Chioléro R, Berger M
Department of Anesthesiology, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland.
New Horiz. 1994 Nov;2(4):432-42.
The neuroendocrine response (NER) is an essential component of the adaptive process to trauma, brain injury, and major surgery. While receiving additive humoral and neural afferent inputs, the brain nuclei responsible for the NER act mainly by efferent pathways to the hypothalamic-pituitary-adrenal (HPA) axis and the sympathoadrenal system, the activations of which induce subsequent circulatory and metabolic responses. The NER to brain injury is similar to the response observed in patients with extracerebral injury, even if the response after brain injury is extremely variable. Generally, there is a biphasic pattern, with a sympathoadrenal storm associated with variable and altered stimulation of the HPA during the ebb phase. The first phase is followed by a decrease in both responses while other endocrine changes develop, involving mainly the counter-regulatory, gonadal, and thyroid hormones. The outcome after brain injury is closely correlated with the intensity of these changes, particularly with catecholamine plasma levels and the severity of the low triiodothyronine syndrome. Alterations of the thyroid hormones are largely related to a reduction in peripheral deiodination of thyroxin. Recent research shows that increased free-radical production and decreased selenium (an antioxidant) serum levels play an important role in thyroid metabolism. Two major issues remain unsolved: a) the precise definition of cerebral death, since endocrine brain function is not abolished in the state currently defined as brain death; and b) the question of whether substitutive hormone therapy should be applied in severe brain injury.
神经内分泌反应（NER）是机体对创伤、脑损伤和大手术产生适应性反应过程中的一个重要组成部分。在接受体液和神经传入信号的叠加输入时，负责NER的脑内核团主要通过传出通路作用于下丘脑 - 垂体 - 肾上腺（HPA）轴和交感肾上腺系统，这两个系统的激活会引发后续的循环和代谢反应。脑损伤后的NER与脑外损伤患者所观察到的反应相似，尽管脑损伤后的反应差异极大。一般来说，存在一种双相模式，在消退期会出现交感肾上腺风暴，同时伴有HPA刺激的变化和改变。第一阶段之后，随着其他内分泌变化的出现，这两种反应都会减弱，这些变化主要涉及反调节激素、性腺激素和甲状腺激素。脑损伤后的结果与这些变化的强度密切相关，尤其是与儿茶酚胺血浆水平和低三碘甲状腺原氨酸综合征的严重程度相关。甲状腺激素的改变在很大程度上与甲状腺素外周脱碘作用的降低有关。最近的研究表明，自由基产生增加和硒（一种抗氧化剂）血清水平降低在甲状腺代谢中起重要作用。仍有两个主要问题尚未解决：a）脑死亡的精确定义，因为在内分泌脑功能在目前定义为脑死亡的状态下并未被消除；b）在严重脑损伤中是否应应用替代激素疗法的问题。
