目的 从行为学及分子水平比较皮质酮（CORT）与慢性不可预见性应激（CUMS）诱导的抑郁症模型的异同，为抑郁症发病机制研究及抗抑郁药物的筛选与评价模型提供一定的参考。 方法 将30只雄性C57BL/6小鼠随机分成对照组（Ctrl）、慢性不可预见应激组（CUMS）和皮质酮注射应激组（CORT）组，制作应激模型21d，期间每3d对小鼠进行称重。21d模型制作结束后，对小鼠进行行为学测试，并于第22天，通过眼眶取血收集动物血清，并用ELISA法测定血清皮质酮含量。眼眶取血后脱颈椎处死动物，取出动物的胸腺和脾脏进行称重，计算脏器指数；取出脑组织，置于液氮罐保存，尼氏（Nissl）染色法观察小鼠大脑海马区神经元损伤情况；采用Western blotting、RT-PCR方法测定抑郁症相关蛋白及基因的表达。 结果 与对照组相比，两种抑郁症模型组开场实验中的行为学指标均改变，强迫游泳和悬尾实验的累积不动时间显著升高。两个模型组的胸腺指数无明显变化，而CORT组的脾脏指数较对照组下降。CUMS和CORT组小鼠血清皮质酮含量高于对照组，CORT组与CUMS组相比有升高趋势，但差异无显著性。CUMS和CORT两种模型均使海马CA1、CA3和DG区神经元密度降低，CORT模型变化更明显。两模型组的促肾上腺素释放激素（CRH）的mRNA和蛋白的表达量均显著性增加，脑源性神经营养因子（BDNF）、磷酸化转录因子环磷腺苷反应元件结合蛋白（p-CREB）和磷酸化细胞外信号调节激酶（p-ERK）的蛋白表达水平均呈现明显地抑制，但CUMS和CORT两组之间差异无显著性。结论 CORT模型和CUMS模型均能成功构建抑郁症模型，且与下丘脑-垂体-肾上腺（HPA）轴紊乱有关，两种模型在小鼠海马结构改变及大脑BDNF-p-CREB和ERK信号通路激活等方面差异无显著性。提示，CORT模型可用于抑郁症机制的研究及抗抑郁药的筛选与评价，尤其可用于以HPA轴功能紊乱所引起的抑郁症分子机制探讨。

Objective To assess the differences in behavior and molecular mechanism of C57BL/6 mice subjected to repeated corticosterone injection (CORT) or chronic unpredictable mild stress (CUMS), and to provide a theoretical reference for antidepressants screening and evaluation. Methods Thirty male C57BL/6 mice were divided into control group, CORT group and CUMS group. During the 3 week stress period, body weights of mice were measured every 3 days. After stress exposure, the open-field test, force swimming test and tail-suspension test were used to evaluate the behavioral changes, with serum corticosterone measured by ELISA. Histological studies were carried out the hippocampal neuron damage with Nissl staining, while the expressions of brain CRH, BDNF, p-CREB and p-ERK protein or gene transcripts were analyzed by Western blotting or PCR. Results Compared with the control group, the number of grooming was significantly decreased in the CORT group, with no significant changes in frequency of crossing and rearing. In the CUMS group, the numbers of rearing and crossing were significantly decreased, while the frequency of grooming was not changed. In the force swimming and tail suspension tests, the time of immobility was significantly increased in both CORT and CUMS groups compared with the control group. Serum corticosterone levels were significantly higher in CORT and CUMS groups than control group. Comparing between the two model and the control groups, there was no significant difference in the thymus index, while the spleen index in the CORT group was significantly decreased. The density of CA1, CA3 and dentate gyrus regions Nissl stained neurons reduced in both CUMS and CORT group, especially in CORT group. Through PCR detection, levels of brain CRH mRNA in both CORT and CUMS group were significantly higher than the control group. Levels of BDNF, p-CREB and p-ERK protein were decreased in the CORT and CUMS groups relative to control, whereas CRH protein levels were higher in the former two groups. Conclusion Both the CORT and CUMS models present depression behaviors, which appears to reflect dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis. There is no significant difference between CORT and CUMS models in behavior alteration, hippocampal formation and protein expression of BDNF-p-CREB and ERK signaling pathway. In conclusion, the CORT model could be a useful model of depression and might be applied for mechanism research and antidepressant screening. The CORT model has an advantage of simple operation and shorter modeling cycle over the CUMS model.