Infertility affects approximately 15% of couples trying to conceive, and a male factor contributes to roughly half of these cases. Oxidative stress (OS) has been identified as one of the many mediators of male infertility by causing sperm dysfunction. OS is a state related to increased cellular damage triggered by oxygen and oxygen-derived free radicals known as reactive oxygen species (ROS). During this process, augmented production of ROS overwhelms the body's antioxidant defenses. While small amounts of ROS are required for normal sperm functioning, disproportionate levels can negatively impact the quality of spermatozoa and impair their overall fertilizing capacity. OS has been identified as an area of great attention because ROS and their metabolites can attack DNA, lipids, and proteins; alter enzymatic systems; produce irreparable alterations; cause cell death; and ultimately, lead to a decline in the semen parameters associated with male infertility. This review highlights the mechanisms of ROS production, the physiological and pathophysiological roles of ROS in relation to the male reproductive system, and recent advances in diagnostic methods; it also explores the benefits of using antioxidants in a clinical setting.
Antioxidants ; Cell Death ; DNA ; Family Characteristics ; Free Radicals ; Humans ; Infertility ; Infertility, Male ; Male ; Oxidative Stress* ; Oxygen ; Reactive Oxygen Species ; Reproduction* ; Semen ; Spermatozoa

AIMTo investigate the in vitro effects of insulin and leptin on human sperm motility, viability, acrosome reaction and nitric oxide (NO) production.

METHODSWashed human spermatozoa from normozoospermic donors were treated with insulin (10 microIU) and leptin (10 nmol). Insulin and leptin effects were blocked by inhibition of their intracellular effector, phosphotidylinositol 3-kinase (PI3K), by wortmannin (10 micromol) 30 min prior to insulin and leptin being given. Computer-assisted semen analysis was used to assess motility after 1, 2 and 3 h of incubation. Viability was assessed by fluorescence-activated cell sorting using propidium iodide as a fluorescent probe. Acrosome-reacted cells were observed under a fluorescent microscope using fluorescein-isothiocyanate-Pisum sativum agglutinin as a probe. NO was measured after treating the sperm with 4,5-diaminofluorescein-2/diacetate (DAF-2/DA) and analyzed by fluorescence-activated cell sorting.

RESULTSInsulin and leptin significantly increased total motility, progressive motility and acrosome reaction, as well as NO production.

CONCLUSIONThis study showed the in vitro beneficial effects of insulin and leptin on human sperm function. These hormones could play a role in enhancing the fertilization capacity of human spermatozoa.

Acrosome Reaction ; drug effects ; Cell Survival ; drug effects ; Flow Cytometry ; Humans ; Hypoglycemic Agents ; pharmacology ; In Vitro Techniques ; Insulin ; pharmacology ; Leptin ; pharmacology ; Male ; Nitric Oxide ; metabolism ; Sperm Motility ; drug effects ; Spermatozoa ; drug effects ; metabolism