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02.10.2013


The anti-catabolic effect of a couple of grams of L-carnitine

Supplementation with a few grams of L-carnitine daily may inhibit the molecular demolition machinery that breaks down your muscles. This is suggested in an animal study published by scientists at Justus-Liebig University, Giessen, Germany in Nutrition & Metabolism.
Supplementation with a few grams of L-carnitine daily may inhibit the molecular demolition machinery that breaks down your muscles. This is suggested in an animal study published by scientists at Justus-Liebig University, Giessen, Germany in Nutrition & Metabolism.

Under conditions of extreme hunger, serious illness and other forms of physical stress, the body starts to sacrifice muscle tissue. The ubiquitin-proteasome system is activated in muscle cells and this breaks down muscle proteins. The catabolic proteins that play an important role in this demolition process are MuRF1 and atrogin-1.

The German scientists are doing research on the effects of adding small quantities of L-carnitine to piglets' food, in the hope that this compound will have a growth-enhancing effect. In 2011 and 2012 they published studies which show that L-carnitine supplementation reduces the functioning of the catabolic ubiquitin-proteasome system in the muscle cells of piglets. [Mol Nutr Food Res. 2011 Mar;55(3):419-29.] [Animal. 2012 Jan;6(1):70-8.]

In 2013 the same researchers published the results of a study in which they gave L-carnitine to rats in an attempt to elucidate more precisely how the anti-catabolic effect of L-carnitine works. The experimental group in the study consisted of four-week-old rats that were given 1250 mg L-carnitine per kg bodyweight. The human equivalent of this dose would be in the region of 1-3 g L-carnitine per day. The control group was given standard food.

During the four weeks that the experiment lasted, the rats built up a little more muscle protein and the amount of fat in their muscle tissue decreased.


Supplementation with a few grams of L-carnitine daily may inhibit the molecular demolition machinery that breaks down your muscles. This is suggested in an animal study published by scientists at Justus-Liebig University, Giessen, Germany in Nutrition & Metabolism.


Supplementation with a few grams of L-carnitine daily may inhibit the molecular demolition machinery that breaks down your muscles. This is suggested in an animal study published by scientists at Justus-Liebig University, Giessen, Germany in Nutrition & Metabolism.


Part of the muscle-strengthening effect is explained in the figure above. L-Carnitine supplementation boosted the concentration of IGF-1 in the rats' blood [above right]. The gene for IGF-1 started to work harder in the rats' liver [above left]. [Hmm… Might that mean that growth-hormone users would grow faster if they took L-carnitine?]

L-Carnitine reduced the production and concentration of the catabolic proteins MuRF1 and atrogin-1 in the muscle cells. In addition, the researchers observed that fewer proteins were being broken down by the ubiquitin-proteasome system [far right in the figure below].


Supplementation with a few grams of L-carnitine daily may inhibit the molecular demolition machinery that breaks down your muscles. This is suggested in an animal study published by scientists at Justus-Liebig University, Giessen, Germany in Nutrition & Metabolism.


In the muscle cells, L-carnitine boosted the activity of anabolic signal molecules such as Akt and mTOR. The number of phosphorylated Akt and mTOR molecules increased.


Supplementation with a few grams of L-carnitine daily may inhibit the molecular demolition machinery that breaks down your muscles. This is suggested in an animal study published by scientists at Justus-Liebig University, Giessen, Germany in Nutrition & Metabolism.


Supplementation with a few grams of L-carnitine daily may inhibit the molecular demolition machinery that breaks down your muscles. This is suggested in an animal study published by scientists at Justus-Liebig University, Giessen, Germany in Nutrition & Metabolism.


The activation of the anabolic signal molecules probably also caused an increase in the number of phosphorylated FoxO1 molecules. FoxO1 is a catabolic signal molecule. When not phosphorylated it tells the cell nucleus – and therefore also muscle proteins – to convert molecules into glycogen. FoxO1 is also responsible for the production of the catabolic MuRF1. But when phosphorylated, FoxO1 is broken down more quickly.

"Probably, the suppression of the ubiquitin-proteasome system by carnitine with respect to muscle protein degradation might be more pronounced and more relevant under condition of negative N balance, chronic diseases and denervation or under unloading conditions", the researchers write. "Under such conditions, the ubiquitin-proteasome system is strongly up-regulated leading to muscle atrophy and a reduction of the mass of skeletal muscles."

Source:
Nutr Metab (Lond). 2013 Mar 15;10(1):28.

More:
L-Carnitine helps centenarians build muscle mass 27.03.2012
Mix of propionyl-L-carnitine and L-arginine improves erection 15.12.2011
L-Carnitine plus carbohydrates helps endurance athletes 14.10.2011