In order to investigate the effects of a fermented soybean product (
Chungkookjang, CKJ) on
nerve growth factor (
NGF) metabolism,
NGF secretion ability and its related signaling pathway were analyzed in B35 neuronal cells and the Tg2576 mouse model of
Alzheimer's disease (AD). In B35 cells, the concentration of
NGF significantly increased upon treatment with Taegwang (TG)-CKJ and Shinhwa (SH)-CKJ extracts compared with vehicle. Further, a significant increase in PC12 cell length as well as the phsophorylation levels of TrkA and Akt, which are members of a high affinity
NGF receptor signaling pathway, were observed
after treatment with TG-CKJ and SH-CKJ conditional medium (CM). On the other hand, there was no difference in activation of the
NGF receptor p75(NTR) signaling pathway between vehicle and all CKJ treated groups. In Tg2576 mice showing early stage of AD, the concentrations of
NGF in the serum and brain were reduced compared with those in Non-Tg mice. Treatment of Tg2576 mice with SH-CKJ, which contains high concentrations of total
flavonoids and phenolic compounds, for 8 weeks dramatically recovered the
NGF level to that of Non-Tg mice. Furthermore, the low phosphorylation levels of TrkA and Erk in the
NGF receptor TrkA signaling pathway were rapidly recovered to those of Non-Tg mice after SH-CKJ treatment in vehicle treated Tg2576 mice, whereas the phosphorylation level of Akt was maintained at a constant level. These results suggest that CKJ may stimulate
NGF secretion ability as well as the
NGF receptor TrkA signaling pathway in PC12 cells and Tg2576 mice.