Wheel running improves REM sleep and attenuates stress-induced flattening of diurnal rhythms in F344 rats

Abstract

Regular physical activity produces resistance to the negative health consequences of stressor exposure. One way that exercise may confer stress resistance is by reducing the impact of stress on diurnal rhythms and sleep; disruptions of which contribute to stress-related disease including mood disorders. Given the link between diurnal rhythm disruptions and stress-related disorders and that exercise both promotes stress resistance and is a powerful non-photic biological entrainment cue, we tested if wheel running could reduce stress-induced disruptions of sleep/wake behavior and diurnal rhythms. Adult, male F344 rats with or without access to running wheels were instrumented for biotelemetric recording of diurnal rhythms of locomotor activity, heart rate, core body temperature (CBT), and sleep (i.e. REM, NREM, and WAKE) in the presence of a 12hr light/dark cycle. Following 6 weeks of sedentary or exercise conditions, rats were exposed to an acute stressor known to disrupt diurnal rhythms and produce behaviors associated with mood disorders. Prior to stressor exposure, exercise rats had higher CBT, more locomotor activity during the dark cycle, and greater %REM during the light cycle relative to sedentary rats. NREM and REM sleep were consolidated immediately following peak running to a greater extent in exercise, compared to sedentary rats. In response to stressor exposure, exercise rats expressed higher stress-induced hyperthermia than sedentary rats. Stressor exposure disrupted diurnal rhythms in sedentary rats; and wheel running reduced these effects. Improvements in sleep and reduced diurnal rhythm disruptions following stress could contribute to the health promoting and stress protective effects of exercise.

Dietary Prebiotics and Bioactive Milk Fractions Improve NREM Sleep, Enhance REM Sleep Rebound and Attenuate the Stress-Induced Decrease in Diurnal Temperature and Gut Microbial Alpha Diversity

“…For example, experiencing work-related stressors (Akerstedt et al, 2002), having low social support (Mellman and Hipolito, 2006), or exposure to trauma/combat (Mellman et al, 1995, 2007; Rothbaum and Foa, 2002; Capaldi et al, 2011) can all disrupt sleep and the sleep/wake cycle. Preclinical studies testing a variety of animal models of stress in early life or adulthood also report similar outcomes on sleep and the sleep/wake cycle (Madan et al, 2008; Pawlyk et al, 2008; McClung, 2011; Yang et al, 2011; Greenwood et al, 2014; Thompson et al, 2016). …”

“…The F40-EET biotelemetry transmitters (Data Sciences International, St.Paul, MN, USA) were implanted into animals as previously described (Thompson et al, 2012, 2013, 2014, 2016; Greenwood et al, 2014). Briefly, animals were fully anesthetized and unresponsive following ketamine (i.p.…”

“…On PND 87, half of the rats were exposed to 100 inescapable tail shocks which is known to induce depression/anxiety-like behavior, to substantially increase corticosterone, and to disrupt diurnal physiology/sleep as previously described (Greenwood et al, 2005, 2014; Thompson et al, 2013, 2014, 2016; Speaker et al, 2014). Inescapable tail shock can produce clear impacts on the dependent measures we examined in this experiment (i.e., both sleep and the gut microbiota).…”

“…Biotelemetry recordings were acquired/analyzed using Dataquest ART 4.3 Gold Acquisition/Analysis Software (Data Sciences International, St. Paul, MN, USA) as previously described (Thompson et al, 2012, 2013, 2014, 2016). LA, heart rate and EEG were recorded at 500 Hz.…”

“…The trace EEG signal was subjected to fast Fourier Transformation (FFT), yielding spectra between 0.5 Hz and 30 Hz in 0.5-Hz frequency bins. The delta frequency band was defined at 0.5–4.5 Hz and the theta frequency band was defined as 6.0–9.0 Hz as previously described (Olivadoti and Opp, 2008; Thompson et al, 2016). After sleep recordings were autoscored they were corrected for accuracy by an observer blind to the experimental treatment of each animal.…”