Berberine Linked to Impaired Muscle Metabolism in Mice

In mouse study, berberine tied to impaired mitochondrial function, expression of atrogin-1

WEDNESDAY, Aug. 25 (HealthDay News) -- The herbal compound berberine stimulates the expression of atrogin-1, leading to protein degradation, suppression of protein synthesis, and muscle atrophy in a mouse model of type 2 diabetes, according to research published in the August issue of Diabetes.

Huiling Wang, of the Jimin Hospital in Shanghai, China, and colleagues analyzed data from wild-type control mice and db/db mice, some of which were treated with berberine, with a hypothesis that the herb could improve muscle protein metabolism in the setting of insulin resistance.

The researchers found that, in both types of mice, berberine was associated with reduced protein synthesis, higher muscle degradation, and decreased muscle mass. The muscle atrophy in the treated mice was associated with stimulation of atrogin-1 expression; this increase accelerated muscle protein degradation and suppressed protein synthesis. Berberine impaired mitochondrial function, which stimulated expression of atrogin-1 without influencing phosphorylation of forkhead transcription factors.

"In summary, we have uncovered two factors that affect the control of muscle protein metabolism. First, a decrease in energy metabolism in muscle can stimulate protein losses by raising protein degradation and suppressing protein synthesis. Second, an increase in atrogin-1 expression not only is associated with increased protein degradation by the ubiquitin-proteasome system, but it also can interfere with protein synthesis by promoting the degradation of factors regulating synthesis," the authors write.

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