Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
Am J Physiol Regul Integr Comp Physiol. 2012 Nov 1;303(9):R929-40. doi: 10.1152/ajpregu.00356.2012. Epub 2012 Sep 5.
The dorsolateral reticular formation of the caudal medulla, or the lateral tegmental field (LTF), has been classified as the brain's "vomiting center", as well as an important region in regulating sympathetic outflow. We examined the responses of LTF neurons in cats to rotations of the body that activate vestibular receptors, as well as to stimulation of baroreceptors (through mechanical stretch of the carotid sinus) and gastrointestinal receptors (through the intragastric administration of the emetic compound copper sulfate). Approximately half of the LTF neurons exhibited graviceptive responses to vestibular stimulation, similar to primary afferents innervating otolith organs. The other half of the neurons had complex responses, including spatiotemporal convergence behavior, suggesting that they received convergent inputs from a variety of vestibular receptors. Neurons that received gastrointestinal and baroreceptor inputs had similar complex responses to vestibular stimulation; such responses are expected for neurons that contribute to the generation of motion sickness. LTF units with convergent baroreceptor and vestibular inputs may participate in producing the cardiovascular system components of motion sickness, such as the changes in skin blood flow that result in pallor. The administration of copper sulfate often modulated the gain of responses of LTF neurons to vestibular stimulation, particularly for units whose spontaneous firing rate was altered by infusion of drug (median of 459%). The present results raise the prospect that emetic signals from the gastrointestinal tract modify the processing of vestibular inputs by LTF neurons, thereby affecting the probability that vomiting will occur as a consequence of motion sickness.
延髓尾侧背外侧网状结构，或称为外侧脑桥被盖区（LTF），已被归类为大脑的“呕吐中枢”，也是调节交感神经输出的重要区域。我们研究了猫的 LTF 神经元对激活前庭感受器的身体旋转、刺激压力感受器（通过颈动脉窦的机械拉伸）和胃肠道感受器（通过胃内给予催吐化合物硫酸铜）的反应。大约一半的 LTF 神经元对前庭刺激表现出重感反应，类似于支配耳石器官的初级传入。另一半神经元具有复杂的反应，包括时空会聚行为，表明它们从各种前庭感受器接收会聚输入。接收胃肠道和压力感受器输入的神经元对前庭刺激有类似的复杂反应；对于有助于晕车发生的神经元，预计会有这种反应。具有会聚的压力感受器和前庭输入的 LTF 单元可能参与产生晕车的心血管系统成分，例如导致苍白的皮肤血流变化。硫酸铜的给药通常会调节 LTF 神经元对前庭刺激反应的增益，特别是对于那些自发放电率因药物输注而改变的单位（中位数为 459%）。这些结果提出了这样一种可能性，即来自胃肠道的催吐信号改变了 LTF 神经元对前庭输入的处理，从而影响晕车导致呕吐的可能性。
