Leon Lisa R
US Army Research Institute of Environmental Medicine, Thermal and Mountain Medicine Division, Kansas Street, Building 42, Natick, Massachusetts 00760-5007, USA.
Toxicol Appl Pharmacol. 2008 Nov 15;233(1):146-61. doi: 10.1016/j.taap.2008.01.012. Epub 2008 Jan 31.
Thermal stress can have a profound impact on the physiological responses that are elicited following environmental toxicant exposure. The efficacy by which toxicants enter the body is directly influenced by thermoregulatory effector responses that are evoked in response to high ambient temperatures. In mammals, the thermoregulatory response to heat stress consists of an increase in skin blood flow and moistening of the skin surface to dissipate core heat to the environment. These physiological responses may exacerbate chemical toxicity due to increased permeability of the skin, which facilitates the cutaneous absorption of many environmental toxicants. The core temperature responses that are elicited in response to high ambient temperatures, toxicant exposure or both can also have a profound impact on the ability of an organism to survive the insult. In small rodents, the thermoregulatory response to thermal stress and many environmental toxicants (such as organophosphate compounds) is often biphasic in nature, consisting initially of a regulated reduction in core temperature (i.e., hypothermia) followed by fever. Hypothermia is an important thermoregulatory survival strategy that is used by small rodents to diminish the effect of severe environmental insults on tissue homeostasis. The protective effect of hypothermia is realized by its effects on chemical toxicity as molecular and cellular processes, such as lipid peroxidation and the formation of reactive oxygen species, are minimized at reduced core temperatures. The beneficial effects of fever are unknown under these conditions. Perspective is provided on the applicability of data obtained in rodent models to the human condition.
热应激会对环境毒物暴露后引发的生理反应产生深远影响。毒物进入人体的效率直接受到高温环境下引发的体温调节效应反应的影响。在哺乳动物中，对热应激的体温调节反应包括皮肤血流量增加和皮肤表面湿润，以将核心热量散发到环境中。这些生理反应可能会加剧化学毒性，因为皮肤通透性增加，这有利于许多环境毒物的皮肤吸收。对高温环境、毒物暴露或两者共同作用引发的核心体温反应，也会对生物体在遭受损伤后存活的能力产生深远影响。在小型啮齿动物中，对热应激和许多环境毒物（如有机磷化合物）的体温调节反应通常具有双相性，最初表现为核心体温的调节性降低（即体温过低），随后出现发热。体温过低是小型啮齿动物用来减轻严重环境损伤对组织稳态影响的一种重要体温调节生存策略。体温过低的保护作用是通过其对化学毒性的影响来实现的，因为在核心体温降低时，脂质过氧化和活性氧形成等分子和细胞过程会降至最低。在这些情况下，发热的有益作用尚不清楚。文中还阐述了从啮齿动物模型获得的数据对人类情况的适用性。
