Patel T B, Clark J B
Biochim Biophys Acta. 1981 Nov 5;677(3-4):373-80. doi: 10.1016/0304-4165(81)90249-x.
The rates of citrate and acetoacetate efflux from rat brain mitochondria (synaptic and free) utilizing different substrates (pyruvate, 3-hydroxybutyrate or acetoacetate) under different conditions have been studied as a function of development. In general there were no marked differences in the acetoacetate efflux rates between 'free' and 'synaptic' brain mitochondria whereas citrate efflux rates were usually higher in 'free' mitochondria. Developmental studies with brain mitochondria utilizing 3-hydroxybutyrate + malate showed a profile for acetoacetate efflux which was at a peak at weaning (21 days) and then decreased by 50% in the adult state. Similar studies measuring citrate efflux showed little change as the brain developed, but when pyruvate + malate were used as substrates the citrate efflux doubled during the period 5--20 days and was then maintained in the adult state. Phenylpyruvate was found to inhibit both acetoacetate and citrate efflux from 21-day-old and adult rat brain mitochondria when they used either 3-hydroxybutyrate or pyruvate as substrate. It is concluded that ketone bodies may be potentially as effective, if not better, than glucose in the brain of the suckling rat as precursors of cytosolic biosynthetic activities whereas in the adult rat brain, ketone bodies are relatively poor precursors of these activities.
研究了在不同条件下，利用不同底物（丙酮酸、3-羟基丁酸或乙酰乙酸）时，大鼠脑线粒体（突触线粒体和游离线粒体）中柠檬酸和乙酰乙酸的流出速率随发育的变化情况。一般来说，“游离”和“突触”脑线粒体之间乙酰乙酸的流出速率没有显著差异，而“游离”线粒体中的柠檬酸流出速率通常更高。对利用3-羟基丁酸 + 苹果酸的脑线粒体进行的发育研究表明，乙酰乙酸流出呈现出一种模式，即在断奶时（21天）达到峰值，然后在成年状态下下降50%。测量柠檬酸流出的类似研究表明，随着大脑发育，柠檬酸流出变化不大，但当使用丙酮酸 + 苹果酸作为底物时，在5 - 20天期间柠檬酸流出增加了一倍，然后在成年状态下保持稳定。当21日龄和成年大鼠脑线粒体以3-羟基丁酸或丙酮酸作为底物时，发现苯丙酮酸会抑制乙酰乙酸和柠檬酸的流出。得出的结论是，在幼鼠大脑中，酮体作为胞质生物合成活动的前体，可能与葡萄糖一样有效，甚至可能更好，而在成年大鼠大脑中，酮体是这些活动相对较差的前体。
