Longitudinal FDG microPET imaging of neuropathic pain: does cerebellar activity correlate with neuropathic pain development in a rat model?

Abstract

Background: We used [F-18] FDG microPET imaging as part of a longitudinal study to investigate changes in the brain. Methods: Glucose metabolism during the development of neuropathic pain after tibial and sural nerve transection (TST) model rats. MicroPET images were obtained 1 week before operation and then weekly for 8 weeks post-operation. Results: The behavioral test was performed immediately after the every FDG administration. After TST modeling, neuropathic pain rats showed increased mechanical sensitivity of the injured hind paw. The withdrawal response to mechanical pain stimulation by von Frey filaments was observed within the first week (3.8 ± 0.73), and it rapidly increased in the third week (7.13 ± 0.82). This response reached a peak in the fourth week after surgery (9.0 ± 0.53), which persisted until the eighth week. In microPET scan imaging, cerebellum, which initially started from the ansiform lobule, was activated gradually to all part from the third week in all image acquisitions through the eighth week. Conclusions: The longitudinal microPET scan study of brains from neuropathic pain rat models showed sequential cerebellar activity that was in accordance with results from behavioral test responses, thus supporting a role for the cerebellum in the development of neuropathic pain.