A new study adds to a growing body of evidence that the nervous system and nerve-growth factor (NGF) play a major role in arthritis. The study was led by researchers at McGill University.
The findings also support the idea that reducing elevated levels of NGF - a protein that promotes the growth and survival of nerves, but also causes pain-may be an important strategy for developing treatment of arthritis pain.
Using an approach established by arthritis researchers elsewhere, the McGill scientists examined inflammatory arthritis in the ankle joint of rats.
In particular, they investigated changes in the nerves and tissues around the arthritic joint, by using specific markers to label the different types of nerve fibres and allow them to be visualized with a fluorescence microscope.
Normally, sympathetic nerve fibres regulate blood flow in blood vessels.
Following the onset of arthritis in the rats, however, these fibres began to sprout into the inflamed skin over the joint and wrap around the pain-sensing nerve fibres instead.
More sympathetic fibres were detected in the arthritic joint tissues, as well.
The results also showed a higher level in the inflamed skin of NGF - mirroring the findings of human studies that have shown considerable increases in NGF levels in arthritis patients.
The study is published in the Journal of Neuroscience.