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.