ANTIOXIDANT AND STRESS REDUCTION EFFECTS OF A NOVEL ANTIOXIDANT DERIVED FROM OYSTER ON OVERSTIMULATION OF THE HYPOTHALAMIC–PITUITARY–ADRENAL AXIS INDUCED BY BRAIN OXIDATIVE STRESS

Katsuya KUROKI¹, Emiko MIKI¹, Yoshihiro URADE², Mitsugu WATANABE¹

¹Watanabe Oyster Laboratory Co., Ltd.and 490-3, Shimoongata-Cho, Hachioji, Tokyo, Japan

²International Institute for Integrative Sleep Medicine, University of Tsukuba and 1-1-1 Tennodai, Tsukuba, Ibaraki Japan.

e-mail: gakujutsu@oyster.co.jp

Key words: antioxidant, hippocampal glucocorticoid receptor, HPA axis, stress, sleep

Objective:

We investigated the effects of a novel antioxidant, 3,5-dihydroxy-4-methoxybenzyl alcohol (DHMBA), which was isolated from the soft tissue of the Pacific oyster (Crassostrea gigas), on intracerebral oxidation, hippocampal glucocorticoid receptor (GRα) levels, and the hypothalamic-pituitary-adrenal (HPA) axis.

Methods:

The Pacific oyster soft tissue extract were fractionated into DHMBA-containing and DHMBA-free fractions. An intracerebral oxidative stress mouse model on 30 male ICR mice were divided into 3 groups i.e. water, DHMBA-containing, DHMBA-free. They were individually housed and fed for 42 days. Following oral administration of water and the fractions with and without DHMBA, intracerebral 8-hydroxy-2’-deoxyguanosine (8-OHdG) levels, Malondialdehyde (MDA) levels, hippocampal GRα levels and plasma corticosterone (CR) levels of the mice were measured.

Results:

Intracerebral 8-OHdG levels of the mice that intake water, DHMBA-containing were 11.32±0.86 ng/g of brain, 7.51±0.71 ng/g of brain, respectively. MDA levels of the mice that intake water, DHMBA-containing were 28.11±1.33 µmol/g of brain, 22.13±0.58 µmol/g of brain, respectively. Hippocampal GRα levels of the mice that intake water, DHMBA-containing were 0.590±0.036 ng/mg of hippocampus, 0.812±0.038 ng/mg of hippocampus, respectively. Plasma CR levels of the mice that intake water, DHMBA-containing were 193.9±9.1 ng/mL, 141.4±9.8 ng/mL, respectively. These results showed that intracerebral 8-OHdG, MDA and plasma CR in the mice were significantly decreased in DHMBA-containing group when compared with the water. In contrast, hippocampal GRα in the mice was significantly increased in DHMBA-containing group when compared with the water (P<0.01).

Conclusion: DHMBA exhibited intracerebral antioxidant properties and stress-relieving properties in the form of inhibited abnormal excitation of the HPA axis.