Von Frey test

The von Frey test was used to assess the sensitivity to mechanical stimuli in our rat migraine model. We chose to measure this in the hind paws of the rats due to the common occurrence of extracephalic allodynia, or sensitivity to pain outside of the head, in migraine sufferers. This test provides an indirect reflection of the state of migraine by measuring changes in overall body pain sensitivity. Von Frey filaments (1.4, 2.0, 4.0, 6.0, 8.0, 10.0, 15.0, and 26.0 g; North Coast Medical, Inc., USA) were successively applied to stimulate the central part of the hind paws of rats. Each stimulation lasted for 2 s and was repeated 5 times with a 5-s interval. Paw withdrawal was considered a positive reaction. The mechanical threshold of rats was determined by the “up-and-down” method.[26]