Unaltered low nerve growth factor and high brain-derived neurotrophic factor levels in plasma from patients with fibromyalgia after a 15-week progressive resistance exercise

Abstract

Background: The pathophysiology of fibromyalgia includes central and peripheral factors. Neurotrophins, such as nerve growth factor and brainderived neurotrophic factor, are involved in peripheral and central nervous system development of pain and hyperalgesia. Few studies have examined circulating nerve growth factor and brainderived 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 brainderived neurotrophic factor in fibromyalgia and in healthy controls, to investigate correlations between levels of nerve growth factor, brainderived 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 15week intervention, and 25 healthy controls participated at baseline. Patients were randomized to a 15week progressive resistance exercise intervention or a relaxation intervention. Results: Brainderived 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 brainderived neurotrophic factor or nerve growth factor. No significant correlations were found between brainderived neurotrophic factor or nerve growth factor plasma levels in fibromyalgia and cytokine levels or clinical variables. Conclusion: Changes in circulating nerve growth factor and brainderived neurotrophic factor levels may affect nociception/pain in fibromyalgia. Clinical improvements were achieved following the exercise intervention, but the levels of brainderived neurotrophic factor and nerve growth factor were not normalized.