Diurnal gene expression profiles in mouse brain tissues constituting the central dopamine system

The circadian regulation of gene expression underlies orchestrated daily rhythms in physiology, metabolism, and behavior. The central dopamine (DA) system arising from DA neurons in the ventral midbrain has been implicated in a wide range of brain functions. Growing evidence suggests that DA transmission follows daily oscillations at multiple regulatory steps, and its dysfunction is closely related to the onset of various neuropsychiatric diseases. We examined diurnal gene expression profiles across key brain areas constituting the central DA pathways in mice by use of microarray analyses to identify rhythmically expressed genes according to the time of day (TOD). Male C57BL/6 mice were entrained to a 12-h light-dark (LD) photoperiod, and sacrificed from the Zeitgeber time 11 (ZT11) at 4-h intervals for 2 successive days. Four brain tissues including the substantia nigra and ventral tegmental area of the ventral midbrain (SN/VTA), prefrontal cortex (PFC), striatum (STR), and habenula (HAB), were bilaterally dissected from 1-mm-thick brain slices, which were coronally sectioned in a brain matrix chilled on ice. A total of 48 RNA samples were analyzed by use of Affymetrix GeneChip Mouse Gene 2.0 ST Array (Affymetirx, Santa Clara, CA, USA).基因表达的昼夜节律调控，是生理、代谢与行为层面有序每日节律的核心基础。起源于腹侧中脑多巴胺能神经元的中枢多巴胺（DA）系统，参与调控众多大脑功能。越来越多的研究证据表明，多巴胺传递在多个调控环节均呈现每日振荡特性，其功能失调与多种神经精神疾病的发病密切相关。本研究采用微阵列分析技术，对构成中枢多巴胺通路的小鼠关键脑区进行昼夜基因表达谱检测，以识别随每日时刻（TOD）呈现节律性表达的基因。将雄性C57BL/6小鼠置于12小时光照-黑暗（LD）光周期环境中驯化，从授时因子时间11（ZT11）开始，每隔4小时实施安乐死，连续采样2天。从冰浴冷却的脑模具中切取1毫米厚的冠状脑片，双侧取材获得4种脑组织：腹侧中脑黑质与腹侧被盖区（SN/VTA）、前额叶皮层（PFC）、纹状体（STR）以及缰核（HAB）。共计48份RNA样本采用Affymetrix GeneChip Mouse Gene 2.0 ST Array芯片（美国加利福尼亚州圣克拉拉市Affymetrix公司）进行检测分析。