Search results for "PROGESTERONE"
showing 10 items of 188 documents
In vitro effects of estradiol, testosterone, and progesterone on 5-methoxyindole content, cyclic adenosine 3',5'-monophosphate synthesis, and norepin…
1986
To examine the effects of estradiol, testosterone, or progesterone on cyclic adenosine 3',5'-monophosphate (AMP) accumulation, 5-methoxyindole levels, and norepinephrine (NE) release by the female guinea pig pineal complex, samples of the deep, intermediate, or superficial portions of the complex were incubated in vitro with varied concentrations of either hormone. Exposure for 10 minutes to physiological amounts of estradiol (10 nM) or to 100 microM NE increased significantly cyclic AMP levels to the same extent in the three pineal regions. A maximal effect on cyclic AMP accumulation was observed at 100-nM concentrations of estradiol, with a tendency to return to basal levels at 1-10 micro…
The non-aromatizable androgen dihydrotestosterone (DHT) facilitates sexual behavior in ovariectomized female rats primed with estradiol
2020
Abstract It is still unclear whether Testosterone (T) increases sexual desire through a stimulation of the androgen receptor in relevant brain regions or through its conversion to estrogens. The aim of this study was to clarify the mechanisms of T facilitation of female sexual desire by assessing the effect of a non-aromatizable androgen (Dihydrotestosterone, DHT) in a validated animal model. Ovariectomized (OVX) Long-Evans rats were treated with oil (O) + O, 10 mcg Estradiol Benzoate (EB) + O, 10 mcg EB + 500 mcg Progesterone (P), O + 500 mcg DHT or 10 mcg EB + 500 mcg DHT (n = 12 per group). EB was administered 48 h, while P and DHT 4 h, prior to 4 sexual behavioral testing sessions in bi…
Increased LH and FSH release from the anterior pituitary of ovariectomized rat, in vivo, by copper-, nickel-, and zinc-LHRH complexes.
1992
Abstract The effect of Cu 2+ , Ni 2+ , Zn 2+ and their complexes with LHRH on the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) was estimated in in vivo experiments with the use of the method proposed by Ramirez and McCann. Ovariectomized, estradiol, and progesterone pretreated rats were injected intraveneously either with LHRH alone, a metal ion alone, a mixture of metal and hormone, or a metal-LHRH complex. A metal alone or a mixture of it with LHRH did not affect gonadotropin release at all or no more than LHRH alone. However, the complex of Cu 2+ with LHRH brought about a high release of LH and even higher release of FSH. This indicates that copper complex i…
Age-dependent changes of nuclear envelope protein phosphokinase and protein phosphatase activities. Significance for altered nucleo-cytoplasmic mRNA …
1984
Nuclear envelopes are associated with a protein phosphokinase and a phosphoprotein phosphatase, whose activities are modulated by poly(A) in an opposite manner. The activities of these enzymes were determined in nuclear ghosts from liver and oviduct of quails of different age and of different hormone status. Under optimal conditions, kinase activity was found to increase in immature animals 8-fold in response to diethylstilbestrol; co-administration of progesterone had no marked effect on enzyme activity. After the initial burst, the activity of the enzyme increased only slightly during ageing. Two proteins present in nuclear ghosts of Mr 64 000 and of Mr 106 000 are phosphorylated during t…
Steroid Receptor Expression in Endometria from Women Treated with Tamoxifen
1998
Abstract Breast cancer patients receiving tamoxifen (Tam) are at an increased risk for developing endometrial carcinomas, possibly due to the partial estrogenic effect of Tam on endometrial cells. Progestational therapy has not routinely been included in Tam regimens. It was our aim to determine the presence of estrogen receptors (ERs) and progesterone receptors (PRs) in normal and abnormal endometria from postmenopausal women with breast cancer who were treated with Tam. Standard immunohistochemical staining of ERs and PRs was performed on paraffin sections from formalin-fixed uterine curettings or hysterectomy specimens from 40 patients who had received 20–40 mg of Tam daily for a minimum…
Endometrial response to concurrent treatment with vaginal progesterone and transdermal estradiol.
2012
ABSTRACT Objective To describe the effect of the intermittent administration of vaginal progesterone and a low-dose estradiol patch on endometrial stability, as assessed by the rate of amenorrhea and endometrial stimulation. Methods This was an open study in which 64 moderately symptomatic, postmenopausal women were treated in the outpatient clinic of our University Hospital for different intervals up to 1 year. The treatment consisted of a combination of patches delivering 25 µg/day estradiol and intravaginal pills containing 100 mg of micronized progesterone. Patches and pills were administered concomitantly in a twice-a-week protocol. The endometrial response was assessed by endovaginal …
Effects of ovariectomy and steroid replacement on GABAA receptor binding in female rat brain.
1991
Abstract The specific binding of tritiated muscimol to γ-aminobutyric acid (GABA) receptor sites was studied in distinct brain areas of female rats during different endocrine states. In diestrous rats with intact ovaries the highest receptor densities were found in the cortex (10.24 pmol/mg protein) and the lowest concentrations in the mediobasal hypothalamus (3.29 pmol/mg protein). Four weeks after removal of the ovaries, the number of binding sites was enhanced up to 2.4-fold in all brain areas investigated: the preoptic brain area, mediobasal hypothalamus, corticomedial amygdala, and cerebral cortex. The affinity of the binding sites remained unchanged. Substitution of estradiol and prog…
3H-cyproterone acetate: binding characteristics to human uterine progestagen receptors
1985
The availability of tritium labeled cyproterone acetate (CPA) facilitated the systematic investigation of the binding characteristics of this compound for human uterine progesterone receptors (PgR). The binding parameters of 3H-CPA are compared to those of 3H-R5020 and 3H-progesterone. The rate constants of association (k1M-1sec-1) to PgR were 7.8 X 10(3) for 3H-R5020, 4.5 X 10(4) for 3H-progesterone and 4.0 X 10(4) for 3H-CPA. The rate constants of dissociation (k-1, sec-1) were 3.6 X 10(-5) for 3H-R5020, 21.3 X 10(-5) for 3H-progesterone and 17.8 X 10(-5) for 3H-CPA. The Kd-values (M), as obtained by titration analysis and subsequent Scatchard plot analysis were 1.2 X 10(-9) for 3H-R5020,…
The effect of oral hormone replacement therapy on lipoprotein profile, resistance of LDL to oxidation and LDL particle size
2001
Abstract Objectives: To disclose if oral estradiol (E 2 ), alone or in combination with natural progesterone (P) or medroxyprogesterone acetate (MPA), may modify the oxidizability of low density lipoprotein (LDL), and if the effect is achieved at physiological dosages. LDL oxidizability was assessed by the resistance to oxidation by copper and by the particle size profile, since small particles have increased oxidation susceptibility. Methods: Thirty-three women received two consecutive, two-month length doses of 1 and 2 mg/day of oral E 2 . They were then randomly assigned to a fourteen-day treatment of 2 mg/day E 2 plus either 300 mg/day P or 5 mg/day MPA. A parallel group of experiments …
Chapter 4 Cholesterol and steroid hormones: modulators of oxytocin receptor function
2002
The function and physiological regulation of the oxytocin-receptor system is strongly steroid-dependent. This is, unexpectedly, only partially reflected by the promoter sequences in the oxytocin receptor and favors the idea that posttranscriptional mechanisms may also play a significant role for the physiological regulation of the oxytocin-receptor system. Our data indicate that cholesterol acts as an allosteric modulator of the oxytocin receptor and stabilizes both membrane-associated and solubilized OT receptors in a high-affinity state for agonists and antagonists. Moreover, high-affinity OT receptors are 2-fold enriched in cholesterol-rich plasma membrane domains in HEK293 fibroblasts s…