Magistretti P J, Sorg O, Yu N, Martin J L, Pellerin L
Institut de Physiologie, Faculté de Médecine, Université de Lausanne, Suisse.
Dev Neurosci. 1993;15(3-5):306-12. doi: 10.1159/000111349.
In recent years a vast array of experimental evidence has indicated the presence of functional receptors for neurotransmitters on nonneuronal cells, in particular astrocytes. The two neurotransmitters vasoactive intestinal peptide (VIP) and noradrenaline (NA) exert profound, receptor-mediated, metabolic actions on astrocytes. Thus both neurotransmitters stimulate glycogenolysis in primary astrocyte cultures, with EC50s of 3 and 20 nM respectively. Astrocytes display basal glucose utilization rates ranging between 3 and 9 nmol/mg prot/min, a value that is remarkably close to glucose utilization of cerebral cortical grey matter as determined by the 2-deoxyglucose autoradiographic technique. NA markedly enhances glucose uptake and phosphorylation by astrocytes, with an EC50 of 1 microM. The metabolic substrate that is released by astrocytes is predominantly lactate and not glucose. Since lactate can support neuronal activity and synaptic function in vitro, the possibility should be considered that glucose uptake by the brain parenchyma occurs predominantly into astrocytes which subsequently release lactate for the use of neurons.
近年来，大量实验证据表明非神经元细胞（尤其是星形胶质细胞）上存在神经递质的功能性受体。两种神经递质，即血管活性肠肽（VIP）和去甲肾上腺素（NA），对星形胶质细胞具有深刻的、受体介导的代谢作用。因此，这两种神经递质均可刺激原代星形胶质细胞培养物中的糖原分解，其半数有效浓度（EC50）分别为3 nM和20 nM。星形胶质细胞的基础葡萄糖利用率在3至9 nmol/mg蛋白/分钟之间，这一数值与通过2-脱氧葡萄糖放射自显影技术测定的大脑皮质灰质的葡萄糖利用率非常接近。NA可显著增强星形胶质细胞对葡萄糖的摄取和磷酸化作用，其EC50为1 μM。星形胶质细胞释放的代谢底物主要是乳酸而非葡萄糖。由于乳酸在体外可支持神经元活动和突触功能，因此应考虑这样一种可能性，即脑实质对葡萄糖的摄取主要发生在星形胶质细胞中，随后星形胶质细胞释放乳酸供神经元利用。
