Abstract
Simple SummaryProgesterone is an endogenous steroid hormone, which can induce capacitation and/or acrosome reactions in semen of certain mammalian species. Our study aimed to investigate the effect of progesterone on the functional status of fresh bovine spermatozoa using a chlortetracycline fluorescent probe. Results showed that heparin induced capacitation in spermatozoa incubated with or without progesterone. The destruction of microfilaments by an inhibitor of cytochalasin D blocked the stimulating effect of heparin. Steroid hormone in mixture with prolactin stimulated the acrosome reaction in spermatozoa, which was blocked by an inhibitor of microtubule polymerization (nocodazole). At the acrosome stage, prolactin provided the undergoing of acrosome reaction in male gametes. This effect was noted both in the presence and absence of progesterone and inhibited by nocodazole. The supplementation of dibutyryl cyclic adenosine monophosphate during the acrosome reaction to progesterone-untreated spermatozoa did not cause changes in proportion of acrosome-reacted cells. However, when progesterone was added during capacitation, a significant increase in the proportion of capacitated cells was noted, which was inhibited by nocodazole. Thus, progesterone under the action of prolactin and dibutyryl cyclic adenosine monophosphate determines the functional status of fresh spermatozoa, which indicates progesterone-modulating effect on the indicators of post-ejaculatory maturation of male gametes.The aim of this study is to identify the effects of progesterone (PRG) on the capacitation and the acrosome reaction in bovine spermatozoa. The fresh sperm samples were incubated with and without capacitation inductors (heparin, dibutyryl cyclic adenosine monophosphate (dbcAMP)), hormones (prolactin (PRL), PRG), inhibitors of microfilaments (cytochalasin D) and microtubules (nocodazole) during capacitation and acrosome reactions. The functional status of spermatozoa was examined using the chlortetracycline assay. Supplementation of heparin stimulated capacitation in the presence and absence of PRG. Cytochalasin D blocked the stimulating effect of heparin on capacitation. The addition of PRL during capacitation (without PRG) did not affect the functional status of spermatozoa, while in PRG-treated cells PRL stimulated the acrosome reaction. PRL (with and without PRG) increased the acrosome reaction in capacitated cells. These PRL-dependent effects were inhibited by nocodazole. During the acrosome reaction, in presence of dbcAMP, PRG decreased the proportion of acrosome-reacted cells compared to PRG-untreated cells. This effect in PRG-treated cells was canceled in the presence of nocodazole. In conclusion, PRG under the action of PRL and dbcAMP determines the changes in the functional status of native sperm cells, which indicates PRG modulating effect on the indicators of post-ejaculatory maturation of spermatozoa.
Highlights
Capacitation is a biochemical process, which includes changes in membrane proteins and lipids, ion fluxes, an increase in the level of cyclic adenosine monophosphateand protein phosphorylation [1]
Progesterone is secreted by cumulus cells and present in high concentration during ovulation in the follicular fluid, where it can act on sperm cells before they bind to the zona pellucida [4]
The aim of this study is to identify the effects of different hormones on the postejaculate processes in bovine spermatozoa, and the role of microtubules and microfilaments in these modifications
Summary
Capacitation is a biochemical process, which includes changes in membrane proteins and lipids, ion fluxes, an increase in the level of cyclic adenosine monophosphate (cAMP)and protein phosphorylation [1]. It has been well established that progesterone induces the capacitation or acrosome reaction in horse and human spermatozoa [6,7], but the data on the effect of the progesterone on bovine sperm cells are contradictory. Progesterone activates the capacitation process; it has been noted that PRG-induced acrosome reaction can happen [11]. By stimulating or inhibiting protein kinases A, C, G and tyrosine kinase, it has been shown that progesterone induces the acrosome reaction via tyrosine kinase and protein kinase C, but in horse sperm cells this process does not depend on protein kinases A, C and bicarbonate [13]. In human sperm, the acrosome reaction is dependent on protein kinase A [14].
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