Beijing Institute of Radiation Medicine, State Key Laboratory of Proteomics, Beijing 100850, China.
Eur Neuropsychopharmacol. 2009 Dec;19(12):868-75. doi: 10.1016/j.euroneuro.2009.07.004. Epub 2009 Aug 6.
Exposure to enriched environment (EE) can influence expression of depression symptoms, however, the underlying mechanism has not been established, although neurogenesis was probably involved. It has been reported that EE stimulates glucocorticoids release. However, the role of corticosterone (CORT) in effects of EE is still unknown. To address these issues, we examined depression-like behaviors of the animals exposed to EE with low dose CORT supplement following bilateral adrenalectomy (ADX+CORT). Two months after housing, tail suspension test and forced swim test were used to assess depression-related behavior of mice. Serum CORT levels were measured by radio-immunoassay. Signals of DNA synthesis marker bromodeoxyuridine and immature neuronal marker doublecortin were measured by immunohistochemistry. Results showed that EE significantly decreased immobility time of the mice in both the tail suspension test and forced swim test, showing distinctive antidepressive behaviors. Exposure to EE also increased serum CORT level, and prevention of this increase with ADX+CORT eliminated the decrease of immobility time of the animals. Both the mice exposed to EE and those receiving ADX+CORT treatment showed enhanced newly born cells and immature granule neurons in the hippocampus. Taken together, our data suggest that glucocorticoids elevation is required for antidepressive behaviors of EE.
暴露于丰富环境（EE）可以影响抑郁症状的表达，然而，尽管神经发生可能涉及其中，但尚未确定其潜在机制。据报道，EE 会刺激糖皮质激素的释放。然而，皮质酮（CORT）在 EE 影响中的作用仍不清楚。为了解决这些问题，我们研究了双侧肾上腺切除术（ADX+CORT）后补充低剂量 CORT 的动物暴露于 EE 时的抑郁样行为。在饲养 2 个月后，使用悬尾试验和强迫游泳试验评估小鼠的抑郁相关行为。通过放射免疫测定法测量血清 CORT 水平。通过免疫组织化学测量 DNA 合成标志物溴脱氧尿苷和未成熟神经元标志物双皮质素的信号。结果表明，EE 显著减少了悬尾试验和强迫游泳试验中小鼠的不动时间，表现出明显的抗抑郁行为。暴露于 EE 还增加了血清 CORT 水平，而 ADX+CORT 预防这种增加消除了动物不动时间的减少。暴露于 EE 的小鼠和接受 ADX+CORT 治疗的小鼠在海马体中都表现出新生细胞和未成熟颗粒神经元的增加。总之，我们的数据表明，皮质酮升高是 EE 抗抑郁行为所必需的。
