Positive emotion-specific changes in gene expression profile in hypothalamus of the tickled rats. Rattus norvegicus

The changes of mRNA expression levels were analyzed in the hypothalamus of the juvenile rat stimulated by tickling for 4 weeks as a positive stimulation. The genes involved in feeding regulation were up-regulated by positive stimulation compared with light-touch stimulation, and the genes related to the stress hormone were down-regulated compared with control (no stimulus). Keywords: Stress response Overall design: Twenty-one-day-old male Wistar rats after weaning were used. All rats were separately maintained in the standard cages which were shielded with screens not to see each other during the study. The rats were then subjected to the following three conditions; tickling, light touch, and no stimulus. The stimulation was given to the rats once every weekday (Monday to Friday) for 4 weeks. Tickling stimulation was used as a mimic of the rough-and-tumble play of rats which induced a positive emotional response [50 kHz ultrasonic vocalization (USV)]. Light touch was a discriminative stimulation to tickling, and neither the rat with light touch nor with no stimulus showed such a response in general. Gene expression changes in hypothalamus of the tickled rats were comprehensively analyzed comparing with light touched and no stimulated rats using microarray techniques. Biological replicates: 4 animals each condition. One replicate per array.

本研究对经4周正向刺激（挠痒）处理的幼年大鼠下丘脑组织的信使核糖核酸（mRNA）表达水平变化进行了分析。相较于轻触刺激组，正向刺激组中参与进食调控的基因表达上调；相较于无刺激对照组，应激激素相关基因表达下调。
关键词：应激反应
实验设计：选用断乳后21日龄的雄性Wistar大鼠。实验期间，所有大鼠均单独饲养于带有屏蔽网的标准笼内，以避免彼此间视觉接触。随后将大鼠分为三组：挠痒刺激组、轻触刺激组与无刺激对照组。每周一至周五每日对大鼠进行一次刺激，持续4周。其中，挠痒刺激模拟大鼠间的嬉闹玩耍行为，可诱导正向情绪反应[50 kHz超声波发声（USV）]。轻触刺激为与挠痒刺激相区分的对照刺激，通常情况下轻触刺激组与无刺激组大鼠均未出现此类正向情绪反应。本研究采用基因微阵列（microarray）技术，全面分析挠痒刺激组大鼠下丘脑相较于轻触刺激组与无刺激对照组的基因表达变化情况。生物学重复：每组设置4只动物，每块芯片对应一个生物学重复样本。