Vatassery G T, Lai J C, Smith W E, Quach H T
Department of Psychiatry, GRECC, VA Medical Center, University of Minnesota, Minneapolis 55455, USA.
Neurochem Res. 1998 Feb;23(2):121-5. doi: 10.1023/a:1022495804817.
We examined the influence of aging upon the uptake of glutamate by synaptosomes, and the oxidation of synaptosomal vitamin E. Synaptosomes isolated from the cerebral hemispheres of Fischer 344 rats, 4 and 24 months old, were suspended at 37 degrees C in buffer (pH 7.4) simulating extracellular fluid containing 10 mM glucose. The Km for the high affinity uptake of tritium labeled glutamate was approximately 10 microM. The uptake of glutamate was lower in synaptosomes from older animals than those from younger animals for periods of up to 20 minutes. Upon incubation with a mixture of ferrous iron and ascorbate, more of the alpha tocopherol in synaptosomes derived from older rats was oxidized than in those derived from younger ones. Older animals may be more susceptible to excitotoxicity because: a) synaptosomal reuptake of glutamate is less efficient and b) oxidative stress induced by various agents including glutamate may be higher in synaptosomes from the older animal.
我们研究了衰老对突触体摄取谷氨酸以及突触体维生素E氧化的影响。从4个月和24个月大的Fischer 344大鼠大脑半球分离出的突触体，于37℃悬浮在模拟细胞外液的缓冲液（pH 7.4）中，该缓冲液含有10 mM葡萄糖。氚标记谷氨酸高亲和力摄取的Km约为10 microM。在长达20分钟的时间内，老年动物突触体中谷氨酸的摄取低于年轻动物突触体。与亚铁离子和抗坏血酸混合物一起孵育时，老年大鼠来源的突触体中α-生育酚的氧化比年轻大鼠来源的突触体中更多。老年动物可能更容易受到兴奋性毒性的影响，原因如下：a）突触体对谷氨酸的再摄取效率较低；b）包括谷氨酸在内的各种因素诱导的氧化应激在老年动物的突触体中可能更高。
