Immunohistochemical & molecular studies of serotonin, substance P, galanin, pituitary adenylyl cyclase-activating polypeptide,& secretoneurin in fibromyalgic muscle tissue

OBJECTIVE: Because former investigations have reported

abnormal changes in the expression of serotonin

(5-hydroxytryptamine [5-HT]) and substance P (SP) in serum and

cerebrospinal fluid, this study sought to determine whether

5-HT and pain-modulating neuropeptides (SP, galanin [GA],

pituitary adenylyl cyclase-activating polypeptide, and

secretoneurin) were expressed abnormally in the muscle tissue

of patients with fibromyalgia (FM).

METHODS: Snap-frozen

muscle tissue specimens (deltoid muscles) from 10 patients

with FM (mean disease duration 15 years) and from 10 healthy

control subjects were examined by reverse

transcriptase-polymerase chain reaction (RT-PCR) of RNA

preparations from muscle cells, and by immunohistochemistry

methods (alkaline phosphatase-anti-alkaline phosphatase and

immunogold-silver) using specific primers as well as

antibodies. When specific messenger RNA (mRNA) was detected by

RT-PCR, in situ RT-PCR was performed for mRNA localization.

RESULTS: Specific mRNA for the examined substances was absent

in 9 of 10 FM patients and in 10 of 10 controls. No

differences between the FM patients and controls could be

detected in the muscle tissue by immunohistochemistry. In 1 FM

patient, mRNA for the GA receptor could be shown.


This study showed that 5-HT and neuropeptides are not produced

in the muscle of patients with FM, and therefore do not appear

to be involved in the peripheral induction of pain in this

chronic, painful disorder.

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