Department of Pathology, Immunology, and Microbiology, Vanderbilt University Medical Center, Nashville, Tennessee; Divison of Animal Care, Vanderbilt University Medical Center, Nashville, Tennessee;, Email:
Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee.
J Am Assoc Lab Anim Sci. 2022 Jul 1;61(4):322-332. doi: 10.30802/AALAS-JAALAS-22-000011. Epub 2022 Jul 15.
Isoflurane has been characterized as a distressing agent for rodents, causing both physiologic and behavioral effects. Using a "darkened home cage" has been recommended during CO₂ administration for rodent euthanasia; this is arguably a similar animal experience to anesthetic induction with isoflurane. Based on the premise that rodents perceive red light as darkness via the primary optic tract, we compared physiologic and behavioral markers of stress in 2 inbred strains of mice (C57BL/6J and BALB/cJ) anesthetized with isoflurane in either a red-tinted (dark) induction chamber or a traditional translucent induction chamber. Physiologic stress was assessed based on plasma levels of norepinephrine, epinephrine, and corticosterone. Stress-related behaviors (rearing, face wiping, and jumping) were recorded on video and scored from initiation of induction to loss of consciousness. No significant correlations were found between chamber type and physiologic stress hormones. As compared with the translucent chamber, stress-related behaviors were more frequent in the red-tinted chamber, including: 1) significantly higher rearing frequencies in BALB/cJ mice; 2) higher behavioral stress scores in BALB/cJ and male C57BL/6J mice; and 3) more face wiping behavior when considering all mice combined. These findings suggest that mice do not experience significant alleviation of physiologic indices of stress when anesthetized in a red-tinted induction chamber. Furthermore, isoflurane induction in the red-tinted chamber appeared to increase the expression of stress-related behaviors, particularly in BALB/cJ mice. Based on our findings and a growing body of literature on the unintended effects of red light, we do not recommend using red-tinted chambers for induction of anesthesia in mice.
异氟醚已被证明是一种令啮齿动物感到痛苦的药物，会引起生理和行为反应。在使用 CO₂对啮齿动物实施安乐死时，建议将“暗化的家笼”用于笼内环境，这与使用异氟醚诱导麻醉的动物体验类似。基于啮齿动物通过初级视束将红光视为黑暗的前提，我们比较了两种近交系小鼠（C57BL/6J 和 BALB/cJ）在异氟醚麻醉下使用红色（深色）诱导室或传统半透明诱导室时的生理和行为应激标志物。生理应激通过血浆去甲肾上腺素、肾上腺素和皮质酮水平来评估。应激相关行为（竖耳、擦脸和跳跃）通过视频记录，并从诱导开始到失去意识进行评分。未发现室类型与生理应激激素之间存在显著相关性。与半透明室相比，红色室中应激相关行为更为频繁，包括：1）BALB/cJ 小鼠的竖耳频率明显更高；2）BALB/cJ 和雄性 C57BL/6J 小鼠的行为应激评分更高；3）考虑所有小鼠时，擦脸行为更多。这些发现表明，当在红色诱导室中麻醉时，小鼠的生理应激指标并未得到显著缓解。此外，在红色诱导室中使用异氟醚诱导似乎增加了应激相关行为的表达，尤其是在 BALB/cJ 小鼠中。基于我们的发现以及越来越多的关于红光意外影响的文献，我们不建议在小鼠麻醉诱导中使用红色诱导室。
