Fractional amplitude of low-frequency fluctuations associated with μ-opioid and dopamine receptor distributions in the central nervous system after high-intensity exercise bouts

Abstract

IntroductionDopaminergic, opiod and endocannabinoid neurotransmission are thought to play an important role in the neurobiology of acute exercise and, in particular, in mediating positive affective responses and reward processes. Recent evidence indicates that changes in fractional amplitude of low-frequency fluctuations (zfALFF) in resting-state functional MRI (rs-fMRI) may reflect changes in specific neurotransmitter systems as tested by means of spatial correlation analyses.MethodsHere, we investigated this relationship at different exercise intensities in twenty young healthy trained athletes performing low-intensity (LIIE), high-intensity (HIIE) interval exercises, and a control condition on three separate days. Positive And Negative Affect Schedule (PANAS) scores and rs-fMRI were acquired before and after each of the three experimental conditions. Respective zfALFF changes were analyzed using repeated measures ANOVAs. We examined the spatial correspondence of changes in zfALFF before and after training with the available neurotransmitter maps across all voxels and additionally, hypothesis-driven, for neurotransmitter maps implicated in the neurobiology of exercise (dopaminergic, opiodic and endocannabinoid) in specific brain networks associated with “reward” and “emotion.”ResultsElevated PANAS Positive Affect was observed after LIIE and HIIE but not after the control condition. HIIE compared to the control condition resulted in differential zfALFF decreases in precuneus, temporo-occipital, midcingulate and frontal regions, thalamus, and cerebellum, whereas differential zfALFF increases were identified in hypothalamus, pituitary, and periaqueductal gray. The spatial alteration patterns in zfALFF during HIIE were positively associated with dopaminergic and μ-opioidergic receptor distributions within the ‘reward' network.DiscussionThese findings provide new insight into the neurobiology of exercise supporting the importance of reward-related neurotransmission at least during high-intensity physical activity.

Acute aerobic exercise does not modulate pain potentially due to differences in fitness levels and sex effects – results from a pharmacological fMRI study

“…Rodent research has implicated the descending pain modulatory system, including the ACC, medial frontal cortex including the ventromedial prefrontal cortex (vmPFC), and the PAG in exercise-induced pain modulation (Lesnak and Sluka, 2020;Stagg et al, 2011, p. 20), which is congruent with early imaging studies (Boecker et al, 2024(Boecker et al, , 2008Geisler et al, 2019;Saanijoki et al, 2018;Scheef et al, 2012). Previous rodent studies have further emphasised sex differences in pain processing (for reviews see (Mogil, 2020(Mogil, , 2012) and analgesic sensitivity (Martin et al, 2019;Mogil, 2020) warranting further investigation in humans (Mogil, 2020).…”