Lotus Root Extract Stimulates BDNF Gene Expression Through Potential Mechanism Depending on HO-1 Activity in C6 Glioma Cells

ABSTRACT

Polyphenolic compounds have been suggested to be involved in the preservation of neural function via the production of neurotrophic factors in the brain. The nonedible joint part of lotus root (a rhizome of Nelumbo nucifera) has been reported to contain large amounts of polyphenolic compounds and, therefore, is expected to improve neural function by stimulating the production of brain-derived neurotrophic factor (BDNF) in glial cells. The effect of the aqueous extract prepared from the joint part of lotus root on BDNF gene expression was examined in C6 glioma cells as an in vitro model. This extract was shown to increase BDNF messenger ribonucleic acid (mRNA) levels to the elevation of HO-1 mRNA levels in the glioma cells, but failed to cause the elevation of BDNF mRNA levels in the cells pretreated with a HO-1 antisense oligodeoxynucleotide (ODN) or an HO-1 enzyme inhibitor zinc protoporphyrin (ZnPP). These findings strongly suggest that the aqueous extract prepared from the nonedible joint part of lotus root might be able to stimulate BDNF gene expression by enhancing HO-1 activity in the glioma cells, proposing the possibility that the joint part of lotus root might potentially improve neural function through the stimulation of BDNF production in glial cells.

KEYWORDS:

• BDNF gene transcription
• HO-1 activity
• lotus root
• neurotrophic factor
• nonedible joint part

Acknowledgments

The authors thank the Naruto Agricultural Cooperative in Tokushima (Naruto, Japan) for the kind donation of lotus roots. The authors also express sincere gratitude to the Tokushima Agriculture, Forestry, and Fisheries Technology Support Center (Tokushima, Japan) for the technical assistance to prepare the lotus root powder.

Declaration of interest

There is no conflict of interest associated with the authors of this article, and the fund sponsor did not cause any inappropriate influence on this work.

Funding

This work was supported in part by funds provided from Kohken Co., Inc. (Sapporo, Japan) and Shikoku Kakoki Co., Ltd. (Tokushima, Japan).

About the authors

Naoyoshi Nishibori, PhD, Professor of the Department of Food Science and Nutrition, Shikoku Junior College.

Reina Kishibuchi, MSc, Student of the Graduate School (doctor's course) of Tokushima University.

Song Her, PhD, Director of the Division of Bio-Imaging, Korea Basic Science Institute.

Mi-Sook Lee, PhD, Assistant Professor of the College of Oriental Medicine, Kyung Hee University.

Kyoji Morita, PhD, Representative of Life Science Research Group, Professor (retired) of Shikoku University School of Health Sciences.