The role of leptin and obesity on male infertility.

Several studies suggest a strong association between leptin, obesity, and infertility with respect to the hypothalamic-pituitary-gonadal (HPG) axis, androgen regulation, and sperm production, but the direct mechanistic association between these is still largely unexplored. This review focuses on understanding the association between leptin, obesity, and male infertility.Obesity is linked to fertility dysfunction in both genders. Obesity in men may affect their fertility by impaired spermatogenesis, reduced testosterone levels, erectile dysfunction, and poor libido by putatively targeting the HPG and hypothalamic-pituitary-adrenal axes. Leptin plays key roles in many metabolic functions, including reproduction. High concentrations of leptin have been found in infertile men with disorders affecting the testicular parenchyma, including nonobstructive azoospermia, oligozoospermia, and oligo-astheno-teratozoospermia. Additionally, serum leptin levels have negative associations with serum testosterone levels and sperm parameters and positive associations with serum follicle-stimulating hormone and luteinizing hormone levels and abnormal sperm morphology.Excessive leptin production may be a significant contributor to the development of androgen insufficiency and reduced reproductive function in obese men. Understanding the relation between leptin, obesity, and reproduction may shed light on future targeted treatments for male infertility.