Hirst W D, Price G W, Rattray M, Wilkin G P
Biochemistry Department, Imperial College, London, UK.
Neurochem Int. 1998 Jul;33(1):11-22. doi: 10.1016/s0197-0186(05)80003-8.
Cultured astrocytes derived from neonatal rat brain exhibited high affinity, Na+-dependent, paroxetine and fluoxetine sensitive [3H]5-HT uptake. Reverse transcriptase-PCR demonstrated that astrocytes in culture expressed messenger RNA for the cloned serotonin transporter protein which has been characterised as the neuronal serotonin transporter. Although the serotonin transporter in cultured astrocytes displayed a Km value approximately 10 times greater than found in adult brain synaptosomes, these observations indicated that astrocytes in vitro may express the same serotonin transporter as neurons. Reverse transcriptase-PCR demonstrated the presence of serotonin transporter mRNA in the adult rat cerebral cortex, suggesting that astrocytes in vivo may express low levels of this mRNA. To investigate whether astrocytes in the adult CNS express functional serotonin transporters, glial plasmalemmal vesicles were prepared from cerebral cortex, representing a subcellular fraction composed primarily of vesicles derived from astrocytes. These vesicles were characterised by [3H]-glutamate and [3H]-dopamine uptake and by immunoblot analysis, using glial and synaptic markers: glutamate synthase, SNAP-25 and synaptobrevin. [3H]5-HT was taken up into glial plasmalemmal vesicles in a high affinity (Km approximately 40 nM), Na+ dependent, paroxetine-sensitive manner. The [3H]5-HT uptake capacity (Vmax) in these vesicles was approximately one quarter of that observed in synaptosomes. These data indicate that astrocytes in culture and in vivo are capable of 5-HT uptake via the previously characterised 'neuronal' serotonin transporter.
源自新生大鼠脑的培养星形胶质细胞表现出高亲和力、钠依赖性、对帕罗西汀和氟西汀敏感的[3H]5-羟色胺摄取。逆转录聚合酶链反应表明，培养中的星形胶质细胞表达了克隆的血清素转运蛋白的信使核糖核酸，该蛋白已被鉴定为神经元血清素转运体。尽管培养的星形胶质细胞中的血清素转运体的Km值比成年脑突触体中的大约高10倍，但这些观察结果表明，体外的星形胶质细胞可能表达与神经元相同的血清素转运体。逆转录聚合酶链反应证明成年大鼠大脑皮层中存在血清素转运体信使核糖核酸，这表明体内的星形胶质细胞可能表达低水平的这种信使核糖核酸。为了研究成年中枢神经系统中的星形胶质细胞是否表达功能性血清素转运体，从大脑皮层制备了神经胶质细胞质膜囊泡，其代表主要由源自星形胶质细胞的囊泡组成的亚细胞部分。这些囊泡通过[3H]-谷氨酸和[3H]-多巴胺摄取以及使用神经胶质和突触标记物（谷氨酸合酶、SNAP-25和突触结合蛋白）的免疫印迹分析来表征。[3H]5-羟色胺以高亲和力（Km约为40 nM）、钠依赖性、对帕罗西汀敏感的方式被摄取到神经胶质细胞质膜囊泡中。这些囊泡中的[3H]5-羟色胺摄取能力（Vmax）约为突触体中观察到的摄取能力的四分之一。这些数据表明，培养中和体内的星形胶质细胞能够通过先前表征的“神经元”血清素转运体摄取5-羟色胺。
