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- Hosokawa, K, et al.
(författare)
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Dominant expression and distribution of oestrogen receptor beta over oestrogen receptor alpha in the human corpus luteum
- 2001
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Ingår i: Molecular human reproduction. - : Oxford University Press (OUP). - 1360-9947 .- 1460-2407. ; 7:2, s. 137-145
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the potential importance of oestrogen as a local regulator of human corpus luteum function, the mRNA expression pattern and cellular localization of oestrogen receptors (ERs), ER-alpha and ER-beta, were studied in corpora lutea grouped according to age, where days 2-5 post-LH rise were designated as the early luteal phase, days 6-10 as mid-luteal and days 11-14 as the late luteal phase respectively. Northern blot analysis using an ER-beta probe in samples from whole ovarian tissue and isolated corpora lutea, revealed a major band at 7.5 kb and several minor bands between 4-10 kb, while no signals for ER-alpha mRNA were obtained. However, using a semi-quantitative reverse transcription-polymerase chain reaction followed by Southern blotting, ER-beta mRNA levels were found to be 63% lower (P: < 0.05, n = 39) in the mid-luteal phase compared with the early luteal phase, while ER-alpha mRNA expression showed no statistical differences between the different age groups. Using in-situ hybridization, ER-beta mRNA expression was localized to the steroidogenic luteal cells as well as perivascular cells and fibroblasts in the corpus luteum. Immunohistochemistry confirmed the localization of ER-beta protein, but no clear staining of luteal cells was found using antibodies against ER-alpha. Collectively, the findings of low to moderate expression of ER-beta mRNA and protein in the steroidogenic cells, and also in vascular endothelial cells of the corpus luteum, as opposed to diminutive amounts of ER-alpha mRNA, suggest that oestrogen activity is primarily transduced via ER-beta in the human corpus luteum.
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| 2. |
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| 3. |
- Ottander, Ulrika, et al.
(författare)
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A putative stimulatory role of progesterone acting via progesterone receptors in the steroidogenic cells of the human corpus luteum
- 2000
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Ingår i: Biology of Reproduction. - : Oxford University Press. - 0006-3363 .- 1529-7268. ; 62:3, s. 655-663
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Tidskriftsartikel (refereegranskat)abstract
- To further explore the proposed auto-regulatory role of progesterone action in the human corpus luteum (CL), the expression and functional roles of progesterone receptor (PR) isoforms A and B during the luteal phase (LP) of the menstrual cycle were investigated. A total of 27 otherwise healthy patients previously scheduled for surgery were recruited after informed consent. An LH rise was detected, and CL were grouped according to age (Days 2-5 post-LH-rise, early LP; Days 6-10, mid LP; Days 11-14, late LP). Using a semiquantitative reverse transcription-polymerase chain reaction assay, the PR-B mRNA levels, which were 100- to 1000-fold lower than PR-A/B mRNA, were 46% lower (P < 0.05, n = 24) in mid LP, compared to early and late LP. CL tissue levels of progesterone and PR-A/B protein levels were inversely correlated to increasing CL age; i.e., significantly reduced levels were observed in the late LP (r(2) = 0.34, P < 0.01, n = 23). Expression of PR-A/B mRNA as well as PR-A/B protein were detected by in situ hybridization and immunohistochemistry, respectively. Both methods revealed a clear and distinct localization to cells in the steroidogenic layer of the CL. Freshly obtained mid-luteal CL cells were cultured in vitro, and media were analyzed for progesterone concentrations after treatment by incremental doses of hCG and the stable PR antagonist mifepristone, alone or in combination. Mifepristone did not per se alter progesterone synthesis, but when it was added in conjunction with hCG, a dose-related inhibitory response was seen, with a maximal 47% reduction in progesterone output at a 10 microM addition (P < 0.05, n = 3). Collectively, these data implicate a stimulatory role of progesterone receptor-mediated action in the steroidogenic cells of the human CL, which may serve as an important pathway for maintaining functional homeostasis during early pregnancy.
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| 4. |
- Ottander, Ulrika, et al.
(författare)
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Intraovarian blood flow measured with color doppler ultrasonography inversely correlates with vascular density in the human corpus luteum of the menstrual cycle
- 2004
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Ingår i: Fertility and Sterility. - : Elsevier BV. - 0015-0282 .- 1556-5653. ; 81:1, s. 154-159
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Tidskriftsartikel (refereegranskat)abstract
- Objective To evaluate the morphologic characteristics underlying the ultrasonographic appearance and blood flow dynamics in the human corpus luteum (CL) of the menstrual cycle. Design Cross-sectional study. Setting Umeå University Hospital, Umeå, Sweden. Patient(s) Twenty-six otherwise healthy women with proven fertility and a history of regular menstrual cycles, scheduled for elective hysterectomy or tubal sterilization. Intervention(s) An ovulatory LH rise in urine was established and the CL age was determined according to the day after the LH rise. Before surgery, a standardized ultrasonographic examination of the CL, including B-mode and color Doppler ultrasonography measurements, was performed. Upon commencing the minilaparotomy, the CL was excised and measured using a digital slide-caliper. The volume density (percentage of CL volume occupied by blood vessels) of factor VIII–related antigen immunostained endothelial cells was determined. Main outcome measure(s) Pulsatility index obtained from intraovarian blood vessels supplying the CL and volume density of blood vessels in CL tissue. The CL maximal and minimal outer and inner dimensions were measured in vivo by ultrasonography and ex vivo by a digital slide caliper. Result(s) A statistically significant decrease of blood vessel density and an increased resistance to blood flow, as indicated by pulsatility index, was established during the course of corpus luteum development. An inverse correlation between pulsatility index and volume density of blood vessels was found. A high degree of agreement between ultrasonographic and anatomic measurements of surgically removed CL was found. Conclusion(s) Transvaginal ultrasonography in combination with intraovarian color Doppler flow measurements is a simple and reliable method to evaluate the size and vascularization of the human CL.
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| 5. |
- Ottander, Ulrika
(författare)
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Intraovarian mechanisms influencing the human corpus luteum
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: The human corpus luteum (CL) is a transient endocrine gland, only functionally active for about 14 days. Its principal function is to produce and secrete progesterone and thereby support the endometrium for implantation of a blastocyst and prevent rejection of the developing embryo. In the event of a non-conceptive cycle, functional and structural demise of the CL follows and a new ovulatory cycle begins. The aims of the thesis were to study different mechanisms involved in the extrinsic and intrinsic regulation of the CL and correlate these findings to available clinical investigations tools. Materials and methods: Sixty women volunteered to donate their CL prior to scheduled surgery due to benign conditions. They were grouped according to CL-age, based on the occurrence of a preovulatory luteinizing hormone (LH) surge where days 2-5 post LH surge were designated as early luteal phase, days 6-9 as mid luteal phase and days 11-14 as late luteal phase. The CL bearing ovary was investigated using transvaginal ultrasonographical B-mode and color Doppler imaging prior to surgery. Following excision, the CL was further characterized using anatomical and morphological measurements, in vivo and in vitro hormone synthesis, isolation and cultures of steroidogenic luteal cells. Moreover, active transcription of putative regulatory genes of interest was targeted using semi-quantitative reverse-transcription polymerase chain reaction, in situ hybridization and Northern blots, and these genes' respective translation products were characterized by immunocytochemistry. Results: The bulk of progesterone is stimulated by human chorionic gonadotropin (hCG) in the peripheral (steroidogenic) layer of the CL, where the LH/hCG receptor, as well as progesterone receptor (PR) isoform A/B and estrogen receptor type β (ER-β), but not ER-α, was localized. The sesitivity towards hCG was highest during the mid luteal phase in concordance with the value of LH/hCG receptor coding mRNAs. During this phase, despite low levels of PR-B mRNA, hCG treatment initiated a significant rise in progesterone output which could be blunted by the PR antagonist mifepristone. Increased amounts of prostaglandin (PG) F2α and its respective receptor (FP) mRNA were detected during the later developmental stages of the CL. However, steroidogenic luteal cells were unresponsive to added PGF2α until late luteal phase, indicative of an acquisition of sensitivity to the proposed luteolytic signal during this stage. Intraluteal vascular density was highest in early luteal phase and dramatically decreased during the course of CL development, a finding which was inversely correlated to resistance to blood flow in intraovarian blood vessels supplying the CL. Furthermore, a high degree of agreement between ultrasonographical and anatomical measurements of the CL was found. Conclusions: Based on the novel findings herein, the hypothesis of steroid influence, acting within or near the steroidogenic luteal cells is confirmed. Alongside the classical extrinsic signals (e.g. hCG) and locally produced factors (e.g. PGF2α) these findings may further explain their modulatory roles during luteolysis or very early pregnancy. Furthermore, transvaginal ultrasonography in combination with color Doppler measurements may serve as a clinical tool to evaluate CL function.
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| 6. |
- Vaskivuo, Tommi E, et al.
(författare)
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Role of apoptosis, apoptosis-related factors and 17beta-hydroxysteroid dehydrogenases in human corpus luteum regression
- 2002
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Ingår i: Molecular and Cellular Endocrinology. - 0303-7207 .- 1872-8057. ; 194:1-2, s. 191-200
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Tidskriftsartikel (refereegranskat)abstract
- The human corpus luteum (CL) is a transient endocrine organ with a life span of 14-16 days. Apoptosis has been suggested to be the mechanism of CL regression and the possible regulatory role of the bcl-2 family in this process has been studied in animals and, to some extent, in humans. In the present study, apoptosis was studied in the human CL and in luteinised granulosa cells by in situ 3'-end labelling and gel electrophoretic DNA fragmentation analysis. The apoptosis-regulating factors Bcl-2, Bax and TNF-alpha, transcription factor NF-kappaB and Caspase-3, a key executioner protein in apoptotic cell death, were studied by immunohistochemistry and in situ hybridisation. Furthermore, we analysed expression of 17beta hydroxysteroid dehydrogenase (17HSD) type 1 and 2, key enzymes in the estrogen metabolism. Apoptosis was found in the CL throughout the luteal phase, but a marked increase of apoptotic luteal cells was observed during the late luteal phase (CL day 11-14). This was preceded by a clear increase of 17HSD type 1 expression. The apoptosis-regulating proteins Bcl-2 and Bax were expressed constantly in the CL throughout the luteal phase. TNF-alpha expression was constant during the early and mid-luteal phases, but in the late luteal phase, some specimens showed increased immunostaining. NF-kappaB and Caspase-3 were present in the CL throughout the luteal phase and in individual specimens, the expression of Caspase-3 was associated with a high rate of apoptosis in the late luteal phase. In conclusion, apoptosis is involved in human luteal regression and estradiol (E(2)) may function as a trigger for this process. The expression of the pro- and anti-apoptotic factors studied in the CL suggest their part in this process, but the conclusive evidence for the exact molecular mechanisms remains open.
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