Anna Jablochkova, Emmanuel Bäckryd, Eva Kosek, Kaisa Mannerkorpi, Malin Ernberg, Björn Gerdle, Bijar Ghafouri
Pain and Rehabilitation Centre, Department of Medical and Health Sciences, Sweden
DOI: 10.2340/16501977-2593

Background: The pathophysiology of fibromyalgia includes central and peripheral factors. Neurotrophins, such as nerve growth factor and brain-derived neurotrophic factor, are involved in peripheral and central nervous system development of pain and hyperalgesia. Few studies have examined circulating nerve growth factor and brain-derived neurotrophic factor in fibromyalgia or have investigated whether exercise interventions affect the levels of these peptides.
Objectives: To compare plasma levels of nerve growth factor and brain-derived neurotrophic factor in fibromy-algia and in healthy controls, to investigate correlations between levels of nerve growth factor, brain-derived neurotrophic factor, and cytokines and clinical variables, and to investigate the effect of exercise on these levels.
Subjects and methods: A total of 75 women with fibromyalgia participated in blood tests at baseline and after the 15-week intervention, and 25 healthy controls participated at baseline. Patients were randomized to a 15-week progressive resistance exercise intervention or a relaxation intervention.
Results: Brain-derived neurotrophic factor level was significantly higher (p  < 0. 001) and nerve growth factor level was significantly lower (p  < 0. 001) in fibromyalgia than in healthy controls. Neither resistance exercise nor relaxation interventions affected the levels of brain-derived neurotrophic factor or nerve growth factor. No significant correlations were found between brain-derived neurotrophic factor or nerve growth factor plasma levels in fibromyalgia and cytokine levels or clinical variables.
Conclusion: Changes in circulating nerve growth factor and brain-derived neurotrophic factor levels may affect nociception/pain in fibromyalgia. Clinical improvements were achieved following the exercise intervention, but the levels of brain-derived neurotrophic factor and nerve growth factor were not normalized.

Patients with fibromyalgia have treatment-resistant chronic pain. More research is needed in order to understand how and why fibromyalgia develops. Neurotrophins, such as nerve growth factor and brain-derived neurotrophic factor, are involved in peripheral and central nervous system development of pain and hyperalgesia, but few studies have examined circulating nerve growth factor and brain-derived neurotrophic factor in fibromyalgia or have investigated whether exercise interventions affect the levels of these peptides. This study compared blood levels of nerve growth factor and brain-derived neurotrophic factor in fibromyalgia with those in healthy controls, and investigated the effect of exercise on these levels. Brain-derived neurotrophic factor levels were higher and levels of nerve growth factor were lower in fibromyalgia, compared with healthy controls. Clinical improvements were achieved following the exercise intervention, but the levels of brain-derived neurotrophic factor and nerve growth factor were not normalized.