High glucose concentrations per se do not adversely affect human sperm function in vitro

Abstract

Diabetes mellitus (DM) represents one of the greatest concerns to global health and it is associated with diverse clinical complications, including reproductive dysfunction. Given the multifactorial nature of DM, the mechanisms that underlie reproductive dysfunction remain unclear. Considering that hyperglycemia has been described as a major effector of the disease pathophysiology, we used anin vitroapproach to address the isolated effect of high glucose conditions on human sperm function, thus avoiding otherin vivoconfounding players. We performed a complete and integrated analysis by measuring a variety of important indicators of spermatozoa functionality (such as motility, viability, capacitation status, acrosomal integrity, mitochondrial superoxide production and membrane potential) in human sperm samples after incubation withd- andl-glucose (5, 25, or 50 mM) for 24 and 48 h. No direct effects promoted by 25 or 50 mMd-glucose were found for any of the parameters assessed (P>0.05), except for the acrosome reaction, which was potentiated after 48 h of exposure to 50 mMd-glucose (P<0.05). Interestingly, non-metabolizablel-glucose drastically increased superoxide production (P<0.05) and suppressed sperm motility (P<0.05) and capacitation (P<0.05) after 24 h of treatment, whereas mitochondrial membrane potential (P<0.05), acrosomal integrity (P<0.01) and viability (P<0.05) were later decreased. The overall results suggest that high glucose levelsper sedo not influence human sperm functionin vitro, which stresses the importance of other factors involved in DM pathology. Nevertheless, the absence of metabolizable glucose contributes to a severe impairment of sperm function and thus compromises male fertility.Free Portuguese abstract: A Portuguese translation of this abstract is freely available athttp://www.reproduction-online.org/content/150/1/77/suppl/DC1.