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Progesterone reverses the neuronal responses to hypoxia in rat nucleus tractus solitarius in vitro.

Pascual O, Morin-Surun MP, Barna B, Denavit-Saubie M, Pequignot JM, Champagnat J.

UPR 2216 Neurobiologie Genetique et Integrative CNRS, Institut de Neurobiologie Alfred Fessard, 1 Avenue de la Terrasse, 91198 Gif/Yvette, France. opascual iaf.cnrs-gif.fr

The nucleus tractus solitarius (NTS) is a relay nucleus that integrates peripheral chemoreceptor input in response to hypoxia and hence influences the generation of respiratory rhythm. Several studies have shown that administration of progesterone stimulates ventilatory responses to hypoxia. There is some evidence that this steroid hormone can act at the level of the arterial peripheral chemoreceptors, whereas its action in the central nervous system remains unclear. To investigate a possible central involvement during hypoxia, we studied the effect of progesterone on neuronal activities recorded extra- and intracellularly in the NTS using brainstem slices. Central chemosensitivity was tested by comparing synaptic activity and intrinsic electro-responsiveness of 38 neurones during normoxia and hypoxia. In more than two-thirds of neurones recorded, hypoxia elicited a hyperpolarisation, a decrease in the input resistance and a decrease in spontaneous activity. In the remaining neurones (n = 12) hypoxia elicited a depolarisation and an increase in spontaneous activity. In all neurones tested, synaptic potentials evoked by stimulation of the tractus solitarius were decreased by hypoxia. While progesterone (1 microM) had no effect under normoxic conditions, it partially reversed all hypoxic neuronal responses. This effect developed over 2-3 min and reversed within 5 min suggesting a non-genomic mechanism of action. Taken together these results suggest that progesterone interacts with the hypoxia-induced cellular signalling. We conclude that in the NTS, transmission of afferent signals is reduced by hypoxia and restored by progesterone administration. Such a mechanism may contribute to the stimulation of breathing in response to hypoxia observed following progesterone administration in vivo.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12381823&dopt=Abstract progesterone, progesterone cream



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Sperm binding to the human zona pellucida and calcium influx in response to GnRH and progesterone.

Morales P, Pizarro E, Kong M, Pasten C.

Unit of Reproductive Biology, Faculty of Health Sciences, University of Antofagasta, Antofagasta, Chile. pmorales uantof.cl

In this study the effect of the sequential exposure of spermatozoa to progesterone and gonadotrophin-releasing hormone (GnRH) upon zona binding and the intracellular free Ca2+ concentration was evaluated. Sperm aliquots were treated as follows: (a) 0.7 micro mol l(-1) progesterone or 0.1% DMSO (progesterone solvent) followed by 50 nmol l(-1) of GnRH; (b) 50 nmol l(-1) of GnRH or distilled water (GnRH solvent) followed by 0.7 micro mol l(-1) of progesterone. Additional aliquots were incubated with DMSO or distilled water (controls) and with 0.7 micro mol l(-1) of progesterone or 50 nmol l(-1) of GnRH. All treatments were for 5 min. Motile spermatozoa were incubated in modified Tyrode's medium, at 37 degrees C, 5% CO2, 10 x 10(6) spermatozoa ml(-1), for 4.5 h. Intracellular Ca2+ concentration and sperm-zona binding was evaluated using fura 2 and the hemizona assay, respectively. GnRH and progesterone increased sperm-zona binding and the Ca2+ concentration. Regarding zona binding, the effect of GnRH was significantly greater when the spermatozoa had been previously treated with progesterone (progesterone-->GnRH=185 +/- 116 zona-bound spermatozoa versus DMSO-->GnRH=99 +/- 15, P < 0.001). On the other hand, previous treatment with GnRH did not modify their subsequent response to progesterone (GnRH-->progesterone= 114 +/- 19 zona-bound spermatozoa versus distilled water-->progesterone=108 +/- 22, NS). The results regarding intracellular Ca2+ showed a similar pattern. These findings suggest a priming effect of progesterone upon a GnRH-induced increase in sperm-zona binding and intracellular Ca2+.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12390088&dopt=Abstract progesterone, progesterone cream



progesterone cream
Development of one-step fluorescence polarization immunoassay for progesterone.

Hong JY, Choi MJ.

Bioanalysis & Biotransformation Research Center, Korea Institute of Science & Technology, Seoul.

A one-step fluorescence polarization immunoassay (FPIA) was developed to measure progesterone level using an immunocomplex single reagent (SR), a preequilibrated mixture of antibody and tracer. Several fluorescence-labeled progesterone tracers were synthesized using the combination of two progesterone derivatives, 11alpha-hemisuccinyloxyprogesterone (P-11HS) and progesterone-3-(O-carboxymethyl)oxime (P-3CMO), and three fluorescence labels, fluoresceinamine isomer I and II, and ethylenediamine fluoresceinthiocarbamyl (EDF). Antiserum was prepared using a progesterone-bovine serum albumin (BSA) imunogen. The influence of the tracer label was significantly different in titer and sensitivity for antibody binding. The best pair of antibody and progesterone tracer was selected for the antigen-antibody reaction. They were the antibody produced from P-11HS-BSA immunogen and P-11HS-EDF tracer. One-step FPIA is a speedy, homogeneous type of immunoassay which needs neither incubation nor separation of free and bound analyte to measure fluorescence polarization. The detection limit of progesterone by SR-FPIA is approximately 2.7 ng/ml with 50 microl samples. The performance characteristics are acceptable for standard curve reproducibility (coefficient of variation (CV): 0.6-6.4%), precision (CV: 3-13%), and mean dilution recovery (95-102%). The total assay time for 10 samples is about 7 min. This immunocomplex SR has proven to be stable compared with the respective solutions of antibody and tracer.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12392074&dopt=Abstract progesterone, progesterone cream



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Cyproterone, norethindrone, medroxyprogesterone and levonorgestrel are less potent local human growth hormone and insulin-like growth factor I secretion stimulators than progesterone in human breast cancer explants expressing the estrogen receptor.

Milewicz T, Kolodziejczyk J, Krzysiek J, Basta A, Sztefko K, Kurek S, Stachura J, Gregoraszczuk EL.

Department of Endocrinology and Fertility, Collegium Medicum, Jagiellonian University, Krakow, Poland.

The aim of the present study was to compare the ability of natural progesterone and synthetic progestins to stimulate local growth hormone (GH) and insulin-like growth factor I (IGF-I) secretion by breast cancer explants. Explants obtained during surgery were divided according to their estrogen/progesterone receptor phenotype - ER(+)PR(-); ER(+)PR(+); ER(-)PR(+) - as determined by immunocytochemistry. Natural progesterone (10(-5) mol/l) and synthetic progestins (cyproterone acetate (5 x 10(-7) mol/l), norethindrone (10(-5) mol/l), medroxyprogesterone acetate (10(-7) mol/l), and levonorgestrel (10(-7) mol/l) were tested in vitro for their ability to induce secretion of proliferation-promoting agents such as human GH (hGH) and IGF-I. All hormone-dependent breast cancer cell types responded to progesterone stimulation with increased local hGH secretion, while in the non-malignant tissue this effect was observed only in PR(+) cells. Moreover, progesterone in only PR(+) cells in vitro stimulated local IGF-I secretion by both malignant and non-malignant tissue. Medroxyprogesterone and levonorgestrel increased GH secretion by both malignant and non-malignant ER(-)PR(+) breast cancer explants, while cyproterone stimulated it only in non-malignant tissue. None of the synthetic progestins tested in this experiment exerted an effect on GH secretion by both malignant and non-malignant tissue of ER(+) breast cancer explants. The present data additionally showed that, apart from cyproterone, which increased IGF-I secretion in the same manner as progesterone by both malignant and non-malignant ER(-)PR(+) breast explants, other progestins tested had either no effect on IGF-I local secretion or decreased it. Medroxyprogesterone and levonorgestrel induced a decrease in IGF-I secretion noted in ER(+) explants of non-malignant tissue and in malignant ER(-)PR(+) breast tissue. All progestins tested decreased IGF-I secretion by malignant ER(+)PR(+) explants. Taken together, the tested synthetic progestins widely used as oral contraceptives and in hormone replacement therapy were less potent than progesterone in inducing secretion of proliferation-promoting agents such as hGH and IGF-I in ER-containing breast tissue. Despite the lack of confirmation of the link between the use of progestins and breast cancer risk, patients should be informed that the use of certain estrogen/progestin preparations is of no influence on breast cancer risk while others may increase it.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12396561&dopt=Abstract progesterone, progesterone cream



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Progesterone and 17 alpha-OH-progesterone in concentrations similar to that of preovulatory follicular fluid is without effect on resumption of meiosis in mouse cumulus enclosed oocytes cultured in the presence of hypoxanthine.

Yding Andersen C, Byskov AG.

Juliane Marie Center for Children, Women and Reproduction, Section 5712, Rigshospitalet, University Hospital of Copenhagen, Blegdamsvej 9, DK-2100, Copenhagen, Denmark. yding rh.dk

Some intermediates in the cholesterol biosynthesis between lanosterol and cholesterol are capable of inducing resumption of meiosis in cultured mouse oocytes without the presence of gonadotropins. The mechanism by which these so-called Meiosis Activating Sterols (MAS) activate the meiotic process is unknown, and it is uncertain whether they participate in the physiological control of resumption of meiosis. Recently, it has been shown that accumulation of MAS occurs in a liver cell line and in rat testis tissue cultured in the presence of micromolar concentrations of progesterone and 17 alpha-OH-progesterone. Such high concentrations of progesterone and 17 alpha-OH-progesterone only occur in fluid of preovulatory follicles. In connection with the mid-cycle surge of gonadotropins, this may represent one mechanism whereby follicular accumulation of MAS takes place. In the present study, the effect of 10 micro M progesterone and 10 micro M 17 alpha-OH-progesterone on resumption of meiosis was evaluated using mouse cumulus enclosed oocytes (CEO) cultured in the presence of 4mM hypoxanthine. By the end of the 24-h culture period, the frequency by which oocytes had resumed meiosis was assessed by the determination of germinal vesicle breakdown (GVBD). Neither progesterone nor 17 alpha-OH-progesterone or a combination showed any effect on GVBD. In addition, progesterone and 17 alpha-OH-progesterone in combination with a sub-optimal dose of FSH (4 IU/l) did not affect GVBD. In conclusion, accumulation of MAS to an extent that allows resumption of meiosis to occur in CEO is unlikely to be induced by progesterone and 17 alpha-OH-progesterone or a combination.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12398990&dopt=Abstract progesterone, progesterone cream



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Progesterone production and actions in the human central nervous system and neurogenic tumors.

Inoue T, Akahira J, Suzuki T, Darnel AD, Kaneko C, Takahashi K, Hatori M, Shirane R, Kumabe T, Kurokawa Y, Satomi S, Sasano H.

Department of Pathology, Second Department of Surgery, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan. tsukasai gonryo.med.tohoku.ac.jp

Progesterone has been suggested to be involved in the functions of the nervous system, but it has yet to be examined in humans. Progesterone has also been postulated to be involved in the biological behavior of various human neurogenic tumors via progesterone receptors A and B (PR-A and PR-B). In this study we examined the expression of PR and the enzymes responsible for progesterone biosynthesis (P450scc, 3betahydroxysteroid dehydrogenase, and steroidogenic acute regulatory protein) in human brain. We also examined the distribution of PR isoforms in neurogenic tumors using immunohistochemistry and RT-PCR analysis. The presence of PR and mRNA for P450scc, 3beta-hydroxysteroid dehydrogenase, and steroidogenic acute regulatory protein was detected in human brain. PR isoforms were detected in neurogenic tumors. PR-A and PR-B were equally expressed in meningiomas, but PR-B was the predominant isoform compared with PR-A in astrocytic tumors and Schwannomas. There was a statistically significant inverse correlation between PR-A and the proliferation index in meningiomas and astrocytic tumors. These findings suggest that progesterone is locally synthesized and exerts its actions through PR in the human central nervous system, and that progesterone may be involved in regulation of the growth and development of neurogenic tumors via PR, especially in the inhibition of tumor cell proliferation via PR-A.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12414909&dopt=Abstract progesterone, progesterone cream



progesterone cream
Overexpression of mdm2 and p53 and association with progesterone receptor expression in benign meningiomas.

Das A, Tan WL, Teo J, Smith DR.

The progesterone receptor is frequently found expressed in meningiomas at robust levels. As several studies of breast and endometrial tumors have shown an inverse correlation between progesterone receptor expression and p53 overexpression, we sought to determine if a similar relationship existed in meningiomas. As p53 may also be inactivated by the overexpression of mdm2, we examined a cohort of 90 benign meningiomas immunohistochemically for the presence of the progesterone receptor as well as overexpression of p53 and mdm2. The progesterone receptor was detected in 67% (61/90) of cases, while p53 and mdm2 overexpression were detected in 14% (13/90) and 46% (42/90) of cases, respectively. An absolute correlation was observed between the overexpression of nuclear mdm2 and overexpression of the progesterone receptor, with nuclear mdm2 overexpression being confined to progesterone receptor-positive tumors (P = 0.001). While p53 overexpression was not associated with progesterone receptor expression, a combination of mdm2 overexpression and/or p53 overexpression was significantly associated with the presence of the progesterone receptor (P = 0.025). These results suggest the existence of a novel relationship between p53 (and its regulatory control) and the presence of the progesterone receptor and, as such, may have fundamental consequences in developing progesterone receptor-targeted therapies for meningiomas.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12416559&dopt=Abstract progesterone, progesterone cream