Interaction between intensity and duration of acute exercise on neuronal activity associated with depression-related behavior in rats

Ryoko Morikawa,Natsuko Kubota,Takeshi Nishijima,Ichiro Kita,Seiichiro Amemiya

doi:10.1186/s12576-020-00788-5

Ryoko Morikawa, Natsuko Kubota + Show 3 more

Open Access

https://doi.org/10.1186/s12576-020-00788-5

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Abstract

We examined the activities of serotonin (5-HT) neurons in the dorsal raphe nucleus (DRN) and corticotropin-releasing factor (CRF) neurons in the hypothalamic paraventricular nucleus (PVN) during acute treadmill running at different speeds (control, low, high) and durations (15, 30, 60 min) in male Wistar rats using c-Fos/5-HT or CRF immunohistochemistry. We also performed elevated plus maze test (EPM) and forced swim test (FST) after acute treadmill running in rats. Acute treadmill running at low speed, regardless of exercise duration, significantly increased c-Fos expression in 5-HT neurons in the DRN compared with controls, whereas high-speed running significantly activated 5-HT neurons only at 60-min duration. In contrast, c-Fos expression in CRF neurons in the PVN was enhanced in an intensity-dependent manner, regardless of exercise duration. c-Fos expression in 5-HT neurons in the DRN induced by the acute treadmill running for 30 or 60 min, but not 15 min, was positively correlated with the time spent on the open arms in the EPM and was negatively correlated with the immobility time in the FST. These results suggest an interaction between exercise intensity and duration on the antidepressant effects of acute physical exercise.

Highlights

Accumulating evidence suggests that physical exercise can help reduce or prevent the incidence of symptoms of depression, including helplessness and anxiety [1,2,3,4,5,6]
We examined the activities of 5-HT neurons in the dorsal raphe nucleus (DRN) and corticotropin-releasing factor (CRF) neurons in the paraventricular nucleus (PVN) during acute treadmill running at different intensities and durations in rats, using doublestaining for c-Fos, which is a well-known transcription factor frequently used as a functional marker of neuronal activity [30,31,32,33], and 5-HT or CRF
We showed that c-Fos expression in CRF neurons in the PVN during acute treadmill running was increased in a running speeddependent manner, regardless of the duration, indicating that the intensity and duration of acute physical exercise do not interact with activation of PVN CRF neurons

Summary

Introduction

Accumulating evidence suggests that physical exercise can help reduce or prevent the incidence of symptoms of depression, including helplessness and anxiety [1,2,3,4,5,6]. Morikawa et al J Physiol Sci (2021) 71:1 acute exercise duration on the spatial and temporal profiles of neuronal activation in the brain [21,22,23,24], to date, few studies have investigated the effects of acute exercise with controlled exercise parameters such as intensity and duration of exercise on antidepressant properties, including behavioral and neural changes. That is, it remains unclear how exercise intensity and duration of acute physical exercise interact with antidepressant effects. Understanding the general concepts regarding acute physical exercise regimens that effectively improve the neuronal activity associated with depression-related behavior may provide a standardized exercise protocol for the treatment of depressive symptoms

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