Acrosome reaction is impaired in spermatozoa of obese men: a preliminary study

Objective: To compare spontaneous (Sp-AR) and P-induced acrosome reaction (AR) in spermatozoa of obese and lean subjects.

Setting: Bariatric unit at a university hospital.

Design: Prospective, observational study.

Patient(s): Twenty-three obese (mean±SD body mass index [BMI], 44.3±5.9 kg/m2) and 25 age-matched lean (BMI, 24.2±3.0 kg/m2) subjects.

Intervention(s): None.

Main outcome measure(s): Spontaneous and P-induced AR in spermatozoa of obese and lean subjects.

Result(s): A statistically significant difference was found between obese and lean cohorts in total T and calculated free T, E2, glycated hemoglobin, and high-density lipoproteins, whereas among the routine semen parameters analyzed, only immotile sperm percentage and ejaculate volume differed significantly. Spermatozoa of obese (n=13) vs. lean men (n=19) showed a higher Sp-AR (17.9%±7.2% vs. 8.3%±4.2%), which resulted in a reduced ability to respond to P evaluated as the AR-after-P-challenge parameter (3.5%±3.2% vs. 17.6%±9.2%). Multivariate analysis adjusted for age revealed a significant correlation between BMI, waist, E2, and glycated hemoglobin with both Sp-AR (age-adjusted r=0.654, r=0.711, r=0.369, and r=0.644, respectively) and AR-after-P-challenge (age-adjusted r=-0.570, r=-0.635, r=-0.507, and r=-0.563, respectively). A significant difference in sperm cholesterol content was reported between obese and lean men (29.8±19.5 vs. 19.1±14.6 ng/μg of proteins).

Conclusion(s): Sperm AR is impaired in obese men, showing reduced response to P and elevated Sp-AR, associated with altered circulating levels of E2 and sperm cholesterol content.