Department of Production Animal Sciences, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., N-0033 Oslo, Norway.
Physiol Behav. 2010 Aug 4;101(1):32-9. doi: 10.1016/j.physbeh.2010.04.003. Epub 2010 Apr 10.
Comparative studies on neural plasticity in non-mammalian vertebrates are increasingly promoted as an important complement to mammalian models. In teleost fishes the number of brain cells increases with age, body weight, and body length throughout life. Neurogenesis persists to a large degree, and both neuron replacement and net brain growth occur during adulthood. Whether environmental factors affect brain cell proliferation has however been scarcely investigated in this animal group. In the current study adult male zebrafish were kept in social isolation in different environments (enriched vs. barren) for one week. Telencephalic cell proliferation was investigated by proliferating cell nuclear antigen (PCNA) immunohistochemistry. Higher numbers of PCNA positive nuclei and significantly increased inter-individual variability was observed in fish kept in aquaria enriched with artificial plants and gravel. Zebrafish rapidly regained feed intake after transfer to social isolation. Whole-body cortisol levels were also generally low in isolated fish, although slightly elevated in fish from enriched environments. In summary, this study demonstrates that environmental alterations can rapidly alter cell cycle dynamics in the zebrafish brain. Furthermore, the results support the idea that mild short-term stressors and concomitant small increases in corticosteroid exposure stimulate brain cell proliferation.
比较非哺乳动物脊椎动物神经可塑性的研究越来越多地被提倡作为哺乳动物模型的重要补充。在硬骨鱼类中，脑细胞数量会随着年龄、体重和体长的增长而终生增加。神经发生在很大程度上持续存在，并且在成年期发生神经元替代和净脑生长。然而，环境因素是否会影响脑细胞增殖在该动物群体中几乎没有得到研究。在本研究中，成年雄性斑马鱼被分别饲养在不同环境（丰富环境与贫瘠环境）中一周，通过增殖细胞核抗原（PCNA）免疫组化来研究端脑细胞增殖。结果发现，在饲养有人工植物和砾石的水族箱中的鱼类中，PCNA 阳性细胞核的数量更高，个体间的差异也显著增加。斑马鱼在转移到社会隔离后迅速恢复摄食。尽管在丰富环境中的鱼类中略有升高，但隔离鱼类的全身皮质醇水平通常较低。总之，本研究表明，环境改变可以迅速改变斑马鱼大脑的细胞周期动态。此外，研究结果支持这样一种观点，即轻度短期应激源和伴随的小剂量皮质类固醇暴露会刺激脑细胞增殖。
