The physiological functions of the ovary and development of the corpus luteum occur through the activation of endocrine hormones. In this process, estrogen, a reproductive hormone, is secreted in the ovarian follicle and corpus luteum and affects corpus luteum formation and regression. Estrogen controls the synthesis of reproductive hormones by binding to estrogen receptor–α and –β. Estradiol–17β, synthesized in the ovary, regulates the physiological function of the corpus luteum and the angiogenesis signaling pathway. Estrogen controls progesterone synthesis, which is regulated by StAR-transported cholesterol, P450scc-converted pregnenolone in mitochondria, and 3β-HSD-synthesized progesterone in the smooth endoplasmic reticulum. Estrogen secretion is also stimulated by kisspeptin and regulated by gonadotropin-releasing hormone, follicle-stimulating hormone, and luteinizing hormone. Moreover, the formation of the corpus luteum is closely regulated by angiogenesis. VEGF is an important factor in angiogenesis and plays a role in the survival, proliferation, and migration of endothelial cells. Especially, VEGF–A is a key factor in the physiological functions of endothelial cells. VEGF binds VEGFR–2 and affects the signaling pathways of PI3K, Akt, MAPK, and ERK. Also, VEGF binds to HIF–1α, inducing VEGF secretion. Estrogen promotes the activation of HIF–1α, while the activation of mTOR and Akt stimulates VEGF secretion. Therefore, estrogen is a major reproductive hormone in physiological function and the synthesis and secretion of endocrine hormones in the ovary and corpus luteum.

Luteolysis is a cyclical regression of the corpus luteum in many non-primate mammalian species. Prostaglandin F2α (PGF2α) from the uterus and ovary induces functional and structural luteolysis in bovine. The action of PGF2α is mediated by PGF2α receptor located on the luteal steroidogenic and endothelial cell membranes. PGF2α plays an important role in regulating nitric oxide production in endothelial cells of the bovine corpus luteum. Nitric oxide production and nitric oxide synthase activity are stimulated and induced by PGF2α in luteal endothelial cells. Moreover, the reactive oxygen species inhibits progesterone secretion in bovine luteal cells and induces apoptosis. Thus, the interaction between PGF2α and reactive oxygen species provides important aspects in physiology of the corpus luteum forfunctional and structural luteolysis.

The aim of this study was to evaluate the changes of protein patterns in granulosa cells and corpus luteum in ovaries during the estrus cycle in cows. The estrus cycle was devided into five steps of follicular, ovulatory, early-luteal, mid-luteal and late-luteal phases. In results, 61 spots of total 85 spots were repeated on follicular phase and 51 spots of total 114 spots were repeated on ovulatory phase. The 40 spots of total 129 spots were repeated on early-luteal phase and 49 spots of total 104 spots were repeated on mid-luteal phase. Also 41 spots of total 60 spots were repeated on late-luteal phase. On the other hands, the 16 spots were indicated difference in follicular phase and ovulation phase had a difference 10 spots. It was showed difference No. 103 spot in ovulation phase, No. 135 spot in early-luteal phase and No. 175 and 176 spots in mid-luteal phase. Also, the 11 spots were expressed specifically in mid-luteal phase and No. 178 and 179 spots were difference of expression in late-luteal phase. We confirmed that there were 7 spots for ovulation, 4 spots for luteinization and 2 spots for luteolysis. Spot No. 89～93 in ovulation phase were transferrin, and spot No.94～98 were HSP60. Spot No. 103 was Dusty PK, spot No. 135 was OGDC- E2, and spot No. 175 and 176 were Rab GDI beta from luteinization. Spot No. 178 and 179 in luteolysis were vimentin. This results suggest that will be help to basic data about infertility.

Sloan-Kettering virus gene product of a cellular pro-oncogene c-Ski is an unique nuclear pro-onco protein and belongs to the Ski/Sno proto-oncogene family. Ski plays multiple roles in a variety of cell types, it can induce both oncogenic transformation and terminal muscle differentiation when expressed at high levels. Ski protein is implicated in proliferation/differentiation in a variety of cells. The alternative fate of granulosa cells other than apoptosis is to differentiate to luteal cells, however, it is unknown whether Ski is expressed and has a role in granulosa cells undergoing luteinization. Thus, the aim of this study was, by means of immunohistochemical methods, to locate Ski protein in the rat ovaries during ovulation and corpora lutea(CL) formation to predict the possible involvement of Ski in luteinization. In addition, to examine whether the initiation of luteinization with luteinizing hormone(LH) directly regulates expression of Ski in the luteinized granulosa and luteal cells after ovulation by in vivo models. In order to examine the expression pattern of Ski protein along with the progress of luteinization, follicular growth was induced by administration of equine chorionic gonadtropin to immature female rat, and luteinization was induced by human chorionic gonadtropin treatment to mimic luteinizing hormone(LH) surge. While no Ski-positive granulosa cells were present in preovulatory follicle, Ski protein expression was induced in response to LH surge, and was maintained after the formation of corpus luteum(CL). These results indicate that Ski is profoundly expressed in the luteinized granulosa cells and luteal cells of CL during luteinization, and suggest that Ski may play a role in luteinization of granulosa cells.

Sloan-Kettering virus gene product of a cellular protooncogene c-Ski is an unique nuclear pro-oncoprotein and belongs to the Ski/Sno proto-oncogene family. Ski plays multiple roles in a variety of cell types, it can induce both oncogenic transformation and terminal muscle differentiation when expressed at high levels. Ski protein is implicated in proliferation/differentiation in a variety of cells. The alternative fate of granulosa cells other than apoptosis is to differentiate to luteal cells, however, it is unknown whether Ski is expressed and has a role in granulosa cells undergoing luteinization. Thus, the aim of this study was, by means of immunohistochemical methods, to locate Ski protein in the rat ovaries during ovulation and corpora lutea (CL) formation to predict the possible involvement of Ski in luteinization. In addition, we performed to examine whether the initiation of luteinization with luteinizing hormone (LH) directly regulates expression of Ski in the luteinized granulosa and luteal cells after ovulation by in vivo models. In order to examine the expression pattern of Ski protein along with the progress of luteinization, follicular growth was induced by administration of equine chorionic gonadtropin to immature female rat, and luteinization was induced by human chorionic gonadtropin treatment to mimic luteinizing hormone (LH) surge. While no Ski-positive granulosa cells were present in preovulatory follicle, Ski protein expression was induced in response to LH surge, and was maintained after the formation of corpus luteum (CL). These results indicate that Ski is profoundly expressed in the luteinized granulosa cells and luteal cells of CL during luteinization, and suggest that Ski may play a role in luteinization of granulosa cells.

The aim of this study was to evaluate the changes of protein patterns in granulosa cells and corpus luteum during the estrus cycle in bovine ovary by proteomics ^techniques. Our study was devided into five steps for follicular, ovulatory, early-lteal, midluteal and late-luteal. The protein was extracted from glanulosa cell and corpus luteum proteins by using M-PER Mammalian Protein Extraction Reagent. Proteins were refined by clean-up kit and quantified by Bradford method until total protein was 700 μg. Immobilized pH gradient (IPG) strip was used 18 cm and 3 11 NL. SDS-PAGE was used 10% acrylamide gel. The protein spots were visualized by Coomassie Brilliant Blue (CBB) staining, analyzed by MALDI mass spectrometry and searched on NCIBlnr. As the result, 61 spots of total 85 spots were repeated on follicular stage and 51 spots of total 114 spots were repeated on ovulatory stage. 40 spots of total 129 were repeated on early-luteal and 49 spots of total 104 spots were repeated on mid-luteal stage. Also 41 spots of total 60 spots were repeated on last-luteal stage. There were differences in the ovulation (follicular∼ovultory stage) in which the spots of follicular stage 19 was only and in ovulation stage was 10 spots. The difference between the luteinization (ovultory∼mid-luteal stage) was the spots counted in each stage. The spots of ovulatory stage was 1, early-luteal stage was 1 and in mid-luteal stage was 2. Eleven spots were found in mid-luteal stage and 2 spots were found in last-luteal stage. In conclusion, we confirmed that there were 7 spots in ovulation, 4 spots in luteinization and 2 spots in luteolysis. Spot No. 89-93 from ovulation were transferrin, and spot No.94 and 95 were HSP60. Spot No. 103 were Dusty PK, spot No. 135 were OGDC-E2, and spot No. 175, 176 were Rab GDI beta from luteinization. Spot No. 178 and 179 from luteolysis were vimentin.

This study was performed to the expressions of pregnancy-associated plasma protein-A (PAPP-A) and 20alpha-hydroxysteroid dehydrogenase (-HSD) in bovine corpus luteum during early pregnancy. To determine the function of PAPP-A gene during early pregnancy, we collected corpus luteum samples on 30, 60 and 90 days of pregnancy in bovine. The mRNA expression of PAPP-A, -HSD, progesterone-receptor (PR) and insulin-like growth factor binding protein4 (IGFBP4) gene was conducted by Real-time PCR. In parallel with mRNA levels, The protein expressions of PAPP-A and -HSD were detected by immunological analysis. The mRNA expressions -HSD and PAPP-A significantly increased on day 90 in the corpus luteum during pregnancy. The mRNA expression of PR and JGFBP4 in the corpus luteum progressively was enhanced at 30 to 60 day, but decreased on 90 day of pregnancy in the corpus luteum. The expression patterns of these genes, PAPP-A and -HSD were similar pattern in these tissues. In conclusion, PAPP-A and -HSD activity in corpus luteum could be played a role for early pregnancy manifestation.

The objective of this work was to determine the effect of corpus luteum (CL) grade on pregnancy rate after embryo transfer in Korean cattle and we found that CL development was linked to pregnancy rate. The in vivo derived blastocyst-stage embryos were transferred to 15 recipients synchronized in the estrus cycles. Based on size and palpable characteristics, CLs were categorized into three grade. The grade three CL is not to be identified by rectal palpation. The pregnancy rates tended to increase with the increase in CL size of recipients. In grade one, two, and three, the pregnancy rates were 62.5%, 50.0%, and 0%, respectively. This result suggests that pregnancy rates after embryo transfer might be affected by the CL status of recipients.

Luteal cells produce progesterone that supports pregnancy. Steroidogenesis requires coordination of the anabolic and catabolic pathways of lipid metabolism. In the present study, the corpus luteum (CL) in early pregnancy established from luteal phase and pregnant phase was analyzed. The first study determined progesterone changes in the bovine CL at day 19 (early maternal recognition period) and day 90 in mid-pregnancy and compared them to the CL from day 12 of the estrous cycle. CL alternation was tested using two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI- TOF). Comparing CL from luteal phase to those from pregnant phase counterparts, significant changes in expression level were found in 23 proteins. Of these proteins 17 were not expressed in pregnant phase CL but expressed in luteal phase counterpart, whereas, the expression of the other 6 proteins was limited only in pregnant phase CL. Among these proteins, vimentin is considered to be involved in regulation of post-implantation development. In particular, vimentin may be used as marker for CL development during pregnancy because the expression level changed considerably in pregnant phase CL tissue compared with its luteal phase counterpart. Data from 2-DE suggest that protein expression was disorientated in mid pregnancy from luteal phase, but these changes was regulated with progression of pregnancy. These findings demonstrate CL development during mid-pregnancy from luteal phase and suggest that alternations of specific CL protein expression may be involved in maintenance of pregnancy.