Johnson Rowsey P, Gordon C J
The University of North Carolina at Chapel Hill, School of Nursing, 27599-7460, USA.
Toxicology. 1997 Sep 5;121(3):215-21. doi: 10.1016/s0300-483x(97)00068-1.
Hypothermia is a commonly reported thermoregulatory response in rodents acutely exposed to organophosphates (OP); however, our laboratory has recently found a delayed hyperthermic response following the initial hypothermia when exposed to the OP, chlorpyrifos. It is well known that rodents display tolerance to OP-induced hypothermia but little is known about tolerance to OP-induced hyperthermia. Twenty female rats of the Long-Evans strain were made tolerant to chlorpyrifos by administering 0 or 10 mg/g chlorpyrifos by gavage daily for four days. Core temperature (T[c]) and motor activity (MA) were monitored continuously by telemetry. Twenty-four hours after the fourth 10 mg/kg injection, the animals were administered a challenge dose of 25 mg/kg chlorpyrifos or corn oil while the telemetry data were monitored for the next 72 h. Non-tolerant rats displayed an initial hypothermic response with reduced MA followed by a delayed increase in T(c) 24 h after exposure. The tolerant animals displayed a blunted hypothermic response with virtually no change in MA, but a delayed increase in T(c) similar to that of non-tolerant animals. The hyperthermic response of the non-tolerant animals persisted for two days, whereas the tolerant animals recovered by the second day. The data indicate that tolerance to the hypothermic and hyperthermic effects of chlorpyrifos involve separate neurochemical pathways.
体温过低是啮齿动物急性接触有机磷（OP）时常见的体温调节反应；然而，我们实验室最近发现，在接触OP毒死蜱后，最初的体温过低之后会出现延迟性体温过高反应。众所周知，啮齿动物对OP诱导的体温过低表现出耐受性，但对OP诱导的体温过高的耐受性知之甚少。将20只长 Evans 品系的雌性大鼠通过每天灌胃给予0或10 mg/g毒死蜱，持续四天，使其对毒死蜱产生耐受性。通过遥测连续监测核心体温（T[c]）和运动活动（MA）。在第四次注射10 mg/kg后的24小时，给动物注射25 mg/kg毒死蜱或玉米油的激发剂量，同时在接下来的72小时监测遥测数据。未耐受的大鼠最初表现出体温过低反应，MA降低，随后在接触后24小时T[c]延迟升高。耐受的动物表现出减弱的体温过低反应，MA几乎没有变化，但T[c]延迟升高，与未耐受的动物相似。未耐受动物的体温过高反应持续两天，而耐受动物在第二天恢复。数据表明，对毒死蜱的体温过低和体温过高作用的耐受性涉及不同的神经化学途径。
