L-carnitine Partially Improves Metabolic Syndrome Symptoms but does not Reverse Perturbed Sperm Function or Infertility in High Fat Diet-Induced Obese Mice

In recent years, adverse effects of obesity on female reproduction and male fertility have received significant attention. In this study, we investigated infertility improvements following L-Carnitine treatment using a high-fat diet (HFD)-induced obesity mouse model. Five-week-old male mice were divided into a control diet (CTD) group, a HFD group, and a HFD with L-Carnitine supplementation (HFD+C) group that received L-Carnitine-supplemented water and a HFD. At 30 weeks of age, mating tests with female mice were conducted to investigate reproductive ability. Dissection was then performed to analyse organ weights, blood glucose and lipid levels, and sperm motility. HFD mice displayed increased body, liver, and visceral fat weights and blood glucose, blood lipid, and liver lipid levels compared with those of CTD mice. In addition, sperm motility was decreased, and female mouse pregnancies could not be confirmed. HFD+C mice displayed significantly decreased body, liver, and visceral fat mass and blood and liver lipid concentrations compared with those of HFD mice. Though fertility was observed in one out of five mice, no significant improvement in sperm motility or fertility was observed. These results suggest that L-Carnitine administration does not reverse male infertility in diet induced obesity but partially improves metabolic syndrome symptoms.