Abstract
BackgroundL-carnitine-mediated beta-oxidation of fatty acids has a well established role in energy supply of oocytes and embryos. Disturbed carnitine metabolism may impair the reproductive potential in IVF and can serve as a biomarker of pregnancy outcome.MethodsOur study was performed between March 24, 2011 and May 9, 2011. We performed 44 unselected IVF cycles, (aged 23–40 years (mean: 32.3+/−5.1 years) and had BMI of 17.3-34.7 (mean: 23.80+/−4.9). Samples were also obtained from 18 healthy women of similar age admitted for minor elective surgery to serve as control for plasma carnitine profile. Serum and follicular fluid (FF) free carnitine (FC) and 20 major acylcarnitines (ACs) were measured by ESI/MS/MS method.ResultsSerum FC and AC levels in IVF patients were comparable to those in healthy control women. In FF FC and short-chain AC concentrations were similar to those in maternal serum, however, the levels of medium-chain, and long-chain AC esters were markedly reduced (p<0.05). The serum to FF ratio of individual carnitine compounds increased progressively with increasing carbon chain length of AC esters (p<0.05). There was a marked reduction in total carnitine, FC and AC levels of serum and FF in patients with oocyte number of >9 and/or with embryo number of >6 as compared to the respective values of <9 and/or <6 (p<0.05).ConclusionsIn IVF patients with better reproductive potential the carnitine/AC pathway appears to be upregulated that may result in excess carintine consumption and relative depletion of carnitine pool. Consequently, IVF patients may benefit from carnitine supplementation.
Highlights
L-carnitine-mediated beta-oxidation of fatty acids has a well established role in energy supply of oocytes and embryos
AC esters were detected in the serum and follicular fluid (FF) samples and there were no significant differences in serum carnitine levels between healthy subjects and In vitro fertilization (IVF) patients
When FF carnitine profile was studied as a function of corresponding serum carnitines, a strong positive correlation was found between the two variables irrespective of their carbon chain length
Summary
L-carnitine-mediated beta-oxidation of fatty acids has a well established role in energy supply of oocytes and embryos. The prominent role of fatty acids in energy supply to acquire developmental competence of oocyte and early embryos has been established [5,6,7,8]. L-carnitine is present in free and esterified forms in tissues and body fluids It has multiple metabolic functions including transport of long-chain fatty acids into the mitochondria for betaoxidation, transfer of short- and medium-chain acyl groups from the peroxisome to mitochondria, regulation of intracellular acyl-CoA/free CoA ratio and export of toxic acyl residues from the mitochondria [12,13,14,15,16,17]. The importance of Lcarnitine in improving oocyte quality and reproductive performance has been demonstrated in animal and human studies [19,20,21,22,23,24]
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