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The influence of estrogens on mouse sperm capacitation and acrosome reaction in vitro
Tejnická, Magda ; Komrsková, Kateřina (advisor) ; Linhart, Otomar (referee)
There are an increasing amount of compounds in the environment that can have a negative effect on reproductive parameters in both male and female organism. There has been a worldwide decline of sperm quality during past decades and this fact lead to an increase of unnatural ways of conception through assisted reproduction techniques in the specialised centres. Natural estrogens are one of these compounds and they get into waste water after being excluded from the body by the urine. They get back into the human body from drinking water or from the food, and they can interfere with function of endogenous hormones in very low concentrations. For these reasons it is up to date to deal with the influence of these compounds on mammalian sperm. For many years, estrogens have been considered typically female sex hormones. It is now certain that they are also very important in the regulation of male reproduction. Endogenous estrogens in mammalian males are an important part of the endocrine system. Estrogens play an important role in the development of germ cells, spermatogenesis and processes leading to successful egg fertilization such as a capacitation or acrosomal reaction. Tyrosine phosphorylation is one of the essential steps for the properly ongoing process of capacitation in sperm followed by a...
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Dynamics of acrosome reaction during intra-specific sperm competition in rodents.
Veselá, Kateřina ; Hortová, Kateřina (advisor) ; Pěknicová, Jana (referee)
Dynamics of acrosome reaction during intra-specific sperm competition in rodents Sperm acrosome integrity is disturbed in promiscuous species field mice (Apodemus) and more than half of the spermatozoa undergoing spontaneous acrosome reaction (AR) before binding to the zona pellucida. In Muridae it is documented a generally high rate of spontaneous AR, and the percentage increases in promiscuous species up to 60 % in 60 min capacitation in vitro. The acrosome integrity positively corellates with presence of CD46 protein which absence in wood mouse is fenotypicaly same as in CD46 knock-out mouse leading to accelerated spontaneous AR. It is necessary to clarify whether for mouse sperm it is essential the primary binding of intact sperm to zona pellucida of the egg or whether it is preferred secondary sperm binding after spontaneous AR. In this context, the question is whether there is a relocalization of the key fusion protein IZUMO in sperm during spontaneous AR. IZUMO relocalization was monitored by immunofluorescence at specific times of capacitation in vitro during spontaneous and induced AR. IZUMO relocalization as closely connected to actin cytoskeleton, and β1 integrins. Dynamics and localization of β1 integrin during spontaneous and induced AR was also detected by immunofluorescence. Our results...
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The effect of estrogens on capacitation and acrosome reaction of boar spermatozoa in vitro.
Dostálová, Pavla ; Pěknicová, Jana (advisor) ; Nedvídek, Josef (referee)
Fertilization is a unique biological event where male and female gametes fuse together to produce a new organism. Before the gametes are able to fuse, however, they must undergo a series of controlled changes. For the male gamete, capacitation and acrosome reaction (AR) must occur, which take place during the sperm migration through the female genital tract. Unfortunately, while the process of capacitation has been known for over half a century, the molecular basis and influential factors behind it are not fully understood. Although estrogens have been considered mainly female reproductive hormones, there is increasing evidence suggesting that these steroids have an important role also in regulation of male reproductive functions. Sperm come into the contact with estrogens during their formation in the male and female genital tract, indicating that the hormone may play an important role in sperm maturation. In this study, we examined the importance of three endogenous estrogens (E1 -estron, E2 - 17β estradiol, E3 - estriol) and one synthetic estrogen (EE2 - 17α ethinylestradiol) on sperm maturation during capacitation and AR. Stimulatory effect were observed with all tested estrogens on both capacitation and zona pellucida induced AR. Moreover, we have determinied that the stimulatory effect on...
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