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Sympathetic hyperinnervation in myofascial trigger points
Lei Cao1, Yanping Gao2, Kai Wu3
1Department of Anesthesiology, Hainan Province Hospital of Traditional Chinese Medicine, Haikou, Hainan, China.
Objective:
To evaluate the local distribution and activity of sympathetic nerves in myofascial trigger points (MTrPs) and explore the pathological mechanism of myofascial pain syndrome (MPS) using a rat model of disease.
Methods:
MPS was modeled in the model group (MG) by a combination of blunt trauma and eccentric exercise in Sprague-Dawley rats (n = 8). Eight rats were randomly assigned to the control group (CG). Histopathology was applied to detect the local conditions of the MTrPs. Tyrosine hydroxylase (TH), nerve growth factor (NGF), and norepinephrine (NE) were detected in the MTrPs to evaluate sympathetic remodeling.
Results:
Muscle fiber rupture, atrophy and shape irregularity were universally observed in the MTrPs. TH expression was significantly increased in the MG, as detected by immunofluorescence, and NGF and TH expression was also higher in MTrPs in the MG than in MTrPs in the CG, as determined by immunohistochemistry. Furthermore, the expression of NE was significantly increased in MTrPs, as determined by ELISA.
Conclusion:
There was sympathetic hyperinnervation in MTrPs, which could partially explain the symptoms of MTrPs and is an interesting and useful new perspective regarding the diagnosis and treatment of MPS.
Perspective:
The sympathetic nerves in MTrPs are remodeled, leading to sympathetic hyperinnervation. Sympathetic hyperinnervation can partially explain the symptoms of MPS. The pathological mechanism of sympathetic hyperinnervation may be a new perspective for the diagnosis and treatment of MPS.
Insights
Sympathetic hyperinnervation was found in myofascial trigger points (MTrPs) in a rat model of myofascial pain syndrome (MPS). This sympathetic remodeling may explain MPS symptoms and offer new diagnostic and treatment approaches.
Area of Science:
- Neuroscience
- Pain Research
- Histopathology
Background:
- Myofascial pain syndrome (MPS) is a common pain condition.
- Myofascial trigger points (MTrPs) are key components of MPS.
- The underlying pathophysiology of MTrPs remains incompletely understood.
Purpose of the Study:
- To investigate sympathetic nerve distribution and activity within MTrPs.
- To explore the pathological mechanisms of MPS using a rat model.
- To evaluate sympathetic remodeling in MTrPs.
Main Methods:
- Myofascial trigger points (MTrPs) were induced in rats via blunt trauma and eccentric exercise.
- Histopathology examined MTrP tissue.
- Immunofluorescence and immunohistochemistry detected tyrosine hydroxylase (TH) and nerve growth factor (NGF) expression.
- ELISA measured norepinephrine (NE) levels.
Main Results:
- Muscle fiber damage, including rupture and atrophy, was observed in MTrPs.
- Significantly increased TH expression was noted in MTrPs of the model group compared to controls.
- Elevated NGF and NE levels were detected in MTrPs, indicating sympathetic hyperinnervation.
Conclusions:
- Sympathetic hyperinnervation occurs in MTrPs.
- This sympathetic remodeling contributes to the symptoms of MPS.
- Sympathetic hyperinnervation presents a novel perspective for MPS diagnosis and treatment.
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