Nitrous oxide causes a regulated hypothermia: rats select a cooler ambient temperature while becoming hypothermic.
Nitrous oxide causes a regulated hypothermia: rats select a cooler ambient temperature while becoming hypothermic.
复制标题
一氧化二氮会引起调节性体温过低：大鼠在体温过低时会选择较冷的环境温度。
DOI：
10.1016/j.physbeh.2010.12.018
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发表时间：
2011
影响因子：
2.9
通讯作者：
Kaiyala,KarlJ
中科院分区：
文献类型：
--
作者：
Ramsay,DouglasS;Seaman,Jana;Kaiyala,KarlJ
An initial administration of 60% nitrous oxide (N2O) evokes hypothermia in rats and if the administration continues for more than 1–2h, acute tolerance typically develops such that the initial reduction in core temperature (Tc) reverses and Tc recovers toward control values. Calorimeter studies at normal ambient temperature indicate that hypothermia results from a transient reduction in heat production (HP) combined with an elevation in heat loss. Acute tolerance develops primarily due to progressive increases in HP. Our aim was to determine whether rats provided a choice of ambient temperatures would behaviorally facilitate or oppose N2O-induced hypothermia. A gas-tight thermally-graded alleyway (range, 6.7–37.0°C) enabled male Long–Evans rats (n=12) to select a preferred ambient temperature during a 5-hour steady-state administration of 60% N2O and a separate paired control gas exposure (order counterbalanced). Tc was measured telemetrically from a sensor surgically implanted into the peritoneal cavity >7days before testing. Internal LED lighting maintained the accustomed day:night cycle (light cycle 0700–1900h) during sessions lasting 45.5h. Rats entered the temperature gradient at 1100h, and the 5-h N2O or control gas period did not start until 23h later to provide a long habituation/training period. Food and water were provided ad libitum at the center of the alleyway. The maximum decrease of mean Tc during N2O administration occurred at 0.9h and was −2.05±0.25°C; this differed significantly (p<0.0001) from the corresponding Tc change at 0.9h during control gas administration (0.01±0.14°C). The maximum decrease of the mean selected ambient temperature during N2O administration occurred at 0.7h and was −13.58±1.61°C; this differed significantly (p<0.0001) from the corresponding mean change in the selected ambient temperature at 0.7h during control gas administration (0.30±1.49°C). N2O appears to induce a regulated hypothermia because the selection of a cool ambient temperature facilitates the reduction in Tc. The recovery of Tc during N2O administration (i.e., acute tolerance development) could have been facilitated by selection of ambient temperatures that were warmer than those chosen during control administrations, but interestingly, this did not occur.
