Carnitine supplementation fails to maximize fat mass loss induced by endurance training in rats.
OBJECTIVE
Carnitine is a co-factor of the enzymatic system involved in long chain fatty acid transport across the mitochondrial membrane. This physiological role of carnitine raised the hypothesis that this compound could act as a 'fat burner' by optimizing fat oxidation and consequently reducing its availability for storage. Our aim was to verify whether carnitine supplementation could maximize fat mass loss in trained rats.


METHODS
Male Wistar rats (200 g) were divided into four groups: control (C), sedentary supplemented (S), trained (T) and trained supplemented (TS). The training protocol consisted of bouts of swimming exercise (60 min x day(-1)) for 6 weeks. During the last 14 days, before sacrifice, the supplemented groups received a daily dose of 28 mg x kg(-1) of L-carnitine. Carcass fat content, weight and fat content of adipose tissues were evaluated in all experimental groups.


RESULTS
Our results indicate that carnitine feeding, per se, failed to promote fat mass loss. Endurance training successfully induced a decrease in the fat content in the carcass (28%) and the weight of adipose tissues (retroperitoneal and mesenteric depots by 41 and 20%, respectively) in comparison to C. Despite the augmented carnitine content in the soleus mitochondria (2-fold) observed in TS, the higher content did not maximize the fat loss induced by endurance training.


CONCLUSIONS
Our data strongly suggest that endurance training, rather than carnitine content, is the major factor involved in fat mass loss.
Institute of Biomedical Sciences, USP, São Paulo, Brazil. msaoki@usp.br
Marcelo
M
Saldanha Aoki
André Luís
AL
Rodriguez Amaral Almeida
Francisco
F
Navarro
Luís Fernando
LF
Bicudo Pereira Costa-Rosa
Reury Frank
RF
Pereira Bacurau
D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D002331:Carnitine / Q000378:metabolism / Q000494:pharmacology*; D019587:Dietary Supplements; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D015431:Weight Loss / Q000187:drug effects*
D002331:Carnitine