Training Rats to Voluntarily Dive Underwater: Investigations of the Mammalian Diving Response

Abstract

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. Video LinkThe video component of this article can be found at

Repetitive Diving in Trained Rats Still Increases Fos Production in Brainstem Neurons after Bilateral Sectioning of the Anterior Ethmoidal Nerve

“…Thus the “type” of dive can affect the observed cardiovascular responses in many diving species (Butler and Jones, 1997 ). Based on this consideration, we have used the term “repetitive trained diving” in the present research, rather than the term “voluntary diving” that we have used previously (McCulloch et al, 2010 ; Chotiyanonta et al, 2013 ; McCulloch, 2014 ). “Voluntary diving” is often reserved to describe the response seen in animals diving in their natural environment, rather than diving in a tank located in a laboratory (Butler and Jones, 1997 ).…”

“…Twenty-four 3 week old rats were trained over 10 weeks to voluntarily swim and then dive through a Plexiglas maze (McCulloch, 2014 ). The training process began by allowing the rats to gradually learn how to swim through the maze by steadily increasing the swim distances each day.…”

“…After the rats could successfully swim the full length of the maze, the dive training would begin. The rats would be trained to dive longer distances through the maze each day until they could dive the full 5 m length of the maze in 10–15 s (McCulloch, 2014 ). To prevent the rats from becoming hypothermic during the training, water temperature was maintained at 30 ± 2°C and rats were dried with a towel between trials.…”

The Mammalian Diving Response: Inroads to Its Neural Control

“…Discussions of techniques employed will not be emphasized in this review. However, interested readers are referred to manuscripts with numerous references detailing the location of the anterior ethmoidal nerve (AEN; Panneton, 1991a) and its recording/stimulation (McCulloch et al, 1999a) stimulating the nasal mucosa with vapors (Panneton, 1991b;Panneton and Yavari, 1995;Yavari et al, 1996;Panneton et al, 2010b), for transganglionic transport techniques from primary afferent fibers (Panneton, 1991a;Panneton et al, 2006;, for pharmacological blockade of central pathways (Panneton and Yavari, 1995;McCulloch et al, 1999b), for neuroanatomical tract-tracing of central pathways (Panneton et al, 2000(Panneton et al, , 2006, for the use of cFos as a neuroanatomical marker of function (Panneton et al, 2010a(Panneton et al, , 2012a, for the training of rats and mice to dive (McCulloch, 2014;Hult et al, 2019), and for deployment of telemetric transmitters to measure cardiovascular changes in both trained rats (Panneton et al, 2010a(Panneton et al, ,b, 2012a) and mice (Hult et al, 2019). The limitations of these techniques are discussed in these manuscripts.…”

Physiology Of Drowning: A Review

“…The diving response is better developed and has a faster onset in diving mammals and children than in adult humans (47,77,91,106,137). Rats have been trained to dive to allow study of the diving response (106,161,162,198).…”