Animal Welfare Program, University of British Columbia, 2357 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada.
Sci Rep. 2019 Dec 12;9(1):19007. doi: 10.1038/s41598-019-55493-0.
Carbon dioxide (CO) is commonly used to kill laboratory rats. Rats find CO aversive and aversion varies between individuals, indicating that rats vary in CO sensitivity. Healthy humans experience feelings of anxiety at concentrations similar to those avoided by rats, and these feelings are diminished by the administration of benzodiazepines. Our aim was to assess the effects of the benzodiazepine midazolam on individual thresholds of rat aversion to CO. Six female Sprague Dawley rats were repeatedly exposed to CO gradual-fill in approach-avoidance testing. The first three exposures were to a control-treatment followed by three exposures to midazolam (0.375 mg/kg). Within each treatment aversion to CO was not affected by exposure number; however, tolerance increased from an average of 10.7% CO avoided during control sessions, to 15.5% CO avoided when treated with midazolam. These results indicate that rats experience anxiety when exposed to CO, and that variation in rat CO sensitivity is driven by individual differences in the onset of these feelings of anxiety. No rat tolerated CO concentrations required to induce loss of consciousness.
二氧化碳（CO）常用于杀死实验大鼠。大鼠对 CO 感到厌恶，个体之间存在差异，表明大鼠对 CO 的敏感性存在差异。健康的人类在与大鼠回避的浓度相似的浓度下会感到焦虑，而这些感觉会被苯二氮䓬类药物（benzodiazepines）的给药所减轻。我们的目的是评估苯二氮䓬类药物咪达唑仑对大鼠对 CO 厌恶的个体阈值的影响。六只雌性 Sprague Dawley 大鼠在逐渐填充的接近-回避测试中反复暴露于 CO。前三次暴露于对照处理，然后再进行三次咪达唑仑（0.375mg/kg）处理。在每种处理中，对 CO 的厌恶不受暴露次数的影响；然而，从对照期平均回避 10.7%的 CO 开始，当用咪达唑仑治疗时，对 CO 的回避增加到 15.5%。这些结果表明，大鼠在暴露于 CO 时会感到焦虑，并且大鼠对 CO 敏感性的差异是由这些焦虑感的出现个体差异驱动的。没有大鼠能耐受引起意识丧失所需的 CO 浓度。
