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Morus alba leaf extract stimulates 5'-AMP-activated protein kinase in isolated rat skeletal muscle
XIAO MA ; IWANAKA Nobumasa ; MASUDA Shinya ; ...
Aim of the study: Morus alba (mulberry) leaf is a natural therapeutic agent that has been shown to have an antidiabetic effect. We explored the possibility that 5'-AMP-activated protein kinase (AMPK) is involved in metabolic enhancement by the Morus alba leaf. Materials and methods: Isolated rat epitrochlearis muscle was incubated in a buffer containing Morus alba leaf hot water extract (MLE) and the AMPK activation and related events were examined. Results: In response to MLE treatment, the Thr172 phosphorylation of the catalytic α subunit of AMPK, an essential step for full kinase activation increased in a dose- and time-dependent manner. Ser79 phosphorylation of acetyl CoA carboxylase, an intracellular substrate of AMPK, increased similarly. Analysis of isoform-specific AMPK activity revealed that MLE activated both the α1 and a2 isoforms of the catalytic subunit. This increase in enzyme activity was associated with an increased rate of 3-O-methyl-D-glucose transport in the absence of insulin and with phosphorylation of AS160, a signaling intermediary leading to glucose transporter 4 translocation. The intracellular energy status, estimated from the ATP and phosphocreatine concentrations, was not affected by MLE. Conclusion: MLE stimulates skeletal muscle AMPK activity acutely without changing the intracellular energy status.
ISSN : 0378-8741 CODEN : JOETD7
Journal of ethnopharmacology A. 2009, vol. 122, n° 1, pp. 54-59 [6 pages] [bibl. : 1 p.]
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