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Liu CL, Mou HL, Na RS, Wang X, Hu PF, Ceccobelli S, Huang YF, E GX. Multiomic meta-analysis suggests a correlation between steroid hormone-related genes and litter size in goats. Anim Genet 2024. [PMID: 39019844 DOI: 10.1111/age.13464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 06/11/2024] [Accepted: 07/05/2024] [Indexed: 07/19/2024]
Abstract
Litter size is a key indicator of production performance in livestock. However, its genetic basis in goats remains poorly understood. In this work, a genome-wide selection sweep analysis (GWSA) on 100 published goat genomes with different litter rates was performed for the first time to identify candidate genes related to kidding rate. This analysis was combined with the public RNA-sequencing data of ovary tissues (follicular phase) from high- and low-yielding goats. A total of 2278 genes were identified by GWSA. Most of these genes were enriched in signaling pathways related to ovarian follicle development and hormone secretion. Moreover, 208 differentially expressed genes between groups were obtained from the ovaries of goats with different litter sizes. These genes were substantially enriched in the cholesterol and steroid synthesis signaling pathways. Meanwhile, the weighted gene co-expression network was used to perform modular analysis of differentially expressed genes. The results showed that seven modules were reconstructed, of which one module showed a very strong correlation with litter size (r = -0.51 and p-value <0.001). There were 51 genes in this module, and 39 hub genes were screened by Pearson's correlation coefficient between core genes > 0.4, correlation coefficient between module members > 0.80 and intra-module connectivity ≥5. Finally, based on the results of GWSA and hub gene Venn analysis, seven key genes (ACSS2, HECW2, KDR, LHCGR, NAMPT, PTGFR and TFPI) were found to be associated with steroid synthesis and follicle growth development. This work contributes to understanding of the genetic basis of goat litter size and provides theoretical support for goat molecular breeding.
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Affiliation(s)
- Cheng-Li Liu
- College of Animal Science and Technology, Southwest University, Chongqing, China
| | - Hui-Long Mou
- College of Animal Science and Technology, Southwest University, Chongqing, China
| | - Ri-Su Na
- Animal Sciences, Inner Mongolia Agricultural University, Hohhot, China
| | - Xiao Wang
- College of Animal Science and Technology, Southwest University, Chongqing, China
| | - Peng-Fei Hu
- Institute of Antler Science and Product Technology, Changchun Sci-Tech University, Changchun, China
| | - Simone Ceccobelli
- Department of Agricultural, Food and Environmental Sciences, Università Politecnica Delle Marche, Ancona, Italy
| | - Yong-Fu Huang
- College of Animal Science and Technology, Southwest University, Chongqing, China
| | - Guang-Xin E
- College of Animal Science and Technology, Southwest University, Chongqing, China
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2
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Guzeloglu A, Bishop JV, Van Campen H, Plewes MR, Gonzalez-Berrios CL, Kincade JN, Davis JS, Hansen TR. Interferon-tau infusion into the ovine corpus luteum delays luteolysis. Biol Reprod 2024:ioae084. [PMID: 38869890 DOI: 10.1093/biolre/ioae084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 04/23/2024] [Indexed: 06/14/2024] Open
Abstract
Conceptus-derived interferon-tau (IFNT) initiates maternal recognition of pregnancy in ewes by paracrine actions on the endometrium and endocrine action on the corpus luteum (CL). To examine the effect of IFNT on the CL without inducing IFN stimulated genes (ISGs) in the endometrium, recombinant ovine IFNT (roIFNT) or bovine serum albumin (BSA) was delivered directly into CLs via osmotic pumps at a rate of 10, 50 or 100 ng/h from days 9 to 12 of the estrous cycle. Endometrial and CL samples were collected on day 12. Fifty ng/h of roIFNT induced ISG15 in the CL on day 12 without affecting endometrial ISG15 concentrations. In a second experiment, roIFNT (50 ng/h) was infused into the CL from days 10 to 17 of the estrous cycle and serum samples were collected daily. Serum progesterone concentrations were significantly higher on days 15 to 17 in roIFNT-infused ewes compared to controls. Levels of LHCGR, STAR, CYP11A1, HSL, OPA1 and PKA mRNA and proteins were higher in the roIFNT-infused CLs compared to the controls. Levels of ISG15 and MX1 mRNA increased in the CLs of roIFNT-infused ewes but not in the endometrium. Endometrial ESR1 mRNA and protein concentrations were higher in the controls compared to roIFNT-infused ewes. In conclusion, intra-luteal delivery of roIFNT induced ISGs, stabilized steroidogenesis in the CL and delayed luteolysis without inducing endometrial ISGs. Inhibition of ESR1 in the endometrium of roIFNT-infused ewes was observed suggesting that direct delivery of IFNT to the CL has an additional anti-luteolytic effect on the endometrium.
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Affiliation(s)
- Aydin Guzeloglu
- Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, 80523
| | - Jeanette V Bishop
- Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, 80523
| | - Hana Van Campen
- Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, 80523
| | - Michele R Plewes
- Olson Center for Women's Health, Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, NE 68198-3255, USA
- Veterans Affairs, Nebraska Western Iowa Health Care System, 4101 Woolworth Ave, Omaha, NE 68105, USA
| | - Carolina L Gonzalez-Berrios
- Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, 80523
| | - Jessica N Kincade
- Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, 80523
| | - John S Davis
- Olson Center for Women's Health, Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, NE 68198-3255, USA
- Veterans Affairs, Nebraska Western Iowa Health Care System, 4101 Woolworth Ave, Omaha, NE 68105, USA
| | - Thomas R Hansen
- Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, 80523
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Berisha B, Thaqi G, Sinowatz F, Schams D, Rodler D, Pfaffl MW. Prostaglandins as local regulators of ovarian physiology in ruminants. Anat Histol Embryol 2024; 53:e12980. [PMID: 37788129 DOI: 10.1111/ahe.12980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 09/14/2023] [Accepted: 09/22/2023] [Indexed: 10/05/2023]
Abstract
Prostaglandins are synthesized from arachidonic acid through the catalytic activities of cyclooxygenase, while the production of different prostaglandin types, prostaglandin F2 alpha (PGF) and prostaglandin E2 (PGE), are regulated by specific prostaglandin synthases (PGFS and PGES). Prostaglandin ligands (PGF and PGE) bind to specific high-affinity receptors and initiate biologically distinct signalling pathways. In the ovaries, prostaglandins are known to be important endocrine regulators of female reproduction, in addition to maintaining local function through autocrine and/or paracrine effect. Many research groups in different animal species have already identified a variety of factors and molecular mechanisms that are responsible for the regulation of prostaglandin functions. In addition, prostaglandins stimulate their intrafollicular and intraluteal production via the pathway of prostaglandin self-regulation in the ovary. Therefore, the objective of the review article is to discuss recent findings about local regulation patterns of prostaglandin ligands PGF and PGE during different physiological stages of ovarian function in domestic ruminants, especially in bovine. In conclusion, the discussed local regulation mechanisms of prostaglandins in the ovary may stimulate further research activities in different methodological approaches, especially during final follicle maturation and ovulation, as well as corpus luteum formation and function.
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Affiliation(s)
- Bajram Berisha
- Animal Biotechnology, Faculty of Agriculture and Veterinary, University of Prishtina, Prishtina, Kosovo
- Academy of Science of Albania, Tirana, Albania
- Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Freising Weihenstephan, Germany
| | - Granit Thaqi
- Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Freising Weihenstephan, Germany
| | - Fred Sinowatz
- Department of Veterinary Sciences, Ludwig-Maximilian-University of Munich, Munich, Germany
- Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Dieter Schams
- Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Freising Weihenstephan, Germany
| | - Daniela Rodler
- Department of Veterinary Sciences, Ludwig-Maximilian-University of Munich, Munich, Germany
| | - Michael W Pfaffl
- Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Freising Weihenstephan, Germany
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Thaqi G, Berisha B, Pfaffl MW. Local Expression Dynamics of Various Adipokines during Induced Luteal Regression (Luteolysis) in the Bovine Corpus Luteum. Animals (Basel) 2023; 13:3221. [PMID: 37893945 PMCID: PMC10603666 DOI: 10.3390/ani13203221] [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: 09/25/2023] [Revised: 10/09/2023] [Accepted: 10/13/2023] [Indexed: 10/29/2023] Open
Abstract
The study aimed to evaluate the mRNA expression levels of various local novel adipokines, including vaspin, adiponectin, visfatin, and resistin, along with their associated receptors, heat shock 70 protein 5, adiponectin receptor 1, and adiponectin receptor 2, in the corpus luteum (CL) during luteal regression, also known as luteolysis, in dairy cows. We selected Fleckvieh cows in the mid-luteal phase (days 8-12, control group) and administered cloprostenol (PGF analog) to experimentally induce luteolysis. We collected CL samples at different time points following PGF application: before treatment (days 8-12, control group) and at 0.5, 2, 4, 12, 24, 48, and 64 h post-treatment (n = 5) per group. The mRNA expression was measured via real-time reverse transcription polymerase chain reaction (RT-qPCR). Vaspin was characterized by high mRNA levels at the beginning of the regression stage, followed by a significant decrease 48 h and 64 h after PGF treatment. Adiponectin mRNA levels were elevated 48 h after PGF. Resistin showed upregulation 4 h post PGF application. In summary, the alterations observed in the adipokine family within experimentally induced regressing CL tissue potentially play an integral role in the local regulatory processes governing the sequence of events culminating in functional luteolysis and subsequent structural changes in the bovine ovary.
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Affiliation(s)
- Granit Thaqi
- Chair of Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Weihenstephan, 85354 Munich, Germany; (B.B.); (M.W.P.)
| | - Bajram Berisha
- Chair of Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Weihenstephan, 85354 Munich, Germany; (B.B.); (M.W.P.)
- Department of Animal Biotechnology, Faculty of Agriculture and Veterinary, University of Prishtina, 10000 Prishtina, Kosovo
| | - Michael W. Pfaffl
- Chair of Animal Physiology and Immunology, School of Life Sciences, Technical University of Munich, Weihenstephan, 85354 Munich, Germany; (B.B.); (M.W.P.)
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Bishop CV, Selvaraj V, Townson DH, Pate JL, Wiltbank MC. History, insights, and future perspectives on studies into luteal function in cattle. J Anim Sci 2022; 100:skac143. [PMID: 35772753 PMCID: PMC9246667 DOI: 10.1093/jas/skac143] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 04/12/2022] [Indexed: 12/12/2022] Open
Abstract
The corpus luteum (CL) forms following ovulation from the remnant of the Graafian follicle. This transient tissue produces critical hormones to maintain pregnancy, including the steroid progesterone. In cattle and other ruminants, the presence of an embryo determines if the lifespan of the CL will be prolonged to ensure successful implantation and gestation, or if the tissue will undergo destruction in the process known as luteolysis. Infertility and subfertility in dairy and beef cattle results in substantial economic loss to producers each year. In addition, this has the potential to exacerbate climate change because more animals are needed to produce high-quality protein to feed the growing world population. Successful pregnancies require coordinated regulation of uterine and ovarian function by the developing embryo. These processes are often collectively termed "maternal recognition of pregnancy." Research into the formation, function, and destruction of the bovine CL by the Northeast Multistate Project, one of the oldest continuously funded Hatch projects by the USDA, has produced a large body of evidence increasing our knowledge of the contribution of ovarian processes to fertility in ruminants. This review presents some of the seminal research into the regulation of the ruminant CL, as well as identifying mechanisms that remain to be completely validated in the bovine CL. This review also contains a broad discussion of the roles of prostaglandins, immune cells, as well as mechanisms contributing to steroidogenesis in the ruminant CL. A triadic model of luteolysis is discussed wherein the interactions among immune cells, endothelial cells, and luteal cells dictate the ability of the ruminant CL to respond to a luteolytic stimulus, along with other novel hypotheses for future research.
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Affiliation(s)
- Cecily V Bishop
- Department of Animal and Rangeland Sciences, College of Agricultural Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Vimal Selvaraj
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853, USA
| | - David H Townson
- Department of Animal and Veterinary Sciences, The University of Vermont, Burlington, VT 05405, USA
| | - Joy L Pate
- Department of Animal Science, Center for Reproductive Biology and Health, Pennsylvania State University, State College, PA 16802, USA
| | - Milo C Wiltbank
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
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The Role of Peroxisome Proliferator-Activated Receptors in PGF2α-Induced Luteolysis in the Bovine Corpus Luteum. Animals (Basel) 2022; 12:ani12121542. [PMID: 35739878 PMCID: PMC9219485 DOI: 10.3390/ani12121542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary The corpus luteum (CL) is responsible for progesterone (P4) secretion. In the absence of pregnancy, luteolysis occurs, which leads to a reduction in P4 production, followed by the structural regression of the CL. In cows, prostaglandin F2α (PGF2α) is the main luteolytic factor. It is also an endogenous ligand for peroxisome proliferator-activated receptors (PPARs), which are important factors regulating mammalian reproductive function. However, the mechanisms of action of PPAR isoforms, i.e., PPARα, PPARδ and PPARγ, in the luteolytic pathways in cattle are still not fully understood. The aim of this in vitro study was to determine the expression of PPAR isoforms in the bovine CL throughout the estrous cycle, and their involvement in PGF2α-induced processes related to luteolysis. The obtained results indicate that the expression of PPARs changes in the bovine CL throughout the estrous cycle; moreover, PGF2α affects its expression. This study provides evidence that PPARγ, among all examined PPAR isoforms, could be involved in the regulation of PGF2α-induced luteolysis in cattle, and PPARs may affect CL regression at multiple sites. These results help to widen the knowledge of the mechanisms of luteal regression in the bovine CL. Abstract The participation of peroxisome proliferator-activated receptors (PPARs) in ovarian function in cattle is still not fully understood. The aim of this in vitro study was to determine: (i) the immunolocalization, mRNA expression and tissue concentration of PPARα, PPARδ and PPARγ in the bovine corpus luteum (CL) (n = 40) throughout the estrous cycle, and (ii) the involvement of PPAR in PGF2α-induced processes related to luteolysis. CL (n = 9) explants were cultured in the presence of PPAR antagonists (10−5 M) in combination with or without PGF2α receptor antagonist (10−5 M) and PGF2α (10−6 M). The mRNA and protein expression of PPARs was evaluated through qPCR, IHC, and ELISA, respectively. The results showed that PPAR mRNA and protein expression differed according to the luteal stages. PGF2α upregulated PPARδ and PPARγ mRNA expression in the bovine CL in vitro, whereas PPARγ increased the inhibitory effect of PGF2α by decreasing progesterone secretion and the mRNA expression of hydroxy-delta-5-steroid dehydrogenase, 3 β- and steroid delta-isomerase 1 (HSD3B1) in the CL explants; mRNA transcription of tumor necrosis factor α (TNFα) and inducible nitric oxide synthase (iNOS) was increased. The obtained results indicate that the mRNA and protein expression of PPARs changes in the bovine CL throughout the estrous cycle and under the influence of PGF2α. We suggest that isoform γ, among all examined PPARs, could be a factor involved in the regulation of PGF2α-induced processes related to luteolysis in the bovine CL. Further studies are needed to understand the role of PPAR in luteal regression in the CL of cattle.
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7
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Dau AMP, da Rosa PR, dos Santos J, Ferst J, de Macedo M, Rovani M, Comim F, Antoniazzi AQ, Gasperin B, Ferreira R, Gonçalves PB. The influence of prorenin/(pro)renin receptor on progesterone secretion by the bovine corpus luteum. Anim Reprod Sci 2022; 241:106985. [DOI: 10.1016/j.anireprosci.2022.106985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 04/06/2022] [Accepted: 04/26/2022] [Indexed: 11/24/2022]
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8
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Berisha B, Thaqi G, Rodler D, Schams D, Sinowatz F, Pfaffl MW. Regulatory changes of local produced prostaglandins in corpus luteum after experimentally induced luteolysis in the cow. Anat Histol Embryol 2022; 51:289-299. [PMID: 35132701 DOI: 10.1111/ahe.12790] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/08/2021] [Accepted: 01/18/2022] [Indexed: 11/30/2022]
Abstract
The objective of the study was to evaluate the expression patterns of prostaglandin F2alpha (PGF), prostaglandin E2 (PGE), PGF receptor (FP), PGE receptors (EP2 and EP4), prostaglandin-endoperoxide synthase 2 (PTGS2) and prostaglandin synthases (PGFS and PGES) in corpora lutea (CL) during experimentally induced luteolysis in cow. The Fleckvieh cows in the mid-luteal phase (days 8-12, control group) were injected with cloprostenol (PGF analogue), and CL were collected by transvaginal ovariectomy before (days 8-12, control group) and at 0.5, 2, 4, 12, 24, 48 and 64 h after PGF application (n = 5 per group). The mRNA expression was determined by RT-qPCR, the hormone concentrations by enzyme immunoassay and localization by immunohistochemistry. PTGS2 gene expression increased significantly 2 h after PGF application, followed by continuous and significant downregulation afterwards. The PGF tissue concentration increased significantly just after PGF injection and again during structural luteolysis (after 12 h), whereas PGE concentration significantly decreased during structural luteolysis. The FP receptor mRNA decreased significantly at 2 h and again at 12 h after PGF. In contrast, EP4 receptor mRNA increased significantly just after the PGF application (0.5 h). The immunostaining of PGES and PTGS2 on day 15-17 shows numerous positive luteal cells, followed by lower activity afterwards on day 18 (luteolysis). In conclusion, the changes of examined prostaglandin family members in CL tissue after PGF application may be key components of the local mechanisms regulating the cascade of actions leading to functional and subsequent structural luteolysis in the bovine ovary.
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Affiliation(s)
- Bajram Berisha
- Faculty of Agriculture and Veterinary, Animal Biotechnology, University of Prishtina, Prishtina, Kosovo.,Academy of Science of Albania, Tirana, Albania.,Animal Physiology and Immunology Weihenstephan, Technical University of Munich, Munich, Germany
| | - Granit Thaqi
- Animal Physiology and Immunology Weihenstephan, Technical University of Munich, Munich, Germany
| | - Daniela Rodler
- Department of Veterinary Sciences, Ludwig-Maximilian-University of Munich, Munich, Germany
| | - Dieter Schams
- Animal Physiology and Immunology Weihenstephan, Technical University of Munich, Munich, Germany
| | - Fred Sinowatz
- Department of Veterinary Sciences, Ludwig-Maximilian-University of Munich, Munich, Germany.,Faculty of Veterinary Medicine, Department of Morphology, Ghent University, Merelbeke, Belgium
| | - Michael W Pfaffl
- Animal Physiology and Immunology Weihenstephan, Technical University of Munich, Munich, Germany
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Jonczyk AW, Piotrowska-Tomala KK, Skarzynski DJ. Comparison of Intra-CL Injection and Peripheral Application of Prostaglandin F 2α Analog on Luteal Blood Flow and Secretory Function of the Bovine Corpus Luteum. Front Vet Sci 2022; 8:811809. [PMID: 35087892 PMCID: PMC8787071 DOI: 10.3389/fvets.2021.811809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
We investigated the effects of different doses of dinoprost injected directly into the bovine corpus luteum (CL) on (i) concentrations of progesterone (P4) and oxytocin (OT) in peripheral blood and (ii) mRNA levels of steroidogenic acute regulatory protein (STAR), cytochrome P450 family 11 subfamily A member 1 (P450scc), hydroxy-delta-5-steroid dehydrogenase, 3 β- and steroid delta-isomerase 1 (HSD3B), and receptor-interacting protein kinases 1 and 3 (RIPK1, RIPK3) in CL tissue. Moreover, we examined the effects of dinoprost, injected intra-CL or administered intramuscularly (IM), on CL secretory function and on indicators of CL vascular network status: luteal tissue area (LTA), CL blood flow (CLBF), and the CLBF:LTA ratio (Adj. CLBF), in cows at the early and mid-luteal phases. In the Experiment 1, cows (day 10 of the cycle) were allocated to (i) an intra-CL injection of saline (control; n = 3); (ii) an intra-CL injection of dinoprost (1.25 mg; 2.5 mg, or 5 mg; n = 3 for each dose); (iii) an IM administration of saline (control; n = 3); or (iv) an IM administration of dinoprost (25 mg; positive control; n = 3). Concentrations of OT and P4 were measured in plasma samples. The mRNA expression of steroidogenesis- or necroptosis-related factors was determined in CL tissue 4 h after treatments. In Experiment 2, cows on day 4 (n = 12) or day 10 (n = 12) were allocated to (i) an intra-CL injection of dinoprost (2.5 mg/0.5 ml; n = 6), or (ii) IM administration of dinoprost (25 mg/5 ml; n = 6). Concentrations of P4 were measured in plasma samples. Luteal tissue area, CLBF, and Adj. CLBF were assessed based on color Doppler ultrasonography. An intra-CL injection of dinoprost increased OT and decreased P4 levels in the jugular vein (JV) in a dose-dependent manner in cows at the mid-luteal phase. Increased CLBF and Adj. CLBF, accompanied by reduced P4 levels, were observed 2 h after intra-CL dinoprost injection in middle-stage CL. Decreased STAR and increased RIPK1 and RIPK3 mRNA levels confirmed that 2.5 mg dinoprost injected directly into CL is the minimum dose that induces luteolytic cascade. Injection of dinoprost directly into the CL (at a dosage lower than recommended for peripheral application) results in a pattern similar to IM dinoprost administration.
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10
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Shrestha HK. Loss of luteal sensitivity to luteinizing hormone underlies luteolysis in cattle: A hypothesis. Reprod Biol 2021; 21:100570. [PMID: 34736159 DOI: 10.1016/j.repbio.2021.100570] [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: 03/16/2021] [Revised: 09/13/2021] [Accepted: 10/09/2021] [Indexed: 11/26/2022]
Abstract
By virtue of the secretion of progesterone (P4), corpus luteum (CL) is important not only for normal cyclicity but also for conception and continuation of pregnancy in female mammals. Luteolysis (also called luteal regression) is defined as loss of the capacity to synthesize and secrete P4 followed by the demise of the CL. There is strong evidence that sequential pulses of prostaglandin F2α (PGF) secreted from the uterus near the end of luteal phase induces luteolysis in farm animals. Loss of luteal sensitivity to luteinizing hormone (LH) at the end of menstrual cycle has been reported to be critical for initiation of luteolysis in primates, however this has not been investigated in farm animals. A closer observation of the published real-time profiles of circulating hormones (P4, LH, and PGF) and their inter-relationships around the time of the beginning of spontaneous luteolysis in cattle revealed- 1) A natural pulse of PGF causes a transient P4 suppression lasting a couple of hours followed by a rebound in P4 concentration, 2) The P4 secretions that occur in response to LH pulses before the beginning of luteolysis (i.e., preluteolysis) either fail or do so to a lesser extent during luteolysis indicating a loss of sensitivity to LH, and 3) The loss of sensitivity coincides with the beginning of luteolysis (i.e., transition), and apparently luteolysis does not initiate until there is loss of sensitivity to LH. The CL is sensitive to LH during preluteolysis, and the LH-stimulated P4-dependent and/or independent local survival mechanisms maintain the steroidogenic capability and viability of the CL until the very end of preluteolysis. Luteolysis does not appear to initiate with the PGF pulse(s) that occur during this period. With the loss of sensitivity to LH at the transition, however, a progressive decline in P4 begins initiating luteolysis. Also, the survival mechanisms become compromised making the CL less viable. The uterine PGF pulses that occur after the beginning of luteolysis induces increase in the local luteolytic factors, which contribute to further luteolysis, more importantly, structural luteolysis with ultimate demise of the CL. Therefore, I hypothesize that the loss of luteal sensitivity to LH underlies luteolysis in cattle. The hypothesis not only unifies the basic mechanism of luteolysis in a farm animal and primates but also provides a perspective to view luteolysis as a process rather than a factor-mediated event. A novel unified working model for luteolysis in a farm animal and primates is described. A better understanding of the luteal physiology including how responsiveness to LH diminishes in aging CL would help in the development of novel strategies in modulating CL structure-function to improve and/or control fertility in humans as well as in animals.
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Affiliation(s)
- Hemanta Kumar Shrestha
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI 53715, USA.
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11
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Ferreira JRDM, Villela SB, Bianconi C, Ormieres M, de Melo GD, Pugliesi G, Gobesso AADO. Uterine Involution of Mares Supplemented with Dietary Algae-Derived Omega-3 Fatty Acids During the Peripartum Period. J Equine Vet Sci 2021; 106:103733. [PMID: 34670687 DOI: 10.1016/j.jevs.2021.103733] [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: 06/18/2021] [Revised: 08/05/2021] [Accepted: 08/09/2021] [Indexed: 11/17/2022]
Abstract
Different approaches have been used to improve conception rates at foal heat. Omega-3 fatty acids family and derivatives have improved reproductive efficiency in ruminants, but literature lacks studies evaluating these components on equines. The objective of this study was to evaluate effects of mare dietary supplementation with microalgae rich in docosahexaenoic acid (DHA) during peripartum on follicular dynamics and uterine involution in early post-partum. Eighteen pregnant mares, no particular breed, 410 ± 39.5 kg body weight (BW), and 7.83 ± 2.01 yr old were used. Mares were randomly assigned to control (CONT) or supplementation with microalgae rich in DHA at 0.06 g/kg BW (ALG). Treatments were supplied from 90 d prior to expected foaling date until 7 d after first ovulation. Reproductive evaluations were performed during early post-partum until 7 d after first ovulation through rectal palpation and ultrasonography of the following parameters: uterine and endometrium diameters, intrauterine fluid (IUF), uterine echogenicity, uterus tone, and follicular dynamics. Endometrial cells samples were collected to assess mRNA expression of CRP, IL-1β and AKR1C4, using RT-qPCR. Data were analyzed by mixed procedure of SAS. ALG mares had smaller uterine horns diameters and greater uterine echogenicity during post-partum in comparison with CONT. No treatment effects were detected for other characteristics evaluated, but a day effect was observed for uterine and endometrium diameter, IUF, uterine echogenicity, and transcript abundance of endometrial AKR1C4. Supplementation with DHA during peripartum may benefit uterine involution process and odds of early conception, but more studies should be performed regarding fertility.
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Affiliation(s)
| | - Saulo Baracat Villela
- Department of Animal Nutrition and Animal Production, University of São Paulo, Pirassununga, Brazil
| | - Camila Bianconi
- Department of Veterinary Clinical and Surgery, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | | | | | - Guilherme Pugliesi
- Department of Animal Reproduction, University of São Paulo, Pirassununga, Brazil
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12
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Hryciuk MM, Jewgenow K, Braun BC. Cloprostenol, a synthetic analog of prostaglandin F2α induces functional regression in cultured luteal cells of felids†. Biol Reprod 2021; 105:137-147. [PMID: 33864060 DOI: 10.1093/biolre/ioab070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/26/2021] [Accepted: 04/05/2021] [Indexed: 12/12/2022] Open
Abstract
In the present study, we investigated the effect of the synthetic analog of prostaglandin F2α (PGF2α)-cloprostenol-on cultured steroidogenic luteal cells of selected felid species over a 2-day culture period. The changes induced by cloprostenol were measured based on progesterone concentration and mRNA expression analysis of selected genes. Cloprostenol significantly reduced concentration of progesterone in cell culture medium of small luteal cells isolated from domestic cat corpora lutea (CL) at the development/maintenance stage (P < 0.05), but did not influence progesterone production in cultured cells from the regression stage. A decrease or complete silencing of progesterone production was also measured in cultured luteal cells of African lion (formation stage) and Javan leopard (development/maintenance stage). Gene-expression analysis by real-time PCR revealed that treatment with cloprostenol did not have an influence on expression of selected genes coding for enzymes of steroidogenesis (StAR, HSD3B, CYP11A1) or prostaglandin synthesis (PTGS2, PGES), nor did it effect hormone receptors (AR, ESR1, PGR, PTGER2), an anti-oxidative enzyme (SOD1) or factors of cell apoptosis (FAS, CASP3, TNFRSF1B, BCL2) over the studied period. Significant changes were measured only for expressions of luteinizing hormone (P < 0.05), prolactin (P < 0.05) and PGF2α receptors (P < 0.005) (LHCGR, PRLR, and PTGFR). The obtained results confirm that PGF2α/cloprostenol is a luteolytic agent in CL of felids and its impact on progesterone production depends on the developmental stage of the CL. Cloprostenol short-term treatment on luteal cells was associated only with functional but not structural changes related to luteal regression.
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Affiliation(s)
- Michał M Hryciuk
- Leibniz Institute for Zoo and Wildlife Research, Department of Reproduction Biology, Berlin, Germany
| | - Katarina Jewgenow
- Leibniz Institute for Zoo and Wildlife Research, Department of Reproduction Biology, Berlin, Germany
| | - Beate C Braun
- Leibniz Institute for Zoo and Wildlife Research, Department of Reproduction Biology, Berlin, Germany
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13
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Wen X, Liu L, Li S, Lin P, Chen H, Zhou D, Tang K, Wang A, Jin Y. Prostaglandin F2α Induces Goat Corpus Luteum Regression via Endoplasmic Reticulum Stress and Autophagy. Front Physiol 2020; 11:868. [PMID: 33013430 PMCID: PMC7516216 DOI: 10.3389/fphys.2020.00868] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/29/2020] [Indexed: 12/11/2022] Open
Abstract
Corpus luteum (CL) is a transient endocrine tissue that produces progesterone for maintaining pregnancy in mammals. In addition, the regression of CL is necessary for the initiation of the estrous cycle. Extensive research has shown that the prostaglandin F2α (PGF2α) induces the regression of CL in ruminants. However, the mechanisms of endoplasmic reticulum (ER) stress and autophagy in the regression of goat CL induced by PGF2α are still unclear. In this study, ovaries of dioestrus goats and goats that were 3 months pregnant were collected to detect the location of the ER stress-related protein GRP78. The relationship between the different stages of the luteal phase of goat CL during the estrous cycle and changes in the expression of ER stress-related proteins and autophagy-related proteins was confirmed by western blot analysis. The results showed that both ER stress and autophagy were activated in the late luteal phase of the goat CL. To reveal the function of ER stress and autophagy in the CL regression process induced by PGF2α, we used 4-phenyl butyric acid (4-PBA) and chloroquine (CQ) for inhibiting ER stress and autophagy, respectively. Through the apoptotic rate detected by the flow cytometry and the expression of ER stress- and autophagy-related proteins detected by western blotting, we demonstrated that ER stress promoted goat luteal cell apoptosis and autophagy, and that apoptosis can be enhanced by the inhibition of autophagy. In addition, knockdown of EIF2S1, which blocked the PERK pathway activation, promoted apoptosis by reducing autophagy in goat luteal cells treated with PGF2α. In conclusion, our study indicates that ER stress promotes goat luteal cell apoptosis to regulate the regression of CL and activates autophagy to inhibit the goat luteal cell apoptosis via PERK signaling pathway.
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Affiliation(s)
- Xin Wen
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Lu Liu
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Shanshan Li
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Pengfei Lin
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Huatao Chen
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, China.,Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Shaanxi, China
| | - Dong Zhou
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, China.,Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Shaanxi, China
| | - Keqiong Tang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, China.,Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Shaanxi, China
| | - Aihua Wang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, China.,Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Shaanxi, China
| | - Yaping Jin
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, China.,Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Shaanxi, China
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14
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Wilson AE, Michaud SA, Jackson AM, Stenhouse G, Coops NC, Janz DM. Development and validation of protein biomarkers of health in grizzly bears. CONSERVATION PHYSIOLOGY 2020; 8:coaa056. [PMID: 32607241 PMCID: PMC7311831 DOI: 10.1093/conphys/coaa056] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 04/09/2020] [Accepted: 05/31/2020] [Indexed: 06/11/2023]
Abstract
Large carnivores play critical roles in the maintenance and function of natural ecosystems; however, the populations of many of these species are in decline across the globe. Therefore, there is an urgent need to develop novel techniques that can be used as sensitive conservation tools to detect new threats to the health of individual animals well in advance of population-level effects. Our study aimed to determine the expression of proteins related to energetics, reproduction and stress in the skin of grizzly bears (Ursus arctos) using a liquid chromatography and multiple reaction monitoring mass spectrometry assay. We hypothesized that a suite of target proteins could be measured using this technique and that the expression of these proteins would be associated with biological (sex, age, sample location on body) and environmental (geographic area, season, sample year) variables. Small skin biopsies were collected from free-ranging grizzly bears in Alberta, Canada, from 2013 to 2019 (n = 136 samples from 111 individuals). Over 700 proteins were detected in the skin of grizzly bears, 19 of which were chosen as targets because of their established roles in physiological function. Generalized linear mixed model analysis was used for each target protein. Results indicate that sample year influenced the majority of proteins, suggesting that physiological changes may be driven in part by responses to changes in the environment. Season influenced the expression of proteins related to energetics, reproduction and stress, all of which were lower during fall compared to early spring. The expression of proteins related to energetics and stress varied by geographic area, while the majority of proteins that were affected by biological attributes (age class, sex and age class by sex interaction) were related to reproduction and stress. This study provides a novel method by which scientists and managers can further assess and monitor physiological function in wildlife.
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Affiliation(s)
- Abbey E Wilson
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 44 Campus Drive, Saskatoon, Saskatchewan S7N 5B3, Canada
| | - Sarah A Michaud
- The University of Victoria Genome BC Proteomics Centre, 4464 Markham St #3101, Victoria, British Columbia V8Z 7X8, Canada
| | - Angela M Jackson
- The University of Victoria Genome BC Proteomics Centre, 4464 Markham St #3101, Victoria, British Columbia V8Z 7X8, Canada
| | - Gordon Stenhouse
- Foothills Research Institute, Grizzly Bear Program, 1176 Switzer Drive, Hinton, Alberta T7V 1V3, Canada
| | - Nicholas C Coops
- Department of Forest Resource Management, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - David M Janz
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 44 Campus Drive, Saskatoon, Saskatchewan S7N 5B3, Canada
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15
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Zou X, Lu T, Zhao Z, Liu G, Lian Z, Guo Y, Sun B, Liu D, Li Y. Comprehensive analysis of mRNAs and miRNAs in the ovarian follicles of uniparous and multiple goats at estrus phase. BMC Genomics 2020; 21:267. [PMID: 32228439 PMCID: PMC7106838 DOI: 10.1186/s12864-020-6671-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 03/13/2020] [Indexed: 12/13/2022] Open
Abstract
Background Fertility is an important economic trait in the production of meat goat, and follicular development plays an important role in fertility. Although many mRNAs and microRNAs (miRNAs) have been found to play critical roles in ovarian biological processes, the interaction between mRNAs and miRNAs in follicular development is not yet completely understood. In addition, less attention has been given to the study of single follicle (dominant or atretic follicle) in goats. This study aimed to identify mRNAs, miRNAs, and signaling pathways as well as their interaction networks in the ovarian follicles (large follicles and small follicles) of uniparous and multiple Chuanzhong black goats at estrus phase using RNA-sequencing (RNA-seq) technique. Results The results showed that there was a significant difference in the number of large follicles between uniparous and multiple goats (P < 0.05), but no difference in the number of small follicles was observed (P > 0.05). For the small follicles of uniparous and multiple goats at estrus phase, 289 differentially expressed mRNAs (DEmRNAs) and 16 DEmiRNAs were identified; and for the large follicles, 195 DEmRNAs and 7 DEmiRNAs were identified. The functional enrichment analysis showed that DE genes in small follicles were significantly enriched in ovarian steroidogenesis and steroid hormone biosynthesis, while in large follicles were significantly enriched in ABC transporters and steroid hormone biosynthesis. The results of quantitative real-time polymerase chain reaction were consistent with those of RNA-seq. Analysis of the mRNA-miRNA interaction network suggested that CD36 (miR-122, miR-200a, miR-141), TNFAIP6 (miR-141, miR-200a, miR-182), CYP11A1 (miR-122), SERPINA5 (miR-1, miR-206, miR-133a-3p, miR-133b), and PTGFR (miR-182, miR-122) might be related to fertility, but requires further research on follicular somatic cells. Conclusions This study was used for the first time to reveal the DEmRNAs and DEmiRNAs as well as their interaction in the follicles of uniparous and multiple goats at estrus phase using RNA-seq technology. Our findings provide new clues to uncover the molecular mechanisms and signaling networks of goat reproduction that could be potentially used to increase ovulation rate and kidding rate in goat.
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Affiliation(s)
- Xian Zou
- College of Animal Science, South China Agricultural University, Wushan Rd., Tianhe Dist, Guangzhou, 510642, Guangdong Province, China.,State Key Laboratory of Livestock and Poultry Breeding, Guangdong Key Laboratory of Animal Breeding and Nutrition, Guangdong Public Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Tingting Lu
- College of Animal Science, South China Agricultural University, Wushan Rd., Tianhe Dist, Guangzhou, 510642, Guangdong Province, China
| | - Zhifeng Zhao
- College of Animal Science, South China Agricultural University, Wushan Rd., Tianhe Dist, Guangzhou, 510642, Guangdong Province, China
| | - Guangbin Liu
- College of Animal Science, South China Agricultural University, Wushan Rd., Tianhe Dist, Guangzhou, 510642, Guangdong Province, China
| | - Zhiquan Lian
- College of Animal Science, South China Agricultural University, Wushan Rd., Tianhe Dist, Guangzhou, 510642, Guangdong Province, China
| | - Yongqing Guo
- College of Animal Science, South China Agricultural University, Wushan Rd., Tianhe Dist, Guangzhou, 510642, Guangdong Province, China
| | - Baoli Sun
- College of Animal Science, South China Agricultural University, Wushan Rd., Tianhe Dist, Guangzhou, 510642, Guangdong Province, China
| | - Dewu Liu
- College of Animal Science, South China Agricultural University, Wushan Rd., Tianhe Dist, Guangzhou, 510642, Guangdong Province, China
| | - Yaokun Li
- College of Animal Science, South China Agricultural University, Wushan Rd., Tianhe Dist, Guangzhou, 510642, Guangdong Province, China.
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16
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Jonczyk AW, Piotrowska-Tomala KK, Kordowitzki P, Skarzynski DJ. Effects of prostaglandin F 2α on angiogenic and steroidogenic pathways in the bovine corpus luteum may depend on its route of administration. J Dairy Sci 2019; 102:10573-10586. [PMID: 31521364 DOI: 10.3168/jds.2019-16644] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 07/24/2019] [Indexed: 12/13/2022]
Abstract
Prostaglandin (PG) F2α and its analogs (aPGF2α) are used to induce regression of the corpus luteum (CL); their administration during the middle stage of the estrous cycle causes luteolysis in cattle. However, the bovine CL is resistant to the luteolytic actions of aPGF2α in the early stage of the estrous cycle. The mechanisms underlying this differential luteal sensitivity, as well as acquisition of luteolytic sensitivity by the CL, are still not fully understood. Therefore, to characterize possible differences in response to aPGF2α administration, we aimed to determine changes in expression of genes related to (1) angiogenesis-fibroblast growth factor 2 (FGF2), fibroblast growth factor receptor 1 (FGFR1), fibroblast growth factor receptor 2 (FGFR2), vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor receptor 1 (VEGFR1), vascular endothelial growth factor receptor 2 (VEGFR2); and (2) steroidogenesis-steroidogenic acute regulatory protein (STAR), cytochrome P450 family 11 subfamily A member 1 (P450scc), and hydroxy-delta-5-steroid dehydrogenase, 3 β- and steroid delta-isomerase 1 (HSD3B) in early- and middle-stage CL that accompany local (intra-CL) versus systemic (i.m.) aPGF2α injection. Cows at d 4 (early stage) or d 10 (middle stage) of the estrous cycle were treated as follows: (1) systemic saline injection, (2) systemic aPGF2α injection (25 mg), (3) local saline injection, and (4) local aPGF2α injection (2.5 mg). Progesterone (P4) concentration was measured in jugular vein blood samples during the entire set of experiments. After 4 h of treatment, CL were collected by ovariectomy, and mRNA and protein expression levels were determined by reverse transcription quantitative-PCR and Western blotting, respectively. Local and systemic aPGF2α injections upregulated FGF2 expression but decreased expression of VEGFA in both CL stages. Both aPGF2α injections increased the expression of STAR in early-stage CL, but downregulated it in middle-stage CL. In the early-stage CL, local administration of aPGF2α upregulated HSD3B, whereas systemic injection decreased its mRNA expression in early- and middle-stage CL. Moreover, we observed a decrease in the P4 level earlier after local aPGF2α injection than after systemic administration. These results indicate that aPGF2α acting locally may play a luteotrophic role in early-stage CL. The systemic effect of aPGF2α on the mRNA expression of genes participating in steroidogenesis seems to be more substantial than its local effect in middle-stage CL.
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Affiliation(s)
- A W Jonczyk
- Department of Reproductive Immunology and Pathology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, 10-748 Olsztyn, Poland
| | - K K Piotrowska-Tomala
- Department of Reproductive Immunology and Pathology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, 10-748 Olsztyn, Poland.
| | - P Kordowitzki
- Department of Reproductive Immunology and Pathology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, 10-748 Olsztyn, Poland
| | - D J Skarzynski
- Department of Reproductive Immunology and Pathology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, 10-748 Olsztyn, Poland
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17
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Abedel-Majed MA, Romereim SM, Davis JS, Cupp AS. Perturbations in Lineage Specification of Granulosa and Theca Cells May Alter Corpus Luteum Formation and Function. Front Endocrinol (Lausanne) 2019; 10:832. [PMID: 31849844 PMCID: PMC6895843 DOI: 10.3389/fendo.2019.00832] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 11/14/2019] [Indexed: 12/31/2022] Open
Abstract
Anovulation is a major cause of infertility, and it is the major leading reproductive disorder in mammalian females. Without ovulation, an oocyte is not released from the ovarian follicle to be fertilized and a corpus luteum is not formed. The corpus luteum formed from the luteinized somatic follicular cells following ovulation, vasculature cells, and immune cells is critical for progesterone production and maintenance of pregnancy. Follicular theca cells differentiate into small luteal cells (SLCs) that produce progesterone in response to luteinizing hormone (LH), and granulosa cells luteinize to become large luteal cells (LLCs) that have a high rate of basal production of progesterone. The formation and function of the corpus luteum rely on the appropriate proliferation and differentiation of both granulosa and theca cells. If any aspect of granulosa or theca cell luteinization is perturbed, then the resulting luteal cell populations (SLC, LLC, vascular, and immune cells) may be reduced and compromise progesterone production. Thus, many factors that affect the differentiation/lineage of the somatic cells and their gene expression profiles can alter the ability of a corpus luteum to produce the progesterone critical for pregnancy. Our laboratory has identified genes that are enriched in somatic follicular cells and luteal cells through gene expression microarray. This work was the first to compare the gene expression profiles of the four somatic cell types involved in the follicle-to-luteal transition and to support previous immunofluorescence data indicating theca cells differentiate into SLCs while granulosa cells become LLCs. Using these data and incorporating knowledge about the ways in which luteinization can go awry, we can extrapolate the impact that alterations in the theca and granulosa cell gene expression profiles and lineages could have on the formation and function of the corpus luteum. While interactions with other cell types such as vascular and immune cells are critical for appropriate corpus luteum function, we are restricting this review to focus on granulosa, theca, and luteal cells and how perturbations such as androgen excess and inflammation may affect their function and fertility.
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Affiliation(s)
| | - Sarah M. Romereim
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - John S. Davis
- Department of Obstetrics and Gynecology, Olson Center for Women's Health, University of Nebraska Medical Center, Omaha, NE, United States
- VA Nebraska-Western Iowa Health Care System, Omaha, NE, United States
| | - Andrea S. Cupp
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE, United States
- *Correspondence: Andrea S. Cupp
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18
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Verma AD, Panigrahi M, Baba NA, Sulabh S, Sadam A, Parida S, Narayanan K, Sonwane AA, Bhushan B. Differential expression of ten candidate genes regulating prostaglandin action in reproductive tissues of buffalo during estrous cycle and pregnancy. Theriogenology 2018; 105:7-14. [DOI: 10.1016/j.theriogenology.2017.09.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 08/16/2017] [Accepted: 09/06/2017] [Indexed: 01/08/2023]
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19
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Talbott H, Hou X, Qiu F, Zhang P, Guda C, Yu F, Cushman RA, Wood JR, Wang C, Cupp AS, Davis JS. Early transcriptome responses of the bovine midcycle corpus luteum to prostaglandin F2α includes cytokine signaling. Mol Cell Endocrinol 2017; 452:93-109. [PMID: 28549990 PMCID: PMC7388008 DOI: 10.1016/j.mce.2017.05.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/17/2017] [Accepted: 05/18/2017] [Indexed: 12/16/2022]
Abstract
In ruminants, prostaglandin F2alpha (PGF2α)-mediated luteolysis is essential prior to estrous cycle resumption, and is a target for improving fertility. To deduce early PGF2α-provoked changes in the corpus luteum a short time-course (0.5-4 h) was performed on cows at midcycle. A microarray-determined transcriptome was established and examined by bioinformatic pathway analysis. Classic PGF2α effects were evident by changes in early response genes (FOS, JUN, ATF3) and prediction of active pathways (PKC, MAPK). Several cytokine transcripts were elevated and NF-κB and STAT activation were predicted by pathway analysis. Self-organizing map analysis grouped differentially expressed transcripts into ten mRNA expression patterns indicative of temporal signaling cascades. Comparison with two analogous datasets revealed a conserved group of 124 transcripts similarly altered by PGF2α treatment, which both, directly and indirectly, indicated cytokine activation. Elevated levels of cytokine transcripts after PGF2α and predicted activation of cytokine pathways implicate inflammatory reactions early in PGF2α-mediated luteolysis.
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Affiliation(s)
- Heather Talbott
- Olson Center for Women's Health/Obstetrics and Gynecology Department, University of Nebraska Medical Center, 989450 Nebraska Medical Center, Omaha, NE 68198-9450, USA; Biochemistry and Molecular Biology Department, University of Nebraska Medical Center, 985870 Nebraska Medical Center, Omaha, NE 68198-5870, USA.
| | - Xiaoying Hou
- Olson Center for Women's Health/Obstetrics and Gynecology Department, University of Nebraska Medical Center, 989450 Nebraska Medical Center, Omaha, NE 68198-9450, USA.
| | - Fang Qiu
- Biostatistics Department, University of Nebraska Medical Center, 984375 Nebraska Medical Center, Omaha, NE 68198-4375, USA.
| | - Pan Zhang
- Olson Center for Women's Health/Obstetrics and Gynecology Department, University of Nebraska Medical Center, 989450 Nebraska Medical Center, Omaha, NE 68198-9450, USA.
| | - Chittibabu Guda
- Department of Genetics, Cell Biology and Anatomy, Bioinformatics and Systems Biology Core, University of Nebraska Medical Center, 985805 Nebraska Medical Center, Omaha, NE 68198-5805, USA.
| | - Fang Yu
- Biostatistics Department, University of Nebraska Medical Center, 984375 Nebraska Medical Center, Omaha, NE 68198-4375, USA.
| | - Robert A Cushman
- Nutrition and Environmental Management Research Unit, United States Department of Agriculture, P.O. Box 166 (State Spur 18D)/USDA-ARS-PA-USMARC, Clay Center, NE 68933, USA.
| | - Jennifer R Wood
- Animal Science Department, University of Nebraska-Lincoln, P.O. Box 830908, C203 ANSC, Lincoln, NE 68583-0908, USA.
| | - Cheng Wang
- Olson Center for Women's Health/Obstetrics and Gynecology Department, University of Nebraska Medical Center, 989450 Nebraska Medical Center, Omaha, NE 68198-9450, USA.
| | - Andrea S Cupp
- Animal Science Department, University of Nebraska-Lincoln, P.O. Box 830908, C203 ANSC, Lincoln, NE 68583-0908, USA.
| | - John S Davis
- Olson Center for Women's Health/Obstetrics and Gynecology Department, University of Nebraska Medical Center, 989450 Nebraska Medical Center, Omaha, NE 68198-9450, USA; Biochemistry and Molecular Biology Department, University of Nebraska Medical Center, 985870 Nebraska Medical Center, Omaha, NE 68198-5870, USA; Veterans Affairs Medical Center, 4101 Woolworth Ave, Omaha, NE 68105, USA.
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20
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Waclawik A, Kaczmarek MM, Blitek A, Kaczynski P, Ziecik AJ. Embryo-maternal dialogue during pregnancy establishment and implantation in the pig. Mol Reprod Dev 2017. [DOI: 10.1002/mrd.22835] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Agnieszka Waclawik
- Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn Poland
| | - Monika M. Kaczmarek
- Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn Poland
| | - Agnieszka Blitek
- Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn Poland
| | - Piotr Kaczynski
- Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn Poland
| | - Adam J. Ziecik
- Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn Poland
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21
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Walusimbi SS, Wetzel LM, Townson DH, Pate JL. Isolation of luteal endothelial cells and functional interactions with T lymphocytes. Reproduction 2017; 153:519-533. [PMID: 28174320 DOI: 10.1530/rep-16-0578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/13/2017] [Accepted: 02/07/2017] [Indexed: 12/23/2022]
Abstract
The objectives of this study were to optimize the isolation of luteal endothelial cells (LEC) and examine their functional interactions with autologous T lymphocytes. Analysis by flow cytometry showed that the purity of LEC isolated by filtration was nearly 90% as indicated by Bandeiraea simplicifolia (BS)-1 lectin binding. LEC expressed mRNA for progesterone receptor (PGR), prostaglandin receptors (PTGFR, PTGER2 and 4, and PTGIR), tumor necrosis factor receptors (TNFRSF1A&B) and interleukin (IL) 1B receptors (IL1R1&2). LEC were pretreated with either vehicle, progesterone (P4; 0-20 µM), prostaglandin (PG) E2 or PGF2α (0-0.2 µM), and further treated with or without TNF and IL1B (50 ng/mL each). LEC were then incubated with autologous T lymphocytes in an adhesion assay. Fewer lymphocytes adhered to LEC after exposure to high compared to low P4 concentrations (cubic response; P < 0.05). In contrast, 0.2 µM PGE2 and PGF2α each increased T lymphocyte adhesion in the absence of cytokines (P < 0.05). LEC induced IL2 receptor alpha (CD25) expression and proliferation of T lymphocytes. In conclusion, filtration is an effective way of isolating large numbers of viable LEC. It is proposed that PGs and P4 modulate the ability of endothelial cells to bind T lymphocytes, potentially regulating extravasation, and that LEC activate T lymphocytes migrating into or resident in the CL.
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Affiliation(s)
- S S Walusimbi
- Department of Animal ScienceCenter for Reproductive Biology and Health, Pennsylvania State University, University Park, Pennsylvania, USA
| | - L M Wetzel
- Department of Animal ScienceCenter for Reproductive Biology and Health, Pennsylvania State University, University Park, Pennsylvania, USA
| | - D H Townson
- Department of Animal and Veterinary SciencesUniversity of Vermont, Burlington, Vermont, USA
| | - J L Pate
- Department of Animal ScienceCenter for Reproductive Biology and Health, Pennsylvania State University, University Park, Pennsylvania, USA
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22
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Lüttgenau J, Lingemann B, Wellnitz O, Hankele A, Schmicke M, Ulbrich S, Bruckmaier R, Bollwein H. Repeated intrauterine infusions of lipopolysaccharide alter gene expression and lifespan of the bovine corpus luteum. J Dairy Sci 2016; 99:6639-6653. [DOI: 10.3168/jds.2015-10806] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/28/2016] [Indexed: 12/25/2022]
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23
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Przygrodzka E, Kaczmarek MM, Kaczynski P, Ziecik AJ. Steroid hormones, prostanoids, and angiogenic systems during rescue of the corpus luteum in pigs. Reproduction 2015; 151:135-47. [PMID: 26577025 DOI: 10.1530/rep-15-0332] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 11/16/2015] [Indexed: 01/07/2023]
Abstract
In order to characterize the transition of the corpora lutea (CL) from acquisition of luteolytic sensitivity to rescue of luteal function: i) the expression of 38 factors associated with steroids, prostanoids, and angiogenic systems and ii) concentrations of the main hormones responsible for maintenance of CL function in cyclic and pregnant pigs were examined. Additionally, the effect of prostaglandin (PG) E2 and F2 α on luteal function during the estrous cycle and pregnancy was evaluated in vitro. Significantly up-regulated gene expression was revealed in CL collected on day 14 of the estrous cycle (CYP19A1, ESR2, PTGS2, HIF1A, and EDN1) and on days 12-14 of pregnancy (SCARB1, PGRMC1, STAR, HSD3B1, NR5A1, PTGFR, PTGER4, and VEGFA). Elevated concentrations of estradiol-17β and PGE2 occurred in CL on days 12 and 14 of pregnancy respectively, while an increased intraluteal PGF2 α content was noted on day 14 of the estrous cycle. Both PGs increased the synthesis of progesterone by cultured luteal slices obtained on day 14 of pregnancy, in contrast to the action of PGF2 α on the corresponding day of the estrous cycle. PGE2 stimulated cAMP production via PTGER2 and PTGER4, while PGF2 α elevated the content of CREB in cultured luteal slices from CL of pregnant pigs. In silico analysis showed that infiltration of lymphocytes and apoptosis of microvascular endothelium were activated in CL on day 12 of the estrous cycle vs pregnancy. Summarizing, an abundance of E2 and PGE2 during pregnancy regulates specific pathways responsible for steroidogenesis, the prostanoid signaling system and angiogenesis during rescue from luteolysis in porcine CL.
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Affiliation(s)
- E Przygrodzka
- Department of Hormonal Action Mechanisms and Molecular Biology LaboratoryInstitute of Animal Reproduction and Food Research of the Polish Academy of Sciences (IARFR PAS), Tuwima 10, 10-748 Olsztyn, Poland
| | - M M Kaczmarek
- Department of Hormonal Action Mechanisms and Molecular Biology LaboratoryInstitute of Animal Reproduction and Food Research of the Polish Academy of Sciences (IARFR PAS), Tuwima 10, 10-748 Olsztyn, Poland
| | - P Kaczynski
- Department of Hormonal Action Mechanisms and Molecular Biology LaboratoryInstitute of Animal Reproduction and Food Research of the Polish Academy of Sciences (IARFR PAS), Tuwima 10, 10-748 Olsztyn, Poland
| | - A J Ziecik
- Department of Hormonal Action Mechanisms and Molecular Biology LaboratoryInstitute of Animal Reproduction and Food Research of the Polish Academy of Sciences (IARFR PAS), Tuwima 10, 10-748 Olsztyn, Poland
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24
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de Moraes CN, Maia L, de Lima PF, Dias MC, Raposo-Ferreira TMM, Sudano MJ, Junior JB, Oba E. Temporal analysis of prostaglandin F2α receptor, caspase 3, and cyclooxygenase 2 messenger RNA expression and prostaglandin F2α receptor and cyclooxygenase 2 protein expression in endometrial tissue from multiparous Nelore (Bos taurus indicus) cows treated with cloprostenol sodium during puerperium. Theriogenology 2014; 83:276-84. [PMID: 25442016 DOI: 10.1016/j.theriogenology.2014.09.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 09/15/2014] [Accepted: 09/15/2014] [Indexed: 10/24/2022]
Abstract
The use of cloprostenol sodium in puerperium is questionable, as both favorable and unfavorable responses during the uterine involution process have been reported in the literature. This study is based on the hypothesis that cloprostenol sodium promotes modifications in the prostaglandin F2α receptor (FP), caspase 3 (CASP-3), and cyclooxygenase 2 (COX-2) mRNA expression that may favor the process of postpartum uterine involution in multiparous Nelore (Bos taurus indicus) females. Additionally, we aimed to describe the presence and immunolocalization of the FP and COX-2 protein in endometrial tissue at different postpartum time points in these females. Multiparous Nelore cows (n = 24) were treated with cloprostenol sodium (n = 12) or saline solution (n = 12) on postpartum Days 1 and 4 (Day 0 = birth), and endometrial biopsies were performed with a Yomann biopsy instrument and collected on Days 1, 7, 14, 28, and 42 postpartum. The mRNA expression from samples on the Days 1, 7, 14, 28, and 42 and the protein expression from samples on the Days 1, 14, 28, and 42 were then analyzed. The treated cows had altered FP and CASP-3 mRNA expression, and FP and COX-2 protein were observed in the endometrial surface epithelium, the stroma, and the glandular epithelium, with cytoplasmic immunolocalization. Although we attribute the change in CASP-3 mRNA expression to physiological phenomena, the results obtained for FP mRNA expression opens new doors for the study of hormonal protocols associated with cloprostenol sodium in the puerperium of Zebu females.
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Affiliation(s)
- Carolina N de Moraes
- Department of Animal Reproduction and Radiology, São Paulo State University-UNESP, Botucatu, São Paulo, Brazil.
| | - Leandro Maia
- Department of Animal Reproduction and Radiology, São Paulo State University-UNESP, Botucatu, São Paulo, Brazil
| | - Paula F de Lima
- Department of Pharmacology, Biosciences Institute, São Paulo State University-UNESP, Botucatu, São Paulo, Brazil
| | - Marianne C Dias
- Department of Animal Reproduction and Radiology, São Paulo State University-UNESP, Botucatu, São Paulo, Brazil
| | | | - Mateus J Sudano
- Laboratory of Genetics and Animal Breeding, Federal University of Pampa-UNIPAMPA, Uruguaiana, Rio Grande do Sul, Brazil
| | - José B Junior
- Department of Pharmacology, Biosciences Institute, São Paulo State University-UNESP, Botucatu, São Paulo, Brazil
| | - Eunice Oba
- Department of Animal Reproduction and Radiology, São Paulo State University-UNESP, Botucatu, São Paulo, Brazil
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25
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Mao D, Hou X, Talbott H, Cushman R, Cupp A, Davis JS. ATF3 expression in the corpus luteum: possible role in luteal regression. Mol Endocrinol 2013; 27:2066-79. [PMID: 24196350 DOI: 10.1210/me.2013-1274] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The present study investigated the induction and possible role of activating transcription factor 3 (ATF3) in the corpus luteum. Postpubertal cattle were treated at midcycle with prostaglandin F2α(PGF) for 0-4 hours. Luteal tissue was processed for immunohistochemistry, in situ hybridization, and isolation of protein and RNA. Ovaries were also collected from midluteal phase and first-trimester pregnant cows. Luteal cells were prepared and sorted by centrifugal elutriation to obtain purified small (SLCs) and large luteal cells (LLCs). Real-time PCR and in situ hybridization showed that ATF3 mRNA increased within 1 hour of PGF treatment in vivo. Western blot and immunohistochemistry demonstrated that ATF3 protein was expressed in the nuclei of LLC within 1 hour and was maintained for at least 4 hours. PGF treatment in vitro increased ATF3 expression only in LLC, whereas TNF induced ATF3 in both SLCs and LLCs. PGF stimulated concentration- and time-dependent increases in ATF3 and phosphorylation of MAPKs in LLCs. Combinations of MAPK inhibitors suppressed ATF3 expression in LLCs. Adenoviral-mediated expression of ATF3 inhibited LH-stimulated cAMP response element reporter luciferase activity and progesterone production in LLCs and SLCs but did not alter cell viability or change the expression or activity of key regulators of progesterone synthesis. In conclusion, the action of PGF in LLCs is associated with the rapid activation of stress-activated protein kinases and the induction of ATF3, which may contribute to the reduction in steroid synthesis during luteal regression. ATF3 appears to affect gonadotropin-stimulated progesterone secretion at a step or steps downstream of PKA signaling and before cholesterol conversion to progesterone.
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Affiliation(s)
- Dagan Mao
- Olson Center for Women's Health, Department of Obstetrics/Gynecology, Nebraska Medical Center, Omaha, NE 68198.
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26
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Skarzynski DJ, Piotrowska-Tomala KK, Lukasik K, Galvão A, Farberov S, Zalman Y, Meidan R. Growth and Regression in Bovine Corpora Lutea: Regulation by Local Survival and Death Pathways. Reprod Domest Anim 2013; 48 Suppl 1:25-37. [DOI: 10.1111/rda.12203] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Accepted: 05/20/2013] [Indexed: 11/30/2022]
Affiliation(s)
- DJ Skarzynski
- Department of Reproductive Immunology and Pathology; Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn; Poland
| | - KK Piotrowska-Tomala
- Department of Reproductive Immunology and Pathology; Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn; Poland
| | - K Lukasik
- Department of Reproductive Immunology and Pathology; Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn; Poland
| | - A Galvão
- Department of Reproductive Immunology and Pathology; Institute of Animal Reproduction and Food Research; Polish Academy of Sciences; Olsztyn; Poland
| | - S Farberov
- Department of Animal Sciences; The Robert H. Smith Faculty of Agriculture, Food and Environment; The Hebrew University of Jerusalem; Rehovot; Israel
| | - Y Zalman
- Department of Animal Sciences; The Robert H. Smith Faculty of Agriculture, Food and Environment; The Hebrew University of Jerusalem; Rehovot; Israel
| | - R Meidan
- Department of Animal Sciences; The Robert H. Smith Faculty of Agriculture, Food and Environment; The Hebrew University of Jerusalem; Rehovot; Israel
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27
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Ginther OJ. Pitfalls in animal reproduction research: how the animal guards nature's secrets. Theriogenology 2013; 80:169-75. [PMID: 23664796 DOI: 10.1016/j.theriogenology.2013.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 04/05/2013] [Accepted: 04/09/2013] [Indexed: 01/18/2023]
Abstract
The estrous cycles of heifers and mares are used for illustrating pitfalls at the animal level in research in reproductive biology. Infrequent monitoring for characterizing the change in hormone concentrations or for detecting a reproductive event can be a pitfall when the interval for obtaining data exceeds the interval between events. For example, hourly collection of blood samples has shown that the luteolytic period (decreasing progesterone) encompasses 24 hours in heifers and mares. Collection of samples every 6-24 hours results in the illusion that luteolysis requires 2-3 days, owing to the occurrence of luteolysis on different days in individuals. A single treatment with PGF2α that causes complete regression of the corpus luteum is an example of an overdose pitfall. A nonphysiological progesterone increase occurs and will be misleading if used for making interpretations on the nature of luteolysis. A pitfall can also occur if a chosen reference point or end point is a poor representation of a physiological event. For example, if on a selected day after ovulation the animals in treatment A are closer on average to luteolysis than animals in treatment B, treatment A will appear to have had an earlier luteolytic effect. Among the techniques that are used directly in the animal, ultrasonography appears to be most prone to research pitfalls. Research during a given month can be confounded by seasonal effects, even in species that ovulate throughout the year. The presence of unknown factors or complex interactions among factors and the sensitivity of the animal to a research procedure separate from the direct effect of a treatment are also research challenges. A hidden factor should be considered nature's challenge to open-minded biologists but a pitfall for the close-minded.
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Affiliation(s)
- O J Ginther
- Eutheria Foundation, Cross Plains, Wisconsin, USA.
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