Identification of novel β-lactoglobulin-derived peptides, wheylin-1 and -2, having anxiolytic-like activity in mice

Authors

  • Ayako Yamada,

    1. Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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  • Takafumi Mizushige,

    1. Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
    2. Research Unit for Physiological Chemistry, C-PIER, Kyoto University, Kyoto, Japan
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  • Ryuhei Kanamoto,

    1. Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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  • Kousaku Ohinata

    Corresponding author
    1. Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
    • Correspondence: Dr. Kousaku Ohinata, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan

      E-mail: ohinata@kais.kyoto-u.ac.jp

      Fax: +81-774-38-3774

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Abstract

Scope

We found that thermolysin digest of β-lactoglobulin, a major protein of bovine milk whey, exhibited anxiolytic-like activity in a behavioral experiment in mice, and then identified active components from the digest.

Methods and results

In the elevated plus-maze test, thermolysin digest of β-lactoglobulin had anxiolytic-like activity after intraperitoneal administration in mice. We identified several low-molecular-weight peptides in a fraction separated by reverse-phase HPLC having the most potent anxiolytic-like activities. Among them, Met-His and Met-Lys-Gly, corresponding to β-lactoglobulin (145–146) and (7–9), had anxiolytic-like activity at a dose of 0.3–1 and 3 mg/kg, respectively, after intraperitoneal administration. We named Met-His and Met-Lys-Gly wheylin-1 and -2, respectively. Next, we focused on wheylin-1, a more potent peptide with anxiolytic-like activity than wheylin-2. Wheylin-1 (1 mg/kg) had anxiolytic-like activity after oral administration. In the open-field test, wheylin-1 was also active. The anxiolytic-like activity of wheylin-1 was blocked by bicuculline, an antagonist of γ-amino butyric acid type A (GABAA) receptor, suggesting that wheylin-1 exhibited anxiolytic-like activity via the GABAA system.

Conclusion

Novel β-lactoglobulin-derived peptides, wheylin-1 and -2, may exhibit anxiolytic-like activities.

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