The Role of Carnitine in the Male Reproductive System

Abstract

Carnitine is highly concentrated in the epididymis and spermatozoa, where it may serve as an intramitochondrial vehicle for the acyl group, which in the form of acyl CoA acts as a substrate for the oxidation process producing energy for sperm respiration and motility. To date, studies in rodents and humans suggest that sperm count, motility, and maturation are related to epididymal free carnitine concentrations. Moreover, supplementation with carnitine improves sperm quality and/or quantity in testes of mice exposed to physical insults, such as heat and X-irradiation, and in men with idiopathic oligoasthenospermia. These benefits may be due to increased mitochondrial fatty acid oxidation resulting in improvement in motility of epididymal sperm. The antiapoptotic effect(s) of carnitine in the testes may also contribute, but this remains speculative and requires further investigation. Research to uncover the many characteristics and mechanisms of action of carnitine in somatic and germ cells may provide insights into the pathophysiology of germ cell apoptosis, the prevention of germ cell death, and possibly specific therapy of some forms of infertility. Further well-controlled, carefully designed, larger-scale studies are necessary and desirable before widespread clinical use as an infertility therapy can be contemplated.

Carnitine partially protects the rat testis against the late damage produced by doxorubicin administered during pre‐puberty

“…Although the D100 rats have shown altered sperm transit time, as formerly mentioned, the carnitine-doxorubicin-treated rats showed normal values in various sperm parameters, including the caput/corpus sperm transit time. These data agree with previously published studies that mentioned an improvement of the spermatic parameters in infertile patients after carnitine treatment (Ng et al, 2004;Agarwal & Said, 2004;Kadhemi et al 2005).…”

“…In fact, endogenous carnitine has an important role in the sperm energy production, motility, and maturation, being largely present in the epididymis (Rodrıguez et al, 2002;Ng et al, 2004). The carnitine transporter OCTN2 is largely present in this duct (Rodrıguez et al, 2002) and mediates the supply of endogenous carnitine and acetylcarnitine to epididymal spermatozoa in mice (Kobayashi et al, 2007).…”

“…It acts on male gamete maturation (Ng et al, 2004) and seems to have a role in the production of energy for sperm motility. Besides, carnitine is also involved in DNA repair (Garcia et al, 2005), germ cell recovery (Tarladacalisir et al, 2009) and Sertoli cell metabolism (Palmero et al, 2000).…”

“…Carnitine, an important quaternary amine (3-hydroxy-4-N,N,N-trimethylaminobutyrate), is an essential nutrient with a major role in cellular energy production and has been considered a promising cytoprotective agent (Sayed-Ahmed, 2010). It is acquired through exogenous dietary sources, mainly from meat and milk, and its endogenous production occurs in liver by the methylation of lysine and methionine requiring the presence of iron and three vitamins: ascorbic acid, niacin, and vitamin B6 (Cerretelli & Marconi, 1990;Evans & Fornas, 2003;Ng et al, 2004). Besides, L-carnitine is essential for energy generation provided by the transportation of long-chain fatty acids into the mitochondria for beta-oxidation (Bieber, 1988).…”

Effect of L-carnitine supplementation on drake semen quality

“…Dietary supplementation of L-carnitine increased sperm concentration, count and motility, semen volume and decreased lipid peroxidation of spermatozoa in breeding roosters (Neuman et al, 2002;Golzar Adabi et al, 2006;Zhai et al, 2007). L-carnitine plays a critical role in the maturation and motility of spermatozoa within the male reproductive tract (Ng et al, 2004).…”