• Korean Journal of Animal Reproduction
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• v.19 no.4
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• pp.307-322
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• 1996

The corpus luteum (CL) is formed by the action of a surge of luteinizing hormone (LH) on the pre-ovulatory follicle. Luteal cells derived from granulosa and theca interna cells continue to secrete progesterone for about two weeks. LH in domestic animals is essential for the normal secretion of progesterone at all stages of the luteal phase. For this process in the rodents, 20$\alpha$-hydroxysteroid dehydrogenase (20$\alpha$-HSD) is indispensable. 20$\alpha$-HSD is an enzyme to be a biologically inactive steroid. This enzyme plays a critical role in the regulation of the rat luteal function and reported to be present in steroid-producing tissues such as the testis and adrenal gland. We have purified 20$\alpha$-HSD and found two distinct 20$\alpha$-HSD molecules (HSD-1 and HSD-2). Their molecular weights are both estimated to be 33kd.The amino acid compositions of HSD-1 and HSD-2 are mostly similar, but there is a slight difference in the content of lysine. We demonstrated that 1) CL of previous generations contribute more to whole ovarian 20$\alpha$-HSD activity, 2) newly formed corpora lutea contain only 20$\alpha$-HSD-1 activity, and 3) old CL express activities of each HSD isozyme as shown in the luteal tissue of cycling rats on the day of diestrus where only degenerating old CL exist. The increase in 20$\alpha$-HSD activity identified seems to be related to the increase in the numbers of 20$\alpha$-HSD-positive cells. Interestingly, 20$\alpha$-HSD-1 activities were strongly found in the follicle fluids and theca interna cells by immunohistochemical study. Thus, the activity of 20$\alpha$-HSD may be related to a survival mechanism of those luteal cells and follicles remaining in the ovaries. Luteal cells arise from two sources. The small luteal cells are all of theca cell origin, while the large luteal cells are mainly of granulosa cell origin. CL of Korean Native Cattle, as those of other animal species, contains two morphologycally and functionally distinct luteal cell populations, such as small and large luteal cells as well as nonluteal cells. In all reproductive states except in the late luteal phase, the bovine CL also contained more small luteal cells than large luteal cells. Luteal tissue secretes a variety of growth factors (proteins) and the pattern of secretion changes during all stages of the luteal phase. These growth factors could be important in regulating the function of the bovine corpus luteum and may act in a potential endocrine autocrine and paracrine mechanisms. Therefore, further work has to be done to elucidate the role of growth factors in the ovary, especially in the corpus luterum. Interest should be focussed on interaction of these growth factors in the regulation of luteal cell and the localization of cytokine synthesis in differnet luteal cells.

• Biomedical Science Letters
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• v.25 no.1
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• pp.107-112
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• 2019

The corpus luteum (CL) is composed to various cells, such as luteal steroidogenic cells (LSCs), luteal thecal steroidogenic cells (LTCs), luteal endothelial cells (LECs), fibroblast, immune cells and blood cells. The life span of CL is controlled by proliferation and apoptosis of luteal cells. Therefore, this study investigated apoptotic factors in luteal cells derived from bovine CL. The CL tissues were collected from bovine ovaries and luteal cells were isolated from middle phase CL. Then, LTCs and LECs were separated according to cellular morphology from LSCs. The expression of Bax, Bcl-2, Fas and tumor necrosis factor 1 receptor (TNF1R) mRNA and protein were analyzed using quantitative RT-PCR and western blot. Results show that, Bax and TNFR1 mRNA expression were significantly increased at late group than early and middle groups, otherwise Bcl-2 were significantly decreased at late group than early group (P<0.05). Fas mRNA expression were significantly decreased in middle group compared to early and late groups (P<0.05). In addition, Bax and Bcl-2 mRNA in LTCs was lower than LSCs, Fas mRNA was higher than LSCs. The Bcl-2 protein expression was lower at LTCs than LSCs, especially Fas protein in LTCs was significantly lower than LSCs and LECs (P<0.05). Otherwise, TNFR1 protein of LTCs were similar with LSCs but higher compared with LECs. In conclusion, we suggest that the results may help understanding of apoptosis ability in luteal cells according to cell type during CL regression of estrous cycle.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.349-359
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• 2003

Corpus luteum (CL) is the primary productive organ of progesterone in pregnant cows. Progesterone levels in bovine plasma depend on the volume, weight and shape of the CL. Progesterone productions during the late stages of gestation occur both in the CL and placenta, and placentas producted more progesterone than CL on progesterone prcduction. Because division of progesterone production of these two organs is impoxxible, the CL function can not be determined by plasma progesterone levels following gestation stages. This study was carried out to evaluate histological findings on the CL spurium and CL verum, and also on the CL following the pregnant stages by histological and immunohistochemical and electron microscopical methods and then we expect to assume the functions of CL by histological findings. 1. Proliferations of luteal cells occur by day 120 of gestation, vessel hyperplasia occur by day 90 of gestation, and the walls and lumens of vessels developed by day 120 of pregnancy. 2. Sizes of CL cells increased to maximum around day 200 of gestation and similarly maintained by day 240. So these findings indicated that the function of Cl is most active around day 200 of gestation. 3. On parturation day, the number and size of luteal cells were maintained but stain intensity of the luteal cells and vessels are declined or disappeared, and fibrosis of luteal cells increased, and the vessel lumens are emptied. These findings indicate that CL is inactive. 4. In immunohistochemical findings, proliferative positive cells by PCNA antibody appeared more in number during early stages of gestation but appeared less following course of pregnant stages and not nearly appeared on day 120 of gestation. Apoptotic positive cells by TUNEL methods not nearly appeared on the early pregnant stages and a few appeared at late pregnant stages. So developments of CL proceed until day 120 of gestation and regression of CL was occurred by transform of luteal cells into fibrocytes than by luteal cell apoptosis. 5. In electron microscopical findings, the size of luteal cells increased more in CL verum than in CL spurium. During gestation stages, the size of luteal cells increased, mitochondria in the luteal cell cytoplasms densely and abundantly developed and also swelled mitochondria increased. The interspace of luteal cells are also dilated, transformation of luteal cells into fibrocytes are more number. The lumens and walls of peripheral capillaries of large luteal cells more broadened and thickened, and transformation of large and small luteal cells to fibrocytes are increased. The above findings suggest that function of pregnant CL more developed by day 120 of gestation and are most active around day 200 of gestation and similarly maintained by day 240 and are promptly regressed on paturation day.

• Korean Journal of Animal Reproduction
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• v.4 no.1
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• pp.13-19
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• 1980

This experiment was carried out to observe early morphological changes of luteal cells in Korean native cattle treated with prostaglandin F2$\alpha$. Twenty five gram of prostaglandin F2$\alpha$ was administrated per cow at 10 days after ovulation and luteal cells were removed 30, 60, 120 and 180 minites after administration. Morphological changes of each luteal cell was observed by electron microscope. the results obtained were summarized as followings: 1. Many electron-dense granules were observed in luteal cells obtained from control cow but those granules were decreased rapidly after 30 minutes of administration and no granules were obresved after 180 minutes of administration. 2. In control, the shape of mitochondria were begining to collapse from the time of 60 minutes after administration. After 180 minutes of administration, mitochondria were swelled extreamly. 3. Lipid droplets in luteal cell were increased in its size and number with the duration of time after administration. 4. Shape of smooth endoplasmic recticulum was vesicular and its dimension and number were increased according to time course after administration.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.2
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• pp.83-94
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• 2004

Objective: To investigate whether GnRH-agonist (GnRH-Ag) using in IVF-ET affects apoptosis of human granulosa-luteal cells and expression of peripheral benzodiazepine receptor (PBR) protein involved in the apoptosis of the cells. Methods: Granulosa-luteal cells obtained during oocyte retrieval were cultured and treated with $10^{-5}M$ GnRH-Ag. Apoptosis of the cells by the treatment was confirmed using DNA fragmentation analysis 24 h after culture. The presence of PBR protein within the cells was examined by immunofluorescence staining and the expression of the protein was analyzed by Western blotting. In addition, it was measured for progesterone and nitric oxide (NO) produced by granulosa-luteal cells after GnRH-Ag treatment. To evaluate the relationship between NO production and PBR expression, sodium nitroprusside (SNP) as a NO donor was added in media and investigated the expression of PBR protein by Western blotting. Results: Apoptosis increased in the granulosa-luteal cells 24 h after GnRH-Ag treatment, whereas the expression of PBR protein significantly decreased. Furthermore, the production of progesterone and nitric oxide (NO) by the cells significantly fell from 12 h after the treatment. In the results of Western blotting after SNP treatment, the expression of PBR protein increased in the treatment with SNP alone to the granulosa-luteal cells, but was suppressed in the treatment with GnRH-Ag and SNP. Additionally, the staining result of PBR protein in the cells showed the even distribution of it through the cell. Conclusion: These results demonstrate that GnRH-Ag treatment induces apoptosis, decreasing expression of PBR protein and NO production in human granulosa-luteal cells. The present study suggests that one of the apoptosis mechanism of human granulosa-luteal cells by GnRH-Ag might be a signal transduction pathway via NO and PBR.

• Korean Journal of Animal Reproduction
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• v.23 no.2
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• pp.105-111
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• 1999

The effects of exogenous spleen cells on the progesterone and insulin like-growth factor-I (IGF-I) secretions in luteal cells were studied by using in vitro luteal cell culture system in the Hanwoo luteal cells. The corpora lutea(CL) were collected and pooled from the Korean native cattle(Hanwoo) ovaries from a local slaughter house. After enzymatic dissociation, combined large and small luteal cells(LLC and SLC)(1.0$\times$10$^{6}$ cells/$m\ell$) were incubated in D-MEM media containing antibiotics and 10% FCS. Spleen cells (1.0$\times$10$^{6}$ cells/$m\ell$) obtained from castrated adult male Hanwoo were added to luteal cells and co-cultured for 24 h in the absence or presence of luteinizing hormone (LH) (100 ng). Progesterone contents from luteal tissues were increased at CL-3 stage during each stage of estrous cycle. Progesterone secretion from luteal cell culture by the presence of LH (100 ng/$m\ell$) was positively stimulated compared with control. However, progesterone secretion was not changed by the addition of 5, 10 and 20% of spleen cells in the absence of LH. Co-culture of luteal cells with 10% of spleen cells in the presence of LH(l00ng/$m\ell$) significantly. enhanced after 24 h of culture. IGF-Isecretion from in vitro luteal cells co-culture by the addition of spleen cells (5%, 10% and 20%) was not significantly effected. Besides, in the presence of LH (100ng/$m\ell$), IGF-Isecretions from luteal cells by addition of spleen cells were higher than control media. However, LH alone significantly increased IGF-I secretion at 24 h of culture. These data provide the demonstrate that spleen cells can enhance LH action so as to stimulate progesterone secretion from Hanwoo luteal cells but have no effect to stimulate IGF-I secretion.

• Development and Reproduction
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• v.26 no.2
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• pp.71-77
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• 2022

In response to luteinizing hormone (LH), a higher concentration of progesterone (P4) is produced in luteal cells of corpus luteum (CL). Mitochondria are an essential cellular organelle in steroidogenesis. The specific engagement of the concept regarding mitochondrial shaping with early stages of steroidogenesis was suggested in reproductive endocrine cells. Although the specific involvement of GTPase dynamin-related protein 1 (Drp1) with steroidogenesis has been demonstrated in luteal cells of bovine CL in vitro, its actual relationship with ovarian steroidogenesis during the estrous cycle remains unknown. In this study, while Fis1 and Opa1 protein levels did not show significant changes during the estrous cycle, Drp1, Mfn1, and Mfn2 proteins exhibited relatively lower levels at proestrus than at estrus or diestrus. 3β-HSD showed higher levels at proestrus than at estrus or diestrus. In addition, Drp1 phosphorylation (s637) was higher in proestrus than in estrus or diestrus. Immune-positive cells for Drp1, pDrp1 (s637), and 3β-HSD were all localized in the cytoplasm of luteal cells in the CL. The immune-positive cells for 3β-HSD were more frequently seen in the CL at proestrus than at estrus or diestrus. Immunoreactivity for Drp1 in luteal cells at proestrus was weaker than that at estrus or diestrus. However, pDrp1 (s637) immune-positive cells were mostly detected in luteal cells at proestrus. These results imply that steroidogenesis (P4 production) in the CL is closely related to phosphorylation of Drp1 at serine 637. Taken together, this study presents evidence that Drp1 phosphorylation at serine 637 is an important step in steroidogenesis in the CL.

• Development and Reproduction
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• v.6 no.2
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• pp.131-139
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• 2002

Since GnRH and its receptor genes are expressed in the ovary, it has been suggested that ovarian GnRH might be involved in the regulation of ovarian function and the apoptosis of ovarian cells. However, it was not known well on the expression and function of GnRH and its receptor in the corpus luteum. The present study was undertaken to investigate whether GnRH and its receptor are expressed in luteal cells and GnRH has any effect on the apoptosis of luteal cells. Luteal cells obtained from the pregnant rats were cultured and stained for GnRH and its receptor proteins. Cultured luteal cells showed distinct immunoreactivity against both anti-GnRH and anti-GnRH receptor antibodies. In addition, the presence of GnRH receptor protein in cultured cells was confirmed by Western blot analysis. To investigate the effect of GnRH on the apoptosis of luteal cells, luteal cells were cultured in the presence of 10$^{-6}$ M GnRH-agonist(GnRH-Ag) for 3, 8, and 12h. TUNEL assay showed that the number of cells undergoing apoptosis increased 12h after culture(P<0.05). DNA fragmentation analysis confirmed the results such that the cells treated for 12h showed the greatest increase of fragmentation(p<0.05). Further, Western blot analysis of cytochrome c in the mitochondrial and cytoplasmic fractions of the luteal cells showed that GnRH-Ag treatment increased the content of cytochrome c in cytoplasm. These results demonstrate that the luteal cells express GnRH and its receptor and GnRH-Ag treatment induces apoptosis of the luteal cells via mitochondrial release of cytochrome c. The present study suggest that the releasing of cytochrome c from mitochondria might be involved in the luteal cell apoptosis induced by GnRH-Ag.

• Reproductive and Developmental Biology
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• v.39 no.1
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• pp.1-6
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• 2015

Luteolysis is a cyclical regression of the corpus luteum in many non-primate mammalian species. Prostaglandin $F_2{\alpha}$($PGF_2{\alpha}$) from the uterus and ovary induces functional and structural luteolysis in bovine. The action of $PGF_2{\alpha}$ is mediated by $PGF_2{\alpha}$ receptor located on the luteal steroidogenic and endothelial cell membranes. $PGF_2{\alpha}$ 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 $PGF_2{\alpha}$ in luteal endothelial cells. Moreover, the reactive oxygen species inhibits progesterone secretion in bovine luteal cells and induces apoptosis. Thus, the interaction between $PGF_2{\alpha}$ and reactive oxygen species provides important aspects in physiology of the corpus luteum forfunctional and structural luteolysis.

• Development and Reproduction
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• v.1 no.1
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• pp.79-89
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• 1997

Recent studies have demonstrated that apoptotic cell death plays an important role in the mechanism underlying follicular atresia and luteolysis. However, the mechanisms responsible for initiating these processes have not been elucidated. In in vitro fertilization (IVF) programs, it is highly possible that continuous and repeated administration of FSH/hMG and GnRH agonists for the usage of ovarian hyperstimulation may induce apoptotic death of granulosa cells leading to atresia in the human ovarian follicles. The present study was performed to investigate whether FSH/hMG and GnRh agonists used for a longer period in controlled ovarian hyperstimulation has any effect on the apoptosis of granulosa-luteal (GL) cells obtained from hyperstimulated ovaries. To examine apoptotic cell death in the GL cells, cells were stained with acridie orange followed by observed in some of GL cells. Similar but distinct staining of apoptotic GL cells was observed when the cells were examined by using in situ TUNEL method. The healthy-looking cells with normal nuclear morphology were not stained, whereas cells with pyknotic nuclei or with apoptotic nuclei were intensively stained. After examining the ultrastructural features of GL cells by TEM, it was confirmed that the majority of cells seemed to have normal nuclei while GL cells undergoing apoptotic cel death were rarely found. The DNA extracted from GL cells showed a typical pattern of fragmentation following DNA electrophoretic analysis. We have confirmed that the apoptosis occurs in granulosa-luteal cells obtained from hyperstimulated ovaries. Technically, in situ apoptosis detection method is simple and reproducible and is well suited to identify the quality of oocytes retrieved from hyperstimulated ovaries.