Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland.
Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland.
BMC Biol. 2023 Aug 17;21(1):177. doi: 10.1186/s12915-023-01679-y.
The Rotarod test with commercial apparatus is widely used to assess locomotor performance, balance and motor learning as well as the deficits resulting from diverse neurological disorders in laboratory rodents due to its simplicity and objectivity. Traditionally, the test ends when rodents drop from the accelerating, turning rod, and the only parameter used commonly is "latency to fall". The values of individual animals can often vary greatly.
In the present study, we established a procedure for mice with 4 consecutive days of training with 4 trials per day and modified the testing procedure by placing the mice back on the rod repeatedly after each fall until the trial ends (5 min). Data from the fourth training day as baseline results showed that the second, third and fourth trial were more consistent than the first, probably due to habituation or learning. There was no difference between the second, third and fourth trial, two trials may be sufficient in testing. We also introduced 3 additional read-outs: Longest duration on the rod (s), Maximal distance covered (cm), and Number of falls to better evaluate the motor capacity over the 5 min of testing. We then used this 4-parameter analysis to capture the motor deficits of mice with mild to moderate traumatic brain injuries (by a weight dropping on the skull (Marmarou model)). We found that normalization of data to individual baseline performance was needed to reduce individual differences, and 4 trials were more sensitive than two to show motor deficits. The parameter of Maximal distance was the best in detecting statistically significant long-term motor deficits.
These results show that by making adjustments to the protocol and employing a more refined analysis, it is possible to expand a widely used routine behavioral test with additional accessible parameters that detect relevant deficits in a model of mild to moderate traumatic brain injury. The modified Rotarod test maybe a valuable tool for better preclinical evaluations of drugs and therapies.
商用转棒仪的转棒测试因其简单、客观，被广泛用于评估实验室啮齿动物的运动表现、平衡和运动学习能力，以及各种神经障碍引起的缺陷。传统上，当啮齿动物从加速旋转的棒上掉落时，测试结束，常用的唯一参数是“坠落潜伏期”。个体动物的数值往往差异很大。
在本研究中，我们为小鼠建立了一个连续 4 天训练、每天 4 次试验的程序，并通过每次掉落后将小鼠放回棒上，直到试验结束（5 分钟），对测试程序进行了修改。第四天训练的数据作为基线结果显示，第二、第三和第四次试验比第一次更一致，可能是由于习惯化或学习。第二、第三和第四次试验之间没有差异，两次试验可能足以进行测试。我们还引入了另外 3 个可读取的参数：在棒上的最长持续时间（s）、最大覆盖距离（cm）和坠落次数，以更好地评估 5 分钟测试期间的运动能力。然后，我们使用这 4 个参数分析来捕捉轻度至中度创伤性脑损伤（通过颅骨上的重物坠落（Marmarou 模型））小鼠的运动缺陷。我们发现，需要将数据归一化为个体基线表现，以减少个体差异，且四次试验比两次试验更能敏感地显示运动缺陷。最大距离参数是检测具有统计学意义的长期运动缺陷的最佳参数。
这些结果表明，通过调整方案并采用更精细的分析，可以在广泛使用的常规行为测试中增加额外的可获取参数，从而在轻度至中度创伤性脑损伤模型中检测到相关缺陷。改良的转棒测试可能是一种更好的临床前药物和治疗评估工具。
