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Abnormal expression of acid glycosidases in seminal plasma and spermatozoa from infertile men with varicocele

Abstract:

The activities of acid β-glucuronidase, α-mannosidase, α-glucosidase, α-galactosidase, β-galactosidase and β-N-acetylglucosaminidase were analysed in seminal plasma and spermatozoa from 26 infertile men with varicocele and from 36 men of normal fertility. Semen samples from ten men with non-obstructive azoospermia were used as control specimens that contained the other components of semen. Spermatozoa were solubilized by both physical (homogenization) and chemical (Triton-X100) methods to obtain the soluble and non-soluble fractions. The activities of several glycosidases measured both in seminal plasma and spermatozoa were directly correlated with the numbers of spermatozoa and sperm motility, confirming previous studies. As some infertile patients with varicocele have normal semen parameters, whereas others have low numbers of spermatozoa and low sperm motility, the varicocele patients were prospectively divided into two groups: one (n = 15) with normal spermiograms and the other (n = 11) with abnormal spermiograms. The activities (expressed in mU ml-1) of α-mannosidase, β-galactosidase and β-N-acetylglucosaminidase in seminal plasma of normozoospermic infertile patients with varicocele were significantly higher than those of fertile controls, but not when expressed in U per 108 spermatozoa. The activities of β-glucuronidase, α-mannosidase, β-galactosidase and β-N-acetylglucosaminidase in seminal plasma when expressed in U per 108 spermatozoa in varicocele patients with abnormal spermiograms were significantly higher than in those of men of normal fertility. The activity of α-mannosidase in the soluble fraction of sperm homogenates, expressed as U per 108 spermatozoa, was significantly higher in infertile patients with varicocele and abnormal spermiograms than in controls. In the non-soluble fraction of spermatozoa from infertile patients with varicocele, there was an increase in the expression of β-galactosidase and β-N-acetylglucosaminidase activities compared with the fraction of spermatozoa from fertile subjects. In summary, infertile patients with varicocele displayed an overexpression of acid α-mannosidase, β-galactosidase and β-N-acetylglucosaminidase activities in seminal plasma and spermatozoa that may be associated with functional defects in spermatozoa as these glycosidases play an important role in mammalian fertilization.