Tuor U I, Kurpita G, Simone C
Division of Neonatology, Hospital for Sick Children Research Institute, Toronto, Canada.
J Comp Neurol. 1994 Apr 15;342(3):439-48. doi: 10.1002/cne.903420310.
Although elevations in cerebral metabolic demand during development may induce angiogenesis, the correlation among ontogenic changes in local cerebral blood flow, cytochrome oxidase activity (an index of oxidative capacity) and capillary density have not been examined previously. We measured these parameters in selected regions of the brains of anesthetized rabbits of various ages. Increases in all three parameters occurred postnatally within the cerebral cortex and striatum, whereas in the medulla, values at birth were similar to those in adults. In newborns, the pattern of distribution of blood flow within the parietal cortex was such that levels were maximal in the outer layers and declined in deeper layers. This distribution correlated closely with that of capillary density, whereas cytochrome oxidase activity was maximal at levels deeper in the cortex. By postnatal day 17, the distribution for all three parameters was similar to that of cytochrome oxidase activity in young animals. A regression analysis of the regional values demonstrated a positive correlation between capillary density and blood flow in young (< or = postnatal day 8) and old (> or = postnatal day 17) animals. In contrast, cytochrome oxidase activity and capillary density were poorly correlated in young animals but positively correlated in older animals, with the slopes being markedly different (P < 0.005). The results suggest that early in postnatal development, the pattern of cytochrome oxidase activity is relatively mature compared with that of capillary density. By postnatal day 17, microvascular anatomy is closely associated to oxidative capacity, likely reflecting a steady state regulation of capillary density to metabolic requirements.
虽然发育过程中脑代谢需求的升高可能会诱导血管生成，但局部脑血流量、细胞色素氧化酶活性（氧化能力指标）和毛细血管密度的个体发生变化之间的相关性此前尚未得到研究。我们在不同年龄的麻醉兔大脑的选定区域测量了这些参数。所有这三个参数在出生后均在大脑皮层和纹状体中升高，而在延髓中，出生时的值与成年时相似。在新生儿中，顶叶皮层内的血流分布模式是外层水平最高，深层则下降。这种分布与毛细血管密度的分布密切相关，而细胞色素氧化酶活性在皮层较深的水平处最高。到出生后第17天，所有这三个参数的分布与幼小动物中细胞色素氧化酶活性的分布相似。对区域值的回归分析表明，幼龄（≤出生后第8天）和老龄（≥出生后第17天）动物的毛细血管密度与血流量之间呈正相关。相比之下，幼龄动物中细胞色素氧化酶活性与毛细血管密度的相关性较差，但在老龄动物中呈正相关，斜率明显不同（P<0.005）。结果表明，在出生后早期发育中，与毛细血管密度相比，细胞色素氧化酶活性模式相对成熟。到出生后第17天，微血管解剖结构与氧化能力密切相关，这可能反映了毛细血管密度对代谢需求的稳态调节。
