Gatti C, Brunetti M, Gaiti A
Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Italy.
Neurobiol Aging. 1989 May-Jun;10(3):241-5. doi: 10.1016/0197-4580(89)90057-2.
Serine phosphoglycerides (SPG) in the nervous tissue are synthesized by base-exchange reaction. SPG may be decarboxylated and converted into ethanolamine phosphoglycerides (EPG). This latter reaction may be followed in turn by several enzymatic reactions leading to choline phosphoglycerides (CPG) via three successive methylations. These metabolic pathways are important for several reasons and their contribution to membrane phospholipid renewal has been clearly demonstrated. Base-exchange is the only metabolic route to synthesize SPG; it was therefore possible to test this pathway in vivo by injecting labeled serine. Serine incorporation into phosphoglycerides was reduced in cortex and hippocampus from aged rat brain as compared to adult, while no change in the SPG successive metabolic transformation was found. Based on both the results presented herein and previous ones obtained in vitro the authors suggest that the reduced serine incorporation may be due to reduced uptake into cells from aged animals. This finding leads to the conclusion that the above mechanisms for partial renewal of the phospholipid molecule may play an important role in the brain structure of aged animals.
神经组织中的丝氨酸磷酸甘油酯（SPG）通过碱基交换反应合成。SPG可能会脱羧并转化为乙醇胺磷酸甘油酯（EPG）。后一反应可能依次引发几个酶促反应，通过三次连续甲基化生成胆碱磷酸甘油酯（CPG）。这些代谢途径因多种原因而很重要，并且它们对膜磷脂更新的贡献已得到明确证实。碱基交换是合成SPG的唯一代谢途径；因此，通过注射标记的丝氨酸在体内测试该途径是可行的。与成年大鼠相比，老年大鼠大脑皮质和海马中丝氨酸掺入磷酸甘油酯的量减少，而未发现SPG连续代谢转化有变化。基于本文给出的结果以及先前在体外获得的结果，作者认为丝氨酸掺入减少可能是由于老年动物细胞摄取减少所致。这一发现得出的结论是，上述磷脂分子部分更新的机制可能在老年动物的脑结构中起重要作用。
