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Physiology and Toxicology of Reproduction

It was found, that progesterone (P4) and other steroids, acting on plasma membrane endometrial cells, inhibits OT binding to its own membrane receptors diminishing OT influence on endometrium. Moreover, it was shown that steroids by non-genomic way can inhibit the secretion of uterine PGF2α which is luteolytic, but not PGE2 which has luteotropic properties. This effect of P4, but also other steroids, may support of corpus luteum function and reduce the action of PGF2α, and this way influence on maintenance of an early pregnancy. Furthermore, that P4 stimulates its own synthesis in CL by stimulation of the mRNA expression of StAR protein, cytochrome P450scc and 3β-HSD. Progesterone and other steroids affect on uterus and ovary cells by both genomic and non-genomic mechanism. The molecular mechanism of non-genomic effect of P4 has not been fully understood. However, it was found mRNA expression of progesterone receptor membrane component 1 (PGRMC1) in bovine CL and endometrial cells. This data suggest that PGRMC1 protein may be involved in non-genomic mechanism of P4. These results enable better understanding the mechanism of local effect of steroids on CL and uterus and also the mechanism of so-called “progesterone block” in cow.

Another area of research includes the impact of xenobiotics (post industrial pollutants: polychlorinated biphenyls – PCBs, pesticides: Dichlorodiphenyltrichloroethane – DDT and hexachlorocyclohexane, HCH), their metabolites (OH-PCBs and DDE) and phytoestrogens on the secretory function of the ovary (steroidogenesis, synthesis and secretion of OT), oviduct and uterus (secretion and synthesis of PGF2α and PGE2) and on the contractions of bovine myometrium. Xenobiotics, which were used in the quantities detected in the tissues of cows (1-10 ng / ml), can significantly interfere with secretory function of granulosa and luteal cells by increasing the synthesis and secretion of OT. Moreover, they disturb the secretory activity of endometrium, myometrium and oviduct, changing the ratio of PGF2α to PGE2 secretion. They may also affect the uterine contractions. Whereas the effect of phytoestrogens on the tested process is unambiguous. Similarly to the xenobiotics, they may increase the synthesis and secretion of ovarian OT, but concomitantly they partially reversed the adverse effects of  PCBs on the uterus. Thus, it is possible that a diet containing flavonoids can be a part of a feeding strategy to prevent disorders in the reproduction process of domestic animals.