Expression of ghrelin and the ghrelin receptor in different stages of porcine corpus luteum development and the inhibitory effects of ghrelin on progesterone secretion, 3β-hydroxysteroid dehydrogenase (3β-honestly significant difference (HSD)) activity and protein expression

Opposing Roles of Leptin and Ghrelin in the Equine Corpus Luteum Regulation: AnIn VitroStudy

“…The inhibition of P 4 secretion from early CL and mid-CL explants indicates that GHR signaling pathway may target P 4 synthetic enzymes during luteolysis promotion. Indeed, GHR decreased 3 β HSD expression in porcine CL [42]. Similar findings were reported in vitro in human luteal cells [49], where GHR decreased human chorionic gonadotrophin triggered P 4 secretion and increased PGF 2 α .…”

“…In a very recent report, an extensive characterization of GHR and Ghr-R1A expression in the bovine reproductive tract showed their expression in bovine CL [41], but no association between GHR signaling and luteolysis was done. Nonetheless, Rak-Mardyła et al [42] showed that GHR expression increases in the latest stage of pig luteal phase.…”

Role of ghrelin in fertilization, early embryo development, and implantation periods

“…This treatment did not comprise the implantation phase; in fact, it includes ovulation and presumably fertilization, as well as a fraction of the early embryo development period. In conclusion, the alterations found in this experiment at the implantation and/or fetal development processes may be linked to defects of other parameters such as oocyte quality or progesterone secretion by corpus luteum (Li et al 2011, Rak-Mardyla et al 2012. Regarding this issue, it has been reported that the corpora lutea secrete ghrelin, especially in the luteal phase and that this peptide significantly inhibits 3b-hydroxysteroid dehydrogenase activity and progesterone secretion (Rak-Mardyla et al 2012).…”

“…In conclusion, the alterations found in this experiment at the implantation and/or fetal development processes may be linked to defects of other parameters such as oocyte quality or progesterone secretion by corpus luteum (Li et al 2011, Rak-Mardyla et al 2012. Regarding this issue, it has been reported that the corpora lutea secrete ghrelin, especially in the luteal phase and that this peptide significantly inhibits 3b-hydroxysteroid dehydrogenase activity and progesterone secretion (Rak-Mardyla et al 2012). In agreement with these findings, results in human obtained in an assisted reproduction center have demonstrated that the follicular fluid concentrations of ghrelin negatively correlated with progesterone values (Li et al 2011).…”

The immunohistochemical presence and distribution of ghrelin, apelin and their receptors in dog ovaries

“…In a very intriguing way, their activity has been correlated to the control of some infectious diseases: in particular the APJ receptor has been seen as a coreceptor for HIV and in this way apelin protein, linking to the receptor, has been seen to block the HIV infection, 7 while the ghrelin protein has been involved in the control of gastric mucosal defense from Helicobacter pylory. 8 Given the presence of apelin, ghrelin and cognate receptors in the female genital tract, as observed in the ovaries of cattle, pig and sheep, [9][10][11][12] one may hypothesize that these molecules are involved in the functional control of ovaries and therefore that they serve as a point of contact between the animal's nutritional status and the functionality of the genital tract.As the primary source of progesterone during pregnancy, the ovary and in particular the corpora lutea seem to be key organs regulating the reproductive cycle in dogs. While several luteotrophic or luteolytic factors have been characterized, 13 the overall understanding of canine CL physiology, especially during pregnancy, remains limited.…”