Aoyama, Bun Kochi Medical School
Kawano, Takashi Kochi Medical School
Iwata, Hideki Kochi Medical School
Nishigaki, Atsushi Kochi Medical School
Yamanaka, Daiki Kochi Medical School
Tateiwa, Hiroki Kochi Medical School
Shigematsu-Locatelli, Marie Kochi Medical School
Locatelli, Fabricio M. Kochi Medical School
Yokoyama, Masataka Kochi Medical School
The beneficial effects of physical activity for pain are denominated exercise-induced hypoalgesia (EIH). Here, we examined the age-related change and potential role of the neurosteroid allopregnanolone (ALLO) on EIH in rats. Adult and aged rats were randomly divided into one of three groups; non-exercise control, Low-exercise, and High-exercise. The animals in the Low- and High-exercise groups were subjected to a 10-minute treadmill workout at 40% and 80% maximum oxygen intake intensity, respectively. In the Low-exercise groups, a significant EIH response was observed in aged but not in adult rats. The pre-treatment with ALLO synthesis inhibitor finasteride, but not opioid-receptor antagonist naloxone, inhibited the Low-exercise induced EIH response in aged rats. Furthermore, the Low-exercise increased brain ALLO levels in aged animals compared with controls, which was correlated with the mechanical pain sensitivity. On the other hand, High-exercise could induce EIH response in both adult and aged animals, but it was more effective in adult rats. The pre-treatment with naloxone, but not finasteride, reduced the EIH observed after High-exercise in both adult and aged rats. Our findings demonstrated that effective EIH can be achieved even by mild-intensity exercise in aged animals via an increase of the brain ALLO levels.
Journal of Pharmacological Sciences
Elsevier|Japanese Pharmacological Society
This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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