Vogt M A, Chourbaji S, Brandwein C, Dormann C, Sprengel R, Gass P
Central Institute of Mental Health Mannheim, University of Heidelberg, Mannheim, Germany.
Exp Neurol. 2008 May;211(1):25-33. doi: 10.1016/j.expneurol.2007.12.012. Epub 2007 Dec 23.
Tamoxifen-induced mutagenesis via the so-called CreER(T2) fusion enzyme is a key technology for the inducible gene knockout in the adult murine brain. However, it requires a subchronic transient treatment with high doses of the non-selective estrogen receptor antagonist tamoxifen. It has been shown earlier that acute tamoxifen treatment causes behavioral alterations, while the long-term behavioral effects of tamoxifen in mice are so far unknown. Therefore C57BL/6 male mice, a common strain used for targeted mutagenesis and behavioral analyses, were subjected to a tamoxifen treatment protocol as used for inducible mutagenesis in vivo, and analyzed for effects on general behavior (locomotion, exploration), emotional behavior (anxiety, depression) and on learning and memory after a drug-free interval period of 4 weeks. The results demonstrate that a test for depression-like behavior, i.e. the Forced Swim Test, is affected even more than 4 weeks after tamoxifen treatment. In contrast, in all other tests, tamoxifen treated mice showed unaltered behaviors, indicating that the currently established 5-day protocol of tamoxifen treatment (40 mg/kg bid) for inducible mutagenesis has no or little effects on the behavior of C57BL/6 male mice after a latency period of 4 weeks. These results are important for all studies using tamoxifen-induced mutagenesis since this protocol obviously does not evoke alterations in general behaviors such as locomotion, exploration or anxiety-like behaviors, which might confound more complex behavioral analyses, nor does it affect standard tests for learning and memory, such as Morris Water Maze, contextual and cued Fear Conditioning and T-Maze learning.
通过所谓的CreER(T2)融合酶进行的他莫昔芬诱导诱变是成年小鼠大脑中诱导基因敲除的关键技术。然而，它需要用高剂量的非选择性雌激素受体拮抗剂他莫昔芬进行亚慢性短暂治疗。早期研究表明，急性他莫昔芬治疗会导致行为改变，而他莫昔芬对小鼠的长期行为影响至今尚不清楚。因此，将常用于靶向诱变和行为分析的C57BL/6雄性小鼠按照用于体内诱导诱变的他莫昔芬治疗方案进行处理，并在4周的无药间隔期后分析其对一般行为（运动、探索）、情绪行为（焦虑、抑郁）以及学习和记忆的影响。结果表明，即使在他莫昔芬治疗4周多后，类似抑郁行为的测试，即强迫游泳试验，仍受到影响。相比之下，在所有其他测试中，接受他莫昔芬治疗的小鼠行为未发生改变，这表明目前用于诱导诱变的他莫昔芬5天治疗方案（40mg/kg，每日两次）在4周的潜伏期后对C57BL/6雄性小鼠的行为没有或几乎没有影响。这些结果对于所有使用他莫昔芬诱导诱变的研究都很重要，因为该方案显然不会引起运动、探索或焦虑样行为等一般行为的改变，而这些改变可能会混淆更复杂的行为分析，也不会影响学习和记忆的标准测试，如莫里斯水迷宫、情境和线索恐惧条件反射以及T迷宫学习。
