Programa de Pós-Graduação em Ciências Biológicas/Bioquímica, Universidade Federal do Rio Grande do Sul, Instituto de Ciências Básicas da Saúde, Departamento de Bioquímica, Porto Alegre/RS, 90035-003, Brazil.
Behav Brain Res. 2011 Mar 17;218(1):80-6. doi: 10.1016/j.bbr.2010.11.030. Epub 2010 Nov 23.
Stress affects learning and memory processes and sensitivity to stress greatly varies between individuals. We studied behavioral and neurobiological effects of unpredictable subchronic stress (USCS) in two behavioral extremes of mice from the same strain (CF1) selected by their exploratory behavior of the central arena of an open field. The top and bottom 25% explorers were classified as low exploratory (LE) and high exploratory (HE) mice, respectively. The open field task, the novel object recognition task (NOR), sucrose intake and tail suspension task were evaluated in LE and HE groups exposed to USCS for two weeks or control conditions. Also serum corticosterone and hippocampal BDNF and S100B levels were analyzed. Both stressed groups exhibited less exploratory activity when submitted to USCS, but their difference in exploratory behavior remained. This short stress protocol did not induce changes in sucrose intake or immobility in the tail suspension task. Also, LE mice exhibited impaired NOR performance after USCS, whereas HE mice changed their pattern of exploration towards less exploration of the familiar object. HE had lower corticosterone levels than LE mice, but corticosterone levels increased after stress only in HE mice. Hippocampal BDNF in LE was lower than in HE but decreased after USCS only in HE mice, whereas S100B levels were not different between groups and did not change with USCS. In conclusion, our results suggest that individual differences in exploratory behavior in rodents from the same strain influence cognitive and biochemical response to stress.
压力会影响学习和记忆过程，而个体对压力的敏感程度差异很大。我们研究了来自同一品系（CF1）的两种行为极端的小鼠（低探索性（LE）和高探索性（HE））的不可预测的亚慢性应激（USCS）的行为和神经生物学效应。通过在开阔场的中央区域的探索行为对 top 和 bottom 25%的探索者进行分类，将其分别归类为低探索性（LE）和高探索性（HE）小鼠。在 LE 和 HE 组中，进行了开放场任务、新物体识别任务（NOR）、蔗糖摄入量和悬尾任务的评估，这些小鼠分别暴露于 USCS 两周或控制条件下。还分析了血清皮质酮和海马脑源性神经营养因子（BDNF）和 S100B 水平。当暴露于 USCS 时，这两个应激组的探索活动都减少了，但它们的探索行为差异仍然存在。这种短期应激方案并没有引起蔗糖摄入量或悬尾任务中不动性的变化。此外，LE 小鼠在 USCS 后 NOR 表现受损，而 HE 小鼠改变了它们对熟悉物体的探索模式，表现为探索减少。HE 小鼠的皮质酮水平低于 LE 小鼠，但只有 HE 小鼠在应激后皮质酮水平升高。LE 小鼠的海马 BDNF 水平低于 HE 小鼠，但只有 HE 小鼠在 USCS 后降低，而 S100B 水平在各组之间没有差异，也没有随 USCS 而变化。总之，我们的结果表明，来自同一品系的小鼠的探索行为的个体差异会影响认知和应激后的生化反应。
