Short-term treadmill running in the rat: what kind of stressor is it?

Abstract

The use of short-term (1-5 days) treadmill running is becoming increasingly common as a model to study physiological adaptations following the exercise. Although the beneficial effects of acute exercise seem clear, a paucity of data exist describing potential markers of stress in response to forced running. We subjected male and female Sprague-Dawley rats to 0, 1, 2, 5, or 10 days of treadmill running. Twenty-four to 32 h after the last bout of exercise animals were killed and examined for training-induced changes in several physiological variables. No effect of skeletal citrate synthase activity was observed in the male animals after any duration, and only at 10 days of running did females show a significant increase in citrate synthase. Myocardial heat shock protein 72 (HSP72) content was higher in male rats than female rats, and exercise led to increased HSP72 in both sexes, although the time course was different between males and females. Animals displayed several markers of systemic stress in response to the treadmill running, and this was done in a sex-dependent manner. Serum corticosterone was significantly elevated in both sexes 24 h after exercise in three of four exercise groups. Corticosterone-binding globulin was higher in females, and decreased after running in female rats. Body and spleen weights decreased in males (but not females) in response to the exercise training, and running did not alter adrenal gland weights in either sex. These data indicate that in response to short-term treadmill running both male and female rats show signs of systemic stress, but that the pattern of changes occurs in a sex-specific manner.

Rat model of exercise-induced cardiac hypertrophy: hemodynamic characterization using left ventricular pressure-volume analysis

“…In order to minimize the influence of stress on the development of exercise-induced cardiac hypertrophy, rats of the exercised group were gradually familiarized with swimming and also untrained control rats were placed into the water for 5 min at every training session. According to the plasma concentrations of stress biomarkers [ACTH and cortisol (3,5)], this regular swim training protocol was not associated with increased stress response in our rats.…”

“…Ejection fraction (EF) was determined as (SV/LVEDV) ϫ 100. LV mass (LV mass) was calculated according to a cubic formula, suggested by Devereux et al (8): LV mass ϭ {[(LVEDD ϩ AWTd ϩ PWTd) 3 Ϫ LVEDD 3 ] ϫ 1.04} ϫ 0.8 ϩ 0.14. To calculate LV mass index and SV index, we normalized the LV mass and SV values to the body weight of the animal, respectively.…”

Mitochondrial KATPchannel inhibition blunts arrhythmia protection in ischemic exercised hearts

“…Short-duration exercise as a model of cardioprotection has several important advantages, including the fact that the cellular mechanisms responsible for acute IR resistance are not confounded by effects related to cardiac remodeling. It should be noted that short-duration exercise exposure may impose a stress response not directly attributable to exercise (14). Whether long-duration exercise preconditioning would have altered anti-arrhythmic protection mediated by either the mito or sarc K ATP channels cannot not be determined currently.…”

Exercising for food: bringing the laboratory closer to nature

“…Thus, experiments are controlled and convenient for the human experimenter, but they do not allow the simulation of the relationship that a wild animal has between its need for resources and how it acquires those resources. It is possible that being put on a treadmill with the threat of an electric shock, if the animal does not run, is a stressful experience and one in which the animal has no choice, as observed by Brown et al (Brown et al, 2007).…”