Opioid-mediated pain sensitivity in mice bred for high voluntary wheel running

Guo, Li; Rhodes, Justin S.; Girard, Isabelle; Gammie, Stephen C.; Garland, Theodore

doi:10.1016/j.physbeh.2004.09.003

Cited by 36 publications

(33 citation statements)

References 63 publications

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“…In uninjured animals there are increases in withdrawal thresholds to noxious stimuli with a single swimming exercise task at either a low intensity or high intensity (4), 3 wk of running wheel activity (28,36,38), or a 12-wk resistance strengthening exercise program (39). In contrast, we show that neither 5 days nor 8 wk of running wheel activity changes withdrawal thresh- .…”

Section: Exercise Effects In Uninjured Animalscontrasting

confidence: 55%

Regular physical activity prevents development of chronic pain and activation of central neurons

Sluka

O’Donnell

Danielson

et al. 2013

Journal of Applied Physiology

167

168

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Section: Exercise Effects In Uninjured Animalscontrasting

confidence: 55%

Regular physical activity prevents development of chronic pain and activation of central neurons

Sluka

O’Donnell

Danielson

et al. 2013

Journal of Applied Physiology

167

168

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“…Reduced energy use may have permissive effects on the behaviour of high voluntary wheel running. For example, a slower, more oxidative mini-muscle phenotype may allow the mice to run faster without significant accumulation of anaerobic by-products, which appear to promote discomfort (Pan et al, 1999;Immke and McCleskey, 2001;Yagi et al, 2006), and may inhibit volition to exercise (see also Li et al, 2004;Keeney et al, 2008). In other words, the mini-muscle phenotype may confer an advantage by enhancing the ability of the mice to run on wheels through reduced reliance on glycolytic metabolism.…”

Section: Discussionmentioning

confidence: 99%

Changes in efficiency and myosin expression in the small-muscle phenotype of mice selectively bred for high voluntary running activity

McGillivray

Garland

Dlugosz

et al. 2009

Journal of Experimental Biology

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SUMMARYMice from lines selectively bred for high levels of voluntary wheel running express a high incidence of a small muscle phenotype ('mini-muscles') that may confer an adaptive advantage with respect to endurance-running capacity. Plantar flexors in the minimuscle phenotype exhibit a high capacity for aerobic activity, including altered enzyme activities, loss of expression of type II b myosin heavy chain (MHC), increased expression of type I, II x and II a MHC, and mechanical performance consistent with slower, more fatigue-resistant muscles. We hypothesized that these changes may accompany enhanced efficiency of contraction, perhaps in support of the enhanced capacity for endurance running. To assess efficiency, we measured work and associated oxygen consumption from isolated soleus and medial gastrocnemius muscles from mice with mini-muscle and normal phenotypes. We also measured the MHC expression of the plantar flexor muscles to better understand the physiological basis of any differences in efficiency. The proportion of the various MHC isoforms in the soleus was shifted toward a slightly faster phenotype in the mini-muscle mice, whereas in the gastrocnemius and plantaris it was shifted toward a markedly slower phenotype, with large reductions in type II b MHC and large increases in type I, II a , and II x MHC. Soleus muscles from normal and mini-muscle mice showed no statistical differences in efficiency, but medial gastrocnemius from mini-muscle mice were significantly less efficient than those from normal mice, despite the distinctly slower MHC phenotype in mini-muscle mice. Thus, based on measures of efficiency from isolated muscles under conditions near optimal for power output, the shift toward a slower phenotype in 'mini' gastrocnemius muscles does not appear to confer advantages directly through increased efficiency. Rather, the slower phenotype may reduce energy used by the muscles and be permissive to enhanced running ability, perhaps by reducing reliance on anaerobic metabolism.

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“…euphoria, anxiety reduction, reduced pain sensation or exercise-induced analgesia) (e.g. Li et al, 2004) to motivate animals to engage in activities, such as endurance running, that otherwise may be painful, stressful, energetically costly, time-consuming or risky (Ekkekakis et al, 2005). This hypothesis can be partially tested using selective breeding experiments (Keeney et al, 2008) (for reviews, see Rhodes and Kawecki, 2009;Swallow et al, 2009;Feder et al, 2010) and through comparisons of species that differ in their propensity for exercise under natural conditions (Raichlen et al, 2010).…”

Section: Neurobiology Of Voluntary Exercisementioning

confidence: 99%

“…For example, HR mice had a 20% increase in mRNA for D2 and D4 receptors in the hippocampus compared with control mice (Bronikowski et al 2004). Pharmacological studies with dopamine transporter blockers found differential effects on wheel running in HR and control mice, attributed to altered functionality of the D1 receptor system (but not the D2 receptor, serotonergic or opioidergic systems) Rhodes and Garland, 2003;Rhodes et al, 2005;Li et al, 2004). In addition, HR and control mice also have different wheel-running responses to D1-like antagonists .…”

Section: Neurobiology Of Voluntary Exercisementioning

confidence: 99%

The biological control of voluntary exercise, spontaneous physical activity and daily energy expenditure in relation to obesity: human and rodent perspectives

Garland

Schutz

Chappell

et al. 2011

Journal of Experimental Biology

381

434

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Summary Mammals expend energy in many ways, including basic cellular maintenance and repair, digestion, thermoregulation, locomotion, growth and reproduction. These processes can vary tremendously among species and individuals, potentially leading to large variation in daily energy expenditure (DEE). Locomotor energy costs can be substantial for large-bodied species and those with high-activity lifestyles. For humans in industrialized societies, locomotion necessary for daily activities is often relatively low, so it has been presumed that activity energy expenditure and DEE are lower than in our ancestors. Whether this is true and has contributed to a rise in obesity is controversial. In humans, much attention has centered on spontaneous physical activity (SPA) or non-exercise activity thermogenesis (NEAT), the latter sometimes defined so broadly as to include all energy expended due to activity, exclusive of volitional exercise. Given that most people in Western societies engage in little voluntary exercise, increasing NEAT may be an effective way to maintain DEE and combat overweight and obesity. One way to promote NEAT is to decrease the amount of time spent on sedentary behaviours (e.g. watching television). The effects of voluntary exercise on other components of physical activity are highly variable in humans, partly as a function of age, and have rarely been studied in rodents. However, most rodent studies indicate that food consumption increases in the presence of wheels; therefore, other aspects of physical activity are not reduced enough to compensate for the energetic cost of wheel running. Most rodent studies also show negative effects of wheel access on body fat, especially in males. Sedentary behaviours per se have not been studied in rodents in relation to obesity. Several lines of evidence demonstrate the important role of dopamine, in addition to other neural signaling networks (e.g. the endocannabinoid system), in the control of voluntary exercise. A largely separate literature points to a key role for orexins in SPA and NEAT. Brain reward centers are involved in both types of physical activities and eating behaviours, likely leading to complex interactions. Moreover, voluntary exercise and, possibly, eating can be addictive. A growing body of research considers the relationships between personality traits and physical activity, appetite, obesity and other aspects of physical and mental health. Future studies should explore the neurobiology, endocrinology and genetics of physical activity and sedentary behaviour by examining key brain areas, neurotransmitters and hormones involved in motivation, reward and/or the regulation of energy balance.

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Opioid-mediated pain sensitivity in mice bred for high voluntary wheel running

Cited by 36 publications

References 63 publications

Regular physical activity prevents development of chronic pain and activation of central neurons

Regular physical activity prevents development of chronic pain and activation of central neurons

Changes in efficiency and myosin expression in the small-muscle phenotype of mice selectively bred for high voluntary running activity

The biological control of voluntary exercise, spontaneous physical activity and daily energy expenditure in relation to obesity: human and rodent perspectives

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