Association of Brain-Derived Neurotrophic Factor with Neurite Outgrowth in HT-22 Hippocampal Neurons Stimulated by Medicinal Mushrooms Hericium erinaceus and Lignosus rhinocerotis (Agaricomycetes)

Neurite outgrowth, also known as neuritogenesis, is among the crucial factors contributing to the overall neuroplasticity and maintenance of a healthy nervous system. The neurite outgrowth activities of two medicinal mushrooms, i.e. Hericium erinaceus and Lignosus rhinocerotis, have been previously demonstrated in multiple in vitro models showcasing their nerve growth factor (NGF)-promoting activities. In this study, the neuritogenic effects of hot aqueous extracts from H. erinaceus (HE) fruiting bodies and the sclerotium of L. rhinocerotis (LR) were investigated in the HT-22 mouse hippocampal neuronal cell line with potential association to the brain-derived neurotrophic factor (BDNF) expression. Findings show that HE and LR up to 400 μg/mL were non-toxic to HT-22 cells, as measured in the MTT viability assay. In neurite outgrowth assays, HEaq at 25 μg/mL significantly (P < 0.05) increased the number of neurite-bearing cells. Meanwhile, LRaq at as low as 6.25 and 12.5 μg/mL remarkably (P < 0.01; P < 0.001) improved the neurite outgrowth activities. Both HEaq and LRaq significantly (P < 0.0001) upregulated the mRNA expressions of BDNF, the neurotrophic factor responsible for hippocampal neuroplasticity. Immunofluorescence studies have further shown the protein expression of BDNF and neurofilament. These findings suggest that the aqueous extracts of HE and LR could play a vital role in enhancing neuroplasticity and maintaining a healthy nervous system, paving the way for their potential application in neurodegenerative disease management and cognitive health.