Obesity, a serious etiologic factor for male subfertility in modern society

Abstract

Obesity, defined as excessive accumulation of fat in adipose tissue, is a metabolic disorder resulting from behavioral, environmental and heritable causes. Obesity increases the risks of hypertension, diabetes, cardiovascular disease, sleep apnea, respiratory problems, osteoarthritis and cancer. Meanwhile, the negative impact of obesity on male reproduction is gradually recognized. According to the clinical investigations and animal experiments, obesity is correlated with reductions in sperm concentration and motility, increase in sperm DNA damage and changes in reproductive hormones. Several mechanisms can elucidate the effects of obesity on sperm functions and male subfertility, i.e., the excessive conversion of androgens into estrogens in redundant adipose tissue causes sexual hormone imbalance, subsequently resulting in hypogonadism. Secondly, adipokines produced by adipose tissue induce severe inflammation and oxidative stress in male reproductive tract, directly impairing testicular and epididymal tissues. Moreover, increased scrotal adiposity leads to increase gonadal heat, continuously hurting spermatogenesis. Therefore, obesity alters the systematic and regional environment crucial for spermatogenesis in testis and sperm maturation in epididymis, and finally results in poor sperm quality including decreased sperm motility, abnormal sperm morphology and acrosome reaction, changed membrane lipids and increased DNA damage. Furthermore, recent studies indicate that epigenetic changes may be a consequence of increased adiposity. A major effort to identify epigenetic determinants of obesity revealed that sperm DNA methylation and non-coding RNA modification are associated with BMI changes and proposed to inherit metabolic comorbidities across generations. This review will explain how obesity-related changes in males to influence sperm function and male fertility as well.Reproduction (2017) 154 R123-R131

Obesity and male hypogonadism: Tales of a vicious cycle

“…In fact, it is estimated that the decline in sperm count is over 50% since the 20th century . Obesity has several negative effects on sperm quality and generally an inverse correlation between BMI and sperm parameters is observed, where men with obesity are more likely to exhibit a reduction in semen quality than men with normal BMI . Several studies show that obesity is linked with abnormal sperm parameters including low sperm concentration and low motility, which results in subfertility.…”

“…12,13 Indeed, nearly 20% of the subfertility and infertility in males can be directly attributed to overweight and obesity. 14,15 Remarkably, in regions of the globe where obesity is less prevalent, such as non-Western countries, the prevalence of male infertility is also lower, providing additional epidemiological evidence on the parallelism between obesity and male fertility potential. 16 Male hypogonadism is defined as a syndrome characterized by androgen deficiency, which can be classified as primary or secondary according to the aetiology of testosterone deficiency.…”

Indirubin, a small molecular deriving from connectivity map (CMAP) screening, ameliorates obesity-induced metabolic dysfunction by enhancing brown adipose thermogenesis and white adipose browning

“…Obesity is defined as a state of excessive or abnormal fat accumulation of sufficient magnitude which may pose a threat to the health of people [4,7]. However, mammals, in fact, possess two kinds of adipose tissue with distinct physiological functions: white adipose tissue (WAT) and brown adipose tissue (BAT).…”

Treatment of idiopathic oligozoospermia with combined human chorionic gonadotropin/human menopausal gonadotrophin: A randomised, double‐blinded, placebo‐controlled clinical study

“…The negative impact of obesity on male reproduction is gradually recognised. Obesity is correlated with reductions in sperm concentration and motility, increase in sperm DNA damage and changes in reproductive hormones (Liu & Ding, ). In this study, no significant differences were observed in body mass among all the groups ( p > 0.05) (Table ).…”