| Popis: |
Metallothioneins (MTs) are small, cysteine-rich, phylogenetically highly conserved proteins with metal binding properties. Acting as a metal acceptor and metal donors, these metalloproteins are involved in numerous fundamental physiological processes, such as regulation of gene expression, cell proliferation and apoptosis. Furthermore, due to rapid oxidation of their structural thiolate clusters, they act as a highly-potent endogenous antioxidants and anti-inflammatory agents. Additional protective features of MTs arise from their ability to bind exogenous heavy metal ions, thereby preventing / reducing toxic effects. Objective of this study was to investigate MT I and II isoform expression in spermatozoa of fertile males and males diagnosed with oligoasthenoteratozoospermia (subnormal spermatozoa count, reduced spermatozoa motility and increased abnormal spermatozoa forms). Since the MTs are closely related to the zinc bioavailability, content of free Zn2+ ions ("labile zinc") was also examined. Semen analysis was performed using standard spermiogram techniques. MTs expression was assesed by immunocytochemistry on cytospin preparations of normal sperm samples and samples with oligoasthenoteratozoospermia. Free zinc content was examined labeling spermatozoa with fluorescent specific Zn2+ chelator Zinquin. Semen samples with oligoasthenoteratozoospermia showed significantly higher proportion of MTs positive spermatozoa compared to the normal samples (20, 2% vs 7, 8%). On the other hand, Zinqiun labeling resulted in significantly lower mean fluorescence intensity of spermatozoa from samples with oligoasthenoteratozoospermia, indicating a lower free zinc content in relation to the normal sperm samples. Results point to the disregulation of MTs expression and consequential disturbance of Zn2+ bioavailability in the pathogenesis of male subfertility. |
