Saturday, October 16, 2010

L-Carnitine Changes Gene Transcription in Muscle - After all, it Works!

L-Carnitine has long been among my favorites of expensive supplements with ostensibly conclusive scientific background which are pretty worthless in practice. Now, a new study by Keller et al. (Keller. 2010) found that L-Carnitine supplementation in piglets had a distinct effect on gene expression in skeletal muscle:
Transcript profiling revealed 211 genes to be differentially expressed in muscle by carnitine supplementation. The identified genes were mainly involved in molecular processes such as cytoskeletal protein binding, insulin-like growth factor (IGF) binding, transcription factor activity, and insulin receptor binding. Identified genes with the molecular function transcription factor activity encoded primarily transcription factors, most of which were down-regulated by carnitine, including pro-apoptotic transcription factors such as proto-oncogene c-fos, proto-oncogene c-jun and activating transcription factor 3. Furthermore, atrophy-related genes such as atrogin-1, MuRF1, and DRE1 were significantly down-regulated by carnitine. IGF signalling and insulin signalling were identified as significantly up-regulated regulatory pathways in the carnitine group.Conclusion: Carnitine may have beneficial effects on skeletal muscle mass through stimulating the anabolic IGF-1 pathway and suppressing pro-apoptotic and atrophy-related genes, which are involved in apoptosis of muscle fibers and proteolysis of muscle proteins, respectively.
For athletes and gymrats the part in bold could be of particular interest, because after all, improved IGF and insulin signalling should translate into enhanced muscle growth.Unfortunately, the scientists from the Justus-Liebig-Universität in Gießen, Germany, do not mention the amount of carnitine the piglets were fed, so we cannot tell, whether the effect may be due to "L-Carnitine-overfeeding" or if the usual amounts of supplemental carnitine (1-5g) would suffice to produce similar results in pig and/or man.