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Effect of Exercise on µ-Opioid Receptor Expression in the Rostral Ventromedial Medulla in Neuropathic Pain Rat Model.

Kim YJ, Byun JH, Choi IS - Ann Rehabil Med (2015)

Bottom Line: Body weight of group C was the lowest among all groups.Withdrawal thresholds and withdrawal latencies were increased with time in groups B and C.MOR expression of group C was significantly decreased, as compared to that of group B in the RVM and spinal cord.

View Article: PubMed Central - PubMed

Affiliation: Department of Physical and Rehabilitation Medicine, Research Institute of Medical Sciences, Center for Aging and Geriatrics, and Regional Cardiocerebrovascular Center, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.

ABSTRACT

Objective: To investigate the effects of aerobic exercise on neuropathic pain and verify whether regular treadmill exercise alters opioid receptor expression in the rostral ventral medulla (RVM) in a neuropathic pain rat model.

Methods: Thirty-two male Sprague-Dawley rats were used in the study. All rats were divided into 3 groups, i.e., group A, sham group (n=10); group B, chronic constriction injury (CCI) group (n=11); and group C, CCI+exercise group (n=11). Regular treadmill exercise was performed for 30 minutes a day, 5 days a week, for 4 weeks at the speed of 8 m/min for 5 minutes, 11 m/min for 5 minutes, and 22 m/min for 20 minutes. Withdrawal threshold and withdrawal latency were measured before and after the regular exercise program. Immunohistochemistry and Western blots analyses were performed using antibodies against µ-opioid receptor (MOR).

Results: Body weight of group C was the lowest among all groups. Withdrawal thresholds and withdrawal latencies were increased with time in groups B and C. There were significant differences of withdrawal thresholds between group B and group C at 1st, 2nd, 3rd, and 4th weeks after exercise. There were significant differences of withdrawal latencies between group B and group C at 3rd and 4th weeks after exercise. MOR expression of group C was significantly decreased, as compared to that of group B in the RVM and spinal cord.

Conclusion: In neuropathic pain, exercise induced analgesia could be mediated by desensitization of central MOR by endogenous opioids, leading to the shift of RVM circuitry balance to pain inhibition.

No MeSH data available.


Related in: MedlinePlus

The changes of withdrawal latency to noxious heat stimuli with time. Withdrawal latencies are increased in group C, as compared to group B at 3rd and 4th weeks after the beginning of the regular exercise program. *p<0.05 compared to group B.
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Figure 3: The changes of withdrawal latency to noxious heat stimuli with time. Withdrawal latencies are increased in group C, as compared to group B at 3rd and 4th weeks after the beginning of the regular exercise program. *p<0.05 compared to group B.

Mentions: Withdrawal latencies to noxious thermal stimuli increased with time in groups B and C (Fig. 3). There was within-subjects effect (p=0.000). Within-subjects difference was significant after 3 weeks of treadmill exercise (p=0.009). There was between-subjects effect (p=0.000). In pairwise comparisons, the mean differences were significant between groups A and B (p=0.000), between groups B and C (p=0.003), and between groups A and C (p=0.000). Treadmill exercise increased withdrawal latencies in group C, as compared to group A (p=0.000) and group B (p=0.029). There were significant differences of withdrawal threshold between group A and group C at every time point. There were significant increase of withdrawal latencies between group B and group C at 3rd (p=0.007) and 4th (p=0.010) weeks after the beginning of the regular exercise program. There was no significant interaction between time and group for withdrawal threshold (p=0.054). Withdrawal latency was inversely correlated with MOR expression in RVM (p=0.043, r=-0.365) and spinal cord (p=0.014, r=-0.439).


Effect of Exercise on µ-Opioid Receptor Expression in the Rostral Ventromedial Medulla in Neuropathic Pain Rat Model.

Kim YJ, Byun JH, Choi IS - Ann Rehabil Med (2015)

The changes of withdrawal latency to noxious heat stimuli with time. Withdrawal latencies are increased in group C, as compared to group B at 3rd and 4th weeks after the beginning of the regular exercise program. *p<0.05 compared to group B.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496503&req=5

Figure 3: The changes of withdrawal latency to noxious heat stimuli with time. Withdrawal latencies are increased in group C, as compared to group B at 3rd and 4th weeks after the beginning of the regular exercise program. *p<0.05 compared to group B.
Mentions: Withdrawal latencies to noxious thermal stimuli increased with time in groups B and C (Fig. 3). There was within-subjects effect (p=0.000). Within-subjects difference was significant after 3 weeks of treadmill exercise (p=0.009). There was between-subjects effect (p=0.000). In pairwise comparisons, the mean differences were significant between groups A and B (p=0.000), between groups B and C (p=0.003), and between groups A and C (p=0.000). Treadmill exercise increased withdrawal latencies in group C, as compared to group A (p=0.000) and group B (p=0.029). There were significant differences of withdrawal threshold between group A and group C at every time point. There were significant increase of withdrawal latencies between group B and group C at 3rd (p=0.007) and 4th (p=0.010) weeks after the beginning of the regular exercise program. There was no significant interaction between time and group for withdrawal threshold (p=0.054). Withdrawal latency was inversely correlated with MOR expression in RVM (p=0.043, r=-0.365) and spinal cord (p=0.014, r=-0.439).

Bottom Line: Body weight of group C was the lowest among all groups.Withdrawal thresholds and withdrawal latencies were increased with time in groups B and C.MOR expression of group C was significantly decreased, as compared to that of group B in the RVM and spinal cord.

View Article: PubMed Central - PubMed

Affiliation: Department of Physical and Rehabilitation Medicine, Research Institute of Medical Sciences, Center for Aging and Geriatrics, and Regional Cardiocerebrovascular Center, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.

ABSTRACT

Objective: To investigate the effects of aerobic exercise on neuropathic pain and verify whether regular treadmill exercise alters opioid receptor expression in the rostral ventral medulla (RVM) in a neuropathic pain rat model.

Methods: Thirty-two male Sprague-Dawley rats were used in the study. All rats were divided into 3 groups, i.e., group A, sham group (n=10); group B, chronic constriction injury (CCI) group (n=11); and group C, CCI+exercise group (n=11). Regular treadmill exercise was performed for 30 minutes a day, 5 days a week, for 4 weeks at the speed of 8 m/min for 5 minutes, 11 m/min for 5 minutes, and 22 m/min for 20 minutes. Withdrawal threshold and withdrawal latency were measured before and after the regular exercise program. Immunohistochemistry and Western blots analyses were performed using antibodies against µ-opioid receptor (MOR).

Results: Body weight of group C was the lowest among all groups. Withdrawal thresholds and withdrawal latencies were increased with time in groups B and C. There were significant differences of withdrawal thresholds between group B and group C at 1st, 2nd, 3rd, and 4th weeks after exercise. There were significant differences of withdrawal latencies between group B and group C at 3rd and 4th weeks after exercise. MOR expression of group C was significantly decreased, as compared to that of group B in the RVM and spinal cord.

Conclusion: In neuropathic pain, exercise induced analgesia could be mediated by desensitization of central MOR by endogenous opioids, leading to the shift of RVM circuitry balance to pain inhibition.

No MeSH data available.


Related in: MedlinePlus