Hyaluronic Acid as Capacitation Inductor: Metabolic Changes and Membrane‐Associated Adenylate Cyclase Regulation

Abstract

The aim of this research was to study the effect of hyaluronic acid on bovine cryopreserved spermatozoa compared with heparin as regards the variation of capacitation induction, cellular oxidative metabolism and intracellular signal induced by membrane-associated adenylate cyclase to propose hyaluronic acid as a capacitation inductor. Heparin or hyaluronic acid and lysophosphatidylcholine were used to induce sperm capacitation and acrosome reaction, respectively. 2',5'-dideoxyadenosine was used as a membrane-associated adenylate cyclase inhibitor. The highest percentages of capacitated spermatozoa and live spermatozoa with acrosome integrity were obtained by incubating sperm for 60 min using 1000 μg/ml hyaluronic acid. In these conditions, capacitation induced by hyaluronic acid was lower compared with heparin; nonetheless both glycosaminoglycans promote intracellular changes that allow true acrosome reaction in vitro induced by lysophosphatidylcholine in bovine spermatozoa. Oxygen consumption in heparin-capacitated spermatozoa was significantly higher than in hyaluronic acid-treated spermatozoa. With all treatments, mitochondrial coupling was observed when a specific uncoupler of the respiratory chain was added. The inhibition of membrane-associated adenylate cyclase significantly blocked capacitation induction produced by hyaluronic acid, maintaining a basal sperm oxygen uptake in contrast to heparin effect in which both sperm parameters were inhibited, suggesting that the membrane-associated adenylate cyclase activation is involved in the intracellular signal mechanisms induced by both capacitation inductors, but only regulates mitochondrial oxidative phosphorylation in heparin-capacitated spermatozoa.

Regulation and roles of the hyaluronan system in mammalian reproduction

“…Studies in mice suggest HA involvement in spermatogenesis (Thakur et al 2006), even though the mechanism still remains to be clarified. HA induces sperm capacitation (Tienthai et al 2004, Tienthai 2015 by the activation of membrane-associated adenylate cyclase (Fernandez & Cordoba 2014), and it also enhances the acrosome reaction in bovine (Gutnisky et al 2007), and porcine (Suzuki et al 2002) without necessarily modifying the sperm nuclear condensation and morphology, possibly by decreasing the formation of vacuoles in the sperm head (Montjean et al 2012). In dog spermatozoa, HA accelerates the calcium influx into the sperm cytoplasm and increases lactate dehydrogenase activity and cAMP production, provoking capacitation (Kawakami et al 2006).…”