Effects of Herbal Bath on Functional Recovery and c-Fos Expression in the Ventrolateral Periaqueductal Gray Region of the Brain after Sciatic Crushed-Nerve Injury in Rats

Peripheral nerve injuries are a commonly encountered clinical problem and often result in chronic pain and severe functional deficits. At the Dept. of Oriental Rehab. Medicine, we have used for pain control a herbal bath containing the following herbs: Harpagophytum radix, Atractylodes japonica and Corydalis tuber. In the present study, we investigated the effects of this herbal bath on the recovery rate of the locomotor function and the expression of c-Fos in the ventrolateral periaqueductal gray (vIPAG) region of the brain following sciatic crushed nerve injury in rats. In the present study, characteristic gait change with decreasing of the sciatic function index (SFI) was observed and c-Fos expression in the vIPAG was suppressed following sciatic crushed nerve injury in rats. Immersion into herbal bath enhanced SFI value and restored c-Fos expression in the vIPAG to the control value. These results suggest the herbal bath might activate neurons in the vIPAG, and could facilitate functional recovery from peripheral nerve injury.