Immunocytochemical localization of relaxin in human corpora lutea: cellular and subcellular distribution and dependence on reproductive state

Relaxin is one of the hormones present during pregnancy and it is synthesized primarily by corpora lutea (CL). Other reproductive tissues including CL of the menstrual cycle may also synthesize this hormone. Very little is known, however, about the cellular and subcellular distribution of relaxin in human CL and dependence of luteal relaxin on the reproductive state. The light and electron microscope immunocytochemical studies described here were undertaken to obtain this information using antisera to porcine and human relaxin. Immunostaining was found in large luteal cells (17-30 microns) but not in small luteal cells (7-16 microns) or in nonluteal cells in any of the reproductive states or in human hepatocytes. Luteal immunostaining was low in early luteal phase; it increased progressively, reaching the highest level in late luteal phase, and then decreased greatly in corpora albicantia. Term pregnancy CL contained similar immunostaining as early luteal phase CL. Mid luteal phase CL contained more immunostained cells than late luteal phase CL, but the late luteal phase CL contained a greater amount of immunostaining per cell than mid luteal phase CL. The immunogold particles due to relaxin were primarily present in secretory granules and to a small extent in rough endoplasmic reticulum. Quantitation revealed that secretory granules contained a much higher number of gold particles than did rough endoplasmic reticulum. These two organelles from late luteal phase CL contained greater numbers of gold particles than those from mid luteal phase.(ABSTRACT TRUNCATED AT 250 WORDS)     

The presence of pregnancy-associated plasma protein-A in human corpora lutea: cellular and subcellular distribution and dependence on reproductive state.

Pregnancy-associated plasma protein-A (PAPP-A) is a high-molecular-weight glycoprotein primarily secreted by syncytiotrophoblasts of human placenta. It is not known, however, whether human CL of menstrual cycle or pregnancy also contain this protein. Therefore, light and electron microscope immunocytochemical studies were undertaken to investigate the presence, cellular and subcellular distribution, and dependence of luteal PAPP-A content on reproductive state. Human CL from early, mid, and late luteal phases and from term pregnancies immunostained specifically for PAPP-A. Immunostaining was found in large luteal cells (17-30 microns) but not in small luteal cells (7-16 microns) or in nonluteal cells in any of the reproductive states. Immunostaining was not found in negative control tissues, i.e. human liver or bovine CL of pregnancy. As expected however, term-pregnancy human placenta used for a positive control tissue immunostained intensely for PAPP-A. The luteal immunostaining was highest in early luteal phase, decreased progressively from early to mid and from mid to late luteal phases, and then disappeared in corpora albicantia. The relative intensity of immunostaining in early luteal phase human CL was similar to that in term-pregnancy human placenta and higher than in term-pregnancy human CL. The immunogold particles due to PAPP-A were primarily associated with secretory granules of large luteal cells. A small number of gold particles were also found in rough endoplasmic reticulum and cytoplasm. In conclusion, human CL contain immunoreactive PAPP-A. The luteal content varies with reproductive state, with the highest amount found in early luteal phase CL.(ABSTRACT TRUNCATED AT 250 WORDS)     

Localization of estrogen and progesterone receptors in the endometrium of common marmosets Callithrix jacchus

In the present study, changes in the immunohistochemical localization of endometrial estrogen receptor (ER) and progesterone receptor (PR) during various stages of the ovarian cyclicity in common marmoset, have been reported. Ovarian cyclicity was monitored by estimating plasma estradiol and progesterone. During the early follicular phase, weak ER immunolocalization was observed in the endometrial stroma. During the late follicular phase under the influence of rising estradiol levels, stromal ER localization was intense. During the luteal phase, ER localization was absent in the stroma indicating that high concentrations of progesterone suppressed ER. PR localization was not observed in the stroma during the early follicular phase, while weak staining was seen in the stroma during the late follicular phase. PR localization was maximum during the mid luteal phase. However in marmoset, endometrial ER and PR localization was restricted only to the stroma. This unique feature may be due to the characteristic reproductive profile of this nonmenstruating species and needs to be studied further. Thus it can be hypothesized that in the marmoset endometrium, steroid hormone mediated effects possibly occur directly in the stroma and are then transmitted to the epithelium by autocrine/paracrine action of growth factors and cytokines.     

Immunohistochemical localisation of cyclooxygenase in the human uterus

The distribution in the human uterus of the enzyme cyclooxygenase, involved in prostaglandin synthesis, was studied using the peroxidase-antiperoxidase immunohistochemical technique. Specific staining was observed only during the luteal phase of the menstrual cycle. It was found that cyclooxygenase was localised in the surface and glandular epithelium of the endometrium but could not be demonstrated in the endometrial stroma, myometrium or blood vessels. The location of specific staining for cyclooxygenase and its variation during the menstrual cycle was the same regardless of the amount of menstrual blood loss. Tissue samples obtained from early pregnant and post-menopausal patients failed to exhibit any specific staining.     

Patterns of inhibin and FSH localization in endometrium of baboon (Papio anubis) during menstrual cycle and early pregnancy.

Immunoreactive 10.5 KDa moiety of inhibin and hFSH was present in the baboon endometrium during menstrual cycle, early pregnancy and in castrated animals treated with steroid hormones, estrogen and/or progesterone. Endometrial differences during the menstrual cycle altered the intensity of immunostaining of inhibin and FSH. Maximum staining was observed in late luteal phase for both the hormones. In early pregnancy (35th day), the conceptus increased the staining for inhibin in the adjoining endometrial glands. Treatment of castrated animals with steroids for 14 days caused increased staining for inhibin. Maximum staining was observed when treated with estradiol or progesterone, whereas combination of estrogen and progesterone treatment decreased the staining reaction. In conclusion, both inhibin and FSH were localized in baboon endometrium and were under the influence of estrogen and progesterone.     

Dynamics of circulating concentrations of gonadotropins and ovarian hormones throughout the menstrual cycle in the bonnet monkey: role of inhibin A in the regulation of follicle‐stimulating hormone secretion

In higher primates, increased circulating follicle‐stimulating hormone (FSH) levels seen during late menstrual cycle and during menstruation has been suggested to be necessary for initiation of follicular growth, recruitment of follicles and eventually culminating in ovulation of a single follicle. With a view to establish the dynamics of circulating FSH secretion with that of inhibin A (INH A) and progesterone (P₄) secretions during the menstrual cycle, blood was collected daily from bonnet monkeys beginning day 1 of the menstrual cycle up to 35 days. Serum INH A levels were low during early follicular phase, increased significantly coinciding with the mid cycle luteinizing hormone (LH) surge to reach maximal levels during the mid luteal phase before declining at the late luteal phase, essentially paralleling the pattern of P₄ secretion seen throughout the luteal phase. Circulating FSH levels were low during early and mid luteal phases, but progressively increased during the late luteal phase and remained high for few days after the onset of menses. In another experiment, lutectomy performed during the mid luteal phase resulted in significant decrease in INH A concentration within 2 hr (58.3±2 vs. 27.3±3 pg/mL), and a 2‐ to 3‐fold rise in circulating FSH levels by 24 hr (0.20±0.02 vs. 0.53±0.14 ng/mL) that remained high until 48 hr postlutectomy. Systemic administration of Cetrorelix (150 µg/kg body weight), a gonadotropin releasing hormone receptor antagonist, at mid luteal phase in monkeys led to suppression of serum INH A and P₄ concentrations 24 hr post treatment, but circulating FSH levels did not change. Administration of exogenous LH, but not FSH, significantly increased INH A concentration. The results taken together suggest a tight coupling between LH and INH A secretion and that INH A is largely responsible for maintenance of low FSH concentration seen during the luteal phase. Am. J. Primatol. 71:817–824, 2009. © 2009 Wiley‐Liss, Inc.     

Differential expression of Akt/protein kinase B, Bcl-2 and Bax proteins in human leiomyoma and myometrium

The expression and activation of serine/threonine protein kinase, Akt, in leiomyoma and in adjacent myometrium of human uteri was studied parallel with the changes of Bcl-2, Bax proteins, estrogen and progesterone receptors during menstrual cycle and early stage of the menopause. Abundant expression of Akt protein was detected in the studied tissues during menstrual cycle, the rate of increase was higher in leiomyoma than in corresponding myometrium. The expression of estrogen receptor alpha, progesterone receptor and of Bcl-2 protein changed parallel with that of Akt protein. The level of phosphorylated Akt (pAkt⁴⁷³) was seen only in leiomyoma samples from the growing period of tumors. At early stage of menopause levels of all studied proteins were lower than that in the menstrual cycle with the exception of Bax protein expression, which was high in leiomyoma. Our data suggest the involvement of phosphatidylinositol 3-kinase/Akt signaling in the pathomechanism of leiomyoma.     

Induction of relaxin secretion in rhesus monkeys by human chorionic gonadotropin: dependence on the age of the corpus luteum of the menstrual cycle

Peripheral concentrations of immunoreactive relaxin are undetectable in primates during the nonfertile menstrual cycle, but become measurable during the interval when chorionic gonadotropin (CG) rises in early pregnancy. The objectives of the current study were to determine if exogenous CG, administered in a dosage regimen which invoked patterns and concentrations resembling those of early pregnancy, would induce relaxin secretion in nonpregnant rhesus monkeys, and whether the induction was dependent on the age of the corpus luteum (CL) at the onset of treatment. Female rhesus monkeys received twice-daily i.m. injections of increasing doses of human CG (hCG) for 10 days beginning in the early (n = 4), mid (n = 6) or late (n = 4) luteal phase of the menstrual cycle [5.3 +/- 0.3, 8.3 +/- 0.5, and 12.0 +/- 0.4 days after the midcycle luteinizing hormone (LH) surge, respectively; means +/- SEM]. Whereas immunoreactive relaxin was nondetectable in the luteal phase of posttreatment cycles, detectable levels of relaxin were observed in 2 of 4, 5 of 6, and 3 of 4 monkeys during hCG treatment in the early, mid and late luteal phase, respectively. Although CG treatment rapidly enhance progesterone levels, the appearance of relaxin was deferred; relaxin was first detectable 9.0 +/- 1.0 and 4.7 +/- 1.9 days after the onset of CG treatment at early and late luteal phases. Patterns of relaxin concentrations differed among groups (P less than 0.05, ANOVA; split plot design) and relaxin levels were lowest (P less than 0.01) in monkeys treated during the early luteal phase.(ABSTRACT TRUNCATED AT 250 WORDS)     

月经周期对女性睡眠-觉醒和静息-活动的影响

目前有关月经周期对睡眠影响的研究结果并不一致,而对月经周期中昼夜睡眠-觉醒及静息-活动节律尚缺乏系统性的研究.本研究旨在观察正常育龄期女性月经周期中睡眠-觉醒及静息-活动昼夜节律的变化.我们采用静息-活动监测仪(actigraphy)和睡眠日志,调查了12个自然生活状态下健康育龄期妇女在月经周期不同阶段,即行经期、围排卵期、黄体早期及黄体晚期中睡眠与活动节律的变化.结果显示,睡眠-觉醒节律参数在四期之间无统计学显著差异;而静息-活动节律方面,所有受试女性静息-活动节律的平均日周期长度为(24.01±0.29)h,并且四期之间无显著性差异.行经期日间稳定系数(interdaily stability,IS)比黄体早期显著增加(P＜0.05).黄体早期日间活动开始时间明显较黄体晚期提前(P＜0.05);黄体早期的活动峰值时相比围排卵期显著提前(P＜0.05).月经周期可以影响静息-活动昼夜节律时相.而总体静息-活动数量与质量未发生显著变化;健康育龄期妇女在月经周期的各阶段中睡眠-觉醒节律亦无明显变异.     

Leukemia inhibitory factor, leukemia inhibitory factor receptor, and glycoprotein 130 in rhesus monkey uterus during menstrual cycle and early pregnancy

This goal of this study was to examine immunohistochemical distribution of leukemia inhibitory factor (LIF), LIF receptor (LIFR), and glycoprotein (gp) 130 in rhesus monkey uterus during the menstrual cycle and early pregnancy. Pregnancy rate was significantly reduced in the control group from 66.7% (12 of 18) to 22.2% (4 of 18) with an injection of goat anti-human recombinant LIF immunoglobulin G into the uterine lumen on Day 8 of pregnancy. LIF was mainly localized in glandular and luminal epithelium. LIF immunostaining during the luteal phase was stronger than it was during the proliferative phase. LIF staining gradually increased from Day 3 of pregnancy and reached its highest level on Day 9. LIFR was mainly localized in the glandular and luminal epithelium. LIFR staining during the luteal phase was stronger than it was during the proliferative phase. LIFR staining began to increase from Day 3 of pregnancy and reached a high level on Days 9 and 11. Gp130, a signal-transducing receptor component of LIF, was mainly localized in the glandular epithelium. A high level of gp130 was found on Days 16 and 20 of menstrual cycle, and from Days 5 to 11 of pregnancy. These results suggest that LIF may play an important role in monkey implantation, as it does in mice.     

Factors associated with estrogen receptors-alpha (ER-alpha) and -beta (ER-beta) and progesterone receptor abundance in obese and non obese pre- and post-menopausal women

There is scarce information about the factors associated with estrogen receptors (ER) at menopause. In 113 volunteers pre- and post-menopausal healthy women, grouped as with and without obesity, estrogen receptors-alpha and -beta, and progesterone receptor (PR) were measured by immunohistochemistry in skin punch biopsies obtained from the external gluteal area. In pre-menopausal women, biopsies and a blood sample were performed between days 7 and 14 of the cycle. Serum hormone levels were measured by immunoradiometric assay or radioimmunoassay. After menopause, ER and PR amounts decreased significantly. At pre-menopause, obese women had lower PR levels than non obese (P<.006). In the post-menopausal group, obese women showed higher ER-alpha (P<.03) and ER-beta (P<.02) levels than the non obese group. In the analysis of factors associated with the amount of steroid receptors for the total group, log[ER-alpha], log[ER-beta], and log[PR] were associated with age (P<.002, <.005, and <.004, respectively). The log[ER-alpha] was also associated with log[FSH] (P<.0008); meanwhile, the log[PR] showed a marginal correlation with log[FSH]. In pre-menopausal women no factor associated with any of the three receptors was found. In post-menopausal women log[ER-alpha] was associated with log[estrone] and log[DHEAS] (P<.003 and <.02, respectively). log[PR] was associated with BMI (P<.002), years since menopause (P<.05), and log[DHEAS] (P<.003). We concluded that ER and PR diminish sharply at post-menopause. At this stage the amount of receptors depends on several factors such as BMI, years since menopause, and androgen precursors.     

Evidence for a switch in the site of relaxin production from small theca-derived cells to large luteal cells during early pregnancy in the pig

The presence of immunoreactive relaxin was studied in corpora lutea of sows during the oestrous cycle and early pregnancy by immunohistochemistry and radioimmunoassay using three different anti-relaxin sera. Sections were immunostained using the peroxidase-anti-peroxidase or the immunogold-silver technique. Before Day 14, staining in corpora lutea from non-pregnant and pregnant animals was indistinguishable. With all antisera, no immunostaining was seen on Day 3, but was detected on Days 5-7 in cells from the theca interna. In non-pregnant animals, this immunostaining decreased and by Day 15 only an occasional large cell in the centre of the corpus luteum was stained. No staining was seen by Day 22. The relaxin content of corpora lutea measured by radioimmunoassay remained low throughout the luteal phase. In contrast, the amount of immunoreactive relaxin in corpora lutea rose dramatically (140-fold) between Days 11 and 14 of pregnancy and by Day 14 of pregnancy immunostaining was seen in the majority of large luteal cells. By Day 20 of pregnancy the concentrations of immunoreactive relaxin had further increased. Histochemical staining for alkaline phosphatase suggested that, while the relaxin-immunoreactive cells seen in the early luteal phase may be theca-derived, those during early pregnancy may be derived from the granulosa. The results are compatible with the suggestion that relaxin is produced by theca-derived cells during the early luteal phase and that between Days 11 and 14 there is a switch in the site of relaxin synthesis from theca-derived cells to granulosa-derived large luteal cells. In the absence of luteolysis, as during pregnancy, this switch is accompanied by a dramatic increase in relaxin synthesis.     

Localisation of the Notch family in the human endometrium of fertile and infertile women

To investigate the spatial and temporal immunolocalisation and staining intensity of the Notch signalling family in endometrium of fertile and infertile women, endometrial biopsies were collected by curettage from 25 fertile women across the menstrual cycle and 10 infertile women in the mid secretory phase of menstrual cycle. Immunohisotchemistry was completed for NOTCH1, -2, -3, -4, cleaved Notch, DLL1, -3, -4, JAGGED1, -2, HES and NUMB and immunostaining intensity measured in both the endometrial glandular and luminal epithelium. NOTCH1 and the ligands DLL1 and JAGGED1 were key proteins displaying increased staining intensity during the receptive phase of the menstrual cycle and dysregulated in infertile endometrium. Conversely, NUMB a negative regulator of Notch signalling was decreased in the mid secretory phase of the menstrual cycle in fertile women and increased with infertility.     

Comparative study of urinary reproductive hormones in great apes

Urinary estrone conjugates (E₁C), pregnanediol-3-glucuronide (PdG), and follicle-stimulating hormone (FSH) were determined by enzyme immunoassays (EIAs) during the normal menstrual cycle in the orangutan, gorilla, chimpanzee, and bonobo. Furthermore, the data were compared to those levels in the human and long-tailed macaque. The results showed a typical preovulatory E₁C surge and postovulatory increase in PdG in all species. The pattern of E₁C during the menstrual cycle in the great apes more closely resembled the human than do the long-tailed macaque. A major difference of E₁C pattern between these species appeared in the luteal phase. In the great apes and the human, E₁C exhibited two peaks, the first peak detected at approximately mid cycle and the second peak detected during the luteal phase. On the other hand, in the long-tailed macaque, increase of E₁C in the luteal phase was small or nonexistent. The gorilla, chimpanzee, and bonobo exhibited similar PdG trends. The orangutan excreted one tenth less PdG than these species during the luteal phase. The long-tailed macaque also excreted low levels of PdG. The patterns of FSH in orangutan, chimpanzee, bonobo and long-tailed macaque showed a marked mid-cycle rise and an early follicular phase rise, similar to those in the human. Comparing similar taxa, a large difference was found in FSH of gorilla; there were three peaks during the menstrual cycle. Thus, there is considerable species variation in the excretion of these hormones during the menstrual cycle and comparative studies could be approached with a single method. The methods and baseline data presented here provide the basis for a practical approach to evaluation and monitoring of ovarian events in the female great apes. Electronic Publication     

Concentration of prostaglandins PGE and PGF, estrone, estradiol, and progesterone in human corpora lutea

The concentrations of prostaglandins PGE and PGF, estrone, estradiol and progesterone in human corpora lutea were measured by radioimmunoassay at various stages of the luteal phase of the menstrual cycle. The concentrations of PGF were found to be significantly higher in both the mid and late luteal phases than in the early luteal phase. In the mid luteal phase there was a concomittant increase in PGE levels, but these levels had declined in the late luteal phase. Steroid concentrations were generally lower in the late luteal phase.

It has been postulated that in the human corpus luteum locally produced prostaglandins may be responsible for luteolysis. Our data on the concentrations of PGF and PGE in corpora lutea at various stages of the luteal phase support such a possibility.     

Detection of Fas ligand in the bovine oviduct

Presence of a Fas-Fas ligand (FasL) system defines the immune-privileged status of certain tissues such as placenta. This study examined the fluids and tissue(s) of the bovine oviduct, where both spermatozoa and early embryos escape elimination by the female immune system, for the presence and the distribution of Fas and FasL, which might provide an explanation for the immune-privileged site of this organ. In the present study, the immunolocalisation of FasL and Fas, as well as the gene expression of FasL, were determined in the uterotubal junction (UTJ), isthmic (I) and ampullar (A) segments of the oviduct during oestrus and the luteal phase of the oestrous cycle. The degree of apoptosis of oviductal epithelium was examined by the TUNEL method. Oviductal fluid (ODF), collected chronically via indwelling catheters from the I or A segments during both non-luteal and luteal phases of the cycle, was analysed for the presence of FasL. The Fas immunostaining was scattered along the epithelium of all regions of the oviduct and cycle stages investigated, whereas FasL immunolabelling was more conspicuous in oestrous samples. This staining disappeared during the luteal phase, which was particularly evident in the sperm reservoir (UTJ and I). There were fewer TUNEL-positive cells than Fas- or FasL-positive cells in the oviductal epithelium, suggesting that tubal Fas and FasL are not directly involved in epithelial apoptosis. Western blot analyses detected FasL in ODF collected from both I and A, most conspicuously as a 24-27kDa band but also at a 40-45kDa band level. FasL mRNA was expressed in the epithelial cells from the sperm reservoir and A during both non-luteal and luteal phases. However, the level of expression differed significantly between segments during the luteal phase. The results provide novel evidence that the Fas-FasL system is present in the bovine oviduct and could be involved in mediating survival of spermatozoa and early embryos.     

Localization of androgen receptor in the follicle and corpus luteum of the primate ovary during the menstrual cycle

Ovarian androgens may act locally to modulate follicular and luteal function in various species. This study examined the distribution of androgen receptors within the primate ovary throughout the menstrual cycle. Ovaries were collected from rhesus and cynomolgus monkeys during the early, mid-, and late (n = 3-5 per stage) follicular and luteal phases of the cycle. The tissues were processed for indirect immunocytochemical localization of androgen receptors with a specific monoclonal antibody against human androgen receptor (AN1-15). In addition, ovaries (n = 3) were collected from rhesus monkeys for biochemical detection of androgen receptor using 3H-androgen and AN1-15. Specific immunocytochemical staining, as determined by comparing adjacent tissue sections incubated with either AN1-15 or a nonspecific control antibody, was exclusively nuclear. Androgen receptor was detected in the germinal epithelium and ovarian stroma at all stages of the cycle. The thecal and granulosa cells of growing follicles, and of many but not all atretic follicles, contained androgen receptors. Luteinizing granulosa cells of the periovulatory follicle and luteal cells from the early and midluteal phase stained intensely for androgen receptor. Regressing corpora lutea of the late luteal phase also stained for androgen receptor; however, fully regressed corpora lutea in the early follicular phase of the next cycle did not exhibit receptor staining. Luteal cells that were androgen receptor-positive also stained histochemically for the presence of 3 beta-hydroxysteroid dehydrogenase. Sucrose gradient analysis with radiolabeled androgen demonstrated a shift in the androgen receptor peak in monkey ovarian tissue upon addition of AN1-15, confirming the presence of androgen receptor.(ABSTRACT TRUNCATED AT 250 WORDS)     

月经周期不同阶段游离皮质醇昼夜节律的变化

为了研究皮质醇分泌的昼夜节律在月经周期中的变化,实验对15位月经周期正常的育龄期健康妇女,在月经周期的不同阶段分别于24h内每隔两小时采样,检测唾液昼夜游离皮质醇水平。采用非线性回归分析模型分析皮质醇昼夜节律。结果显示,皮质醇昼夜节律在整个月经周期都具有复杂的明显受到亚节律(ultradian)影响的分泌形式;与月经期相比,围排卵期和黄体晚期昼夜节律波峰宽度(peak-width)明显减低(P=0．005与0．031),而昼夜节律波谷(trough)有抬高趋势(P=0．0622与0．066);黄体晚期的亚节律波幅(ultradian amplitude)与月经期相比显著减低(P=0．002)而与围排卵期相比有减低趋势(P=0．05)。这些结果提示月经周期的不同阶段对皮质醇分泌的昼夜节律有影响。     

Expression and regulation of tumor necrosis factor (TNF) and TNF-receptor family members in the macaque corpus luteum during the menstrual cycle

Members of the tumor necrosis factor (TNF)-receptor (R) family may be involved in the tissue remodeling that occurs in the primate corpus luteum (CL) during development and regression. As a first step towards addressing this issue, studies assessed TNF ligand-R expression and regulation in CL collected from monkeys during the early (ECL, Days 3-5), mid (MCL, Days 7-8), mid-late (MLCL, Days 10-11), late (LCL, Days 14-16), and very late (VLCL, menses) luteal phase of the menstrual cycle. CL were also collected after gonadotropin and/or steroid ablation and replacement (with hLH and the progestin R5020) for 3 days at mid-late luteal phase. TNF-alpha, -beta, FAS ligand (FASL), and TNF-R1 mRNA levels were two- to sixfold greater (P < 0.05) at the MLCL or LCL phase as compared to earlier (ECL, MCL). In contrast, TNF-R2 and FAS mRNA levels did not change during the luteal phase. Immunohistochemical staining for TNF-beta, TNF-R1, TNF-R2, FAS, and FASL was observed in luteal cells, whereas only TNF-beta staining was observed in endothelial cells. Several TNF-R components were influenced by LH and/or steroid ablation; notably, steroid ablation reduced (P < 0.05) luteal TNF-alpha, but not TNF-beta, mRNA levels, which was prevented by progestin treatment. In contrast, steroid ablation increased (P < 0.05) luteal cell immunostaining for FAS and FASL, which was reduced by progestin treatment. Thus, several members of the TNF R-ligand family are expressed in the primate CL in an LH- and/or progestin-dependent manner. Peak expression in the late luteal phase may signify a role for the TNF-R system in death receptor-mediated apoptosis during luteolysis.     

Microsomal epoxide hydrolase expression in the endometrial uterine corpus is regulated by progesterone during the menstrual cycle

We have shown previously that high expression levels of microsomal epoxide hydrolase (mEH) correlate with a poor prognosis of breast cancer patients receiving tamoxifen, suggesting that enhanced mEH expression could lead to antiestrogen resistance (Fritz et al. in J Clin Oncol 19:3–9, 2001). Thus, the purpose of this study was to gain insights into the role of mEH in hormone-responsive tissues. We analyzed biopsy samples of the endometrium by immunohistochemical staining, pointing to a regulation of mEH during the menstrual cycle: during the first half mEH expression was low, increased during the second half and reached highest levels during pregnancy. Additionally, the progesterone receptor (PR) positive human endometrial cell lines IKPRAB-36 (estrogene receptor α [ERα] negative) and ECC1-PRAB72 (ERα positive) were chosen to further investigate the hormonal regulation of mEH expression. Western Blot and quantitative RT-PCR analysis revealed an increase of mEH expression after treatment with medroxy-progesterone 17-acetate (MPA) in the ERα containing ECC1-PRAB72 cells. In contrast our results suggest that MPA had no influence on the mEH protein level in the ERα- IKPRAB-36 cells. In conclusion, mEH expression is regulated by progesterone in the presence of both PRs and ERα.