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Smallman MA, Filtz TM, Stormshak F. Mifepristone and PGF 2α activate phosphatidylinositol hydrolysis in the ovine corpus luteum. Prostaglandins Other Lipid Mediat 2021; 153:106538. [PMID: 33545368 DOI: 10.1016/j.prostaglandins.2021.106538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 01/18/2021] [Accepted: 01/26/2021] [Indexed: 10/22/2022]
Abstract
Two experiments were conducted to determine whether mifepristone (RU486) and PGF2α activate the phosphatidylinositol hydrolysis pathway during the midluteal phase of the ovine estrous cycle. In experiment 1, ewes on day 8 of the cycle were given 10 μg RU486 or vehicle into the ovarian artery with removal of the corpus luteum (CL) after 10 min. Blood collected prior to and after treatment was analyzed for progesterone. Aliquots of CL were incubated with 10 μCi of 3H-inositol and in the presence and absence of PGF2α (10 nM) for 15 min. Exposure of CL to RU486 and PGF2α increased phosphatidylinositol hydrolysis (p < 0.05). Serum progesterone was reduced in both control and RU486-treated ewes (p < 0.05) compared to concentrations before treatments. In experiment 2, aliquots of CL collected from ewes on day 8 of the cycle were incubated with 3H-inositol and exposed to RU486 (2 μM) in the presence and absence of PGF2α (1 μM) for 15 min. Treatments stimulated phosphatidylinositol hydrolysis as in Exp 1 (p < 0.05). Progesterone concentrations in incubation medium were increased in response to RU486 and PGF2α (p < 0.05). Collectively, these data suggest that RU486 and PGF2α act to stimulate phosphatidylinositol hydrolysis in the mature ovine CL.
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Affiliation(s)
- Mary A Smallman
- Oregon State University, Department of Animal and Rangeland Science, Corvallis, OR 97331, USA.
| | - Theresa M Filtz
- Oregon State University, College of Pharmacy, Corvallis, OR 97331, USA
| | - Fredrick Stormshak
- Oregon State University, Department of Animal and Rangeland Science, Corvallis, OR 97331, USA
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Tepekoy F, Ustunel I, Akkoyunlu G. Protein kinase C isoforms α, δ and ε are differentially expressed in mouse ovaries at different stages of postnatal development. J Ovarian Res 2014; 7:117. [PMID: 25491605 PMCID: PMC4271327 DOI: 10.1186/s13048-014-0117-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 11/29/2014] [Indexed: 11/11/2022] Open
Abstract
Background The protein kinase C (PKC) is a family of serine/threonine kinases that consists of 12 different isoforms. Since PKC isoform expressions are known to be specific for different cell types and postnatal developmental stages, we aimed to determine immunolocalizations and protein expression levels of different PKC isoforms in pre-pubertal, pubertal and adult mouse ovaries. Methods Ovaries were obtained from postnatal day 1 (PND1) and PND7 of pre-pubertal, PND21 of pubertal and PND60 of adult mice. Immunolocalizations of PKCα, PKCδ and PKCε isoforms were determined and immunostainings in different cellular components of all follicular stages were evaluated by H-Score. PKCα, PKCδ and PKCε protein expression levels were determined by Western blot. The bands were quantified via ImageJ software. The data obtained from H-Score and ImageJ evaluations were analyzed by ANOVA statistical test. Results PKCα immunostainings were more intense in oocytes when compared to granulosa and theca cells at different follicular stages of all groups. The Western blot analysis revealed that PKCα expression was significantly higher in PND60 adult ovaries. Conversely, PKCδ immunostainings were more intense in granulosa cells. According to the Western blot analysis, PKCδ protein expression was also higher in PND60 and significantly lower in PND1 ovaries. PKCε immunostaining was more apparent in oocytes. PKCε protein expression was significantly higher in adult PND60 and pubertal PND21 ovaries when compared to pre-pubertal PND7 and PND1 ovaries. Interestingly, PKCε immunostaining was significantly higher in primordial follicles, though PKCα and PKCδ immunostainings were more apparent in larger follicles. PKCα immunostainings of corpora lutea (CL) were significantly higher when compared to follicles in PND60 ovaries. Conclusions This study demonstrates that PKCα, PKCδ and PKCε isoforms are differentially expressed in particular cellular components of pre-pubertal, pubertal and adult mouse ovarian follicles. Therefore, we suggest that each PKC isoform has unique functions that are controlled by gonadotropin dependent mechanisms during follicular growth, oocyte maturation, ovulation and luteinization.
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Wright MF, Bowdridge E, McDermott EL, Richardson S, Scheidler J, Syed Q, Bush T, Inskeep EK, Flores JA. Mechanisms of intracellular calcium homeostasis in developing and mature bovine corpora lutea. Biol Reprod 2014; 90:55. [PMID: 24501170 DOI: 10.1095/biolreprod.113.113662] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Although calcium (Ca(2+)) is accepted as an intracellular mediator of prostaglandin F2 alpha (PGF2alpha) actions on luteal cells, studies defining mechanisms of Ca(2+) homeostasis in bovine corpora lutea (CL) are lacking. The increase in intracellular Ca(2+) concentration ([Ca(2+)]i) induced by PGF2alpha in steroidogenic cells from mature CL is greater than in those isolated from developing CL. Our hypothesis is that differences in signal transduction associated with developing and mature CL contribute to the increased efficacy of PGF2alpha to induce a Ca(2+) signal capable of inducing regression in mature CL. To test this hypothesis, major genes participating in Ca(2+) homeostasis in the bovine CL were identified, and expression of mRNA, protein, or activity, in the case of phospholipase Cbeta (PLCbeta), in developing and mature bovine CL was compared. In addition, we examined the contribution of external and internal Ca(2+) to the PGF2alpha stimulated rise in [Ca(2+)]i in LLCs isolated from developing and mature bovine CL. Three differences were identified in mechanisms of calcium homeostasis between developing and mature CL, which could account for the lesser increase in [Ca(2+)]i in response to PGF2alpha in developing than in mature CL. First, there were lower concentrations of inositol 1,4,5-trisphosphate (IP3) after similar PGF2alpha challenge, indicating reduced phospholipase C beta (PLCbeta) activity, in developing than mature CL. Second, there was an increased expression of sorcin (SRI) in developing than in mature CL. This cytoplasmic Ca(2+) binding protein modulates the endoplasmic reticulum (ER) Ca(2+) release channel, ryanodine receptor (RyR), to be in the closed configuration. Third, there was greater expression of ATP2A2 or SERCA, which causes calcium reuptake into the ER, in developing than in mature CL. Developmental differences in expression detected in whole CL were confirmed by Western blots using protein samples from steroidogenic cells isolated from developing and mature CL. Localization of these genes in steroidogenic luteal cells was confirmed by immunohistochemistry. Therefore, it is concluded that the cellular mechanisms that allow PGF2alpha to induce a calcium signal of greater magnitude in mature than in developing CL involve 1) greater PLCbeta activity with enhanced generation of IP3, 2) an enhanced Ca(2+) release from the ER via unrestrained RYR2 due to a decrease in SRI expression, and 3) a reduction in calcium reuptake to the ER due to lower expression of ATP2A2. Accordingly, the increase in [Ca(2+)]i induced by PGF2alpha in mature large steroidogenic cells had less dependency from extracellular calcium than in those isolated from immature CL.
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Affiliation(s)
- Marietta F Wright
- Division of Animal and Nutritional Sciences, Davis College of Agriculture, Natural Resources and Design, West Virginia University, Morgantown, West Virginia
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Dozier BL, Watanabe K, Duffy DM. Two pathways for prostaglandin F2 alpha synthesis by the primate periovulatory follicle. Reproduction 2008; 136:53-63. [PMID: 18390687 DOI: 10.1530/rep-07-0514] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Prostaglandin E2 (PGE2) has been identified as a PG necessary for ovulation, but the ovulatory gonadotropin surge also increases PGF2 alpha levels in primate periovulatory follicles. To better understand the role of PGF2 alpha in ovulation, pathways utilized for PGF2 alpha synthesis by the primate follicle were examined. Monkeys were treated with gonadotropins to stimulate multiple follicular development; follicular aspirates and whole ovaries were removed before and at specific times after administration of an ovulatory dose of hCG to span the 40 h periovulatory interval. Human granulosa cells were also obtained (typically 34-36 h after hCG) from in vitro fertilization patients. PGF2 alpha can be synthesized from PGH2 via the aldo-keto reductase (AKR) 1C3. AKR1C3 mRNA and protein levels in monkey granulosa cells were low before hCG and peaked 24-36 h after hCG administration. Human granulosa cells converted PGD2 into 11 beta-PGF2 alpha, confirming that these cells possess AKR1C3 activity. PGF2 alpha can also be synthesized from PGE2 via the enzymes AKR1C1 and AKR1C2. Monkey granulosa cell levels of AKR1C1/AKR1C2 mRNA was low 0-12 h, peaked at 24 h, and returned to low levels by 36 h after hCG administration. Human granulosa cell conversion of [(3)H]PGE2 into [(3)H]PGF2 alpha was reduced by an AKR1C2-selective inhibitor, supporting the concept that granulosa cells preferentially express AKR1C2 over AKR1C1. In summary, the ovulatory gonadotropin surge increases granulosa cell expression of AKR1C1/AKR1C2 and AKR1C3. Both of these enzyme activities are present in periovulatory granulosa cells. These data support the concept that follicular PGF2 alpha can be synthesized via two pathways during the periovulatory interval.
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Affiliation(s)
- Brandy L Dozier
- Department of Physiological Sciences, Eastern Virginia Medical School, 700 Olney Road, Lewis Hall, Norfolk, Virginia 23507, USA
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Goravanahally MP, Sen A, Inskeep EK, Flores JA. PKC epsilon and an increase in intracellular calcium concentration are necessary for PGF2 alpha to inhibit LH-stimulated progesterone secretion in cultured bovine steroidogenic luteal cells. Reprod Biol Endocrinol 2007; 5:37. [PMID: 17760987 PMCID: PMC2041951 DOI: 10.1186/1477-7827-5-37] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Accepted: 08/30/2007] [Indexed: 11/10/2022] Open
Abstract
The hypotheses that PKC epsilon is necessary for: 1) PGF2 alpha to inhibit LH-stimulated progesterone (P4) secretion, and 2) for the expression of key prostaglandin synthesizing/metabolizing enzymes were tested in bovine luteal cells in which PKC epsilon expression had been ablated using a validated siRNA protocol. Steroidogenic cells from Day -6 bovine corpus luteum (CL) were isolated and transfected to reduce PKC epsilon expression after 48, 72 and 96 h. A third tested hypothesis was that an increase in intracellular calcium concentration ([Ca(2+)]i) is the cellular mechanism through which PGF2 alpha inhibits luteal progesterone. The hypothesis was tested with two pharmacological agents. In the first test, the dose-dependent effects on raising the [Ca(2+)]i with the ionophore, A23187, on basal and LH-stimulated P4 secretion in cells collected from early (Day -4) and mid-cycle (Day -10) bovine CL was examined. In the second test, the ability of PGF2 alpha to inhibit LH-stimulated P4 secretion in Day-10 luteal cells was examined under conditions in which an elevation in [Ca(2+)]i had been buffered by means of the intracellular calcium chelator, Bapta-AM.PKC epsilon expression was reduced 65 and 75% by 72 and 96 h after transfection, respectively. In cells in which PKC epsilon expression was ablated by 75%, the inhibitory effect of PGF2 alpha on LH-stimulated P4 secretion was only 29% lower than in the LH-stimulated group. In contrast, it was reduced by 75% in the group where PKC epsilon expression had not been reduced (P < 0.05). Real time PCR analysis indicated that there were no differences in the expression of cyclooxygenase-2 (COX-2), aldoketoreductase 1B5 (AKR1B5), prostaglandin E synthase (PGES), hydroxyprostaglandin-15 dehydrogenase (PGDH) and PGE2 -9-reductase as a function of PKC epsilon down-regulation. Finally, LH stimulated secretion of P4 at each luteal stage (Day -4 and -10), and PGF2 alpha inhibited this only in Day -10 cells (P < 0.05). When A23187 was used at concentrations greater than 0.1 mumol, the induced elevation in [Ca(2+)]i inhibited the effect of LH on secretion of P4 in Day -4 and -10 cells (P < 0.05, Fig. 5). The inhibitory effect of PGF2 alpha on LH-stimulated P4 in Day -10 cells was reduced if an increase in [Ca(2+)]i was prevented with Bapta-AM. These results support the hypothesis that differential expression of PKC epsilon and an elevation of [Ca(2+)]i are important for acquisition of luteolytic response to PGF2 alpha.
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Affiliation(s)
| | - Aritro Sen
- Department of Biology, West Virginia University, Morgantown, West Virginia, USA
- Department of Animal Sciences, Michigan State University, East Lansing, Michigan, USA
| | - Emmet K Inskeep
- Animal and Veterinary Sciences, West Virginia University, Morgantown, West Virginia, USA
| | - Jorge A Flores
- Department of Biology, West Virginia University, Morgantown, West Virginia, USA
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Rosiansky-Sultan M, Klipper E, Spanel-Borowski K, Meidan R. Inverse relationship between nitric oxide synthases and endothelin-1 synthesis in bovine corpus luteum: interactions at the level of luteal endothelial cell. Endocrinology 2006; 147:5228-35. [PMID: 16887911 DOI: 10.1210/en.2006-0795] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Endothelin-1 (ET-1) and nitric oxide (NO) play pivotal roles in corpus luteum (CL) function. The present study examined the interplay between NO and ET-1 synthesis in the bovine CL. We found similar inducible and endothelial NO synthase (iNOS and eNOS, respectively) activities in the young CL (d 1-5) expressing the highest levels of both eNOS and iNOS mRNA. These values later declined at mid-cycle (d 8-15) and remained low at later stages (d 16-18). Luteolysis, initiated by prostaglandin F2alpha analog administration, further reduced NOS mRNA and by 24 h, NOS values dropped to approximately 15% of those at mid-cycle. eNOS protein levels followed a similar pattern to its mRNA. Because endothelial cells (ECs) are the main site for ET-1 and NO production in the CL, we examined the direct effects of the NO donor, NONOate on luteal ECs (LECs). Elevated NO levels markedly decreased ET-1 mRNA, and peptide concentrations in cultured and freshly isolated LECs in a dose-dependent manner. In agreement, NOS inhibitor, NG-nitro-l-arginine methyl ester, stimulated ET-1 mRNA expression in these cells. Interestingly, NO also up-regulated prostaglandin F2alpha receptors in LECs. These data show that there is an inverse relationship between NOS and ET-1 throughout the CL life span, and imply that this pattern may be the result of their interaction within the resident LECs. NOS are expressed in a physiologically relevant manner: elevated NO at an early luteal stage is likely to play an important role in angiogenesis, whereas reduced levels of NO during luteal regression may facilitate the sustained up-regulation of ET-1 levels during luteolysis.
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Affiliation(s)
- Maya Rosiansky-Sultan
- Department of Animal Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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Choudhary E, Sen A, Inskeep EK, Flores JA. Developmental Sensitivity of the Bovine Corpus Luteum to Prostaglandin F2α (PGF2α) and Endothelin-1 (ET-1): Is ET-1 a Mediator of the Luteolytic Actions of PGF2α or a Tonic Inhibitor of Progesterone Secretion?1. Biol Reprod 2005; 72:633-42. [PMID: 15537863 DOI: 10.1095/biolreprod.104.034736] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
We examined the responsiveness of large luteal cells (LLC), small luteal cells (SLC), and endothelial cells of the Day 4 and Day 10 bovine corpus luteum (CL) to prostaglandin (PG) F2alpha and endothelin (ET)-1. Using a single-cell approach, we tested the ability of each agonist to increase the cytoplasmic concentration of calcium ions ([Ca2+]i) as function of luteal development. All tested concentrations of agonists significantly (P = 0.05) increased [Ca2+]i in all cell populations isolated from Day 4 and Day 10 CL. Day 10 steroidogenic cells were more responsive than Day 4 cells to PGF2alpha and ET-1. Response amplitudes and number of responding cells were affected significantly by agonist concentration, luteal development, and cell type. Response amplitudes were greater in LLC than in SLC; responses of maximal amplitude were elicited with lower agonist concentrations in Day 10 cells than in Day 4 cells. Furthermore, on Day 10, as the concentration of PGF2alpha increased, larger percentages of SLC responded. Endothelial cells responded maximally, regardless of agonist concentration and luteal development. In experiment 2, we tested the developmental responsiveness of total dispersed and steroidogenic-enriched cells to the inhibitory actions of PGF2alpha and ET-1 on basal and LH-stimulated progesterone accumulation. The potency of PGF2alpha steroidogenic-enriched cells on Day 4 was lower than on Day 10; in contrast, the potency of ET-1 was not different. Therefore, ET-1 was a tonic inhibitor of progesterone accumulation rather than a mediator of PGF2alpha action. The lower efficacy of PGF2alpha in the early CL more likely is related to signal transduction differences associated with its receptor at these two developmental stages than to the inability of PGF2alpha to up-regulate ET-1.
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Affiliation(s)
- Ekta Choudhary
- Department of Biology, Eberly College of Arts and Sciences, West Virginia University, Morgantown, West Virginia 26506-6057, USA
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Sen A, Choudhary E, Inskeep EK, Flores JA. Effects of selective protein kinase c isozymes in prostaglandin2alpha-induced Ca2+ signaling and luteinizing hormone-induced progesterone accumulation in the mid-phase bovine corpus luteum. Biol Reprod 2004; 72:976-84. [PMID: 15601909 DOI: 10.1095/biolreprod.104.037432] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
A single-cell approach for measuring the concentration of cytoplasmic calcium ions ([Ca(2+)](i)) and a protein kinase C-epsilon (PKCepsilon)-specific inhibitor were used to investigate the developmental role of PKCepsilon in the prostaglandin F(2alpha)(PGF(2alpha))-induced rise in [Ca(2+)](i) and the induced decline in progesterone accumulation in cultures of cells isolated from the bovine corpus luteum. PGF(2alpha) increased [Ca(2+)](i) in Day 4 large luteal cells (LLCs), but the response was significantly lower than in Day 10 LLCs (4.3 +/- 0.6, n = 116 vs. 21.3 +/- 2.3, n = 110). Similarly, the fold increase in the PGF(2alpha)-induced rise in [Ca(2+)](i) in Day 4 small luteal cells (SLCs) was lower than in Day 10 SLCs (1.6 +/- 0.2, n = 198 vs. 2.7 +/- 0.1, n = 95). A PKCepsilon inhibitor reduced the PGF(2alpha)-elicited calcium responses in both Day 10 LLCs and SLCs to 3.5 +/- 0.3 (n = 217) and 1.3 +/- 0.1 (n = 205), respectively. PGF(2alpha) inhibited LH-stimulated progesterone (P(4)) accumulation only in the incubation medium of Day 10 luteal cells. Both conventional and PKCepsilon-specific inhibitors reversed the ability of PGF(2alpha) to decrease LH-stimulated P(4) accumulation, and the PKCepsilon inhibitor was more effective at this than the conventional PKC inhibitor. In conclusion, the evidence indicates that PKCepsilon, an isozyme expressed in corpora lutea with acquired PGF(2alpha) luteolytic capacity, has a regulatory role in the PGF(2alpha)-induced Ca(2+) signaling in luteal steroidogenic cells, and that this in turn may have consequences (at least in part) on the ability of PGF(2alpha) to inhibit LH-stimulated P(4) synthesis at this developmental stage.
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Affiliation(s)
- Aritro Sen
- Department of Biology, Eberly College of Arts and Sciences, West Virginia University, Morgantown, West Virginia 26506, USA
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Sen A, Browning J, Inskeep EK, Lewis P, Flores JA. Expression and Activation of Protein Kinase C Isozymes by Prostaglandin F2α in the Early- and Mid-Luteal Phase Bovine Corpus Luteum1. Biol Reprod 2004; 70:379-84. [PMID: 14522831 DOI: 10.1095/biolreprod.103.020420] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Western blotting was used to identify the array of protein kinase C (PKC) isozymes expressed in the early (Day 4) and midcycle (Day 10) bovine corpus luteum (CL). PCKalpha, betaI, betaII, epsilon, and micro isozymes were detected in total protein samples prepared from both Day-4 and Day-10 corpora lutea. In contrast, specific antibodies for PKCgamma, eta, lambda, and theta isozymes failed to detect protein bands in the luteal samples. PKCbetaII and epsilon isozymes were expressed differentially at these two developmental stages of the bovine CL. In the Day-4 luteal samples, PKCepsilon was barely detectable; in contrast, in the Day-10 samples, the actin-corrected ratio for PKCepsilon was 1.16 +/- 0.13. This ratio was higher than the detected ratio for PKCbetaI and micro at this developmental phase of the CL (P < 0.01), but it was comparable with the ratio detected for the PCKalpha and betaII. The amount of PKCbetaII was, although not as dramatic, also greater in the Day-10 CL (actin-corrected ratio was 0.85 +/- 0.2) than in the Day-4 CL (0.35 +/- 0.09 [P < 0.01]). The actin-corrected ratios for all other PKC isozymes, alpha (Day 4 = 0.93 +/- 0.16, Day 10 = 0.97 +/- 0.09), betaI (Day 4 = 0.54 +/- 0.073, Day 10 = 0.48 +/- 0.74), and micro (Day 4 = 0.21 +/- 0.042, Day 10 = 0.21 +/- 0.38) were not different at these 2 days of the cycle. An experiment was designed to test whether activation of specific isozymes differed between CL that do or do not regress in response to PGF(2alpha). Bovine CL from Day 4 and Day 10 of the estrous cycle were collected and 1 mm CL fragments were treated in vitro for 0, 2.5, 5, 10 or 20 min with PGF(2alpha) (0.1, 1.0, and 10 nM) or minimal essential medium-Hepes vehicle. Translocation of PKC from cytoplasm to membrane fraction was used as indication of PKC activation by PGF(2alpha). Evidence for PKC activation was observed in both Day-4 and Day-10 luteal samples treated with 10 nM PGF(2alpha). Therefore, if PKC, an intracellular mediator associated with the luteal PGF(2alpha) receptor, contributes to the lesser sensitivity of the Day-4 CL, it is likely due to the differential expression of the epsilon and betaII isozymes of PKC at this stage and not due to an inability of the PGF(2alpha) receptor to activate the isozymes expressed in the early CL.
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Affiliation(s)
- Aritro Sen
- Department of Biology, Eberly College of Arts & Sciences, West Virginia University, Morgantown, West Virginia 26506, USA
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Stormshak F. Biochemical and endocrine aspects of oxytocin production by the mammalian corpus luteum. Reprod Biol Endocrinol 2003; 1:92. [PMID: 14613532 PMCID: PMC280731 DOI: 10.1186/1477-7827-1-92] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2003] [Accepted: 11/10/2003] [Indexed: 11/10/2022] Open
Abstract
A review of the current state of knowledge of oxytocin production by the preovulatory follicle and corpus luteum is presented. Corpora lutea of a number of mammalian species have been found to synthesize oxytocin. However, the synthesis and secretion of this nanopeptide by the corpus luteum of the ruminant has been most extensively studied because of the potential role of this peptide in facilitating luteal regression. While much information exists relative to various biochemical and endocrine factors that impact on oxytocin gene expression, this aspect about luteal synthesis of this peptide hormone remains enigmatic. Prostaglandin F-2alpha (PGF-2alpha) has been shown to be a primary endogenous hormone responsible for triggering luteal secretion of oxytocin. Details are provided regarding the PGF-2alpha-induced intracellular signal transduction pathway that ultimately results in exocytosis of luteal oxytocin. Evidence is also presented for potential autocrine/paracrine actions of oxytocin in regulating progesterone production by luteal and granulosa cells. Concluding remarks highlight aspects about luteal oxytocin production that require further research.
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Affiliation(s)
- Fredrick Stormshak
- Department of Biochemistry/Biophysics, Oregon State University, Corvallis, OR, USA.
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Yadav VK, Sudhagar RR, Medhamurthy R. Apoptosis during spontaneous and prostaglandin F(2alpha)-induced luteal regression in the buffalo cow (Bubalus bubalis): involvement of mitogen-activated protein kinases. Biol Reprod 2002; 67:752-9. [PMID: 12193381 DOI: 10.1095/biolreprod.102.004077] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The present study was conducted to evaluate whether the corpus luteum (CL) of the water buffalo (Bubalus bubalis) cow undergoes luteal regression by the process of apoptosis and to examine the involvement of mitogen-activated protein (MAP) kinases during prostaglandin (PG) F(2alpha)-induced luteolysis. Sections of CL from late in the estrous cycle, i.e., during spontaneous luteolysis, stained for 4',6'-diamidino-2-phenylindole revealed increased numbers of condensed nuclei, indicating cell death by apoptosis, which was confirmed further by the occurrence of pronounced oligonucleosome formation. For morphological and biochemical characterization during PGF(2alpha)-induced apoptosis, CL were collected at 0, 4, 12, and 18 h after injection of 750 micro g of Tiaprost, a synthetic analogue of PGF(2alpha), to midestrous buffalo cows. Serum progesterone concentrations fell within 4 h and decreased (P < 0.05) maximally by 18 h. Concomitant decreases (P < 0.05) in the levels of steroidogenic acute regulatory mRNA and protein were observed in CL during 12-18 h, with the more profound effect on mRNA levels. Quantitative analysis of the genomic DNA showed a >5-fold increase (P < 0.05) in the low molecular weight DNA fragments by 18 h postinjection. Immunoblot analysis of CL tissue lysates showed increased (P < 0.05) levels of phospho-Jun N-terminal kinase (JNK) 1 (4- to 14-fold during 4-18 h) and phospho-p38 (2- to 4-fold at 18 h). Immunohistochemical evaluation of CL sections revealed an increased nuclear localization of phospho-JNK after treatment. These findings demonstrate that the CL of the buffalo cow undergoes cell death by the process of apoptosis both during spontaneous and PGF(2alpha)-induced luteolysis and that MAP kinases are involved during PGF(2alpha)-mediated apoptosis in the CL.
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Affiliation(s)
- Vijay K Yadav
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India
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Salli U, Supancic S, Stormshak F. Phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS) protein is associated with bovine luteal oxytocin exocytosis. Biol Reprod 2000; 63:12-20. [PMID: 10859236 DOI: 10.1095/biolreprod63.1.12] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The ruminant corpus luteum, in addition to producing progesterone, synthesizes and secretes oxytocin (OT) during the estrous cycle. Secretion of oxytocin occurs by exocytosis of membrane-encapsulated granules of this hormone. Exocytosis of oxytocin involves transport of granules through a cytoskeletal matrix including an actin cortex closely associated with the plasma membrane (PM). Actin filaments crosslinked by various proteins give rise to the structural integrity of the cortex. Myristoylated alanine-rich C kinase substrate (MARCKS), a protein specifically phosphorylated by protein kinase C (PKC), crosslinks actin filaments and anchors the actin network to the inner leaflet of the PM. There is evidence that the intact actin cortex may serve as a barrier, precluding fusion of transport vesicles with the PM. In some secretory cells, phosphorylation of MARCKS has resulted in its translocation from the PM to the cytoplasm with an associated disassembly of the actin cortex. Prostaglandin F(2alpha) (PGF(2alpha)) stimulation of the bovine corpus luteum during the midluteal phase of the estrous cycle activates PKC, which is associated with an increase in OT secretion in vivo and in vitro. Data are presented demonstrating that stimulation of bovine luteal cells with PGF(2alpha) on Day 8 of the cycle promotes rapid phosphorylation of MARCKS protein and causes its translocation from the PM to the cytoplasm and concomitant, enhanced exocytosis of OT. These data are consistent with the premise that MARCKS plays a role in the exocytotic process.
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Affiliation(s)
- U Salli
- Departments of Biochemistry/Biophysics and Animal Sciences, Oregon State University, Corvallis, Oregon 97331, USA
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Filley S, Supancic S, Salli U, Orwig K, Stormshak F. Myristoylated alanine-rich C kinase substrate protein and mRNA in bovine corpus luteum during the estrous cycle. Endocrine 2000; 12:289-94. [PMID: 10963050 DOI: 10.1385/endo:12:3:289] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/1999] [Revised: 02/17/2000] [Accepted: 02/17/2000] [Indexed: 11/11/2022]
Abstract
The bovine corpus luteum contains a myristoylated alanine-rich C kinase substrate (MARCKS) protein known to crosslink actin filaments in the cytoskeletal cortex associated with the plasma membrane. We conducted experiments to determine whether concentrations of MARCKS mRNA and protein in the bovine corpus luteum varied during the estrous cycle. Using Northern blots probed with a MARCKS cDNA, we found that luteal concentrations of MARCKS mRNA were greatest on d 4, 8, and 12 and markedly reduced on d 16 of the cycle (p < 0.08). Similarly, Western blot analysis of luteal proteins revealed that concentrations of MARCKS protein were greatest on d 8 and least on d 16 of the cycle (p < 0.01). Exposure of slices from a d 8 corpus luteum to prostaglandin F2alpha (PGF2alpha) during a 10-min incubation in the presence of [32P]-ortho-phosphate resulted in enhanced phosphorylation of MARCKS in membrane and cytosolic fractions compared to that of controls. We therefore concluded that expression of the luteal MARCKS protein gene may be regulated and that PGF2alpha-induced phosphorylation of this protein is attributable to activation of protein kinase C.
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Affiliation(s)
- S Filley
- Department of Biochemistry/Biophysics, Oregon State University, Corvallis 97331, USA
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14
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Niswender GD, Juengel JL, Silva PJ, Rollyson MK, McIntush EW. Mechanisms controlling the function and life span of the corpus luteum. Physiol Rev 2000; 80:1-29. [PMID: 10617764 DOI: 10.1152/physrev.2000.80.1.1] [Citation(s) in RCA: 629] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The primary function of the corpus luteum is secretion of the hormone progesterone, which is required for maintenance of normal pregnancy in mammals. The corpus luteum develops from residual follicular granulosal and thecal cells after ovulation. Luteinizing hormone (LH) from the anterior pituitary is important for normal development and function of the corpus luteum in most mammals, although growth hormone, prolactin, and estradiol also play a role in several species. The mature corpus luteum is composed of at least two steroidogenic cell types based on morphological and biochemical criteria and on the follicular source of origin. Small luteal cells appear to be of thecal cell origin and respond to LH with increased secretion of progesterone. LH directly stimulates the secretion of progesterone from small luteal cells via activation of the protein kinase A second messenger pathway. Large luteal cells are of granulosal cell origin and contain receptors for PGF(2alpha) and appear to mediate the luteolytic actions of this hormone. If pregnancy does not occur, the corpus luteum must regress to allow follicular growth and ovulation and the reproductive cycle begins again. Luteal regression is initiated by PGF(2alpha) of uterine origin in most subprimate species. The role played by PGF(2alpha) in primates remains controversial. In primates, if PGF(2alpha) plays a role in luteolysis, it appears to be of ovarian origin. The antisteroidogenic effects of PGF(2alpha) appear to be mediated by the protein kinase C second messenger pathway, whereas loss of luteal cells appears to follow an influx of calcium, activation of endonucleases, and an apoptotic form of cell death. If the female becomes pregnant, continued secretion of progesterone from the corpus luteum is required to provide an appropriate uterine environment for maintenance of pregnancy. The mechanisms whereby the pregnant uterus signals the corpus luteum that a conceptus is present varies from secretion of a chorionic gonadotropin (primates and equids), to secretion of an antiluteolytic factor (domestic ruminants), and to a neuroendocrine reflex arc that modifies the secretory patterns of hormones from the anterior pituitary (most rodents).
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Affiliation(s)
- G D Niswender
- Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, Colorado, USA
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15
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Ohtani M, Kobayashi SI, Miyamoto A. Direct Effect of PGF2.ALPHA., TPA and lonophore A23187 on Progesterone Release from Microdialyzed Corpus Luteum inthe Cow. J Reprod Dev 1999. [DOI: 10.1262/jrd.45.233] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
| | - Shu-ichi Kobayashi
- Department of Animal Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
| | - Akio Miyamoto
- Department of Animal Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
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16
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OKUDA K, UENOYAMA Y, LEE KW, SAKUMOTO R, SKARZYNSKI DJ. Progesterone Stimulation by Prostaglandin F2.ALPHA. Involves the Protein Kinase C Pathway in Cultured Bovine Luteal Cells. J Reprod Dev 1998. [DOI: 10.1262/jrd.44.79] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Kiyoshi OKUDA
- Laboratory of Reproductive Endocrinology, Division of Animal Science and Technology, Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
| | - Yoshihisa UENOYAMA
- Laboratory of Reproductive Endocrinology, Division of Animal Science and Technology, Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
| | - Kang Woo LEE
- Laboratory of Reproductive Endocrinology, Division of Animal Science and Technology, Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
| | - Ryosuke SAKUMOTO
- Laboratory of Reproductive Endocrinology, Division of Animal Science and Technology, Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
| | - Dariusz Jan SKARZYNSKI
- Laboratory of Reproductive Endocrinology, Division of Animal Science and Technology, Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
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17
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Milvae RA, Hinckley ST, Carlson JC. Luteotropic and luteolytic mechanisms in the bovine corpus luteum. Theriogenology 1996; 45:1327-49. [PMID: 16727885 DOI: 10.1016/0093-691x(96)00100-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/1995] [Accepted: 03/05/1996] [Indexed: 10/16/2022]
Abstract
The function of the corpus luteum (CL) is a key element in many reproductive processes including ovulation, length of the estrous cycle, recognition of pregnancy and embryo survival in all mammalian species. The main function of the CL is to produce progesterone which acts on its tissues to prepare them for successful pregnancy. The CL is controlled by numerous biological compounds which provide luteotropic support during the estrous cycle and pregnancy and for inducing luteolysis at the end of the cycle The purpose of this paper is to review the mechansims responsible for controlling the endocrine function of this tissue in the bovine ovary.
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Affiliation(s)
- R A Milvae
- University of Connecticut, Storrs, CT, USA
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18
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Davis JS, May JV, Keel BA. Mechanisms of hormone and growth factor action in the bovine corpus luteum. Theriogenology 1996; 45:1351-80. [PMID: 16727886 DOI: 10.1016/0093-691x(96)00101-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/1995] [Accepted: 03/05/1996] [Indexed: 10/17/2022]
Abstract
The binding of hormones and growth factors to their cell surface receptors leads to an orderly cascade of events leading to activation of cytoplasmic effector molecules. The mechanism of action of luteinizing hormone involves the stimulation of multiple signal transduction effector systems including adenylyl cyclase and inositol phospholipid-specific phospholipase C (PLC). This results in the formation of second messengers that activate cAMP-dependent, Ca(2+)-dependent and lipid-dependent protein kinases. Prostaglandin F(2alpha) activates PLC which increases intracellular calcium and activates protein kinase C. This results in the activation of a series of protein kinases in the mitogen-activated protein (MAP) kinase cascade, leading to the activation of nuclear transcription factors c-fos and c-jun. Hormone responsive effector systems, therefore, operate by activating families of protein kinases which regulate cell metabolism, secretion, and gene transcription. Growth factors activate specific receptor protein tyrosine kinases which recruit additional signaling molecules (phospholipase Cgamma, phosphatidylinositol 3-kinase, Shc, Grb2, etc.) initiating a cascade of events mediated via MAP kinases. The signaling pathways activated by hormones interact or cross talk with the signaling pathways activated by growth factors. The diversity of cellular signaling mechanisms elicited by hormones and the potential for interactions with signals generated by growth factor receptor tyrosine kinases, may allow fine tuning of cellular responses during the life span of the corpus luteum.
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Affiliation(s)
- J S Davis
- The Women's Research Institute, Department of Obstetrics and Gynecology, University of Kansas School of Medicine-Wichita, KS 67214-3199, USA
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19
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Affiliation(s)
- A E Michael
- Department of Biochemistry, Royal Free Hospital School of Medicine, London, UK
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20
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Abayasekara DR, Jones PM, Persaud SJ, Michael AE, Flint AP. Prostaglandin F2 alpha activates protein kinase C in human ovarian cells. Mol Cell Endocrinol 1993; 91:51-7. [PMID: 8472854 DOI: 10.1016/0303-7207(93)90254-h] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Recent studies in several non-primate species have suggested that prostaglandin F2 alpha (PGF2 alpha) inhibits luteal cell progesterone production by activating the calcium and phospholipid-dependent protein kinase, protein kinase C (PKC). This study investigated the presence of PKC in human ovarian cells and assessed the ability of PGF2 alpha and its structural analogue, cloprostenol, to generate inositol polyphosphates and activate PKC. PKC was detected in cultured human granulosa-lutein cells and human luteal cells (from mid-late luteal phase). The major proportion of PKC detected was cytosol-associated in both cell types. Cloprostenol increased the generation of inositol polyphosphates in cultured human granulosa-lutein cells in a dose- and time-dependent manner. In addition both cloprostenol and PGF2 alpha activated PKC (as assessed by redistribution of enzyme activity from a principally cytosol-associated form to a membrane-associated form) in both granulosa-lutein and luteal cells. Short-term exposure of both cell types to phorbol myristate acetate (4 beta-PMA) activated PKC, whilst prolonged exposure of human granulosa-lutein cells to 4 beta-PMA led to a > 85% loss of total PKC activity. The inactive phorbol ester, 4 alpha-PMA, had no effect on PKC activity when exposed to cells for up to 20 h. These results demonstrate the presence of PKC in human ovarian cells and the ability of PGF2 alpha to induce translocation/activation of this kinase.(ABSTRACT TRUNCATED AT 250 WORDS)
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21
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Boone DL, Currie WD, Leung PC. Arachidonic acid and cell signalling in the ovary and placenta. Prostaglandins Leukot Essent Fatty Acids 1993; 48:79-87. [PMID: 8424126 DOI: 10.1016/0952-3278(93)90013-m] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Arachidonic acid (AA) and its metabolites make up a diverse group of signalling molecules important to mediation of metabolic and endocrine function of ovarian and placental cell membranes. This paper reviews recent literature examining AA and eicosanoid involvement in the functional dynamics of follicular development, ovulation and corpus luteum function. The putative roles of AA metabolites in establishment and maintenance of pregnancy are reviewed with reference to decidualization, trophoblast invasion and implantation, maintenance of perfusion of the feto-placental unit and lipid transfer. Finally, recent evidence implicating AA metabolism in mediation of enzyme activity following hormone-receptor coupling within various cells types comprising the placental membranes is reviewed.
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Affiliation(s)
- D L Boone
- University of British Columbia, Obstetrics and Gynecology, Vancouver, Canada
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22
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Kraak GVD. Mechanisms by which calcium ionophore and phorbol ester modulate steroid production by goldfish preovulatory ovarian follicles. ACTA ACUST UNITED AC 1992. [DOI: 10.1002/jez.1402620306] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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23
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Seseke FG, Gardemann A, Jungermann K. Signal propagation via gap junctions, a key step in the regulation of liver metabolism by the sympathetic hepatic nerves. FEBS Lett 1992; 301:265-70. [PMID: 1577164 DOI: 10.1016/0014-5793(92)80254-e] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cell-to-cell communication via gap junctions has been proposed to be involved in the metabolic actions of sympathetic liver nerves in the rat. The effects of hepatic nerve stimulation and noradrenaline-, PGF2 alpha- and glucagon infusion on glucose metabolism and perfusion flow were studied in perfused rat liver in the absence and presence of the gap junctional inhibitors, heptanol, carbenoxolone and (4 beta)phorbol 12-myristate 13-acetate (4 beta PMA). (i) Stimulation of the hepatic nerve plexus increased glucose output, decreased flow and caused an overflow of noradrenaline into the hepatic vein. (ii) Heptanol completely inhibited not only the nerve stimulation-dependent metabolic and hemodynamic alterations but also the noradrenaline overflow. Thus the heptanol-dependent inhibitions were caused primarily by a strong impairment of transmitter release. (iii) Carbenoxolone inhibited the effects of neurostimulation on glucose metabolism partially by about 50%, whereas it left perfusion flow and noradrenaline overflow essentially unaltered. (iv) 4 beta PMA reduced the nerve stimulation-dependent enhancement of glucose release by about 80% but the noradrenaline-dependent increase in glucose output only by about 30%; the increase in glucose release by PGF2 alpha and by glucagon remained essentially unaltered. 4 beta PMA reduced the nerve stimulation-dependent decrease in portal flow by about 35% but did not affect the noradrenaline-and PGF2 alpha-elicited alterations, nor did it alter noradrenaline overflow. The results allow the conclusion that gap junctional communication plays a major role in the regulation of hepatic carbohydrate metabolism by sympathetic liver nerves, but not by circulating noradrenaline, PGF2 alpha or glucagon.
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Affiliation(s)
- F G Seseke
- Institut für Biochemie, Universität Göttingen, Germany
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24
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Jacobs AL, Homanics GE, Silver WJ. Activity of phospholipase C in ovine luteal tissue in response to PGF2 alpha, PGE2 and luteinizing hormone. PROSTAGLANDINS 1991; 41:495-500. [PMID: 1862228 DOI: 10.1016/0090-6980(91)90055-k] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Four ewes were utilized to determine the effects of prostaglandin (PG) F2 alpha, PGE2 and luteinizing hormone (LH) on activity of phospholipase C (PLC) in ovine luteal tissue. Corpora lutea were collected on d 10 post-estrus and six slices from one corpus luteum from each ewe were pre-incubated with [3H]-inositol prior to incubation with one of 6 treatments. Treatments were 1) control, 2) PGF2 alpha (100 ng/ml), 3) PGE2 (10 ng/ml), 4) LH (10 ng/ml), 5) PGF2 alpha + PGE2 and 6) PGF2 alpha + LH. Phospholipase C was determined indirectly by measuring the accumulation of [3H]-inositol mono-, bis- and tris-phosphates (IP, IP2, IP3). Effects of PGF2 alpha (0 vs. PGF2 alpha) and luteotropic treatment (0 vs. PGE2 vs. LH) and their interactions were determined by analysis of variance. There was a significant main effect of PGF2 alpha (P less than 0.01) as concentrations of IP, IP2, IP3 and total [3H]-inositol phosphates were greater in tissue slices treated with PGF2 alpha, regardless of luteotropic treatment. Within groups receiving no PGF2 alpha (1,3,4), no effect of luteotropic treatment was observed. Within groups receiving PGF2 alpha (2,5,6), LH caused a significant (P less than .05) increase in the accumulation of total [3H]-inositol phosphates. Thus, PGF2 alpha can stimulate the activity of PLC in ovine luteal tissue and LH can potentiate this effect.
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Affiliation(s)
- A L Jacobs
- Department of Animal Sciences, University of Kentucky, Lexington 40502-0215
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25
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Affiliation(s)
- J L Tilly
- Department of Animal Sciences Rutgers, State University of New Jersey New Brunswick 08903-0231
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26
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Alila HW, Davis JS, Dowd JP, Corradino RA, Hansel W. Differential effects of calcium on progesterone production in small and large bovine luteal cells. JOURNAL OF STEROID BIOCHEMISTRY 1990; 36:687-93. [PMID: 2170770 DOI: 10.1016/0022-4731(90)90189-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We studied the effects of calcium (Ca2+) ions in progesterone (P) production by separated small and large luteal cells. Corpora lutea were collected from 31 heifers between days 10 and 12 of the estrous cycle. Purified small and large cells were obtained by unit gravity sedimentation and flow cytometry. P accumulation in cells plus media was determined after incubating 1 x 10(5) small and 5 x 10(3) large cells for 2 and 4 h respectively. Removal of Ca2+ from the medium did not influence basal P production in the small cells (P greater than 0.05). However, stimulation of P by luteinizing hormone (LH), prostaglandin E2 (PGE2), 8-bromo-cyclic 3',5' adenosine monophosphate (8-Br-cAMP) and prostaglandin F2 alpha (PGF2 alpha) was impaired (P less than 0.05) by low Ca2+ concentrations. LH and PGE2-stimulated cAMP production was not altered by low extracellular Ca2+ concentrations, and PGF2 alpha had no effect on cAMP. In contrast, basal as well as LH and forskolin-stimulated P production were attenuated (P less than 0.05) in Ca2(+)-deficient medium in the large cells. However, P production stimulated by 8-Br-cAMP was not altered in Ca2(+)-deficient medium. Steroidogenesis in large cells was also dependent on intracellular Ca2+, since 8-N, N-diethylamineocytyl-3,4,5-trimethoxybenzoate (TMB-8), an inhibitor of intracellular Ca2+ release and/or action, suppressed (P less than 0.05) basal, LH and 8-Br-cAMP stimulated P. In contrast, basal P in small cells was not altered by TMB-8; whereas LH-stimulated P was reduced 2-fold (P less than 0.05). The calcium ionophore, A23187, inhibited LH-stimulated P in small cells and both basal and agonist-stimulated P in large cells. These studies show that basal P production in small cells does not require Ca2+ ions, while hormone-stimulated P production in small cells and both basal and hormone-stimulated P in large cells do require Ca2+. The inhibitory effect of Ca2+ ion removal was exerted prior to the generation of cAMP in the large cells, but distal to cAMP generation in hormone-stimulated small cells. The calmodulin/protein kinase C antagonist, W-7, also inhibited both basal and hormone-stimulated P production in both small and large luteal cells, indicating that P production in luteal cells also involves Ca2(+)-calmodulin/protein kinase C-dependent mechanisms.
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Affiliation(s)
- H W Alila
- Department of Physiology, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853
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27
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Alila HW, Corradino RA, Hansel W. Arachidonic acid and its metabolites increase cytosolic free calcium in bovine luteal cells. PROSTAGLANDINS 1990; 39:481-96. [PMID: 2112769 DOI: 10.1016/0090-6980(90)90032-q] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We studied the effects of arachidonic acid and its metabolites on intracellular free calcium concentrations ([Ca2+]i) in highly purified bovine luteal cell preparations. Corpora lutea were collected from Holstein heifers between days 10 and 12 of the estrous cycle. The cells were dispersed and small and large cells were separated by unit gravity sedimentation and flow cytometry. The [Ca2+]i was determined by spectrofluorometry in luteal cells loaded with the fluorescent Ca2+ probe, Fura-2. Arachidonic acid elicited a dose-dependent increase in [Ca2+]i in both small and large luteal cells, having an effect at concentrations as low as 5 microM; and was maximally effective at 50 microM. Several other fatty acids failed to exert a similar response. Addition of nordihydroguaiaretic acid (NDGA) or indomethacin failed to suppress the effects of arachidonic acid. In fact, the presence of both inhibitors resulted in increases of [Ca2+]i, with NDGA exerting a greater stimulation of [Ca2+]i than indomethacin. Prostaglandin F2 alpha (PGF2 alpha) as well as prostaglandin E2 (PGE2) increased [Ca2+]i in the small luteal cells. These results support the idea that arachidonic acid exerts a direct action in mobilizing [Ca2+]i, in the luteal cells. Furthermore, they demonstrate that the cyclooxygenase (PGF2 alpha and PGE2) and lipoxygenase products of arachidonic acid metabolism also play a role in increasing [Ca2+]i in bovine luteal cells. Since the bovine corpus luteum contains large quantities of arachidonic acid, these findings suggest that this compound may regulate calcium-dependent functions of the corpus luteum, including steroid and peptide hormone production and secretion.
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Affiliation(s)
- H W Alila
- Department of Physiology, New York State College of Veterinary Medicine, Ithaca 14853
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28
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Dowd JP, Alila HW, Hansel W. Phorbol ester receptors in bovine luteal cells: relationship to protein kinase C. Mol Cell Endocrinol 1990; 69:199-206. [PMID: 2328828 DOI: 10.1016/0303-7207(90)90013-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We investigated the binding kinetics of the tumor-promoting phorbol ester, phorbol-12,13-dibutyrate (PBt2) to dispersed total bovine luteal cells, purified small luteal cells, and purified luteal protein kinase C (PKC). Saturation analysis and competitive displacement techniques were used. Binding of [3H]PBt2 to total luteal cell preparations resulted in two distinct affinities. The high affinity component was characterized by a Kd of 4.5 +/- 1.5 nM. Analysis of [3H]PBt2 binding to total cells using competitive displacement demonstrated that the low affinity binding was specific and displaceable but dependent on concentrations of [3H]PBt2 far above the Kd for the high affinity binding. In contrast to the total cell preparations, only high affinity binding was observed in intact purified small luteal cells (Kd = 0.96 +/- 0.04 nM). Partial purification of luteal cytosolic PKC by DEAE-Sephadex chromatography resulted in co-elution of PKC enzyme activity and the [3H]PBt2 binding activity. Under conditions of saturating calcium (0.1 mM) and phosphatidylserine (PS) (100 micrograms/tube) concentrations, binding to the partially purified PKC preparation was found to be of a single high affinity and exhibited a Kd (1.3 +/- 0.2 nM) similar to the high affinity binding observed in intact cells. These results suggest that the primary phorbol ester receptor in luteal cells is PKC. However, a low affinity, high capacity [3H]PBt2 binding site also exists within the corpus luteum, either in the large cells or in the accessory cell fraction which consists mainly of endothelial cells.
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Affiliation(s)
- J P Dowd
- Department of Physiology, NYS College of Veterinary Medicine, Cornell University, Ithaca 14853
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29
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Benhaim A, Bonnamy PJ, Mittre H, Leymarie P. Involvement of the phospholipase C second messenger system in the regulation of steroidogenesis in small bovine luteal cells. Mol Cell Endocrinol 1990; 68:105-11. [PMID: 2155835 DOI: 10.1016/0303-7207(90)90182-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have previously suggested that the interaction between luteinizing hormone (LH) and its receptor, in addition to stimulating adenylate cyclase, is able to trigger a negative regulatory signal at a step beyond cAMP synthesis (Benhaim et al. (1987) FEBS Lett. 223, 321-326). The present study was conducted to determine whether the phospholipase C system is involved in this phenomenon. Small bovine luteal cells from pregnant cows were incubated with phospholipase C, A23187, an ionophore of calcium and/or phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC), in the presence or absence of bovine luteinizing hormone or dibutyryl cyclic AMP (dbcAMP). A23187 associated with PMA was able to mimic the stimulatory effect of phospholipase C on basal progesterone production, whereas neither A23187 nor PMA alone had any effect. In the presence of high doses of LH, phospholipase C inhibited progesterone and cAMP production in a dose-dependent manner. A23187 and PMA were able to mimic the inhibition of progesterone synthesis but stimulated LH-induced cAMP accumulation. When cells were stimulated by high doses of dbcAMP, phospholipase C and A23187 but not PMA inhibited progesterone synthesis. These observations suggest that (1) phospholipase C can mimic the post-cAMP negative regulatory signal induced in vitro by high doses of LH, in the presence of an activation of PKC; (2) phospholipase C is also able to mimic in vitro the luteolytic properties of prostaglandin F2 alpha that we previously described (Benhaim et al. (1987) Prostaglandins 33, 227-239); and (3) under basal conditions or in the presence of low doses of LH, the phospholipase C system slightly stimulates steroidogenesis.
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Affiliation(s)
- A Benhaim
- Laboratoire de Biochimie, CNRS UA-609, CHU Côte de Nacre, Caen, France
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30
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Athari A, Jungermann K. Direct activation by prostaglandin F2 alpha but not thromboxane A2 of glycogenolysis via an increase in inositol 1,4,5-trisphosphate in rat hepatocytes. Biochem Biophys Res Commun 1989; 163:1235-42. [PMID: 2551282 DOI: 10.1016/0006-291x(89)91110-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In rat liver prostaglandin F2 alpha (PGF2 alpha) and thromboxane A2 (TXA2), released from non-parenchymal cells, have been implicated as mediators of the enhancement of glucose and lactate output from parenchymal cells caused by sympathetic nerve stimulation [Iwai, M. et al. (1988) Eur. J. Biochem. 175, 45-50]. In isolated rat hepatocytes PGF2 alpha, of which 75% were degraded within 10 min, but not the TXA2 analogue U46619 increased inositol 1,4,5-trisphosphate (IP3), glycogen phosphorylase a activity and glucose output like noradrenaline and vasopressin; cyclic AMP remained unaltered. The maximal increase in IP3 was reached within 20 s and in phosphorylase activity as well as glucose release within 1 min. The results indicate that only PGF2 alpha but not TXA2 can play a role as a direct mediator of the sympathetic metabolic nerve actions in rat liver and that hepatocytes contain also stimulatory prostaglandin receptors linked to phospholipase C in addition to the inhibitory receptors linked to adenylate cyclase known thus far.
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