Functional annotation of genes differentially expressed between primary motor and prefrontal association cortices of macaque brain. Macaca mulatta

DNA microarray-based genome-wide transcriptional profiling and gene network analyses were used to characterize the molecular underpinnings of the frontal neocortical organization in rhesus macaque, with particular focus on the differences in the functional annotation of genes in the primary motor cortex and the prefrontal association cortex. Biofunctional analysis of the differentially expressed genes showed that the list of genes selectively expressed in the primary motor cortex were enriched with genes involved in development, oligodendrocyte function, and increased energy consumption, whereas the list of genes selectively expressed in the prefrontal association cortex were enriched with genes involved in cell morphology and calcium dynamics. These functional differences in selectively expressed genes may reflect the fundamental molecular structure of each cortex. Overall design: Brain tissue was obtained from 4 adolescent rhesus monkeys (Macaca mulatta) aged between 2.6 and 2.7 years that had been bred in group cages without being subjected to any experimental treatment. Adequate measures were taken to minimize pain and discomfort, in accordance with the National Institute of Health Guide for the Care and Use of Laboratory Animals (NIH Publication No. 80–23). The monkeys were perfused with 500–1000 ml of ice-cold saline containing heparin sodium (1000 U/ml, Novo Heparin; Leo Pharmaceutical Products, Ballerup, Denmark) through the ascending aorta within 15 min of an overdose injection of pentobarbital sodium (50 mg/kg, i.p., Somnopentyl; Kyoritsu Shoji, Tokyo, Japan). The 2 neocortical areas (M1 and A46) were identified by sulcal landmarks. We used the forelimb region of M1 for the present analysis, which is located around the superior genu of the central sulcus. A46 was obtained from both the upper and lower banks of the principal sulcus. Each area from the left hemispheres was dissected on crushed ice and immediately frozen in liquid nitrogen.

DNA微阵列（DNA microarray）介导的全基因组转录谱分析与基因网络分析，被用于解析恒河猴（rhesus macaque）额叶新皮质组织的分子基础，重点聚焦初级运动皮层（primary motor cortex）与前额叶联合皮层（prefrontal association cortex）的基因功能注释差异。对差异表达基因（differentially expressed genes）的生物功能富集分析显示：初级运动皮层中选择性表达的基因富集于发育进程、少突胶质细胞（oligodendrocyte）功能以及能量代谢增强相关基因；而前额叶联合皮层中选择性表达的基因则富集于细胞形态与钙动态平衡（calcium dynamics）相关基因。此类选择性表达基因的功能差异，或可反映两种皮层各自的核心分子架构。

总体实验设计：本研究的脑组织取自4只2.6至2.7岁的青春期恒河猴（Macaca mulatta），所有个体均以群养方式繁育，未接受任何实验处理。实验操作严格遵循美国国立卫生研究院（National Institute of Health, NIH）《实验动物护理与使用指南》（NIH Publication No. 80–23），采取充分措施以最大程度减轻动物的疼痛与不适。在腹腔注射过量戊巴比妥钠（50 mg/kg，商品名Somnopentyl；Kyoritsu Shoji，日本东京）后的15分钟内，通过升主动脉向恒河猴灌注500~1000 ml含肝素钠（1000 U/ml，商品名Novo Heparin；Leo Pharmaceutical Products，丹麦巴勒鲁普）的冰生理盐水。研究人员通过脑沟标志定位两个新皮层区域（M1与A46）：本研究选取M1的前肢代表区进行分析，该区域位于中央沟上膝附近；A46标本取自主沟的上下壁。左侧半球的每个目标区域均在碎冰上解剖分离，并立即置于液氮中冻存。