Octylphenol induces changes in glycosylation pattern, calcium level and ultrastructure of bank vole spermatozoa in vitro

• Fucosylated and sialylated oligosaccharides, N-acetylglucosamine and fucose residues are present on bank vole spermatozoa.
• Octylphenol modulates glycan expression and its distribution in bank vole spermatozoa.
• Octylphenol affects calcium level in bank vole spermatozoa.
• Octylphenol induces ultrastructural changes in acrosome region.

Our previous studies revealed that in bank vole testicular cells octylphenol (OP) action is related either to its binding to estrogen receptors or increasing cAMP level that modulates spermatozoa motility and acrosome reaction (AR), (Kotula-Balak et al., 2011, 2014). To better understand the mechanisms underlying these changes, in the present study we aimed at evaluating the glycosylation pattern, calcium (Ca2+) level and ultrastructure of OP-treated vole spermatozoa. Glycans were recognized by lectins and localized for the first time on the surface of acrosomal cap and tail of vole spermatozoa. Expression and localization of glycans were determined histochemically and analyzed quantitatively. Following OP the expression of glycans markedly changed with concomitant increase of intracellular Ca2+ concentration. Altered Ca2+ signaling pathway and ultrastructural changes in sperm acrosome region were revealed by immunoenzymatic assay and electron microscope analysis together with hypo-osmotic swelling test, respectively. In detail, AR advancement reflected by the presence of small vesicles in the close vicinity to the sperm head was observed, while tail membrane integrity remained intact.Our study provides a new insight on OP direct effects on precocious AR of vole spermatozoa through modulation of the glycan expression and its distribution concomitantly with changes in Ca2+ signaling pathway and acrosome ultrastructure in vitro.