Metabolomics profiling of seminal plasma in obesity-induced asthenozoospermia

Abstract

Background: Asthenozoospermia is one of the essential causes of male infertility, and its incidence is significantly higher in obese men. Due to its complex etiology and unknown pathomechanism, the diagnosis and treatment of obesity-induced asthenozoospermia is a prevalent problem in reproductive medicine.

Objective: This study aims to explore major differential metabolites and metabolic pathways in seminal plasma and pathological mechanisms for obesity-induced asthenozoospermia.

Materials and methods: We performed non-target metabolomic studies on the seminal plasma of healthy men with normal semen parameters (HN group, n = 20), obese men with normal semen parameters (ON group, n = 20), and men with obesity-induced asthenozoospermia (OA group, n = 20) based on gas chromatography-mass spectrometry. Metabolic profilings and related pathway analyses were conducted to discriminate differential metabolites and metabolic pathways.

Results: A total of 20 differential metabolites including fructose, succinic acid, aconitic acid, methylmaleic acid, glucopyranose, serine, valine, leucine, phenylalanine, glycine, glutamic acid, alanine, proline and threonine were identified in HN group and ON group; 24 differential metabolites including glucose, fructose, pyruvic acid, citric acid, succinic acid, aconitic acid, glucopyranose, glutamic acid, valine, leucine, glycine, phenylalanine, lysine, citrulline, proline and alanine were produced in OA group and ON group; and 28 differential metabolites including glucose, fructose, citric acid, succinic acid, glucopyranose, valine, glycine, serine, leucine, phenylalanine, alanine, threonine, proline, glutamic acid, citrulline, lysine and tyrosine were produced in OA group and HN group. In addition, abnormal energy metabolism including carbohydrate metabolism (TCA cycle, glycolysis/gluconeogenesis, and pyruvate metabolism) and amino acid metabolism (phenylalanine, tyrosine, and tryptophan biosynthesis, D-glutamine and D-glutamate metabolism; phenylalanine metabolism, etc.) were found in ON group and OA group.

Conclusion: Obesity could affect the metabolite composition in seminal plasma and abnormal energy metabolism in seminal plasma mainly including carbohydrate metabolism and amino acid metabolism were closely related to obesity-induced asthenozoospermia.

Keywords: asthenozoospermia; metabolomics; obesity; seminal plasma.