Effect of Treadmill Running on c-Fos Expression in the Ventrolateral Periaqueductal Gray and Nucleus Raphe Magnus Regions of the Streptozotocin-Induced Diabetic Neuropathic Pain Mice

The mammalian nervous system contains descending pain control system, such as periaqueductal gray (PAG) and nucleus raphe magnus (NRM). In chronic diabetic neuropathic pain, the activity of descending pain control system may be reduced, further amplifying pain perception. c-Fos protein is rapidly expressed in neurons in response to various stimuli, and c-Fos expression is recognized as a marker of increased neuronal activity. Upregulations of c-Fos expression in the ventrolateral PAG (vlPAG) and NRM suggests the activation of descending pain control system. In the present study, we investigated the effect of treadmill running on the expression of c-Fos in the vlPAG and NRM regions of brains in the streptozotocin (STZ)-induced diabetic mice. Mice in the treadmill exercise group were forced to run on treadmill for 30 min once a day for 30 consecutive days. In mice with STZ-induced diabetes, the expression of c-Fos in the vlPAG and NRM was suppressed. Treadmill running, as like as insulin treatment, significantly increased c-Fos expression in the vlPAG and NRM. These results suggest that treadmill running might activate neurons in the vlPAG and NRM, and thus it alleviate the diabetes-related neuropathic pain through activation of descending pain control system. (Korean J Str Res. 2009;17:307∼312)