We present a model case study of the activity of aqueous extract of Hericium erinaceus fresh fruit bodies in promoting functional recovery following crush injury to the peroneal nerve in adult female Sprague-Dawley rats. The aim was to explore the possible use of this mushroom in nerve repair. The activities of aqueous extract were compared to activities exhibited by mecobalamin (vitamin B12), which has been widely used in the treatment of peripheral nerve disorders. Analysis of walking track indicated that return of hind limb function and normal toe spreading occurred earlier in treated groups than in the negative control (non-treated) group. Regeneration of axons and reinnervation of motor endplates/neuromuscular junction in extensor digitorum longus muscle of rats in treated groups developed better than in the negative control group. Further, immunofluorescence studies also showed that dorsal root ganglia neurons ipsilateral to the crush injury in rats of treated groups expressed higher immunoreactivities for Akt and MAPK signaling pathways as well as c-Jun and c-Fos genes compared to the negative control group. Akt cascade plays a major role in mediating neurotrophin-promoted cell survival, while MAPK cascade is involved in mediating neurite outgrowth. Immediate early gene expression was also involved in the cascade of events leading to regeneration. Local axonal protein synthetic machinery was also enhanced in the distal segments of crushed nerves in treated groups. Therefore, daily oral administration of H. erinaceus could promote the regeneration of injured rat peroneal nerve in the early stage of recovery.
Neurotrophic factors are important in promoting the growth and differentiation of neurons. Nerve growth factor (NGF) is essential for the maintenance of the basal forebrain cholinergic system. Hericenones and erinacines isolated from the medicinal mushroom Hericium erinaceus can induce NGF synthesis in nerve cells. In this study, we evaluated the synergistic interaction between H. erinaceus aqueous extract and exogenous NGF on the neurite outgrowth stimulation of neuroblastoma-glioma cell NG108-15. The neuroprotective effect of the mushroom extract toward oxidative stress was also studied. Aqueous extract of H. erinaceus was shown to be non-cytotoxic to human lung fibroblast MRC-5 and NG108-15 cells. The combination of 10 ng/mL NGF with 1 μg/mL mushroom extract yielded the highest percentage increase of 60.6% neurite outgrowth. The extract contained neuroactive compounds that induced the secretion of extracellular NGF in NG108-15 cells, thereby promoting neurite outgrowth activity. However, the H. erinaceus extract failed to protect NG108-15 cells subjected to oxidative stress when applied in pre-treatment and co-treatment modes. In conclusion, the aqueous extract of H. erinaceus contained neuroactive compounds which induced NGF-synthesis and promoted neurite outgrowth in NG108-15 cells. The extract also enhanced the neurite outgrowth stimulation activity of NGF when applied in combination. The aqueous preparation of H. erinaceus had neurotrophic but not neuroprotective activities.