Berberine-induced activation of 5'-adenosine monophosphate-activated protein kinase and glucose transport in rat skeletal muscles.

Berberine (BBR) is the main alkaloid of Coptis chinensis, which has been used as a folk medicine to treat diabetes mellitus in Asian countries. We explored the possibility that 5'-adenosine monophosphate-activated protein kinase (AMPK) is involved in metabolic enhancement by BBR in skeletal muscle, the important tissue for glucose metabolism. Isolated rat epitrochlearis and soleus muscles were incubated in a buffer containing BBR, and activation of AMPK and related events were examined.

Leucine modulates contraction- and insulin-stimulated glucose transport and upstream signaling events in rat skeletal muscle.

Leucine has profound effects on glucose metabolism in muscle; however, the effects of leucine on glucose transport in muscle have not been well documented. We investigated the effects of leucine on contraction- and insulin-stimulated glucose transport in isolated rat epitrochlearis muscle in vitro. In the absence of insulin, tetanic contraction increased 3-O-methyl-D-glucose (3-MG) transport and Thr(172) phosphorylation of the catalytic alpha-subunit of 5'-AMP-activated protein kinase (AMPK), a signaling intermediary leading to insulin-independent glucose transport.

Caffeine acutely activates 5'adenosine monophosphate-activated protein kinase and increases insulin-independent glucose transport in rat skeletal muscles.

Caffeine (1,3,7-trimethylxanthine) has been implicated in the regulation of glucose and lipid metabolism including actions such as insulin-independent glucose transport, glucose transporter 4 expression, and fatty acid utilization in skeletal muscle. These effects are similar to the exercise-induced and 5'adenosine monophosphate-activated protein kinase (AMPK)-mediated metabolic changes in skeletal muscle, suggesting that caffeine is involved in the regulation of muscle metabolism through AMPK activation. We explored whether caffeine acts on skeletal muscle to stimulate AMPK.

Morus alba leaf extract stimulates 5'-AMP-activated protein kinase in isolated rat skeletal muscle.

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.