An epidemic of obesity is prevalent in the world. Recent evidences have linked obesity to male infertility, but the underlying mechanisms remain to be elucidated. Although spermatozoa dysfunction is the most cause of infertility and defective mitochondrial function plays a key role in impairing the sperm quality, there was little study on the role of mitochondria within spermatozoa in obese male infertility.

In this study, the semen parameters in Chinese obesity (BMI≥28kg/m², n=51) and normal (BMI of 18.5 to 23.9kg/m², n=42) volunteers were investigated. Moreover, the oxidative stress injury was explored in human spermatozoa by examining the activity of intracellular SOD and MDA in sperm and LDH release from sperm. The activity test of mitochondrial respiratory chain complexes and the mitochondrial membrane potential were also performed.

We found that obesity had a negative influence on the quality of semen. Furthermore, oxidative stress was detected in sperm from obese males. Oxidative stress-related mitochondrial dysfunction was also observed in the spermatozoa of obese males.

In total, these results indicated that oxidative stress-related mitochondrial dysfunction might be a reason for obesity-induced infertility, which provided the insights into the pathophysiological mechanism behind obesity-induced infertility in obese human males.