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Effects of Shiikuwasha extract supplementation on muscle protein synthesis in the rat model of insulin resistance
Author(s) -
Narita Kazusa,
Maeda Naho,
Okamoto Tomoyuki,
Sakata Yasuyuki,
Oshio Kazutaka,
Nakamura Hirohiko,
Iwamoto Hiroshi,
Namba Kazuyoshi,
Takeda Yasuhiro,
Yoshizawa Fumiaki
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.967.3
Subject(s) - skeletal muscle , medicine , endocrinology , insulin resistance , sarcopenia , muscle atrophy , atrophy , insulin , chemistry
The loss of skeletal muscle mass with aging, referred to as sarcopenia, is a significant problem that has serious implications on the quality of life of the elderly, especially in an aging society such as Japan. The etiology of skeletal muscle atrophy is reported to be multifaceted and involve insulin resistance. Recently, we reported that Shiikuwasha ( Citrus depressa ) extract as an inhibitory effect on dexamethasone‐induced skeletal muscle atrophy. The aim of this study was to examine whether supplementation with Shiikuwasha extract has an inhibitory effect on loss of skeletal muscle mass caused by insulin resistance in Zucker diabetic fatty (ZDF) rats. Male ZDF rats were assigned to three groups: (1) lean control (LC), (2) diabetic control (DC), (3) Shiikuwasha extract supplementation (SE). LC and DC animals received an AIN‐93G diet, whereas SE animals were maintained on a diet containing 1% ( w/w ) SE for 2 weeks. As skeletal muscle mass was assessed, significant decrease was observed in the mass of the gastrocnemius, soleus, plantaris, tibialis anterior, and extensor digitorum longus muscles in the DC group compared to that in the LC group. By contrast, the SE group exhibited significant increases in all the skeletal muscles except the soleus muscle. There was no significant increase in the phosphorylation states of p70 S6 kinase and 4E‐BP1 in the SE group. However, the SE group showed higher mRNA expression level of IGF‐1 than the DC group. Moreover, the levels of blood HbA1c and plasma insulin were lower in the SE group than in the DC group. Our data show that Shiikuwasha extract supplementation may ameliorate loss of skeletal muscle mass associated with insulin resistance. This mechanism might depend on the improvement of insulin sensitivity and partially, on the activation of protein synthesis.