Neuro Endocrinol Lett. 2003 Jun-Aug;24(3-4):185-91.
The effect of estradiol, but not progesterone, on the production of cytokines in stimulated whole blood, is concentration-dependent.

Matalka KZ.

Faculty of Pharmacy and Medical Technology, University of Petra, Amman, Jordan. kzop.edu.jo

OBJECTIVES: The purpose of this study was to determine the effects of estradiol and progesterone on interferon-gamma (IFN-gamma), interleukin (IL)-12, IL-10 and tumor necrosis factor-alpha (TNF-alpha) productions in polyclonal activators (phytohemagglutinin+lipopolysaccharide)-stimulated whole blood cultures. METHODS: Nineteen healthy males and females volunteered in the study. Blood samples were drawn, diluted, and cultured for 24h with different concentrations of estradiol, progesterone or hydrocortisone and then PHA+LPS was added for another 24 h. The supernatant, then, was harvested and assayed for IL-12 p70, IFN-gamma, IL-10 and TNF-alpha. RESULTS: At preovulatory concentrations, estradiol enhanced significantly IFN-gamma, IL-12 and IL-10, but not TNF-alpha, production levels and reversed the suppressive effect of hydrocortisone in PHA+LPS stimulated whole blood. While IL-10 levels kept increasing at pregnancy estradiol concentrations, IFN-gamma, IL-12 levels and IFN-gamma/IL-10 ratio decreased significantly. No effect of progesterone on IL-12 p70, IFN-gamma, IL-10 and TNF production levels was observed. CONCLUSIONS: The present study shows that those pregnancy estradiol concentrations (and higher) enhance the production of IL-10 and reduce IL-12, IFN-gamma levels and IFN-gamma/IL-10 ratio in stimulated whole blood cells. Because of the known IL-10 inhibitory actions on T helper (Th) 1 cells and monocytes/macrophages, these high IL-10 levels keep Th2 cytokines favored during pregnancy and may be useful in shifting Th1-mediated autoimmune diseases towards non-pathogenic Th2 pathway.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14523355&dopt=Abstract estradiol




J Huazhong Univ Sci Technolog Med Sci. 2003;23(3):283-5.
Effects of estradiol and tamoxifen on proliferation of human breast cancer cells and human endometrial cells.

Zhang B, Chen D, Wang G, Wu Y.

Department of General Surgery, Xiehe Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022.

The effects of estradiol and tamoxifen on the proliferation of estrogen receptor positive cells and the relationship between the tamoxifen tolerance and cell origin were investigated. The tissues of human endometrium and breast cancer were randomly selected following dissection for primary cell culture. After the breast cancer cells and endometrial cells were treated with 1 x 10(-8) mol/L estradiol and/or 1 x 10(-6) tamoxifen, 3H-labelled thymine nucleotide was used to trace the kinetics of cell proliferation. There was no significant difference in the inhibition on the human endometrial cells between tamoxifen-treated group (6.3%) and control group (6.4%), but tamoxifen could significantly inhibit the proliferation of the human breast cancer cells (45.84%) as compared with control group (52.72%). Moreover, tamoxifen could significantly stimulate the proliferation of tamoxifen resistant breast cancer cells (9.64%) as compared with control group (6.32%). Estradiol could significantly stimulate the proliferation of all the three kinds of cells as compare with control group. The combined use of estradiol and tamoxifen could inhibit the proliferation of the endometrial cells and breast cancer cells as compared with estradiol used alone, but on the tamoxifen resistant breast cancer cells, they could more significantly stimulate the proliferation than E2. It was concluded that E2 could stimulate the proliferation of these three kinds of cells. However, the inhibitive effects of tamoxifen on the proliferation of these cells were dependent on the estradiol.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14526435&dopt=Abstract estradiol




Arch Histol Cytol. 2003 Aug;66(3):229-38.
The effects of sex steroids on the formation of gap junctions between folliculo-stellate cells; a study in castrated male rats and ovariectomized female rats.

Sakuma E, Herbert DC, Soji T.

Department of Functional Morphology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan. esakumed.nagoya-cu.ac.jp

We investigated the relationship between gap junction formation and the sex steroids testosterone, progesterone and 17beta-estradiol in the anterior pituitary glands of castrated male rats and ovariectomized female rats. Male and female 30-day-old Wistar-Imamichi strain rats were castrated or ovariectomized, and 30 days later they were subcutaneously injected with the above sex steroids. They were divided into six groups according to the injected materials: sesame oil (control), testosterone, progesterone, 17beta-estradiol, testosterone with 17beta-estradiol, and progesterone with 17beta-estradiol. Five rats from each group were sacrificed 1, 2, 3, 4 and 5 days after the injections, and the anterior pituitary glands were prepared for observation by transmission electron microscopy. We quantified the number of follicles and gap junctions and calculated the rate of occurrence of gap junctions as the ratio of the number of gap junctions existing between folliculo-stellate cells per intersected follicle profile in electron photomicrographs. The administration of testosterone to castrated male rats increased the rate of gap junctions between folliculo-stellate cells; however, progesterone and 17beta-estradiol did not affect the formation of gap junctions. The administration of progesterone to ovariectomized female rats increased the rate of gap junctions between folliculo-stellate cells; this progesterone effect was prevented by the simultaneous administration of 17beta-estradiol, which by itself did not affect the rate of gap junctions between folliculo-stellate cells. These observations indicate that the formation of gap junctions




Chin Med J (Engl). 2003 Sep;116(9):1413-7.
Effects of estradiol on proliferation and metabolism of rabbit mandibular condylar cartilage cells in vitro.

Cheng P, Ma X, Xue Y, Li S, Zhang Z.

Center for Temporomandibular Disorders, Peking University School of Stomatology, Beijing 100081, China.

OBJECTIVE: To investigate the effects in vitro of 17 beta-estradiol (E2) on the proliferation and metabolism of rabbit mandibular condylar cartilage cells. METHODS: Chondrocytes were derived from neonatal rabbit mandibular condylar cartilage using a modified enzyme method. 17 beta-estradiol was added to the culture medium in a variety of concentrations. Cell growth and DNA, collagen, and proteoglycan synthesis were used as indicators of proliferation and differentiation of condylar chondrocytes. These were measured by cell number, 3H-proline and 35S-incorporation, respectively. RESULTS: E2 increased cell number and 3H-thymidine incorporation at 10(-8) to 10(-10) mol/L, and 10(-8) to 10(-11) mol/L in a dose-dependent manner, peaking at 10(-8) mol/L and 10(-9) mol/L, respectively. However, further increase in the concentration of estradiol caused inhibition of both cell number and 3H-thymidine incorporation, and this was significant at 10(-6) mol/L. The effect of E2 on proteoglycan synthesis was similar; the maximum stimulating effect was at 10(-8) mol/L, and inhibition was significant at 10(-6) mol/L. There was no obvious stimulatory effect of E2 on 3H-thymidine incorporation observed. CONCLUSIONS: Estradiol affects condylar chondrocyte cell growth, DNA, and proteoglycan synthesis in a biphasic manner depending on its concentration. This indicates that estrogen may be important in the proliferation and differentiation of mandibular condylar chondrocytes, and could be relevant to some aspects of certain temporomandibular joint diseases by modulating the function of the chondrocytes.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14527378&dopt=Abstract estradiol




Skin Pharmacol Appl Skin Physiol. 2003 Nov-Dec;16(6):356-66.
Testosterone metabolism in human skin cells in vitro and its interaction with estradiol and dutasteride.

Munster U, Hammer S, Blume-Peytavi U, Schafer-Korting M.

Abteilung fur Pharmakologie und Toxikologie, Institut fur Pharmazie, Freie Universitat Berlin, Berlin, Deutschland.

Since the limited knowledge of cutaneous drug metabolism can impair the development of specifically acting topical dermatics and transdermal application systems, the cell-type-specific androgen metabolism in human skin and its inhibition by drugs were investigated. Cultured human foreskin and scalp skin keratinocytes and fibroblasts as well as occipital scalp dermal papilla cells (DPC) were incubated with testosterone 10(-6) and 10(-8)M alone and in the presence of 17alpha-estradiol, 17beta-estradiol or dutasteride for 24 h. Androgens extracted from culture supernatants were subjected to thin-layer chromatography and quantified by beta-counting. In keratinocytes and DPC, dihydrotestosterone (DHT) was only formed to a low extent while androstenedione was the main metabolite. In fibroblasts, DHT formation was pronounced following 10(-8)M testosterone. Dutasteride 10(-8)M completely suppressed 5alpha-dihydro metabolite formation. 17alpha-Estradiol and 17beta-estradiol at nontoxic concentrations decreased 17-ketometabolites. Human skin regulates testosterone action by cell-type-specific activation or deactivation. Effects of 17alpha-estradiol in androgenetic alopecia are not due to 5alpha-reductase inhibition. Dutasteride may be useful in acne and androgenetic alopecia. Copyright 2003 S. Karger AG, Basel

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14528059&dopt=Abstract estradiol




Endocrinology. 2004 Jan;145(1):221-7. Epub 2003 Oct 09.
Endotoxin inhibits the surge secretion of gonadotropin-releasing hormone via a prostaglandin-independent pathway.

Breen KM, Billings HJ, Debus N, Karsch FJ.

Reproductive Sciences Program, Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109-0404, USA.

Immune/inflammatory challenges, such as bacterial endotoxin, disrupt gonadotropin secretion and ovarian cyclicity. We previously determined that endotoxin can block the estradiol-induced LH surge in the ewe. Here, we investigated mechanisms underlying this suppression. First, we tested the hypothesis that endotoxin blocks the estradiol-induced LH surge centrally, by preventing the GnRH surge. Artificial follicular phases were created in ovariectomized ewes, and either endotoxin or vehicle was administered together with a surge-inducing estradiol stimulus. In each ewe in which endotoxin blocked the LH surge, the GnRH surge was also blocked. Given this evidence that endotoxin blocks the estradiol-induced LH surge at the hypothalamic level, we began to assess underlying central mechanisms. Specifically, in view of the prior demonstration that prostaglandins mediate endotoxin-induced suppression of pulsatile GnRH secretion in ewes, we tested the hypothesis that prostaglandins also mediate endotoxin-induced blockade of the surge. The prostaglandin synthesis inhibitor flurbiprofen was delivered together with endotoxin and the estradiol stimulus. Although flurbiprofen abolished endotoxin-induced fever, which is a centrally generated, prostaglandin-mediated response, it failed to reverse blockade of the LH surge. Collectively, these results indicate endotoxin blocks the LH surge centrally, suppressing GnRH secretion via a mechanism not requiring prostaglandins. This contrasts with the suppressive effect of endotoxin on GnRH pulses, which requires prostaglandins as intermediates.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14551234&dopt=Abstract estradiol




Reprod Toxicol. 2003 Sep-Oct;17(5):585-92.
Dibromoacetic acid-induced elevations in circulating estradiol: effects in both cycling and ovariectomized/steroid-primed female rats.

Goldman JM, Murr AS.

Endocrinology Branch, Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA. goldman.jerompa.gov

Oral exposures to high concentrations of the drinking water disinfection by-product dibromoacetic acid (DBA) over the course of 14 days have been found to disrupt estrous cyclicity in the female rat. In order to investigate possible alterations in the relevant hormonal regulatory mechanisms, female Sprague-Dawley rats were gavaged for 2 weeks with 270 mg/kg DBA, ovariectomized (OVX) and implanted with estradiol capsules. For these females, the induced luteinizing hormone (LH) surge in these animals showed a borderline suppression in peak LH concentrations that was accompanied by a marked increase in circulating estradiol. This elevation in estradiol was DBA dose-related and, for intact, normally cycling females receiving lower doses of DBA (60 and 120 mg/kg, 14 days), was present on the day of estrus, at a time when a dramatic fall from proestrous concentrations is normally evident. Evaluations of liver microsomal cytochrome p450 activity in OVX/estradiol-implanted rats showed a suppression in ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-deethylase (PROD) activity (indications of the activity of CYP1A and 2B, respectively-two key enzymes in estradiol oxidative metabolism). Phenobarbital (PhB) exposure in these animals did show induction of this activity, but was unable to lower E2 concentrations. This suggests that a DBA-induced suppression in estradiol catabolism is present and may either involve a targeted effect on the estrogen binding site on the CYP2B1/2 and CYP1A genes apart from the PhB-responsive unit, or a second pathway (possi




J Biol Chem. 2004 Jan 9;279(2):1217-23. Epub 2003 Oct 10.
Estradiol binding to maxi-K channels induces their down-regulation via proteasomal degradation.

Korovkina VP, Brainard AM, Ismail P, Schmidt TJ, England SK.

Department of Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA.

Estrogens exert their biological action via both genomic and non-genomic mechanisms. Proteins different from classical estradiol receptors are believed to mediate the latter effects. Here we demonstrate that the maxi-K channel functions as an estrogen-binding protein in transfected HEK293 cells. Whole-cell maxi-K channel currents and protein expression were attenuated by exposure to either 17alpha- or 17beta-estradiol. This effect was dose-dependent for 17beta-estradiol at concentrations ranging from 10 nm to 1 microm, while 17alpha-estradiol inhibited channel expression only at 1 microm. These effects were mediated by direct low affinity binding of estradiol to the maxi-K channel but not to its accessory beta1-subunit, as revealed by cell membrane estradiol binding assays. However, specific binding of estradiol to the channel was facilitated by the presence of the beta1 subunit. Addition of MG-132, a blocker of proteasomal degradation, stabilized channel expression. These data suggest that channel down-regulation is mediated by estrogen-induced proteasomal degradation, similar to the pathway used for estrogen receptor degradation. Membrane expression of endogenous maxi-K channels in cultured vascular smooth muscle cells was also attenuated by prolonged exposure to 17alpha- and 17beta-estradiol. Thus our studies demonstrate that estrogen binds to maxi-K channels and may directly regulate channel expression and function. These results will have important implications in understanding estradiol-induced effects in multiple tissues including vascular smooth muscle.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14555652&dopt=Abstract estradiol




Aquat Toxicol. 2003 Jan 24;62(2):85-103.
Effects of 17a-ethinylestradiol on the expression of three estrogen-responsive genes and cellular ultrastructure of liver and testes in male zebrafish.

Islinger M, Willimski D, Volkl A, Braunbeck T.

Department of Zoology, University of Heidelberg, Im Neuenheimer Feld 230, D-69120, Heidelberg, Germany. islingeorph.zoo.uni-heidelberg.de

In order to monitor the influence of estrogenic compounds on the reproductive physiology of fish, molecular markers for zebrafish vitellogenin, estrogen receptor and ZP2 were developed. For this purpose, sequence information about the zebrafish estrogen receptor and vitellogenin had to be obtained. By means of RT-PCR, a sequence fragment of the zebrafish estrogen receptor alpha was cloned and sequenced. Continuous cDNAs of two zebrafish vitellogenin-like gene products (zfvg1 and zfvg3) were constructed by the help of expressed sequence tags of zebrafish and completely sequenced. The sequences of the estrogen receptor and of the vitellogenins showed significant similarities to corresponding cDNAs of other fish species. Expression of these gene products was measured following exposure to 17alpha-ethinylestradiol and compared with histological endpoints. RT-PCR was used as a semiquantitative technique to record gene expression in adult male zebrafish, which were exposed to 17alpha-ethinylestradiol in time-and dose-response experiments. As for time-dependent expression, all hepatic genes investigated were expressed at considerable amounts from 24 h after onset of exposure to 50 ng/l 17alpha-ethinylestradiol to the end of experiment (17 days). In testes, expression of the estrogen receptor- as well as ZP2-mRNA remained unchanged for the entire experiment, except for the individuals exposed for 17 days, which displayed elevated expression levels of ZP2. In the dose-response experiment, male zebrafish were exposed to 17alpha-ethinylestradiol in concentrations from 0.25-85 ng/l for 4 and 21 days. LOECs for vitellogenin as wel