Physiological mechanisms involved in maintaining the corpus luteum during the first two months of pregnancy

Abstract

Maintenance of the corpus luteum (CL) during pregnancy is essential for continuing the elevated circulating progesterone (P4) that is required to maintain pregnancy. The mechanisms that protect the CL during early pregnancy when the non-pregnant animal would typically undergo CL regression have been extensively investigated. It is clear uterine prostaglandin F2α (PGF) causes regression of the CL in non-pregnant ruminants and that maintenance of the CL during early pregnancy is dependent upon secretion of interferon-tau (IFNT) from the elongating embryo. A number of specific mechanisms appear to be activated by IFNT. Most studies indicate that there is an inhibition of oxytocin-induced secretion of uterine PGF. There is also evidence for increased resistance to PGF action, perhaps due to secretion of PGE2 and PGE1 or direct endocrine actions of circulating IFNT. These mechanisms occur concurrently and each may help to maintain the CL during the first month of pregnancy. However, during the second month of pregnancy, IFNT is no longer secreted by the embryo. Attachment of the embryo to the uterus and subsequent placentome development have been linked to silencing of expression from the IFNT gene. In addition, there is some evidence that oxytocin responsiveness of the uterus returns during the second month of pregnancy leading to substantial basal secretion of PGF and perhaps PGF pulses. There is also no evidence that the CL during the second month of pregnancy is resistant to the actions of PGF as observed during the first month. Thus, this manuscript attempts to compare the mechanisms that maintain the CL during the first and second months of pregnancy in ruminants and provides a new, speculative, physiological model for maintenance of the CL during month two of pregnancy that is distinct from the previously-described mechanisms that maintain the CL during the first month of pregnancy.

Comparison of Hormonal Treatment Kisspeptin with GnRH and hCG on the some Reproductive Performance of Cyprus, Does during Non-Breeding Season

“…In the present study, increase kilogram kids per goats joined in groups B2 and B5 than other groups indicated maintenance of pregnancy that is require elevated progesterone and protect the corpus luteum during early pregnancy and inhibition prostaglandin F2α from uterine by interferon-tau (IFNT) from the elongating embryo (Wiltbank et al, 2018) and accelerate embryonic development and improve pregnancy rates (Nephew et al, 1994). However, the results obtained in this study in group B5 agreement with (Medan et al, 2002;Husein et al, 2005;Zonturlu et al, 2018).…”

Resumption of Cyclic Ovarian Activity by Herbal Preparation AyuFertin in Bulgarian Murrah Buffaloes at Early Postpartum

“…According to Arosh et al [40], prostaglandins biosyn-thesis is selectively directed toward PGF2α during luteolysis and to PGE2 at the time of the establishment of pregnancy. Decreased progesterone levels in our experimental animals after treatment with AyuFertin, are likely to indirectly confirm increased PGF2α, which plays important role in stopping progesterone production, leading to the onset of a new estrous cycle and follicular growth [41]. Our data are supported by the results of Dirandeh et al [39], who reported that feeding n-6 polyunsaturated fatty acids (PUFA) increases the endometrial percentages of linoleic and arachidonic acids (AA), enhances the synthesis of prostaglandin F2α (PGF2α), and improves the uterine health.…”

“…Prostaglandin E2 plays a very important role during early pregnancy as a luteoprotective factor. It helps maintain CL and completely blocks the action of PGF at the CL level [41]. In addition to increasing the prostaglandin E2 synthesis, eicosapentaenoic acid (EPA,20:5) generates the less-inflammatory and less potent prostaglandin E3 (PGE3) [45], which could reduce the immunological problems of maternal pregnancy recognition.…”

Prostaglandin E2`nin Koyunlarda Erken Luteal Dönemde Korpus Luteum Üzerine Etkisi

“…Prostaglandin E appears to play an important role in luteal function in domestic animals by regulating angiogenesis, proliferation and steroidogenesis. Luteotrophic effect of PGE2 has been shown in many domestic animal species such as dog, cow, sheep, pig and human (Hahlin et al, 1988;Ford and Christenson, 1991;Kowalewski et al, 2013;Weems et al, 1985;Weems et al, 1995;Weems et al, 2006;Wiltbank et al, 2018). However, indirect effect of PGE2 on luteal function has not yet been investigated in detail.…”

“…While PGF2α exerts luteolytic effect, PGE2 shows luteoprotective effect in sheep and cows (Weems et al, 1985;Weems et al, 1995;Weems et al, 2006;Wiltbank et al, 2018). Luteotropic effect of PGE2 has been shown in a variety of species such as dog, pig and human as well (Hahlin et al, 1988;Ford and Christenson, 1991;Kowalewski et al, 2013).…”