C57 mice increase wheel-running behavior following stress: Preliminary findings
University of Vermont, USA. Perceptual and Motor Skills
(Impact Factor: 0.66).
10/2011; 113(2):605-18. DOI: 10.2466/06.16.20.PMS.113.5.605-618
Exercise has been shown to reduce anxiety in both humans and animals. To date, there are few, if any studies that examine the effect of stress on self-selected exercise using an animal model. This study examined the effect of acute stress on wheel-running distance in mice. Forty 8-week-old, male C57BL/6J mice were randomly assigned to one of three groups: no stress + wheel-running experience, stress + wheel-running experience, or stress with no wheel-running experience. Stressed mice were exposed to foot shock in a brightly lit environment. Following treatment, wheel-running distances were observed for three hours. Stress significantly increased voluntary wheel-running in mice with wheel-running experience as compared to nonstressed controls and stressed mice with no wheel-running experience. These results suggest that mice familiar with wheel-running may self-select this exercise as a modality for the mitigation of accumulated anxiety.
Available from: Judith Grisel
- "Considerable data also suggest that wheel running has antidepressant effects, including stimulation of hippocampal neurogenesis (Crews et al., 2004;Onksen et al., 2012) and dampening of hypothalamic–pituitary–adrenal (HPA) hormone responses to emotional stressors (Droste et al., 2003). Running may also reduce anxiety-related behaviors in mice (Salam et al., 2009), and wheel running has been shown to increase following exposure to acute stress (footshock;Sibold et al., 2011). Several studies have investigated the effects of wheel running on voluntary alcohol consumption in rodents. "
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The effects of stress, including neuroendocrine and behavioral sequelae aimed at maintaining homeostasis, are associated with increased alcohol consumption. Because both stress and drinking are multifactorial, the mechanisms underlying the relationship are difficult to elucidate. We therefore employed an animal model investigating the influence of blocked access to a running wheel on drinking in C57BL/6J (B6) mice.Methods
In the first experiment, naïve, adult male and female subjects were individually housed for 2 weeks with 24-hour access to a running wheel and 12% ethanol (EtOH) in a 2-bottle, free choice paradigm. After determining baseline consumption and preference, experimental subjects had the running wheel placed in a locked position for 6 hours, and the EtOH bottle was removed during the first half of this period. Two subsequent experiments, again in adult, naïve B6 mice, examined the influence of locked running wheels on self-administration of 20% EtOH in a limited access paradigm, and blood EtOH concentrations (BECs) were determined on the final day of this protocol.ResultsIn all 3 studies, using both between- and within-subject analyses, females showed transient yet reliable increases in alcohol drinking during blocked access to a rotating activity, while drinking in male mice was largely insensitive to this manipulation, although both sexes showed appreciable BECs (>130 mg/dl in females and 80 mg/dl in males) following a 2-hour EtOH access period.Conclusions
These data add to a burgeoning literature suggesting that the factors contributing to excessive alcohol use differ between males and females and that females may be especially sensitive to the influence of wheel manipulation. Elucidating the sex-dependent mechanisms mediating differences in alcohol sensitivity and response is critical to understanding the causes of alcoholism and in developing effective treatments and interventions.
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ABSTRACT: Pain and reward have been suggested to interact, and some evidence is provided by a rodent study showing that acutely injured animals are more motivated to reach a food reward while they do not increase food consumption, pointing at unaltered reward liking. Since no data exist in humans, we conducted a psychophysical experiment to test the effects of experimentally induced tonic pain on (1) the motivation to receive reward and (2) hedonic responses when being rewarded.
Forty healthy participants underwent two experimental sessions: in one, painful heat stimulation was continuously applied while participants played a monetary reward task; in the other, participants experienced non-painful warm stimulation while playing the task. In the task, participants needed to react quickly enough to a target cue to win the money associated with the particular trial ($0.04, $1 or $4). Reaction time to the target cue served as measure of motivation. Ratings after each trial on how much the participant liked the trial's outcome served as a measure of hedonic responses.
Pain increased the motivation to obtain reward when the incentive was high, indexed by decreased reaction times (repeated-measures analysis of variance, interaction pain × incentive; p = 0.009). In contrast to motivational drive, hedonic ratings of the rewarding stimuli were not influenced by pain.
Similar to existing rodent data, our results suggest a pain-induced mismatch of increased motivational drive with a lack of increased hedonic responses. This mismatch is discussed as perhaps reflecting a failed coping attempt, which is potentially relevant for chronic pain patients.
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