Nitrogen gas produces less behavioural and neurophysiological excitation than carbon dioxide in mice undergoing euthanasia
Nitrogen gas produces less behavioural and neurophysiological excitation than carbon dioxide in mice undergoing euthanasia
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DOI：
10.1371/journal.pone.0210818
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发表时间：
2019-01-31
期刊：
影响因子：
3.7
通讯作者：
Gent, Thomas C.
中科院分区：
文献类型：
--
作者：
Detotto, Carlotta;Isler, Sarah;Gent, Thomas C.
二氧化碳（CO2）是老鼠最常用的气体安乐死剂之一，尽管有报道称会引起厌恶和伤害。惰性气体如氮（N-2）可能是二氧化碳的可行替代品。在这里，我们比较了气体安乐死C57Bl/6小鼠在缓慢填充或快速填充时对CO2或N-2的行为和电生理反应。我们发现，与基线相比，被CO2安乐死的小鼠运动活动增加，而暴露于n2的小鼠运动活动减少。此外，暴露于CO2的小鼠比暴露于n2的小鼠表现出更多的垂直跳跃和冻结事件。我们进一步发现，二氧化碳暴露导致脑电图的θ: δ增加，这是一种兴奋的测量，而N-2则减少了θ: δ。反应的差异不依赖于氧浓度。综上所述，这些结果表明，二氧化碳增加行为和电生理兴奋以及产生恐惧反应，而N-2减少行为活动和中枢神经抑制，可能不那么厌恶，但仍产生恐惧反应。需要进一步的研究来评估N-2是否适合作为老鼠的安乐死剂。
Carbon dioxide (CO2) is one of the most commonly used gas euthanasia agents in mice, despite reports of aversion and nociception. Inert gases such as nitrogen (N-2) may be a viable alternative to carbon dioxide. Here we compared behavioural and electrophysiological reactions to CO2 or N-2 at either slow fill or rapid fill in C57Bl/6 mice undergoing gas euthanasia. We found that mice euthanised with CO2 increased locomotor activity compared to baseline, whereas mice exposed to N-2 decreased locomotion. Furthermore, mice exposed to CO2 showed significantly more vertical jumps and freezing episodes than mice exposed to N-2. We further found that CO2 exposure resulted in increased theta: delta of the EEG, a measure of excitation, whereas the N-2 decreased theta: delta. Differences in responses were not oxygen-concentration dependent. Taken together, these results demonstrate that CO2 increases both behavioural and electrophysiological excitation as well as producing a fear response, whereas N-2 reduces behavioural activity and central neurological depression and may be less aversive although still produces a fear response. Further studies are required to evaluate N-2 as a suitable euthanasia agent for mice.