Abstract
It has been demonstrated that physical activity contributes to a healthier life. However, there is a knowledge gap regarding the neural mechanisms producing these effects. One of the keystones to deal with this problem is to use training programs with equal loads of physical activity. However, irregular motor and stress responses have been found in murine exercise models. Habituation to forced exercise facilitates a complete response to a training program in all rodents, reaching the same load of physical activity among animals. Here, it was evaluated if glucose and lactate – which are stress biomarkers – are increased during the habituation to exercise. Sprague-Dawley rats received an 8-days habituation protocol with progressive increments of time and speed of running. Then, experimental and control (non-habituated) rats were subjected to an incremental test. Blood samples were obtained to determine plasmatic glucose and lactate levels before, immediately after and 30 min after each session of training. Crh and Avp mRNA expression was determined by two-step qPCR. Our results revealed that glucose and lactate levels are not increased during the habituation period and tend to decrease toward the end of the protocol. Also, Crh and Avp were not chronically activated by the habituation program. Lactate and glucose, determined after the incremental test, were higher in control rats without previous contact with the wheel, compared with habituated and wheel control rats. These results suggest that the implementation of an adaptive phase prior to forced exercise programs might avoid non-specific stress responses.
Highlights
Active people have a reduced risk of developing non-communicable diseases such as obesity, osteoporosis, type 2 diabetes, or heart diseases (Dishman et al, 2012; Ortega et al, 2016; Ruegsegger and Booth, 2017; Warburton and Bredin, 2017; World Health Organization [WHO], 2018)
The paraventricular nucleus (PVN) is localized in the alar peduncular hypothalamus and is at the top of the hypothalamic-pituitary-adrenal axis, which is involved in stress responses (Sawchenko and Swanson, 1985; Morales-Delgado et al, 2011; Morales-Delgado et al, 2014; Ferran et al, 2015c)
In order to determine if Crh and Avp mRNA was chronically induced after the HAB period, it was firstly confirmed by in situ hybridization that at postnatal 35 days Crh mRNA was only present in the hypothalamic region as part of
Summary
Active people have a reduced risk of developing non-communicable diseases such as obesity, osteoporosis, type 2 diabetes, or heart diseases (Dishman et al, 2012; Ortega et al, 2016; Ruegsegger and Booth, 2017; Warburton and Bredin, 2017; World Health Organization [WHO], 2018). Voluntary running is the most used exercise model in rodents; and the animals are rarely exposed to the equal intensities and volumes of running (Van Praag et al, 2005; Kregel et al, 2006; Leasure and Jones, 2008; Creer et al, 2010; Marlatt et al, 2012) These individual differences can be avoided using forced models such as treadmill or motorized wheels. Some authors proposed that forced exercise, like the HAB program, produces non-specific stress responses (Moraska et al, 2000; Dishman et al, 2006; Yanagita et al, 2007; Lin et al, 2012; Morgan et al, 2015)
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