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Memory formation is influenced by neurogenesis and long-term potentiation (LTP) of neurons in the hippocampus. In this study, we aimed to elucidate the mechanism of action of tocotrienol-rich fraction (TRF) involved in memory formation. Two cell models were employed, differentiated and undifferentiated HT22 neuronal cells. Our findings demonstrated that treatment with TRF increased cell proliferation of undifferentiated HT22 cells in a time-dependent manner by activating the brain-derived neurotrophic factor/tropomyosin receptor kinase B (BDNF/TrkB) pathway. Elevated levels of cyclin D and E were also observed, indicating an increase in cell cycle progression and proliferation. In differentiated HT22 cells, TRF upregulated expressions of BDNF, phosphorylation of glutamate receptor 1 and Ca2+/calmodulin-dependent protein kinase II, potentially leading to stronger synaptic strength and contributing to LTP. Taken together, these findings suggest that TRF supplementation may enhance memory formation in HT22 cells through modulation of the BDNF/TrkB pathway.

Stoichiometric gadolinium oxide thin films have been grown on silicon (100) substrates with a low-energy dual ion-beam epitaxial technique. Gadolinium oxide shares Gd[sub 2]O[sub 3] structures although the ratio of gadolinium and oxygen in the film is about 2:1 and a lot of oxygen deficiencies exist. Photoluminescence (PL) measurements have been carried out within a temperature range of 5–300 K. The detailed characters of the PL emission integrated intensity, peak position, and peak width at different temperature were reported and an anomalous photoluminescence behavior was observed. The character of PL emission integrated intensity is similar to that of some other materials such as porous silicon and silicon nanocrystals in silicon dioxide. Four peaks relative to α band and β band were observed also. Therefore we suggest that the nanoclusters with the oxygen deficiencies contribute to the PL emission and the model of singlet-triplet exchange splitting of exciton was employed for discussion. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]