McCulloch Paul F
Department of Physiology, Midwestern University;
J Vis Exp. 2014 Nov 12(93):e52093. doi: 10.3791/52093.
Underwater submergence produces autonomic changes that are observed in virtually all diving animals. This reflexly-induced response consists of apnea, a parasympathetically-induced bradycardia and a sympathetically-induced alteration of vascular resistance that maintains blood flow to the heart, brain and exercising muscles. While many of the metabolic and cardiorespiratory aspects of the diving response have been studied in marine animals, investigations of the central integrative aspects of this brainstem reflex have been relatively lacking. Because the physiology and neuroanatomy of the rat are well characterized, the rat can be used to help ascertain the central pathways of the mammalian diving response. Detailed instructions are provided on how to train rats to swim and voluntarily dive underwater through a 5 m long Plexiglas maze. Considerations regarding tank design and procedure room requirements are also given. The behavioral training is conducted in such a way as to reduce the stressfulness that could otherwise be associated with forced underwater submergence, thus minimizing activation of central stress pathways. The training procedures are not technically difficult, but they can be time-consuming. Since behavioral training of animals can only provide a model to be used with other experimental techniques, examples of how voluntarily diving rats have been used in conjunction with other physiological and neuroanatomical research techniques, and how the basic training procedures may need to be modified to accommodate these techniques, are also provided. These experiments show that voluntarily diving rats exhibit the same cardiorespiratory changes typically seen in other diving animals. The ease with which rats can be trained to voluntarily dive underwater, and the already available data from rats collected in other neurophysiological studies, makes voluntarily diving rats a good behavioral model to be used in studies investigating the central aspects of the mammalian diving response.
水下浸没会引发自主神经变化，几乎在所有潜水动物身上都能观察到这种变化。这种反射性诱导反应包括呼吸暂停、副交感神经诱导的心动过缓以及交感神经诱导的血管阻力改变，后者可维持心脏、大脑和运动肌肉的血液供应。虽然在海洋动物中已经对潜水反应的许多代谢和心肺方面进行了研究，但对这种脑干反射的中枢整合方面的研究相对较少。由于大鼠的生理学和神经解剖学特征明确，因此可以用大鼠来帮助确定哺乳动物潜水反应的中枢通路。文中提供了详细的指导说明，介绍如何训练大鼠通过一条5米长的有机玻璃迷宫在水下游泳和自主潜水。还给出了关于水箱设计和操作室要求的注意事项。行为训练的方式旨在减轻原本可能与强迫水下浸没相关的压力，从而最大限度地减少中枢应激通路的激活。训练程序在技术上并不困难，但可能会很耗时。由于对动物的行为训练只能提供一个与其他实验技术配合使用的模型，因此还提供了一些示例，说明如何将自主潜水的大鼠与其他生理和神经解剖学研究技术结合使用，以及可能需要如何修改基本训练程序以适应这些技术。这些实验表明，自主潜水的大鼠表现出与其他潜水动物通常所见相同的心肺变化。大鼠易于训练自主在水下潜水，而且在其他神经生理学研究中已经收集了有关大鼠的现有数据，这使得自主潜水的大鼠成为研究哺乳动物潜水反应中枢方面的良好行为模型。
