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

Abstract

Peripheral nerve injuries are a commonly encountered clinical problem and often result in a chronic pain and severe functional deficits. c-Fos expression is sometimes used as a marker of increased neuronal activity. We have developed herbal bath "HAC" for pain control using the following herbs: Harpagophytum procumbens, Atractylodes japonica, and Corydalis tuber. In the present study, we investigated the effects of herbal bath "HAC" on the recovery rate of the locomotor function and the expression of c-Fos in the ventrolateral periaqueductal gray (vlPAG) region of brain following sciatic crushed nerve injury in rats. Walking track analysis for the evaluation of functional recovery and immunohistochemistry for the c-Fos expression were used for this study. In the present results, characteristic gait change with dropping of the sciatic function index (SFI) was observed and c-Fos expression in the vlPAG was suppressed following sciatic crushed nerve injury in rats. Immersion into herbal bath "HAC" enhanced SFI value and restored c-Fos expression in the vlPAG to the control value. These results suggest that herbal bath "HAC" might activate neurons in the vlPAG, and it facilitates functional recovery from peripheral nerve injury. Here we showed that herbal bath "HAC" could be used as a new therapeutic intervention for pain control and functional recovery from peripheral nerve injury.