Direct Effect Of Progesterone Research Articles

Molecular identification of a PGRMC-2 receptor in maturing oocytes of the zoonotic nematode parasite Trichinella spiralis

We previously reported that the Trichinella nematode showed higher parasite loads in one gender than another, but also the parasite molting rate decreased when it was cultivated in the presence of progesterone. In this study we explored the hypothesis that the direct effect of progesterone on Trichinella spiralis could be mediated by a steroid-binding parasite protein.We sequenced, cloned and amplified the Cyt-domain of the progesterone receptor membrane component-2 of Trichinella spiralis (PGRMC2-Ts). Furthermore, we expressed the protein and developed an antibody to perform confocal microscopy and flow cytometry. The expression of the PGRMC2-Ts protein was exclusively detected at the oocyte and the parasite’s cuticle in cross-sections of the parasite, and this expression was confirmed by western blot and flow cytometry. Molecular modeling studies and computer docking for the PGRMC2-Ts protein showed that it is potentially able to bind to progesterone, estradiol, testosterone, and dihydrotestosterone with different affinities. Furthermore, phylogenetic analysis demonstrated that T. spiralis PGRMC2 is related to a steroid-binding protein of another platyhelminth. Progesterone probably acts upon Trichinella spiralis oocytes by binding to PGRMC2-Ts. Our data showed that the PGRMC2-Ts protein is present in the parasite’s oocytes, a development step that is crucial for the life cycle of the parasite. Indeed, this research might have implications in the field of host-parasite co-evolution and the sex-associated susceptibility to this infection. In a more practical matter, these results may contribute to the design of new drugs with anti-parasite effects.

Characterization of Membrane-Associated Progesterone Receptor Component-2 (MAPRC2) from Trichinella spiralis and Its Interaction with Progesterone and Mifepristone.

Trichinellosis is a foodborne zoonotic disease caused by Trichinella spp., including Trichinella spiralis. In the present study, T. spiralis membrane-associated progesterone receptor component-2 (Ts-MAPRC2) gene was cloned and characterized using protein sequencing analysis. Furthermore, the expression, purification, immunoblot assay, binding ability with progesterone antibody, and immunofluorescence assay were performed. A direct effect of progesterone (P4) and mifepristone (RU486) on the Ts-MAPRC2 gene was determined using in vitro cell culture that showed different expression levels at all developmental stages (muscle larvae (ML), female adult worm (F-AL), male adult worm (M-AL), and newborn larvae (NBL)). Subsequently, the in vitro phenotypic effects of P4, RU486, and rTs-MAPRC2-Ab on F-AL and ML stages were measured. Later, the in vivo phenotypic effect and relative mRNA expression of mifepristone on the F-AL stage were studied. Our results revealed that the Ts-MAPRC2 gene is critical to maintaining pregnancy in the female adult worm (F-AL) of T. spiralis. The 300 ng/mL of P4 and 100 ng/mL of RU486 showed downregulation of the Ts-MAPRC2 gene in F-AL (p ≤ 0.05). This plays an important role in abortion and possibly decreases the worm burden of T. spiralis in the host. Only 30 ng/mL P4 showed significant upregulation in F-AL (p ≤ 0.05). The current study provides new insights regarding the antihormone (P4 and RU486) drug design and vaccine therapy of recombinant (rTs-MAPRC2) protein as well as their combined effects to control T. spiralis infection.

Differential effects of estrogen and progesterone on development of primate secondary follicles in a steroid-depleted milieu in vitro.

What are the direct effects of progesterone (P4) and estradiol (E2) on the development and function of primate follicles in vitro from the pre-antral to early antral stage? In a steroid-depleted milieu, E2 improved follicle survival, growth, antrum formation and oocyte health, whereas P4 exerted minimal beneficial effects on follicle survival and reduced oocyte health. Effects of P4 and E2 on follicle development have been studied primarily in large antral and pre-ovulatory follicles. Chronic P4 exposure suppresses antral follicle growth, but acute P4 exposure promotes oocyte maturation in pre-ovulatory follicles. Effects of E2 can be stimulatory or inhibitory depending upon species, dose and duration of exposure. Non-human primate model, randomized, control versus treatment. Macaque (n = 6) secondary follicles (n = 24 per animal per treatment group) were cultured for 5 weeks. Adult rhesus macaque secondary follicles were encapsulated in 0.25% alginate and cultured individually in media containing follicle stimulating hormone plus (i) vehicle, (ii) a steroid-synthesis inhibitor, trilostane (TRL, 250 ng/ml), (iii) TRL + low E2 (100 pg/ml) or progestin (P, 10 ng/ml R5020) and (iv) TRL + high E2 (1 ng/ml E2) or P (100 ng/ml R5020). Follicles reaching the antral stage (≥750 µm) were treated with human chorionic gonadotrophin for 34 h. End-points included follicle survival, antrum formation, growth pattern, plus oocyte health and maturation status, as well as media concentrations of P4, E2 and anti-Müllerian hormone (AMH). In a steroid-depleted milieu, low dose, but not high dose, P improved (P < 0.05) follicle survival, but had no effect (P > 0.05) on antrum formation and AMH production. Low-dose P increased (P < 0.05) P4 production in fast-grow follicles, and both doses of P elevated (P < 0.05) E2 production in slow-grow follicles. Additionally, low-dose P increased (P < 0.05) the percentage of no-grow follicles, and high-dose P promoted oocyte degeneration. In contrast, E2, in a steroid-depleted milieu, improved (P < 0.05) follicle survival, growth, antrum formation and oocyte health. E2 had no effect on P4 or E2 production. Follicles exposed to E2 yielded mature oocytes capable of fertilization and early cleavage, at a rate similar to untreated control follicles. This study is limited to in vitro effects of P and E2 during the interval from the secondary to small antral stage of macaque follicles. This study provides novel information on the direct actions of P4 and E2 on primate pre-antral follicle development. Combined with our previous report on the actions of androgens, our findings suggest that androgens appear to be a survival factor but hinder antral follicle differentiation, E2 appears to be a survival and growth factor at the pre-antral and early antral stage, whereas P4 may not be essential during early folliculogenesis in primates. NIH P50 HD071836 (NCTRI), NIH ORWH/NICHD 2K12HD043488 (BIRCWH), ONPRC 8P51OD011092. There are no conflicts of interest.

Progesterone Upregulates Gene Expression in Normal Human Thyroid Follicular Cells.

Thyroid cancer and thyroid nodules are more prevalent in women than men, so female sex hormones may have an etiological role in these conditions. There are no data about direct effects of progesterone on thyroid cells, so the aim of the present study was to evaluate progesterone effects in the sodium-iodide symporter NIS, thyroglobulin TG, thyroperoxidase TPO, and KI-67 genes expression, in normal thyroid follicular cells, derived from human tissue. NIS, TG, TPO, and KI-67 mRNA expression increased significantly after TSH 20 μUI/mL, respectively: 2.08 times, P < 0.0001; 2.39 times, P = 0.01; 1.58 times, P = 0.0003; and 1.87 times, P < 0.0001. In thyroid cells treated with 20 μUI/mL TSH plus 10 nM progesterone, RNA expression of NIS, TG, and KI-67 genes increased, respectively: 1.78 times, P < 0.0001; 1.75 times, P = 0.037; and 1.95 times, P < 0.0001, and TPO mRNA expression also increased, though not significantly (1.77 times, P = 0.069). These effects were abolished by mifepristone, an antagonist of progesterone receptor, suggesting that genes involved in thyroid cell function and proliferation are upregulated by progesterone. This work provides evidence that progesterone has a direct effect on thyroid cells, upregulating genes involved in thyroid function and growth.

The effect of progesterone replacement on gene expression in the corpus luteum during induced regression and late luteal phase in the bonnet monkey (Macaca radiata)

BackgroundIn higher primates, although LH/CG play a critical role in the control of corpus luteum (CL) function, the direct effects of progesterone (P4) in the maintenance of CL structure and function are unclear. Several experiments were conducted in the bonnet monkey to examine direct effects of P4 on gene expression changes in the CL, during induced luteolysis and the late luteal phase of natural cycles.MethodsTo identify differentially expressed genes encoding PR, PR binding factors, cofactors and PR downstream signaling target genes, the genome-wide analysis data generated in CL of monkeys after LH/P4 depletion and LH replacement were mined and validated by real-time RT-PCR analysis. Initially, expression of these P4 related genes were determined in CL during different stages of luteal phase. The recently reported model system of induced luteolysis, yet capable of responsive to tropic support, afforded an ideal situation to examine direct effects of P4 on structure and function of CL. For this purpose, P4 was infused via ALZET pumps into monkeys 24 h after LH/P4 depletion to maintain mid luteal phase circulating P4 concentration (P4 replacement). In another experiment, exogenous P4 was supplemented during late luteal phase to mimic early pregnancy.ResultsBased on the published microarray data, 45 genes were identified to be commonly regulated by LH and P4. From these 19 genes belonging to PR signaling were selected to determine their expression in LH/P4 depletion and P4 replacement experiments. These 19 genes when analyzed revealed 8 genes to be directly responsive to P4, whereas the other genes to be regulated by both LH and P4. Progesterone supplementation for 24 h during the late luteal phase also showed changes in expression of 17 out of 19 genes examined.ConclusionThese results taken together suggest that P4 regulates, directly or indirectly, expression of a number of genes involved in the CL structure and function.

Activity lysosomal enzymes in rat skin fibroblasts after treatment with progesterone and new gestagen ABMP

The effects of a new synthetic gestagen 17alpha-acetoxy-3beta-butanoyloxy-6-methyl-pregna-4,6-dien-20-on (ABMP) and reference drug progesterone on rat skin fibroblasts were evaluated by variations in lysosomal enzyme activity (cathepsin D and beta-glucosidase). Our results suggest that ABMP exhibits lysosomotropic properties, which depended on its concentration and time of treatment. The direct effect of progesterone on lysosomal enzyme activity in skin fibroblasts was compared to the influence of systemic treatment with gestagens on skin lysosomes. The data indicate that local application of gestagen preparations holds much promise for the therapy of skin diseases accompanied by increased proliferation (e.g. psoriasis).

Transactivation of a growth hormone (GH) promoter-luciferase construct in canine mammary cells

The gene encoding growth hormone (GH) is expressed not only in the pituitary but also in a variety of non-pituitary tissues. In the female dog, progestins are known to stimulate GH expression in the mammary gland. In order to investigate the regulation of the GH gene expression in the mammary gland, we transfected the canine mammary tumor cell line CMT-U229 with 3 different canine GH promoter-luciferase constructs. The constructs, varying in length between 252bp and 673bp, were transfected followed by an incubation for 4h, 24h and 48h with cAMP, all-trans-retinoic acid (RA), 3,3′,5-triiodothyronine (T3), 1,25-dihydroxy-vitamin D (VitD), progesterone and EGF. Promoter activity was stimulated by cAMP, T3 and RA whereas VitD clearly inhibited gene expression. However, despite the presence of nuclear and membrane receptors for progesterone, no direct effects of progesterone on promoter activity could be demonstrated.It is concluded that progesterone alone has no direct stimulatory effect on GH transcription. This finding is discussed in relation to the slow onset of progesterone-stimulated GH release in vivo and the absence of Pit-1 in canine mammary tissue.

Direct inhibitory effect of progesterone on oxytocin-induced secretion of prostaglandin F(2alpha) from bovine endometrial tissue.

The effect of progesterone on oxytocin-induced secretion of prostaglandin (PG) F(2alpha) from bovine endometrial tissue explants was examined. Endometrial tissue from the late luteal phase were preincubated for 20 h in control medium. Explants were then treated for 6 h with control medium, oxytocin (10(-7) M), progesterone (10(-5) M), or both hormones. Oxytocin increased the medium concentration of 13,14-dihydro-15-keto-PGF(2alpha), whereas progesterone completely suppressed the stimulatory effect of oxytocin. In experiment 2, isolated endometrial epithelial cells were incubated with progesterone (10(-5) M), oxytocin (10(-7) M), and combinations of these hormones with or without actinomycin D (1 ng/ml). Only oxytocin stimulated secretion of PGF(2alpha), and this response was suppressed by progesterone. Oxytocin induced a rapid increase in intracellular concentrations of Ca(2+) detected within 1 min of exposure of epithelial cells from the same cows. Progesterone pretreatment diminished this response. In experiment 3, direct effects of progesterone (2 nM-20 microM) on binding of (3)H-oxytocin to the membrane preparation from epithelial cells were determined by saturation analysis. Oxytocin binding was suppressed by progesterone at every dosage tested. Progesterone is capable of suppressing the ability of oxytocin to induce endometrial secretion of PGF(2alpha). This effect appears to be mediated through a direct interference in the interaction of oxytocin with its own receptor.

Implantation defects in infertile women with endometriosis.

The endometrium undergoes characteristic histologic changes during the menstrual cycle as it prepares for embryo implantation. Historic and current data suggest the presence of a defined period of maximal uterine receptivity during the mid-secretory phase occurring between days 7 and 10 postovulation. In recent years, we and others have sought to define biochemical markers of receptivity that might be used to better understand this time of endometrial differentiation. Based on the work with cell adhesion molecules, we have discovered three different integrins that are only coexpressed during this time in the cycle when embryos will successfully implant. By studying the regulation of one of these, the alpha(v)beta3 integrin, and its extracellular matrix ligand, osteopontin (OPN), we have defined two separate regulatory pathways that may regulate endometrial receptivity. While alpha(v)beta3 expression appears to be stimulated by EGF or heparin-binding EGF, osteopontin is stimulated by progesterone. We now believe the former pathway is a paracrine-mediated signal, while the latter is a direct effect of progesterone on the estrogen-primed endometrial epithelium. In women with endometriosis, it appears that alpha(v)beta3 expression is reduced, while OPN expression is unaffected. Interestingly, binding of OPN to the surface epithelium appears quite limited when alpha(v)beta3 expression is lacking. Such evidence continues to reinforce the notion that endometrium from some women with endometriosis is dysfunctional and may account for the reduction in cycle fecundity noted in this group of patients.

Induction of osteocalcin gene expression in vitro by progesterone.

The effect of progesterone on osteocalcin gene expression was investigated in order to understand how progesterone acts on osteoblast in vitro. For this purpose, fetal rat calvarial osteoblasts were cultured in the medium containing 10(-9) M-10(-6) M progesterone respectively for two weeks while the cells progressing differentiation. Northern blot analysis showed that progesterone increased the level of osteocalcin mRNA in a dose-dependent manner. Among those doses of progesterone employed in this study, only 10(-6) M hormone caused a significant induction of osteocalcin gene expression (2.3 fold, P < 0.01). Our results demonstrated for the first time that the osteocalcin gene expression is regulated by progesterone. In addition, the results obtained from our study provides a good evidence for the direct effect of progesterone on osteoblast in vitro.

Regulation of oxytocin, oestradiol and progesterone receptor concentrations in different uterine regions by oestradiol, progesterone and oxytocin in ovariectomized ewes.

The regulation of oxytocin, oestradiol and progesterone receptors in different uterine cell types was studied in ovariectomized ewes. Animals were pretreated with a progestogen sponge for 10 days followed by 2 days of high-dose oestradiol to simulate oestrus. They then received either low-dose oestradiol (Group E), low-dose oestradiol plus progesterone (Group P) or low-dose oestradiol, progesterone and oxytocin (via osmotic minipump; Group OT). Animals (three to six per time-point) were killed following ovariectomy (Group OVX), at oestrus (Group O) or following 8, 10, 12 or 14 days of E, P or OT treatment. In a final group, oxytocin was withdrawn on day 12 and ewes were killed on day 14 (Group OTW). Oxytocin receptor concentrations and localization in the endometrium and myometrium were measured by radioreceptor assay, in situ hybridization and autoradiography with the iodinated oxytocin receptor antagonist d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH2(9)]-vasotocin. Oestradiol and progesterone receptors were localized by immunocytochemistry. Oxytocin receptors were present in the luminal epithelium and superficial glands of ovariectomized ewes. In Group O, endometrial oxytocin receptor concentrations were high (1346 +/- 379 fmol [3H]oxytocin bound mg protein-1) and receptors were also located in the deep glands and caruncular stroma in a pattern resembling that found at natural oestrus. Continuing low-dose oestradiol was unable to sustain high endometrial oxytocin receptor concentrations with values decreasing significantly to 140 +/- 20 fmol mg protein-1 (P < 0.01), localized to the luminal epithelium and caruncular stroma but not the glands. Progesterone treatment initially abolished all oxytocin receptors with none present on days 8 or 10. They reappeared in the luminal epithelium only between days 12 and 14 to give an overall concentration of 306 +/- 50 fmol mg protein-1. Oxytocin treatment caused a small increase in oxytocin receptor concentration in the luminal epithelium on days 8 and 10 (20 +/- 4 in Group P and 107 +/- 35 fmol mg protein-1 in Group OT, P < 0.01) but the rise on day 14 was not affected (267 +/- 82 in Group OT and 411 +/- 120 fmol mg protein-1 in Group OTW). In contrast, oestradiol treatment was able to sustain myometrial oxytocin receptors (635 +/- 277 fmol mg protein-1 in Group O and 255 +/- 36 in Group E) and there was no increase over time in Groups P, OT and OTW with values of 61 +/- 18, 88 +/- 53 and 114 +/- 76 fmol mg protein-1 respectively (combined values for days 8-14). Oestradiol receptor concentrations were high in all uterine regions in Group O. This pattern and concentration was maintained in Group E. In all progesterone-treated ewes, oestradiol receptor concentrations were lower in all regions at all time-points. The only time-related change occurred in the luminal epithelium in which oestradiol receptors were undetectable on day 8 but developed by day 10 of progesterone treatment. Progesterone receptors were present at moderate concentrations in the deep glands, caruncular stroma, deep stroma and myometrium in Group O. Oestradiol increased progesterone receptors in the luminal epithelium, superficial glands, deep stroma and myometrium. Progesterone caused the loss of its own receptor from the luminal epithelium and superficial glands and decreased its receptor concentration in the deep stroma and myometrium at all time-points. There was a time-related loss of progesterone receptors from the deep glands of progesterone-treated ewes between days 8 and 14. These results show differences in the regulation of receptors between uterine regions. In particular loss of the negative inhibition by progesterone on the oxytocin receptor by day 14 occurred only in the luminal epithelium, but is unlikely to be a direct effect of progesterone as no progesterone receptors were present on luminal epithelial cells between days 8 and 14.

Effect of progestogens and oestrogens on the contractile response of rat detrusor muscle to electrical field stimulation.

1. The effect of oestradiol and progesterone pretreatment on the contractile response of isolated rat detrusor muscle to electrical field stimulation was investigated. The response to direct administration of 2 mumol/l progesterone and 2 mumol/l diethylstilboestrol in the organ bath was also examined. 2. Virgin female Wistar rats were injected subcutaneously with oestradiol benzoate (150 micrograms/kg) for 3 days followed by 1 day of progesterone (160 micrograms/kg). This cycle was repeated once. Control rats received no injections. 3. In controls, progesterone significantly reduced the maximum contractile response of rat detrusor muscle in vitro by 12% (P < 0.01). The EF50 was significantly increased compared with control. When 2 mumol/l diethylstilboestrol, was added, the maximum contractile response was significantly reduced by 42% (P < 0.01) and the frequency-response curve showed a further increase in EF50. 4. Progesterone had no effect on the atropine-resistant component of electrical field stimulation, but progesterone and diethylstilboestrol reduced the atropine-resistant response by 16% (P < 0.01). 5. Detrusor muscle from pretreated rats showed a non-significant increase in maximum contractile response compared with untreated controls. The addition of 2 mumol/l progesterone to the bath chamber had no effect on this response, but the further addition of 2 mumol/l diethylstilboestrol reduced the maximum contraction. 6. Pretreatment with oestradiol and progesterone had no effect on the atropine- or tetrodotoxin-sensitive response to electrical field stimulation. 7. In conclusion, the direct effect of progesterone and diethylstilboestrol inhibited the contractile response of detrusor muscle to electrical field stimulation and the effects of each summated.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of progesterone and cortisol on the release of gonadotropin-releasing hormone from the perifused pituitary stalk-median eminence and on luteinizing hormone release from the pituitary of cows

The direct effects of progesterone and cortisol on the release of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) were examined by perifusing tissues from the bovine pituitary stalk-median eminence and the anterior pituitary. These tissues were isolated and perifused for 160 min and 8 h, respectively. To assess the effect of progesterone and cortisol, from 0 to 10 μM of progesterone or cortisol was added separately to the tissues and the amounts of GnRH and LH assayed in the effluent medium. The release of GnRH from the hypothalamic fragments was significantly reduced within 20 min after the addition of 0.1 and 10 μM of progesterone when compared with the values for the control group ( P<0.05), but GnRH release was not markedly affected by the addition of up to 10 μM cortisol. Spontaneous release of LH from the anterior pituitary was not markedly affected by the addition of 0.1 or 10 μM progesterone, although the GnRH-stimulated release of LH was significantly higher than that of the control group ( P<0.05). GnRH-stimulated release of LH was not markedly affected by addition of cortisol. These results suggest that high concentrations of progesterone act directly on the bovine pituitary stalk-median eminence to inhibit the release of GnRH, but they enhanced the release of LH from the anterior pituitary in response to the same GnRH stimulus.

Acute Progesterone Treatment Has No Effect on Bupivacaine-Induced Conduction Blockade in the Isolated Rabbit Vagus Nerve

Pregnancy decreases anesthetic requirements during regional anesthesia. Using an in vitro animal model, this study attempts to elucidate the mechanism of hormonal effects on nerve conduction in desheathed rabbit vagus nerve. The acute effects of progesterone administration on neural blockade induced by bupivacaine were investigated in terms of changes in compound action potentials of A, B, and C fibers. No change in baseline compound action potential was found after 30 min of perfusion of the nerve with progesterone. Exposure of the nerve to progesterone before exposure to bupivacaine did not significantly increase the degree of conduction blockade produced by bupivacaine, and a radioactive assay demonstrated that progesterone was taken up acutely by neural tissue over a 45-min measurement period. These results indicate that although progesterone was taken up in significant amounts by neural tissue, an acute exposure does not increase the sensitivity of the nerves to bupivacaine. Hence, the increased sensitivity of nerves to local anesthetics seen with pregnancy or with chronic progesterone treatment requires some period of time to occur. The mechanism is therefore unlikely to be a direct effect of progesterone on the cell membrane but may involve hormonal effects on protein synthesis.

3 Prostaglandins and growth factors in the endometrium

Prostaglandins are the products of cyclo-oxygenase and endoperoxide breakdown of free intracellular arachidonic acid (AA). Arachidonic acid is cleaved from membrane phospholipids by phospholipase A2 (PLA2) and phospholipase C (PLC). The human placenta is a rich source of lipocortin like PLA2 inhibitors. Human endometrium contains both PLA2 and PLC activity, and it is under research which pathway is predominant. Prostaglandin F2-alpha is derived from PLC endoperoxide, while prostaglandin E2 is formed by degradation of PG endoperoxide. Dated studies have found that prostaglandin F2-alpha was the predominant PG in the endometrium, whereas concentrations of PGE2 did not change during the cycle. In women estradiol stimulates PG synthesis from glands, and it has a role in mediating intracellular calcium in the human. Progesterone reduces the release of PGs from endometrial explants maintained in culture, while anti-progestins RU486 and ZK98734 stimulate the release of PGs from glandular cells of decidua. There seems to be a direct effect of progesterone on expression of PG synthetase, on the expression of a PG synthesis inhibitory protein, or an effect on a PLA2 activating protein. ZK98734 does not alter the metabolism of PGF2-alpha in the absence of added AA. Calmodulin also plays a role in regulating PG synthesis. Verapamil suppresses basal release of PGF2-alpha and prevents the rise in PG release caused by ZK98734. Progesterone suppresses PG synthesis in human endometrium. Colony stimulating factor- 1 (CSF-1) stimulates Ishikawa cell proliferation, acts on the hemopoietic system, and promotes the release of cytokines like interleukin-2, tumor necrosis factor (TNF), and interferons. Transforming growth factor alpha (TGF-alpha) mediates wound healing by promoting epithelial proliferation and angiogenesis and repairs desquamated endometrium. Epidermal growth factor (EGF) is present in the luminal surface of epithelial cells and myometrium but not in stromal cells. EGF p[lays a role in the proliferation of human endometrium and steroids modify this effect. INsulin-like growth factor (IGF-1) potentiates the activities of other mitogens like EGF. Basic fibroblast growth factor (bFGF) and acidic FGF (aFGF) have been detected in the uterine flushings and tissue of the guinea pig. FGF is a mediator of angiogenesis. different PGs affect vascular contractility, hemostasis, and myometrial contractility. PG synthesis is linked to menstrual dysfunction. The functions of growth factors and PGs may be related reflecting the autocrine and paracrine regulation of endometrial cell proliferation, a topic still under study.

Effects of progestins and antiprogestins on mitochondria in uterine glandular cells in the rat. A quantitative investigation.

The administration of progesterone to ovariectomized rats induces an increase in the volume density (Vv) of the mitochondria and the appearance of giant mitochondria in the uterine glandular cells. This experimental model, including a stereological analysis, allowed us to investigate and quantify a direct effect of progesterone on a well-defined cellular structure without the intervention of estrogen in a priming phase. Synthetic compounds, promegestone, gestrinone and RU 38486, were tested in this model either in place of progesterone or simultaneously with progesterone. The potent progestomimetic activity of promegestone was confirmed by the proliferation of giant mitochondria and a high Vv value for the mitochondria, the two other compounds being inactive even at higher doses. At lower doses, gestrinone and RU 38486 partially inhibit the action of progesterone and at higher doses they both show a complete antagonist effect by preventing the development of the mitochondria.

Effect of ovarian steroids on the metabolism of noradrenaline in rabbit uterus.

The metabolism of (-)-3H-noradrenaline was examined in uterine slices from ovariectomized rabbits which were either untreated or treated with 17 beta-oestradiol, alone or in combination with progesterone. 17 beta-oestradiol caused uterine enlargement which was not accompanied by a change in the formation per g of O-methylated metabolites (3H-NMN, 3H-VMA, 3H-MOPEG). Accumulation of unchanged 3H-noradrenaline and the formation of deaminated catechols (3H-DOMA and 3H-DOPEG) were decreased per g tissue, but increased per uterine horn. Progesterone produced further enlargement of the oestrogen-dominated uteri which was accompanied by (a) a decrease in deaminated catechol formation and (b) an increase in 3H-NMN formation per unit mass of tissue. In all uteri (control and hormone-treated), cocaine inhibited the formation of deaminated catechols, but not that of the O-methylated metabolites. It is suggested, therefore, that, per unit of uterine mass, the neuronal deamination of (-)-3H-noradrenaline is decreased by 17 beta-oestradiol and further decreased by progesterone, and that these changes reflect failure of the intraneuronal deaminating system in the whole uterus to increase in proportion to the increase in uterine mass. Since other agents which decreased the deamination of (-)-3H-noradrenaline (cocaine and nialamide) did not affect 3H-NMN formation in oestrogen-dominated uteri, it is suggested that stimulation of 3H-NMN formation represents a direct effect of progesterone on the extraneuronal O-methylation of noradrenaline.

Evidence that changes in tonic luteinizing hormone secretion determine the growth of preovulatory follicles in the rat.

Physiological concentrations of progesterone (20-100 ng/ml), maintained by the insertion of implants into 30-day-old rats, delayed first ovulation, and withdrawal of progesterone on day 47 of age synchronized first ovulation in rats. Inhibition of ovulation involved negative feedback regulation of tonic LH and FSH secretion, blockage of gonadotropin surges, and suppression of preovulatory, but not antral, follicular growth. Removal of implants resulted in a rapid decline in serum progestrone from 100 to 5 ng/ml within 0-12 h. Between 0-36 h there were progressive increases in serum concentrations of LH and FSH, enhanced accumulation of estradiol by individual follicles incubated in vitro with or without exogenous substrate, and marked progressive increases in the content of LH (but not FSH) receptors in both thecal and granulosa cells. These events were followed by gonadotropin surges at 48 h (1800 h on day 49), ovulation, and morphological and biochemical signs of luteinization, including decreases in follicular gonadotropin receptor content and estradiol accumulation, evident by 60 h. With the exception of changes in basal LH, this sequence of events is remarkably similar in time and pattern to that after the decline of progesterone on diestrous day 2 and ovulation on proestrus of a 5-day cycle. Although a direct effect of progesterone on ovarian follicular cell function cannot be excluded, the data suggest that subtle but sustained increases in LH (and possibly FSH) are required for the enhanced follicular accumulation of estradiol and LH-binding activity occurring between diestrus and proestrus of the rat estrous cycle. Thus, perhaps some of the mystery surrounding the endocrine events between diestrus and proestrus can be ascribed to changes in serum LH that have been too small and/or variable for current nonserial sampling methods and RIAs to detect reliably.

Effect of sex steroids on bone collagen synthesis in vitro.

Although sex steroids are known to affect skeletal metabolism, their effects on bone collagen synthesis have not been studied. We have examined the direct effects of progesterone, 17β estradiol, testosterone, 5α dihydrotestosterone and dehydroepiandrosterone on bone collagen and noncollagen protein synthesis in cultures of calvaria obtained from 21-day fetal rats. Bones were incubated for 24 to 168 h and3H-proline was added for the last 2 h of culture. Incorporation of the label into collagenase-digestible protein (CDP)1 and noncollagen protein (NCP) was determined using repurified bacterial collagenase.

Direct Effect of Progesterone on the Activity of Alkaline Phosphatase in the Oviduct of the Newt, Triturus pyrrhogaster

Direct Effect of Progesterone on the Activity of Alkaline Phosphatase in the Oviduct of the Newt, Triturus pyrrhogaster