Diurnal gene expression in the retina of a mouse model of diabetic retinopathy

The mammalian retina contains an endogenous circadian clock system, located in various cell types. This system enables timing of a broad range of essential retinal functions to anticipate daily changes in environmental lighting conditions. Furthermore, the circadian clocks appear to promote retinal health. A leading cause of blindness in developed countries is diabetic retinopathy. While it is clear that diabetes affects the master clock and its circadian output in the SCN, the effect of diabetic retinopathy on the retinal clock system is unknown. To investigate the influence of diabetic retinopathy on circadian regulation of the retina at a genome-wide level, microarray analysis was used to compare retinal transcriptomes between light- and dark-adapted non-diabetic and diabetic mice. Retinae of adult non-diabetic (db/+) and diabetic (db/db) mice (BKS.Cq-Dock7m +/+ Leprdb/J) were sampled at two different zeitgeber times (ZTs) during the 24-hour light/dark-cycle namely 6 hours after lights-on (ZT6) and 6 hours after lights-off (ZT18) for RNA extraction and hybridization on Affymetrix microarrays. 3 mice were used for each genotype and time-point.哺乳动物视网膜内存在一套内源性昼夜节律时钟系统，该系统广泛分布于多种细胞类型中。该系统可调控一系列核心视网膜功能的节律性时序，使视网膜能够提前预判环境光照条件的每日周期性变化。此外，昼夜节律时钟似乎有助于维持视网膜健康状态。发达国家中，糖尿病视网膜病变（diabetic retinopathy）是导致失明的首要病因之一。尽管已有研究证实糖尿病会影响下丘脑视交叉上核（SCN）中的主时钟及其昼夜节律输出，但糖尿病视网膜病变对视网膜时钟系统的具体影响仍未明确。为在全基因组水平探究糖尿病视网膜病变对视网膜昼夜节律调控的影响，本研究采用微阵列（microarray）分析技术，对比了光适应与暗适应状态下非糖尿病小鼠与糖尿病小鼠的视网膜转录组。实验采集了成年非糖尿病（db/+）与糖尿病（db/db）小鼠（品系编号BKS.Cq-Dock7m +/+ Leprdb/J）在24小时明暗周期内两个不同授时时间（zeitgeber time，ZT）点的视网膜组织，分别为光照开启后6小时（ZT6）与光照关闭后6小时（ZT18），用于RNA提取及Affymetrix微阵列杂交。每个基因型与时间点均使用3只小鼠作为实验样本。