Hypothalamic Crh/Avp, Plasmatic Glucose and Lactate Remain Unchanged During Habituation to Forced Exercise

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 biomarkersare increased during the habituation to exercise. Sprague-Dawley rats received an 8days 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.

Dopaminergic Modulation of Forced Running Performance in Adolescent Rats: Role of Striatal D1 and Extra-striatal D2 Dopamine Receptors

“…An 8-day exercise habituation protocol was implemented using a forced running wheel system (Lafayette-Campden, model 8085A). Speed and time of running were progressively increased throughout the sessions of the protocol, from 5 at 0 m/min the first day to 30 min running at 9 m/min the last day, as described in Toval et al (2017Toval et al ( , 2020 [42,43]. Nonhabituated rats remained in locked wheels, without any exercise stimulus, for the same time as the habituated groups.…”

“…During the test, running speed was gradually increased 0.5 m/min every minute from a starting speed of 5 m/min (Fig. 1b, modified from Toval et al (2017Toval et al ( , 2020 [42,43]). The test was concluded when the rat was unable to maintain a regular running path (e.g., crawling, jumping, or rolling inside the wheel) for 20 s in a row.…”

“…The aim of the present study is to determine whether the dopamine system modulates exercise capacity during adolescence using a rodent model of forced running wheel we recently implemented. Briefly, rats were exposed to an 8day period of habituation in the running wheel before assessing their locomotor performance in response to an incremental load of forced running [42,43]. Both systemic and striatal administration of dopamine D1 (SCH23390) and D2 (raclopride) receptor antagonists were delivered 15-30 min prior to the onset of the incremental test, and changes in the level of locomotor performance were compared.…”

The effects of voluntary complex and regular wheel running exercises on the levels of 8‐oxoguanine DNA glycosylase, semaphorin 3B, H2O2, and apoptosis in the hippocampus of diabetic rats

“…Unlike forced treadmill running, performing voluntary wheel running exercise does not overstimulate stress hormones, and thus maintains healthy cognitive capabilities. However, Toval et al (2020) suggested that the implementation of an adaptive phase prior to performing forced exercise protocols might prevent non-specific stress responses (Toval et al, 2020). Voluntary exercise has been shown to exert beneficial effects on the functions of the hippocampus dentate gyrus.…”

“…However, Toval et al. (2020) suggested that the implementation of an adaptive phase prior to performing forced exercise protocols might prevent non‐specific stress responses (Toval et al., 2020). Voluntary exercise has been shown to exert beneficial effects on the functions of the hippocampus dentate gyrus.…”