Prostaglandins differentially modulate progesterone receptor-A and -B expression in human myometrial cells: evidence for prostaglandin-induced functional progesterone withdrawal

We tested the hypothesis that prostaglandin (PGs), PGE2, and PGF2 alpha, stimulate labor and delivery in women, in part, by inducing functional progesterone withdrawal in myometrial cells by increasing the progesterone receptor (PR)-A/PR-B expression ration. PHM1-31 cells (an immortal pregnant human myometrial cell line) were exposed to PGE2, PGF2 alpha, cyclic-8-bromoadenosine monophosphate (8-Br-cAMP) and phorbol 12-myristate 13-acetate (PMA) at various concentrations for 24h. Effects on PR-A and PR-B expression were then assessed by quantitative RT-PCR. PGF2 alpha dose dependently increased PR-A mRNA and the PR-A/PR-B expression ration but did not effect PR-B mRNA. PGE2 dose-dependently increased mRNAs encoding PR-A and PR-B. The PGE2 dose-threshold for PR-A (0.01 nM) was lower than that for PR-B (0.1 nM), which resulted in an initial rise then a gradual fall in PR-A/PR-B expression ration to basal levels in response to PGE2. Activation of the protein kinase (PK)-A signaling pathway with 8-Br-cAMP coordinately increased expression of PR-A and PR-B and therefore did not alter the PR-A/PR-B expression ration. In contrast, activation of the PKC signaling pathway with PMA increased expression of PR-A without affecting PR-B and therefore significantly (P<0.05) increased the PR-A/PR-B expression ration. These data demonstrate differential control of myometrial PR-A and PR-B expression by PGE2 and PGF2 alpha and by specific intracellular signaling pathways. We conclude that PGs acting via the PKC pathway facilitate functional progesterone withdrawal by increasing the myometrial PR-A/PR-B expression ratio.     

Oviduct progesterone receptor: Physical and chemical studies

Chicken oviduct progesterone receptor has been purified to homogeneity. The protein consists of two dissimilar hormone-binding subunits, A and B, present in equal amounts in the complex. They have molecular weights of 79,000 and 108,000, respectively, as shown by both SDS-gel electrophoresis of the purified proteins and photoaffinity labeling of both with a labeled synthetic progestin. The two subunits show considerable homology (or identity) of structure at the hormone-binding domain, located at the N-terminus of the proteins. Considerable divergence of sequence must exist elsewhere in A and B, as shown by tryptic peptide mapping and by the fact that subunit A has a strong DNA-binding site lacking in B. Both are phosphorylated in vitro by cAMP-dependent protein kinase; this phosphorylation appears to be responsible for creation of a second, weaker progesterone-binding site on each subunit.     

Effect of progesterone supplementation in repeat-breeder cattle on conception and plasma progesterone.

Reposital-type progesterone (75 mg/d for cows, 40 mg/d for heifers) or saline were administered to 24 Holstein cattle to assess the effects of exogenous progesterone (P) on fertility in repeat-breeders. Treatments were administered daily from day 6 to 10 after fourth, fifth and sixth insemination. Cumulative conception rate (57.1%) for the fourth through sixth insemination was affected by lactation number, service number, plasma P (4.67 ng/ml for pregnant cows vs 4.06 ng/ml for nonpregnant cows) and corpus luteum size on days 5 and 15. Plasma P concentrations were affected by day of cycle and size of corpus luteum on both ovaries on day 15. A treatment by day interaction accounted for higher plasma P in P-treated cattle than saline-treated cattle from day 5 through 15. Administration of exogenous P during early life of the corpus luteum in the repeat-breeder increased plasma P. Higher plasma P was associated with insemination success.     

Monoclonal antibodies to rabbit progesterone receptor: crossreaction with other mammalian progesterone receptors.

A mouse was immunized with purified rabbit uterine cytosolic progesterone receptor (specific activity: 3 nmol of steroid bound per mg of protein). After fusion of its spleen cells with Sp2-OAg myeloma cells, supernatants of 11 hybrid cultures were found to react in both an immunoenzymatic test and a double-immunoprecipitation test with the progesterone receptor. Clones were obtained from the five hybrid cells that gave the strongest response in both tests. Antibodies from cell culture supernatants and ascitic fluids were characterized. Three are of the IgG1 and two of the IgG2a isotype. Their apparent affinity for the progesterone receptor was measured by immunoprecipitation in physiological salt conditions. The equilibrium dissociation constants were between 0.1 and 4 nM. All five monoclonal antibodies crossreacted with the rabbit nuclear receptor, the human cytosolic receptor, and other mammalian (rat, guinea pig) but not avian (chicken) cytosolic progesterone receptors. There was no interaction with the glucocorticoid receptor and corticosteroid binding globulin.     

Parathyroid hormone secretion: effect of estradiol and progesterone

Previous studies have shown that estrogen therapy in postmenopausal women results in an increase in serum immunoreactive parathyroid hormone (iPTH) levels. It has been assumed that this effect of estrogen on PTH secretion is indirect, being mediated via mild hypocalcemia resulting from an inhibition of bone resorption. We evaluated the direct effect of 17 beta-estradiol (E2) and of progesterone (Prog) on secretion of PTH from bovine parathyroid tissue in vitro. Both E2 and Prog caused a significant stimulation of PTH secretion within one hour, which was progressive for the three-hour observation period. The responses were dose-related from 10(-7) to 5 X 10(-10) mol/L. There was no PTH response to 10(-7) mol/L alpha-E2, 3-methoxy estriol, estrone, testosterone, or 20-alpha-hydroxy progesterone, indicating specificity of the responses to E2 and Prog. There was a minimal PTH secretory response to 10(-6) mol/L cortisol and 10(-6) mol/L estrone. The E2 receptor antagonist tamoxifen did not inhibit the E2 effect on PTH secretion. This observation plus the rapid PTH response suggests that this hormonal effect may not be via the conventional intracellular E2 receptor. Therefore, E2 and Prog can stimulate PTH secretion by rapid, direct, and specific effects on parathyroid cells. These gonadal hormones may, therefore, be important in calcium homeostasis via their direct stimulatory effect on PTH secretion.     

Sex-specific alterations in neutrophil apoptosis: the role of estradiol and progesterone

Women are conferred with greater immunologic and survival benefits compared to men. Female sex steroids contribute to this sexual dimorphism. Furthermore, during human pregnancy when female sex hormones are elevated, neutrophil apoptosis is delayed. This study examines the specific effects of estradiol and progesterone on neutrophil apoptosis and function in healthy adult men and women. We also examined the contribution of these hormones to the persistence and resolution of an inflammatory response. Spontaneous apoptosis was significantly decreased in women compared with men. Physiologic doses of estradiol and progesterone caused a further delay in spontaneous apoptosis in both men and women but did not diminish Fas antibody-induced apoptosis. The delay in apoptosis was mediated at the level of the mitochondria with decreased release of cytochrome c, which may alter caspase cleavage and activity. There were no associated alterations in neutrophil CD11b, but production of reactive oxygen intermediates (ROIs) in women was increased. Thus, female sex hormones mediate delayed neutrophil apoptosis in both sexes and enhance female intracellular production of ROIs. Modulating hormonal responses may be an effective therapeutic tool in combating inflammatory diseases.     

Estrogen and progesterone receptors in esophageal carcinoma

SUMMARY.  Information is sparse and contradictory in the literature regarding the role of estrogen receptor (ER) and progesterone receptor (PR) in esophageal carcinoma. This study was conducted over a period of 18 months from September 2004 with the primary aim of determining the PR, ER alpha (ERα) and ER beta (ERβ) status of esophageal carcinoma and normal esophageal mucosa (NEM). The receptor status was correlated with tumor type, tumor differentiation and tumor stage. A total of 45 patients with histologically proven squamous cell carcinoma (SCC) ( n  = 30) and adenocarcinoma (AC) ( n  = 15) were studied. Receptor status was detected by immunohistochemistry (IHC) and semiquantitative assessment was done by quick score method of endoscopic biopsy specimens. The mean age for SCC and AC were not significantly different. The gender ratio in favor of males was 3 : 2 for SCC and 4 : 1 for AC. None of the specimens from SCC or AC showed positivity for PR both in NEM and tumor tissue. Likewise none of the specimens were positive for ERα by IHC. The mean ERβ score for AC was significantly higher than SCC. For SCC it was seen that ERβ positivity in tumor cells increases with dedifferentiation and increasing tumor stage. This trend was seen for AC as well. ERβ is over-expressed in poorly differentiated SCC and AC compared to NEM. Thus ERβ may be a marker for poor biological behavior, that is dedifferentiation or higher stage of disease. In view of these findings we propose a large-scale prospective, longitudinal interventional study using selective estrogen modulators.     

Serum progesterone and estrogens in elephants.

Serum progesterone and estrogens were measured by radioimmunoassay in the serum of immature, mature, and pregnant African and Asian elephants. Progesterone was elevated from 26 to 215 pg/ml in nonpregnant animals and up to 480 pg/ml in late pregnancy animals. No relationship to reproductive state was evident for the low levels of estrogens which ranged from 9 to 37 pg/ml.     

Estrogen and progesterone receptors in human gallbladder

Gallbladder disease is more prevalent in women than men. Estrogen therapy has been associated with an increased incidence of gallbladder disease in both sexes. Further, increased progesterone levels have been implicated in impairment of gallbladder motility in pregnancy. Because sex hormones often exert their action through specific receptors, we investigated whether human gallbladder contains receptors for estrogen and progesterone. Binding of radiolabeled hormones in cytosol and nuclei prepared from human gallbladder of both sexes is indicative of the presence of receptors for both estrogen and progesterone. The binding is saturable, of high affinity and highly specific for its particular type of hormone but not other steroids. Fractionation of sodium molybdate-stabilized gallbladder cytosol on Sephadex G-100 demonstrates that the labeled hormones are not bound to defined proteins such as sex steroid binding globulin or albumin. These studies indicate that human gallbladder contains both estrogen and progesterone receptors, that the presence of these receptors may explain the sensitivity of gallbladder tissue to these hormones and that certain aspects of gallbladder function may be mediated by the interaction of steroid hormones with these receptors.     

Preserved forearm endothelial responses with acute exposure to progesterone: A randomized cross-over trial of 17-beta estradiol, progesterone, and 17-beta estradiol with progesterone in healthy menopausal women

Regularly menstruating women are relatively protected from cardiovascular disease. Epidemiological and endothelial function studies attribute this protection to estradiol (E(2)), but both progesterone (P) and E(2) are normally present. A range of vascular effects of added progestins have been described, from neutral to detrimental, but the effects of P per se on endothelial function in humans have not been reported. We therefore investigated the acute effects of E(2), P, and E(2) combined with P, on endothelium-dependent and -independent forearm blood flow responses. Using venous occlusion plethysmography, forearm blood flow (FBF) was measured during acute brachial artery infusions, achieving physiologic levels of 17-beta-E(2), P, and 17-beta-E(2) with P in healthy menopausal women with no cardiovascular disease risk factors. Vehicle or hormones were infused, in random order, on 4 days, 1 week apart. Flow responses were measured during coinfusions of hormone with the endothelium-dependent vasodilator acetylcholine and the endothelium-independent vasodilator sodium nitroprusside. Twenty-seven healthy menopausal women were studied, and all had normal baseline endothelial responses. Small ( approximately 15%), statistically nonsignificant increases in endothelium-dependent flow responses were seen after all acute hormone treatments. No impairment in response was seen with P alone or in combination with 17-beta-E(2). In healthy menopausal women without cardiovascular disease risk factors and without baseline defects in endothelial function, acute exposure to physiologic levels of 17-beta-E(2), P, and 17-beta-E(2) with P produced equivalent endothelium-dependent responses. These data suggest that P does not have detrimental vascular effects in humans.     

Luteal phase deficiency: abnormal gonadotropin and progesterone secretion patterns

Luteal phase deficiency (LPD) is a reproductive disorder associated with infertility and spontaneous abortion. This study was undertaken to determine whether LPD might be related to an abnormal pattern of gonadotropin secretion. We tested this hypothesis by evaluating the pattern of pulsatile LH secretion in both the follicular and luteal phases of the menstrual cycle in normal women (n = 21) and women with LPD (n = 20), which was diagnosed on the basis of two out of phase endometrial biopsies. In addition, we sought to determine whether changes in progesterone (P) pulse patterns could account for the decrease in average serum P levels in women with LPD. To this end, we examined the pulse patterns of P and compared these patterns between normal women and those with LPD. Frequent blood sampling was performed in both groups to determine their respective hormone secretion patterns. In the follicular phase, blood samples were obtained every 10 min for 12 h; in the luteal phase the samples were obtained every 10 min for 12 h; in the luteal LH, FSH, and P were assayed in each sample. Pulse detection was performed by an adaptive threshold method of pulse analysis. The LH pulse frequency was significantly higher in the women with LPD than in the normal women in the early follicular phase [P less than 0.05; LPD, 12.8 +/- 1.4 (+/- SE); normal, 8.2 +/- 0.7 pulses/12 h]. LH pulse frequency was similar in the early and late follicular phases in the women with LPD, whereas it was higher in the late follicular phase in normal women. Mean serum FSH levels were not different between groups in both the early and late follicular phases. In the luteal phase the P pulse amplitude and mean serum P level were significantly lower in the LPD group than in the normal women (P less than 0.01). We conclude that 1) a too rapid LH pulse pattern in the early follicular phase may lead to inadequate LH support of the corpus luteum and become manifest as LPD; 2) the mechanism for inadequate P secretion in LPD is decreased P pulse amplitude; 3) the finding of similar serum FSH levels in the two groups in both the early and late follicular phases did not support compromised folliculogenesis as an etiological factor for LPD.     

Decline in lung function in lymphangioleiomyomatosis: relation to menopause and progesterone treatment.

The progression of lymphangioleiomyomatosis, a rare lung disease in women, is thought to be influenced by hormonal factors. We studied the rate of decline in FEV(1) and carbon monoxide transfer factor (TL(CO)) in a national cohort of patients with lymphangioleiomyomatosis in the United Kingdom and its relation to two factors that might influence the disease, menopausal status and progesterone treatment. We used retrospective data from hospital notes, and of the 50 patients identified 43 had suitable lung function data spanning at least 3 mo. Mean (SD) annual decline in FEV(1) was 118 (142) ml for all patients, and these figures changed little when only data spanning at least 2 and 3 yr were analyzed. There was considerable variation in the rate of decline between subjects, however, and although it tended to be less among postmenopausal women and those receiving progesterone, patient numbers were smaller and the findings were not significant. There was a significant reduction in decline in TL(CO) in premenopausal patients receiving progesterone and in both FEV(1) and TL(CO) after starting progesterone in six patients who had data before and after starting treatment. This study documents the rapid decline in lung function in lymphangioleiomyomatosis, confirms the wide variation between patients, and provides some support for the suggestion that disease progression may be reduced by progesterone. The data provide a basis for designing prospective studies of treatment for lymphangioleiomyomatosis.