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A review of the physiology behind letrozole applications in infertility: are current protocols optimal? J Assist Reprod Genet 2020; 37:2093-2104. [PMID: 32712844 PMCID: PMC7492298 DOI: 10.1007/s10815-020-01892-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 07/13/2020] [Indexed: 11/23/2022] Open
Abstract
Letrozole is a targeted aromatase inhibitor which has primarily been used in post-menopausal women with breast cancer. Recently, it has been utilized in infertile pre-menopausal women because of its ability to enhance FSH production for ovulation induction. However, the ovarian follicle’s response to FSH is only a part of the endocrine events occurring in a developing follicle. The health of the small antral follicles is driven primarily by androgens, which contribute to granulosa cell mitosis, sensitivity to FSH, and resistance to atresia. In contrast, elevated androgens in the late antral to pre-ovulatory follicle have a negative impact on follicle health and lead to atresia and cystic follicle formation. This ovarian physiologic data suggests that current applications of letrozole to infertility may be squandering some of the primary benefits available in using letrozole to promote follicle development. Four applications of letrozole to infertility that have appeared in the medical literature are reviewed. Androgen-related benefits are reviewed and various questions put forward about how letrozole could be more effectively used to help patients in these settings.
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An explanation of the mechanisms underlying fragile X-associated premature ovarian insufficiency. J Assist Reprod Genet 2020; 37:1313-1322. [PMID: 32377997 PMCID: PMC7311620 DOI: 10.1007/s10815-020-01774-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/01/2020] [Indexed: 12/22/2022] Open
Abstract
Fragile X and fragile X-associated tremor-ataxia syndrome (FXTAS) are caused by mutations of the FMR1 gene. The mutations causing FXTAS can expand in a generation to a "full mutation" causing fragile X syndrome. The mutations causing FXTAS and the phenotype, fragile X-associated premature ovarian insufficiency (FXPOI), are referred to as the FMR1 premutation (PM). The objective of this paper was to formulate a theory to explain the Mechanism for FXPOI.Recent research on fragile X syndrome and FXTAS has led to sophisticated theories about the mechanisms underlying these diseases. It has been proposed that similar mechanisms underlie FXPOI. Utilizing recent research on FXTAS, but a more detailed application of ovarian physiology, we present a more ovarian specific theory as to the primary mechanism explaining the development of FXPOI.The FXPOI phenotype may best be viewed as derivative of the observation that fragile X PM carriers experience menopause an average of 5 years earlier than non-carriers. Women carrying the PM experience an earlier menopause because of an accelerated activation of their primordial follicle pool. This acceleration of primordial follicle activation occurs, in part, because of diminished AMH production. AMH production is diminished because of accelerated atresia of early antral follicles. This accelerated atresia likely occurs because the fragile X PM leads to a slowing of the rate of granulosa cell mitosis in some follicles.
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Supplementation of in vitro culture medium with FSH to grow follicles and mature oocytes can be replaced by extracts of Justicia insularis. PLoS One 2018; 13:e0208760. [PMID: 30532263 PMCID: PMC6286020 DOI: 10.1371/journal.pone.0208760] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Accepted: 11/20/2018] [Indexed: 12/04/2022] Open
Abstract
The present study evaluated the effect of supplementing in vitro culture medium with J. insularis compared to FSH on isolated secondary follicles and in vitro maturation of oocytes from those follicles. Secondary follicles were isolated from sheep ovaries and individually cultured for 18 days in α-MEM+ (Control), α-MEM+ supplemented with 100 ng/mL recombinant bovine follicle stimulating hormone (FSH) or with 0.3, 1.25, or 2.5 mg/mL of J. insularis extract (JI0.3, JI1.25, and JI2.5, respectively). Culture medium collected every 2 days was used to measure ROS levels. At the end of the culture period, cumulus oocytes complex (COCs) were collected and matured in vitro. Follicular walls were used for mRNA quantitation. JI0.3 led to a higher (P < 0.05) percentages of intact follicles than other groups after 18 days of culture. While follicular diameter remained unchanged from Day 6 onwards with JI0.3 and FSH, percentages of antral cavity formation were higher (P < 0.05) with JI0.3 at Day 6 than in all other treatments. No differences were observed between controls and treatment groups regarding ROS levels and mRNA expression of genes. Viability of resulting oocytes was higher (P < 0.05) in JI0.3 compared to FSH. Interestingly, in control experiment, supplementation of maturation medium with JI0.3 led to higher (P < 0.05) percentages of metaphase II compared to controls. Although more validations will be needed, it seems that this natural extract could be used as a cheap and easily available alternative to commercial FSH.
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Juengel JL. How the quest to improve sheep reproduction provided insight into oocyte control of follicular development. J R Soc N Z 2018. [DOI: 10.1080/03036758.2017.1421238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Jennifer L. Juengel
- Reproduction, Animal Science, AgResearch Ltd, Invermay Agricultural Centre, Mosgiel, New Zealand
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Padmanabhan V, Salvetti NR, Matiller V, Ortega HH. Developmental programming: prenatal steroid excess disrupts key members of intraovarian steroidogenic pathway in sheep. Endocrinology 2014; 155:3649-60. [PMID: 25061847 PMCID: PMC4138569 DOI: 10.1210/en.2014-1266] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Prenatal testosterone (T) excess disrupts ovarian cyclicity and increases circulating estradiol levels as well as follicular recruitment and persistence culminating in multifollicular ovary similar to women with polycystic ovary syndrome. We tested whether prenatal T excess, by androgenic or estrogenic action, disrupts the steroid biosynthetic machinery in sheep in a cell-, follicle stage-, age-, and treatment-specific manner consistent with the ovarian disruptions and increased estradiol release. Impact of T/dihydrotestosterone (DHT) treatments from days 30-90 of gestation on steroidogenic acute regulatory protein, 3β-hydroxysteroid dehydrogenase, cytochrome P-450 17α-hydroxylase/C17, 20-lyase (CYP17A1), and cytochrome P-450 aromatase (CYP19A1) were examined on fetal day 90, 140 and 10 months (postpubertal), and 21 months (adult, no DHT group) of age by immunohistochemistry. All 4 markers changed in a cell-, follicle stage-, and age-specific manner. Both treatments increased steroidogenic acute regulatory protein expression in preantral follicles of postpubertal and adult females. Effects of prenatal T and DHT on 3β-hydroxysteroid dehydrogenase differed in a follicle- and age-specific manner. CYP17A1 was reduced in the theca interna of antral follicles by T, but not DHT, in 10- and 21-month-old females. CYP19A1 was reduced by both T and DHT at all ages barring an increase on fetal day 140. Reduced granulosa CYP19A1 and thecal CYP17A1 in adults likely disrupt the intrafollicular androgen/estrogen balance contributing to follicular persistence. The reduced thecal CYP17A1 expression suggests that the hyperandrogenic ovarian phenotype may originate from increased enzyme activity or alternatively via a different isoform of CYP17. The reduced CYP19A1 in antral follicles of adults indicates that the increased circulating estradiol release likely arises from the increased number of persisting follicles.
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Affiliation(s)
- Vasantha Padmanabhan
- Department of Pediatrics and the Reproductive Sciences Program (V.P.), University of Michigan, Ann Arbor, Michigan 48109-5404; and Department of Morphological Sciences (N.R.S., V.M., H.H.O.), Faculty of Veterinary Sciences, National University of Litoral, Esperanza, Santa Fe, and Argentine National Research Council (CONICET), Buenos Aires, 1033 Argentina
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Developmental programming: Impact of prenatal testosterone treatment and postnatal obesity on ovarian follicular dynamics. J Dev Orig Health Dis 2014; 3:276-86. [PMID: 23766891 DOI: 10.1017/s2040174412000128] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Prenatal testosterone (T) excess leads to reproductive dysfunctions in sheep with obesity exaggerating such defects. Developmental studies found ovarian reserve is similar in control and prenatal T sheep at fetal day 140, with prenatal T females showing increased follicular recruitment and persistence at 10 months of age (postpubertal). This study tested if prenatal T sheep show accelerated depletion prepubertally and if depletion of ovarian reserve would explain loss of cyclicity in prenatal T females and its amplification by postnatal obesity. Stereological examinations were performed at 5 (prepubertal, control and prenatal T) and 21 months (control, prenatal T and prenatal T obese, following estrus synchronization) of age. Obesity was induced by overfeeding from weaning. At 5 months, prenatal T females had 46% less primordial follicles than controls (P < 0.01), supportive of increased follicular depletion. Depletion rate was slower and a higher percentage of growing follicles was present in 21 month than 5 month old prenatal T females (P < 0.01). Postnatal obesity did not exaggerate the impact of prenatal T on follicular recruitment indicating that compounding effects of obesity on loss of cyclicity females is not due to depletion of ovarian reserve. Assessment of follicular dynamics across several time points during the reproductive life span (this and earlier study combined) provides evidence supportive of a shift in follicular dynamics in prenatal T females from one of accelerated follicular depletion initiated prior to puberty to stockpiling of growing follicles after puberty, a time point critical in the development of the polycystic ovary syndrome phenotype.
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Pires ES, Hlavin C, Macnamara E, Ishola-Gbenla K, Doerwaldt C, Chamberlain C, Klotz K, Herr AK, Khole A, Chertihin O, Curnow E, Feldman SH, Mandal A, Shetty J, Flickinger C, Herr JC. SAS1B protein [ovastacin] shows temporal and spatial restriction to oocytes in several eutherian orders and initiates translation at the primary to secondary follicle transition. Dev Dyn 2013; 242:1405-26. [PMID: 24038607 DOI: 10.1002/dvdy.24040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 08/07/2013] [Accepted: 08/16/2013] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Sperm Acrosomal SLLP1 Binding (SAS1B) protein (ovastacin) is an oolemmal binding partner for the intra-acrosomal sperm protein SLLP1. RESULTS Immunohistochemical localization revealed that SAS1B translation is restricted among adult tissues to the ovary and oocytes, SAS1B appearing first in follicles at the primary-secondary transition. Quiescent oocytes within primordial follicles and primary follicles did not stain for SAS1B. Examination of neonatal rat ovaries revealed SAS1B expression first as faint signals in postnatal day 3 oocytes, with SAS1B protein staining intensifying with oocyte growth. Irrespective of animal age or estrus stage, SAS1B was seen only in oocytes of follicles that initiated a second granulosa cell layer. The precise temporal and spatial onset of SAS1B expression was conserved in adult ovaries in seven eutherian species, including nonhuman primates. Immunoelectron micrographs localized SAS1B within cortical granules in MII oocytes. A population of SAS1B localized on the oolemma predominantly in the microvillar region anti-podal to the nucleus in ovulated MII rat oocytes and on the oolemma in macaque GV oocytes. CONCLUSIONS The restricted expression of SAS1B protein in growing oocytes, absence in the ovarian reserve, and localization on the oolemma suggest this zinc metalloprotease deserves consideration as a candidate target for reversible female contraceptive strategies.
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Affiliation(s)
- Eusebio S Pires
- Department of Cell Biology, Center for Research in Contraceptive and Reproductive Health, University of Virginia, Charlottesville, Virginia
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Peralta OA, Bucher D, Fernandez A, Berland M, Strobel P, Ramirez A, Ratto MH, Concha I. Granulocyte-macrophage colony stimulating factor (GM-CSF) enhances cumulus cell expansion in bovine oocytes. Reprod Biol Endocrinol 2013; 11:55. [PMID: 23799974 PMCID: PMC3738149 DOI: 10.1186/1477-7827-11-55] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 06/17/2013] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND The objectives of the study were to characterize the expression of the α- and β-subunits of granulocyte-macrophage colony stimulating factor (GM-CSF) receptor in bovine cumulus cells and oocytes and to determine the effect of exogenous GM-CSF on cumulus cells expansion, oocyte maturation, IGF-2 transcript expression and subsequent competence for embryonic development. METHODS Cumulus-oocyte complexes (COC) were obtained by aspirating follicles 3- to 8-mm in diameter with an 18 G needle connected to a vacuum pump at -50 mmHg. Samples of cumulus cells and oocytes were used to detect GM- CSF receptor by immunofluorescence. A dose-response experiment was performed to estimate the effect of GM-CSF on cumulus cell expansion and nuclear/cytoplasmic maturation. Also, the effect of GM-CSF on IGF-2 expression was evaluated in oocytes and cumulus cells after in vitro maturation by Q-PCR. Finally, a batch of COC was randomly assigned to in vitro maturation media consisting of: 1) synthetic oviductal fluid (SOF, n = 212); 2) synthetic oviductal fluid supplemented with 100 ng/ml of GM-CSF (SOF + GM-CSF, n = 224) or 3) tissue culture medium (TCM 199, n = 216) and then subsequently in vitro fertilized and cultured for 9 days. RESULTS Immunoreactivity for both α and β GM-CSF receptors was localized in the cytoplasm of both cumulus cells and oocytes. Oocytes in vitro matured either with 10 or 100 ng/ml of GM-CSF presented a higher (P < 0.05) cumulus cells expansion than that of the control group (0 ng/ml of GM-CSF). GM-CSF did not affect the proportion of oocytes in metaphase II, cortical granules dispersion and IGF-2 expression. COC exposed to 100 ng/ml of GM-CSF during maturation did not display significant differences in terms of embryo cleavage rate (50.4% vs. 57.5%), blastocyst development at day 7 (31.9% vs. 28.7%) and at day 9 (17.4% vs. 17.9%) compared to untreated control (SOF alone, P = 0.2). CONCLUSIONS GM-CSF enhanced cumulus cell expansion of in vitro matured bovine COC. However, GM-CSF did not increase oocyte nuclear or cytoplasmic maturation rates, IGF-2 expression or subsequent embryonic development.
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Affiliation(s)
- Oscar A Peralta
- Departamento de Fomento de la Producción Animal, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
| | - Danai Bucher
- Institutos de Ciencia Animal y Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile
| | - Ana Fernandez
- Institutos de Ciencia Animal y Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile
| | - Marco Berland
- Facultad de Recursos Naturales, Universidad Católica de Temuco, Temuco, Chile
| | - Pablo Strobel
- Institutos de Ciencia Animal y Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile
| | - Alfredo Ramirez
- Institutos de Ciencia Animal y Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile
| | - Marcelo H Ratto
- Institutos de Ciencia Animal y Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile
| | - Ilona Concha
- Institutos de Ciencia Animal y Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile
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Young JM, Henderson S, Souza C, Ludlow H, Groome N, McNeilly AS. Activin B is produced early in antral follicular development and suppresses thecal androgen production. Reproduction 2012; 143:637-50. [PMID: 22450673 PMCID: PMC3342735 DOI: 10.1530/rep-11-0327] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Little is known about the role of activin B during folliculogenesis. This study investigated the expression levels of activin/inhibin subunits (βA, βB, and α), steroid enzyme, and gonadotrophin receptors in theca (TC) and granulosa cells (GC) by QPCR and activin A and B and inhibin A protein levels in follicular fluid (FF) of developing sheep follicles during estrus and anestrus. The effect of activin B on androgen production from primary TC cultures in vitro was also assessed. During folliculogenesis, in anestrus and estrus, FF activin B concentrations and thecal and GC activin βB mRNA levels decreased as follicle diameter increased from 1–3 to >6 mm regardless of estrogenic status. Estrogenic preovulatory follicles had reduced concentrations of FF activins B and A, and TC and GCs expressed higher levels of activin βA mRNA at 3–4 mm, and TCs more inhibin α mRNA at >4 mm stages of development compared with nonestrogenic follicles. Activin B decreased androstenedione production from primary TCs in vitro, an effect blocked by inhibin A. Thus, sheep follicles 1–3 mm in diameter contained high FF levels of activin B, which decreased as the follicle size increased, and, like activin A, suppressed thecal androgen production in vitro, an effect blocked by inhibin. Furthermore, the theca of large estrogenic follicles expressed high levels of inhibin α and activin βA mRNA suggesting local thecal derived inhibin A production. This would inhibit the negative effects of thecal activins B and A ensuring maximum androgen production for enhanced estradiol production by the preovulatory follicle(s).
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Affiliation(s)
- J M Young
- MRC Human Reproductive Sciences Unit, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
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McElroy SL, Byrne JA, Chavez SL, Behr B, Hsueh AJ, Westphal LM, Reijo Pera RA. Parthenogenic blastocysts derived from cumulus-free in vitro matured human oocytes. PLoS One 2010; 5:e10979. [PMID: 20539753 PMCID: PMC2881862 DOI: 10.1371/journal.pone.0010979] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2010] [Accepted: 05/11/2010] [Indexed: 01/25/2023] Open
Abstract
Background Approximately 20% of oocytes are classified as immature and discarded following intracytoplasmic sperm injection (ICSI) procedures. These oocytes are obtained from gonadotropin-stimulated patients, and are routinely removed from the cumulus cells which normally would mature the oocytes. Given the ready access to these human oocytes, they represent a potential resource for both clinical and basic science application. However culture conditions for the maturation of cumulus-free oocytes have not been optimized. We aimed to improve maturation conditions for cumulus-free oocytes via culture with ovarian paracrine/autocrine factors identified by single cell analysis. Methodology/Principal Finding Immature human oocytes were matured in vitro via supplementation with ovarian paracrine/autocrine factors that were selected based on expression of ligands in the cumulus cells and their corresponding receptors in oocytes. Matured oocytes were artificially activated to assess developmental competence. Gene expression profiles of parthenotes were compared to IVF/ICSI embryos at morula and blastocyst stages. Following incubation in medium supplemented with ovarian factors (BDNF, IGF-I, estradiol, GDNF, FGF2 and leptin), a greater percentage of oocytes demonstrated nuclear maturation and subsequently, underwent parthenogenesis relative to control. Similarly, cytoplasmic maturation was also improved as indicated by development to blastocyst stage. Parthenogenic blastocysts exhibited mRNA expression profiles similar to those of blastocysts obtained after IVF/ICSI with the exception for MKLP2 and PEG1. Conclusions/Significance Human cumulus-free oocytes from hormone-stimulated cycles are capable of developing to blastocysts when cultured with ovarian factor supplementation. Our improved IVM culture conditions may be used for obtaining mature oocytes for clinical purposes and/or for derivation of embryonic stem cells following parthenogenesis or nuclear transfer.
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Affiliation(s)
- Sohyun L. McElroy
- Center for Human Embryonic Stem Cell Research and Education, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Palo Alto, California, United States of America
- Department of Obstetrics and Gynecology, Stanford University, Palo Alto, California, United States of America
| | - James A. Byrne
- Center for Human Embryonic Stem Cell Research and Education, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Palo Alto, California, United States of America
- Department of Obstetrics and Gynecology, Stanford University, Palo Alto, California, United States of America
| | - Shawn L. Chavez
- Center for Human Embryonic Stem Cell Research and Education, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Palo Alto, California, United States of America
- Department of Obstetrics and Gynecology, Stanford University, Palo Alto, California, United States of America
| | - Barry Behr
- Department of Obstetrics and Gynecology, Stanford University, Palo Alto, California, United States of America
- Division of Reproductive Endocrinology and Infertility, Stanford Hospital and Clinics, Palo Alto, California, United States of America
| | - Aaron J. Hsueh
- Department of Obstetrics and Gynecology, Stanford University, Palo Alto, California, United States of America
| | - Lynn M. Westphal
- Department of Obstetrics and Gynecology, Stanford University, Palo Alto, California, United States of America
- Division of Reproductive Endocrinology and Infertility, Stanford Hospital and Clinics, Palo Alto, California, United States of America
| | - Renee A. Reijo Pera
- Center for Human Embryonic Stem Cell Research and Education, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Palo Alto, California, United States of America
- Department of Obstetrics and Gynecology, Stanford University, Palo Alto, California, United States of America
- * E-mail:
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Arvisais E, Hou X, Wyatt TA, Shirasuna K, Bollwein H, Miyamoto A, Hansen TR, Rueda BR, Davis JS. Prostaglandin F2alpha represses IGF-I-stimulated IRS1/phosphatidylinositol-3-kinase/AKT signaling in the corpus luteum: role of ERK and P70 ribosomal S6 kinase. Mol Endocrinol 2010; 24:632-43. [PMID: 20160123 DOI: 10.1210/me.2009-0312] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Little is known about the early intracellular events that contribute to corpus luteum regression. Experiments were designed to determine the effects of prostaglandin F2alpha (PGF2alpha) on phosphatidylinositol-3-kinase (PI3K)/Akt signaling in the corpus luteum in vivo and in vitro. Treatment of midluteal-phase cows with a luteolytic dose of PGF2alpha resulted in a rapid increase in ERK and mammalian target of rapamycin (mTOR)/p70 ribosomal protein S6 kinase (p70S6K1) signaling and a rapid suppression of Akt phosphorylation in luteal tissue. In vitro treatment of primary cultures of luteal cells with PGF2alpha also resulted in an increase in ERK and mTOR/p70S6K1 signaling and a diminished capacity of IGF-I to stimulate PI3K, Akt, and protein kinase C zeta activation. Accounting for the reductions in PI3K and Akt activation observed in response to PGF2alpha treatment, we found that PGF2alpha promoted the phosphorylation of serine residues (307, 612, 636) in the insulin receptor substrate 1 (IRS1) peptide sequence in vivo and in vitro. Serine phosphorylation of IRS1 was associated with reduced formation of IGF-I-stimulated IRS1/PI3Kp85 complexes. Furthermore, treatment with inhibitors of the MAPK kinase 1/ERK or mTOR/p70S6K1 signaling pathways prevented PGF2alpha-induced serine phosphorylation of IRS1 and abrogated the inhibitory actions of PGF2alpha on Akt activation. Taken together, these experiments provide compelling evidence that PGF2alpha treatment stimulates IRS1 serine phosphorylation, which may contribute to a diminished capacity to respond to IGF-I. It seems likely that the rapid changes in phosphorylation events are among the early events that mediate PGF2alpha-induced corpus luteum regression.
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Affiliation(s)
- Edward Arvisais
- Omaha Veterans Affairs Medical Center, Omaha, Nebraska 68105, USA
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Abstract
ABSTRACT
Testis and ovary serve an important role of producing male and female gametes. Their normal functioning is very important for the proper formation of sperm and ovum and thus has a critical role in the successful fertility outcome. Synchronized activity of various cells in the gonads is needed to provide favorable niche for the growth and development of the germ cells. Among various ways of cellular communication, intercellular communication is mediated by gap junctions, which provides open but selective exchange of ion and molecules of restricted size between two adjoining cells. The basic unit of gap junction is connexins. Their important role has been speculated in the maintenance of homeostasis, morphogenesis, cell differentiation, and growth control in higher organisms. The expression of gap junction proteins in reproductive tissues has drawn the attention and interest of researcher to investigate their role in the reproductive outcome. The reports about the correlation of gap junction protein expression pattern in infertility patients and in animal models have suggested their implication in fertility. Some of these gap junction proteins seem to have redundant functions, whereas some could be very critical in the normal fertility and could not be dispensable for the successful outcome of the reproduction.
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Haouzi D, Hamamah S. Pertinence of apoptosis markers for the improvement of in vitro fertilization (IVF). Curr Med Chem 2009; 16:1905-16. [PMID: 19442154 DOI: 10.2174/092986709788186075] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In assisted reproductive technology (ART), the pregnancy and birth rates following in vitro fertilization (IVF) attempts are still low. Recently, apoptotic markers have been suggested as new criteria for oocyte and embryo quality selection. Many studies have provided evidence that poor oocyte and embryo quality can be associated with apoptosis. The aim of this review is to summarize our current knowledge on the apoptotic process in oocytes and embryos, and focus on the possibility for using apoptotic markers as a reliable and predictive marker to select competent oocytes and embryos during IVF. Moreover, it is currently accepted that IVF failures, linked to poor embryo quality, are, in part, associated with suboptimal in vitro culture conditions. Here, we also review the current state of knowledge concerning how the genetic control of apoptosis during folliculogenesis and pre-implantation embryonic development is affected by in vitro culture conditions during IVF. In the future, identification of apoptotic markers in ART for oocyte and embryo selection should result in the development of new agonistic or antagonistic molecules of apoptosis by medicinal chemistry.
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Affiliation(s)
- D Haouzi
- CHU de Montpellier, Institut de recherche en biothérapie, hôpital Saint-Eloi, F-34295 Montpellier cedex 5, France
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Orisaka M, Tajima K, Tsang BK, Kotsuji F. Oocyte-granulosa-theca cell interactions during preantral follicular development. J Ovarian Res 2009; 2:9. [PMID: 19589134 PMCID: PMC2715405 DOI: 10.1186/1757-2215-2-9] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 07/09/2009] [Indexed: 01/27/2023] Open
Abstract
The preantral-early antral follicle transition is the penultimate stage of follicular development in terms of gonadotropin dependence and follicle destiny (growth versus atresia). Follicular growth during this period is tightly regulated by oocyte-granulosa-theca cell interactions. Formation of the theca cell layer is a key event that occurs during this transitional stage. Granulosal factor(s) stimulates the recruitment of theca cells from cortical stromal cells, while oocyte-derived growth differentiation factor-9 (GDF-9) is involved in the differentiation of theca cells during this early stage of follicular development. The preantral to early antral transition is most susceptible to follicular atresia. GDF-9 promotes follicular survival and growth during transition from preantral stage to early antral stage by suppressing granulosa cell apoptosis and follicular atresia. GDF-9 also enhances preantral follicle growth by up-regulating theca cell androgen production. Thecal factor(s) promotes granulosa cell proliferation and suppress granulosa cell apoptosis. Understanding the intraovarian mechanisms in the regulation of follicular growth and atresia during this stage may be of clinical significance in the selection of the best quality germ cells for assisted reproduction. In addition, since certain ovarian dysfunctions, such as polycystic ovarian syndrome and gonadotropin poor-responsiveness, are consequences of dysregulated follicle growth at this transitional stage, understanding the molecular and cellular mechanisms in the control of follicular development during the preantral-early antral transition may provide important insight into the pathophysiology and rational treatment of these conditions.
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Affiliation(s)
- Makoto Orisaka
- Department of Obstetrics & Gynecology, University of Fukui, Matsuoka, Fukui, 910-1193, Japan.
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Webb R, Garnsworthy PC, Campbell BK, Hunter MG. Intra-ovarian regulation of follicular development and oocyte competence in farm animals. Theriogenology 2007; 68 Suppl 1:S22-9. [PMID: 17540442 DOI: 10.1016/j.theriogenology.2007.04.036] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In both mono-ovulatory species, such as cattle, and poly-ovulatory species, such as pigs, the interactions among extra-ovarian gonadotropins, metabolic hormones and intra-ovarian growth factors determine the continued development of follicles, the number of follicles that ovulate and the developmental competence of the ovulated oocyte. FSH and then subsequently LH are the main hormones regulating antral follicle growth in both mono- and poly-ovular species. However, a range of intra-ovarian growth factors, such as insulin-like growth factors (IGFs) and bone morphogenetic proteins (BMPs), are expressed throughout follicle and oocyte development and interact with gonadotropins to control follicle maturation. In addition, environmental factors such as nutrition, including both the amount and composition of the diet consumed prior to ovulation, can influence follicle development and the quality of the oocyte. Recent progress in our understanding has resulted in the development of diets that enhance oocyte quality and improve pregnancy rate in both pigs and cattle. In conclusion, despite some species-specific differences, similar interacting mechanisms control follicular development and influence oocyte quality.
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Affiliation(s)
- R Webb
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK.
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