Voluntary Forelimbs Exercise Reduces Immobilization-Induced Mechanical Hyperalgesia in the Rat Hind Paw

Voluntary exercise is sufficient to protect against neuropathic pain. However, it is unclear whether voluntary exercise reduces immobilization-induced hyperalgesia. We examined the effect of voluntary forelimb exercise on immobilized-induced hyperalgesia in hind paws of rats. Wistar rats were random...

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Main Authors: Kumiko Ishikawa, Satoshi Oga, Kyo Goto, Junya Sakamoto, Ryo Sasaki, Yuichiro Honda, Hideki Kataoka, Minoru Okita
Format: Article
Language:English
Published: Wiley 2021-01-01
Series:Pain Research and Management
Online Access:http://dx.doi.org/10.1155/2021/5592992
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author Kumiko Ishikawa
Satoshi Oga
Kyo Goto
Junya Sakamoto
Ryo Sasaki
Yuichiro Honda
Hideki Kataoka
Minoru Okita
author_facet Kumiko Ishikawa
Satoshi Oga
Kyo Goto
Junya Sakamoto
Ryo Sasaki
Yuichiro Honda
Hideki Kataoka
Minoru Okita
author_sort Kumiko Ishikawa
collection DOAJ
description Voluntary exercise is sufficient to protect against neuropathic pain. However, it is unclear whether voluntary exercise reduces immobilization-induced hyperalgesia. We examined the effect of voluntary forelimb exercise on immobilized-induced hyperalgesia in hind paws of rats. Wistar rats were randomly divided into the (1) both hind limbs immobilized group (IM group), (2) immobilization and exercise with nonimmobilized fore limbs group (EX group), and (3) control group. In the IM and EX groups, the bilateral ankle joints of each rat were immobilized in full plantar flexion with a plaster cast for eight weeks. In the EX group, voluntary exercise using nonimmobilized forelimbs in the running wheel was administered during the immobilization period, while hind limbs were kept immobilized (60 min/day, 5 days/week). Mechanical hyperalgesia in the hind paw was measured using a digital von Frey device every week. To investigate the abnormality of primary sensory neurons and central sensitization, the number of calcitonin gene-related peptide-positive cells in the dorsal root ganglion and the expression level of calcitonin gene-related peptide in the spinal dorsal horn were analyzed by immunohistochemical staining. Immobilization-induced mechanical hyperalgesia was inhibited in the EX group compared to the IM group at three weeks after immobilization. In the EX group, the number of calcitonin gene-related peptide-positive cells in the dorsal root ganglion and the expression level of calcitonin gene-related peptide were significantly decreased compared to those in the IM group. Our results therefore suggest that voluntary forelimb exercise during hind limb immobilization partially reduces immobilization-induced hyperalgesia by suppressing that the plastic changes of the primary sensory nerves that excessively transmit pain and increased responsiveness of nociceptive neurons in the spinal dorsal horn.
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spelling doaj-art-7ee427f9020040309e0e03aabea8887f2025-02-03T06:10:47ZengWileyPain Research and Management1203-67651918-15232021-01-01202110.1155/2021/55929925592992Voluntary Forelimbs Exercise Reduces Immobilization-Induced Mechanical Hyperalgesia in the Rat Hind PawKumiko Ishikawa0Satoshi Oga1Kyo Goto2Junya Sakamoto3Ryo Sasaki4Yuichiro Honda5Hideki Kataoka6Minoru Okita7Department of Rehabilitation, Nagasaki University Hospital, Nagasaki, JapanDepartment of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, JapanDepartment of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, JapanDepartment of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, JapanDepartment of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, JapanDepartment of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, JapanDepartment of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, JapanDepartment of Physical Therapy Science, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, JapanVoluntary exercise is sufficient to protect against neuropathic pain. However, it is unclear whether voluntary exercise reduces immobilization-induced hyperalgesia. We examined the effect of voluntary forelimb exercise on immobilized-induced hyperalgesia in hind paws of rats. Wistar rats were randomly divided into the (1) both hind limbs immobilized group (IM group), (2) immobilization and exercise with nonimmobilized fore limbs group (EX group), and (3) control group. In the IM and EX groups, the bilateral ankle joints of each rat were immobilized in full plantar flexion with a plaster cast for eight weeks. In the EX group, voluntary exercise using nonimmobilized forelimbs in the running wheel was administered during the immobilization period, while hind limbs were kept immobilized (60 min/day, 5 days/week). Mechanical hyperalgesia in the hind paw was measured using a digital von Frey device every week. To investigate the abnormality of primary sensory neurons and central sensitization, the number of calcitonin gene-related peptide-positive cells in the dorsal root ganglion and the expression level of calcitonin gene-related peptide in the spinal dorsal horn were analyzed by immunohistochemical staining. Immobilization-induced mechanical hyperalgesia was inhibited in the EX group compared to the IM group at three weeks after immobilization. In the EX group, the number of calcitonin gene-related peptide-positive cells in the dorsal root ganglion and the expression level of calcitonin gene-related peptide were significantly decreased compared to those in the IM group. Our results therefore suggest that voluntary forelimb exercise during hind limb immobilization partially reduces immobilization-induced hyperalgesia by suppressing that the plastic changes of the primary sensory nerves that excessively transmit pain and increased responsiveness of nociceptive neurons in the spinal dorsal horn.http://dx.doi.org/10.1155/2021/5592992
spellingShingle Kumiko Ishikawa
Satoshi Oga
Kyo Goto
Junya Sakamoto
Ryo Sasaki
Yuichiro Honda
Hideki Kataoka
Minoru Okita
Voluntary Forelimbs Exercise Reduces Immobilization-Induced Mechanical Hyperalgesia in the Rat Hind Paw
Pain Research and Management
title Voluntary Forelimbs Exercise Reduces Immobilization-Induced Mechanical Hyperalgesia in the Rat Hind Paw
title_full Voluntary Forelimbs Exercise Reduces Immobilization-Induced Mechanical Hyperalgesia in the Rat Hind Paw
title_fullStr Voluntary Forelimbs Exercise Reduces Immobilization-Induced Mechanical Hyperalgesia in the Rat Hind Paw
title_full_unstemmed Voluntary Forelimbs Exercise Reduces Immobilization-Induced Mechanical Hyperalgesia in the Rat Hind Paw
title_short Voluntary Forelimbs Exercise Reduces Immobilization-Induced Mechanical Hyperalgesia in the Rat Hind Paw
title_sort voluntary forelimbs exercise reduces immobilization induced mechanical hyperalgesia in the rat hind paw
url http://dx.doi.org/10.1155/2021/5592992
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