胞系D407相比，猪RPE细胞中他莫昔芬和托瑞米芬的IC50值更低。谷氨酸摄取是他莫昔芬和托瑞米芬作用的敏感靶点，该功能的紊乱可被视为视网膜缺陷的可能机制之一。
