| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Other Original Articles |
Baker Medical Research Institute and Alfred Hospital, Victoria, Australia 3181
Address all correspondence and requests for reprints to: Associate Professor Paul Komesaroff, Baker Medical Research Institute, P.O. Box 6492, St. Kilda Road Central, Melbourne, Victoria, Australia 8008. E-mail: paul.komesaroff{at}baker.edu.au
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Interest in DHEA(S) stems from epidemiological studies showing an inverse relationship between cardiovascular mortality and plasma DHEA(S) levels in men (7, 8). Although both the occurrence and the clinical manifestation of coronary atherosclerosis have been correlated with plasma levels of DHEA(S), the favorable vascular effects of this hormone remain controversial, and its role in vascular physiology is still unclear. In addition, the underlying mechanisms by which DHEA(S) might potentially influence cardiovascular mortality are not clear.
Vascular smooth muscle cell (VSMC) proliferation contributes to the remodeling of blood vessels and has been implicated in the pathogenesis of atherosclerosis. Although 17ß-estradiol has been shown to inhibit VSMC proliferation and therefore possibly to prevent atherosclerosis (9), it is unclear whether DHEA has similar actions and if so by which subcellular pathways these actions occur.
In addition, the possibility of specific receptors and subcellular mechanisms whereby DHEA might potentially exert vascular effects have not been explored. In the current study, therefore, we sought to examine the actions of DHEA in cultured VSMCs and the pathways through which their effects on cell proliferation might be mediated.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
VSMCs were harvested from human internal mammary artery (IMA) by an explant technique (10). In brief, a segment of IMA was cut out and placed into ice-cold DMEM. All external fat and connective tissue were microscopically cleaned from the vessel. Following the removal of the endothelial layer, the vessel was cut longitudinally, and the remaining strips were transferred to 60-mm dishes with DMEM in the presence of 5 mmol/liter glucose and 10% FBS and placed into an incubator of 5% CO2 at 37 C. Culture media were changed every 3 d. Following migration from the vessel strips, the cells were allowed to proliferate and subsequently subcultured to near confluence. Smooth muscle cells were characterized by incubation with smooth muscle 
-actin followed by immunofluorescence staining and Western blot analysis. Cells at passages 11–15 were used in the current study.
Cell proliferation
Cell proliferation was determined by a [3H]-thymidine incorporation assay measuring DNA synthesis and by counting cell numbers. Cells were seeded in 24-well plates (10,000 cells/ml) and grown to 80–90% confluence in DMEM with 10% FBS. Following serum deprivation for 24 h, the cells were incubated with DHEA, 17ß-estradiol, androstenedione or T for 4 h and subsequently with the hormones and platelet-derived growth factor (PDGF) BB (10ng/ml) together for 20 h. [3H]-thymidine 1 µCi/well was added during the last 3 h of PDGF BB treatment, the cells washed twice with ice-cold Dulbecco’s PBS, and then incubated with ice-cold 0.2 N HClO4 (1 ml/well) on ice for 30 min. After washing three times (0.5 ml/well) with 0.2 N HClO4, cells were incubated with 0.5 ml/well of 0.2N NaOH in 37 C for over 1 h, which was then neutralized with 0.2 ml/well of 6% acetic acid. The contents of each well were transferred into scintillation vials with 3 ml Instagel (Bio-Rad Laboratories, Inc., Sydney, Australia) and counted for 2 min/vial in a ß-counter. For counting cell numbers, cells were seeded in to 24-well plates at a density of 5000 cells/ml, grown to 60–70% confluence, and treated with the hormones and PDGF BB as described above. After 48 h, cells were harvested and counted in an automatic cell counter (S.ST.II/ZM, Coulter Electronics Ltd., Miami, FL).
Pharmacological antagonism of ERs and ARs
To determine whether the effects of DHEA on cell proliferation are mediated via ERs or ARs, measurements of DNA synthesis were performed in the presence and absence of the ER antagonist ICI 182,780 or the AR antagonist flutamide added 2 h before the addition of the various hormones.
ER and AR studies
ER and AR density was determined by radioligand-binding assay. IMA VSMCs were seeded and allowed to grow to confluence on 6-well plates (
10 x 105 cells/well) and incubated with [3H]-estradiol (0.315–5.0 nmol/liter) with or without nonradioactive diethylstilbestrol (1 µmol/liter) for ER and [3H]-R1881 (0.31–5 nmol/liter) with 1 µmol/liter triamcindore plus or minus nonradioactive dihydrotestosterone (1 µmol/liter) for AR for 90 min. Cells were washed with D-PBS and scraped out in the presence of 0.1% Triton acetic acid (1.5 ml/well). Extracts were put into scintillation vials with 5 ml scintillation liquid (Instagel, Bio-Rad Laboratories, Inc.) for counting (5 min/vial) in a ß-counter.
ER and AR protein expression was analyzed by Western blot. Cells were washed twice with ice-cold PBS and lysed by incubation on ice for 30 min with lysis buffer (20 mmol/liter Tris-base pH7.7, 250 mmol/liter NaCl, 2 mmol/liter EDTA, 2 mmol/liter EGTA, 0.5% NP-40, 10% glycerol, 20 mmol/liter ß-glycerophosphate, and 1 mmol/liter Na-vanadate). Leupeptin (10 µl/ml), 5 µl/ml aprotinin, 1 µmol/liter pepstatin, 1 mmol/liter 4-(2-aminoethyl)-benzenesulfonylfluoride, and 10 mmol/liter dithiothereitol were added before use. Total proteins were isolated by centrifuging at 5000 rpm for 15 min, 30 µg protein electrophoresed on 10% SDS-polyacrylamide gels, and transferred to Hybond ECL filters (Sigma, St. Louis, MO). The filters were blocked with 5% nonfat dry milk in TBS (20 mmol/liter Tris, pH7.5, 50 mmol/liter NaCl, and 0.1% Tween-20) overnight, and then washed and incubated with primary antibodies against ER, ERß, or AR (Santa Cruz Biotechnology, Inc., Santa Cruz, CA) for 1 h. After washing (10 min x 3), blots were incubated with HRP-conjugated secondary antibody (DAKO Corp., Glostrup, Denmark) for 1 h, washed three times (10 min), incubated for 1 min with enhanced chemiluminescence reagents (Amersham Pharmacia Biotech, Buckinghamshire, UK), and exposed to x-ray film. For protein loading controls, the blots were washed again and probed with an antihuman smooth -actin antibody (DAKO Corp.) by the method described above. For relative quantification, bands were scanned in a PowerLook scanner (Industrial Park, Hsinchu, Taiwan).
AR- and ER-binding assays
Competitive binding assays were carried out to determine the relative binding affinity of DHEA for AR and ER. Confluent monolayers of cells in 6-well plates were exposed to DHEA (1–1000 nmol/liter) plus 1 µmol/liter of either [3H]-estradiol or [3H]-R1881, with appropriate amounts of T or 17ß-estradiol as controls. Following incubation at 37 C for 60 min, cells were washed with D-PBS, treated with 0.1% Triton acetic acid, and harvested. Extracts were transferred to scintillation vials with 5 ml scintillation liquid for counting (5 min/sample) in a ß-counter.
DHEA binding assays
Similar competitive binding assays were carried out to explore DHEA binding to intact cells. Confluent monolayers of cells in 6-well plates were treated with [3H]-DHEA (10 nmol/liter) and 1–10 000 nmol/liter unlabeled DHEA. Following incubation at 37 C for 90 min, cells were washed with D-PB,S and bound DHEA was determined as above.
Scatchard analysis was carried out to determine the affinity and capacity of DHEA binding. Confluent monolayers of cells in 6-well plates were treated with [3H]-DHEA (49–1.5 nmol/liter) in the presence or absence of 10 000 nmol/liter unlabeled DHEA. Following incubation at 37 C for 90 min, cells were washed with D-PBS and bound DHEA was determined as above.
Cell culture for protein kinase assays
IMA VSMC (10,000 cells/ml) were seeded in 60-mm culture dishes and grown to near confluence in DMEM with 10% FBS. Following serum deprivation for 24 h, the cells were treated with DHEA (0.1–100 nM) for 4 h and then with PDGF-BB (10 ng) for 15 min. Cells were then washed with ice-cold PBS and scraped into ice-cold lysis buffer containing 0.25 M sucrose, 25 mM Tris-HCl (pH 7.5), 1 mM EDTA, 10 mM NaF, 0.1% 2-ß-mercaptoethanol, 1 mM phenylmethylsulfonyl fluoride, 1 µM pepstatin A, 10 µM leupeptin, and 0.23 U/ml aprotinin. After centrifugation at 100,000 g for 10 min at 4 C, the supernatant was taken for MAPK activity assay and cell lysate protein levels measured by the Bradford method. For positive controls of the c-jun N-terminal protein kinase (JNK) and p38 assay systems, IMA VSMCs were treated with TNF (20 ng) for 10 min or UV light (15 sec) before isolating cystolic protein fractions.
ERK-1, JNK, and p38 protein kinase assays
Kinase assays for ERK-1, JNK, and p38 kinases have been previously described (10A ). Briefly, 50 µg cytosolic protein was incubated (4 C for 1 h) in lysis buffer containing 50 mg/ml BSA and specific anti-ERK1, anti-JNK, or anti-p38 antibodies. This was followed by a second incubation (4 C for 1 h) with protein A-Sepharose beads and a third incubation (30 C for 15 min) with 40 µl protein kinase buffer containing 20 mM HEPES (pH 7.6), 10 mM MgCl2, 10 mM 2-ß-glycerophosphate, 0.1 mM Na-vanadate, 2 mM dithiothreitol, 0.1 µM microcystin, 5 µg/ml protein kinase inhibitor, 50 µM ATP, 3 µCi/tube [
-32P]-ATP, and specific substrate proteins for the kinase type; 0.25 mg/ml MBP for ERK1 kinase, 0.3 mg/ml c-Jun (5–79)-glutathione S-transferase fusion protein for JNK kinase, and ATF-2 glutathione S-transferase fusion protein for p38 kinase. Following termination of the reaction by the addition of 20 µl SDS buffer and cooling to 4 C, samples (20 µl) were subjected to electrophoresis on 15% SDS/polyacrylamide gel. Proteins were transferred onto a nitrocellulose membrane, and the membrane was then autoradiographed to show kinase phosphorylation. To verify the immunoreactivity of the kinases, Western blotting was carried out on the nitrocellulose membrane using the same antibodies as for immunoprecipitation.
Statistics
All data are presented as mean ± SEM. Statistical analysis between two observations was by t test and in multiple comparisons by ANOVA. The null hypothesis was rejected at P more than 0.05.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Both DHEA and 17ß-estradiol (0.1–100 nmol/liter) attenuated PDGF BB-induced increases in DNA synthesis in VSMCs in a dose-dependent manner, with a maximum inhibitory effect of DHEA to 61% plus or minus 3%, compared with 17ß-estradiol (53% ± 4% of control). Conversely, T at the same concentrations enhanced DNA synthesis, as did androstenedione (167% ± 9% and 131% ± 3% of control, respectively) (Fig. 1
). Consistent with the [3H]-thymidine incorporation assay data, cell numbers decreased in DHEA-treated groups, compared with control (data not shown). These results indicate that DHEA inhibits PDGF BB-induced VSMC proliferation in a fashion similar to estrogen and in a direction opposite that of T and androstenedione.
|
The inhibitory effect of DHEA (10 nmol/liter) on PDGF-BB induced cell proliferation was not affected by either the AR antagonist flutamide or the ER antagonist ICI 182,780 (100 nmol/liter). Flutamide completely abolished the stimulatory effects of T, and ICI 182,780 blocked the inhibitory effects of 17ß-estradiol on the cells (Fig. 2), evidence that the actions of DHEA are not mediated by either ARs or ERs.
|
Radioligand-binding assays confirmed the presence of both ARs and ERs in these VSMCs at the density of 20,000 sites/cell [kilodalton (Kd) = 0.44 nmol/liter] for ARs and approximately 24,000 sites/cell (Kd = 0.51 nmol/liter) for ERs. DHEA at concentrations of 1000 nmol/liter showed approximately 5% displacement of 1 nM [3H]R1881 binding to ARs and no specific binding to ERs. The presence of saturable binding sites for DHEA was demonstrated by the ability of nonradioactive DHEA to compete for binding with [3H]DHEA (10 nM); nonspecific binding (in the presence of 10 µM DHEA) varied from 50% to 65% of total (Fig. 3A). Scatchard analysis of specific [3H]DHEA (1.4–49 nM) binding with and without 500-fold excess of nonradioactive DHEA showed that there were 37,000 binding sites/cell, binding [3H]DHEA with an affinity given by Kd 37 C 14 nM (Fig. 3B).
|
DHEA (10-10 to 10-7 M) inhibited PDGF-BB-induced increases in ERK1 kinase activity in a dose-dependent manner (Fig. 4A). Neither JNK nor p38 kinase phosphorylation was influenced by either PDGF-BB or DHEA, although both were appropriately stimulated by TNF and UV light in human VSMCs (Fig. 4B).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
DHEA is quantitatively the most abundant circulating adrenal steroid and has been the subject of many studies; however, the possibility of its having biological actions in its own right has been largely overlooked, in that it has generally been assumed that its actions reflect conversion to androgenic and estrogenic metabolites. Evidence in favor of this assumption includes the presence of the enzymes responsible for 3ß oxidation of DHEA to androstenedione (3ß-hydroxysteroid dehydrogenase), for 17ß reduction of androstenedione to T and estrone to estriol (17ß-hydroxysteroid dehydrogenase), and for aromatization of androgens into estrogens (P450 aromatase) in many peripheral tissues and perhaps also in VSMCs (11, 12). Furthermore, numerous studies have shown that DHEA administration results in increased levels of androgens and estrogens (5, 6) and that prolonged pretreatment periods with DHEA is required before an effect is observed, suggesting that the actions of DHEA may result from the production and subsequent action of estrogenic or androgenic metabolites arising from DHEA conversion (13).
Recently, however, the possibility of direct actions of DHEA has been increasingly canvassed, but the studies to date have yielded conflicting results. Bruder et al. (14) reported that DHEA stimulates the estrogen response element independently of conversion to estrogens. However, because this effect was blocked by the ER antagonist ICI 182,780, it suggests that DHEA may have been acting via ERs or that the ICI compound also blocked the putative DHEA receptor; in addition, the possibility of DHEA conversion to other, androgenic metabolites cannot be excluded in this study.
Although estrogen-like effects of DHEA have been observed both in vitro and in vivo, androgenic effects have also been demonstrated. Sourla et al. (15) showed that DHEA had androgenic effects on rat mammary gland histomorphology and structure, which were abolished by the AR antagonist flutamide but not by the ER antagonist EM-800. The findings of this study thus suggest that in the rat mammary gland, DHEA exerts its effects via the AR. They do not, however, exclude the possibility of DHEA conversion to androgens and therefore do not constitute convincing evidence for a specific DHEA action independent of conversion.
Our finding that DHEA inhibits the proliferation of human IMA VSMCs is consistent with findings previously reported from studies in other cell lines, such as human aortic VSMCs (13), fibroblasts (16), T lymphocytes ( 17), and preadipocytes (18). However, the present study has also demonstrated that the inhibitory effects of DHEA on VSMC proliferation are independent of both ARs and ERs, evidenced by the DHEA-induced response being unaffected by either flutamide or ICI 182,780. In contrast, the inhibitory effect of 17ß-estradiol and the stimulatory effect of T were completely abolished by their respective receptor antagonists. These results strongly suggest that although DHEA has an estrogen-like effect on VSMC proliferation, its mode of action is unlike that of either 17ß-estradiol or T. The demonstration that androstenedione, the principal product of DHEA conversion in human VSMCs, showed stimulatory effects on cell proliferation (e.g. opposite to those seen with DHEA) is further evidence that the observed effects are because of a direct interaction rather than conversion. It is possible that the effects of DHEA we have observed are because of the actions of yet another metabolite: for example, there is evidence that in nonvascular tissues androstenediol, the direct reduction product of DHEA, may exert either estrogenic (19) or androgenic effects ( 20); if such metabolites are relevant, however, our study shows that their effects, too, are independent of ER- and AR-mediated processes.
As expected, in this study, T and 17ß-estradiol bound respectively to the AR and ER in VSMCs with DHEA showing no binding to either receptor. DHEA did, however, exhibit specific binding to intact cells in a manner consistent with steroid hormone receptor-like interactions. Although specific DHEA-binding sites have previously been reported in rat liver (21) and murine T cells (17), this is the first time a putative receptor has been shown in VSMCs. The affinity of this binding (Kd 37 C 14 nM), measured by saturation analysis and shown in Fig. 1B
, is consistent with the circulating levels of DHEA in vivo. The high levels of nonspecific binding (70–85% of total, across the range of tracer concentrations used) make the value of 14 nM for the affinity an approximate one; the displacement of tracer down to 55% by an equal concentration (10 nM) of nonradioactive DHEA is consistent with an affinity up to an order of magnitude lower (1–2 nM).
In addition to the effects of DHEA on human VSMC proliferation, the subcellular mechanisms of DHEA action were also a focus of this study. We suspected that DHEA may exert its effects on VSMC proliferation by subcellular mechanisms involving MAPK, which has been implicated in other steroid responses, including those induced by estrogens and androgens (22, 23). MAPK belongs to a superfamily of protein kinases including ERK, JNK, and reactivating protein kinase (p38) (24). A previous study has demonstrated that DHEA inhibited PDGF-BB-induced MAPK phosphorylation in a dose-dependent manner (25), suggesting that one of the subcellular mechanisms of DHEA action is via the MAPK pathway. However, the authors of this report did not differentiate among the different kinases that make up the MAPK superfamily.
The present study investigated the effects of DHEA on PDGF-BB-induced ERK-1, JNK, and p38 phosphorylation. We have demonstrated that DHEA significantly inhibits PDGF-BB-induced ERK-1 phosphorylation in a dose-dependent manner. JNK and p38 kinase protein were shown to be present in high levels but not phosphorylated in quiescent human VSMC; neither PDGF-BB nor DHEA affected JNK or p38 kinase levels or phosphorylation status; we therefore suggest that endogenous JNK and p38 kinases are inactive in human quiescent VSMCs and that the observed DHEA effects are mediated specifically via ERK-1 signaling pathways.
In conclusion, we have shown, for the first time, that DHEA inhibits the proliferation of human VSMCs independently of ARs and ERs. These effects may be attributable to interactions between DHEA and DHEA-specific binding complexes and are mediated, at least in part, by ERK-1 signaling pathways.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
Received July 23, 2001.
Accepted September 28, 2001.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
 |
|
 |
|
  A. Aversa, R. Bruzziches, D. Francomano, M. Natali, and A. Lenzi Testosterone and phosphodiesterase type-5 inhibitors: new strategy for preventing endothelial damage in internal and sexual medicine? Therapeutic Advances in Urology, October 1, 2009; 1(4): 179 - 197. [Abstract] [PDF]
|
|
|
|
 |
|
 S. Bonnet, R. Paulin, G. Sutendra, P. Dromparis, M. Roy, K. O. Watson, J. Nagendran, A. Haromy, J. R.B. Dyck, and E. D. Michelakis Dehydroepiandrosterone Reverses Systemic Vascular Remodeling Through the Inhibition of the Akt/GSK3-{beta}/NFAT Axis Circulation, September 29, 2009; 120(13): 1231 - 1240. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. A. Komesaroff Unravelling the Enigma of Dehydroepiandrosterone: Moving Forward Step by Step Endocrinology, March 1, 2008; 149(3): 886 - 888. [Full Text] [PDF]
|
|
|
|
|
|
D. Liu, M. Iruthayanathan, L. L. Homan, Y. Wang, L. Yang, Y. Wang, and J. S. Dillon Dehydroepiandrosterone Stimulates Endothelial Proliferation and Angiogenesis through Extracellular Signal-Regulated Kinase 1/2-Mediated Mechanisms Endocrinology, March 1, 2008; 149(3): 889 - 898. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. G. Ziegler, F. Sicard, P. Lattke, S. R. Bornstein, M. Ehrhart-Bornstein, and A. W. Krug Dehydroepiandrosterone Induces a Neuroendocrine Phenotype in Nerve Growth Factor-Stimulated Chromaffin Pheochromocytoma PC12 Cells Endocrinology, January 1, 2008; 149(1): 320 - 328. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Liu, H. Si, K. A. Reynolds, W. Zhen, Z. Jia, and J. S. Dillon Dehydroepiandrosterone Protects Vascular Endothelial Cells against Apoptosis through a G{alpha}i Protein-Dependent Activation of Phosphatidylinositol 3-Kinase/Akt and Regulation of Antiapoptotic Bcl-2 Expression Endocrinology, July 1, 2007; 148(7): 3068 - 3076. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Oka, V. Karoor, N. Homma, T. Nagaoka, E. Sakao, S. M. Golembeski, J. Limbird, M. Imamura, S. A. Gebb, K. A. Fagan, et al. Dehydroepiandrosterone upregulates soluble guanylate cyclase and inhibits hypoxic pulmonary hypertension Cardiovasc Res, June 1, 2007; 74(3): 377 - 387. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Wang, Y.-D. Wang, W.-J. Wang, Y. Zhu, and D.-J. Li Dehydroepiandrosterone improves murine osteoblast growth and bone tissue morphometry via mitogen-activated protein kinase signaling pathway independent of either androgen receptor or estrogen receptor J. Mol. Endocrinol., April 1, 2007; 38(4): 467 - 479. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Arlt, F. Hammer, P. Sanning, S. K. Butcher, J. M. Lord, B. Allolio, D. Annane, and P. M. Stewart Dissociation of Serum Dehydroepiandrosterone and Dehydroepiandrosterone Sulfate in Septic Shock J. Clin. Endocrinol. Metab., July 1, 2006; 91(7): 2548 - 2554. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A Dagre, J Lekakis, C Mihas, A Protogerou, L Thalassinou, D Tryfonopoulos, G Douridas, C Papamichael, and M Alevizaki Association of dehydroepiandrosterone-sulfate with endothelial function in young women with polycystic ovary syndrome. Eur. J. Endocrinol., June 1, 2006; 154(6): 883 - 890. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. K. Natoli, T. L. Medley, A. A. Ahimastos, B. G. Drew, D. J. Thearle, R. J. Dilley, and B. A. Kingwell Sex Steroids Modulate Human Aortic Smooth Muscle Cell Matrix Protein Deposition and Matrix Metalloproteinase Expression Hypertension, November 1, 2005; 46(5): 1129 - 1134. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Nakamura, M. Yoshimura, M. Nakayama, T. Ito, Y. Mizuno, E. Harada, T. Sakamoto, Y. Saito, K. Nakao, H. Yasue, et al. Possible Association of Heart Failure Status With Synthetic Balance Between Aldosterone and Dehydroepiandrosterone in Human Heart Circulation, September 28, 2004; 110(13): 1787 - 1793. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. R. I. Williams, T. Dawood, S. Ling, A. Dai, R. Lew, K. Myles, J. W. Funder, K. Sudhir, and P. A. Komesaroff Dehydroepiandrosterone Increases Endothelial Cell Proliferation in Vitro and Improves Endothelial Function in Vivo by Mechanisms Independent of Androgen and Estrogen Receptors J. Clin. Endocrinol. Metab., September 1, 2004; 89(9): 4708 - 4715. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Iwasaki, M. Asai, M. Yoshida, T. Nigawara, M. Kambayashi, and N. Nakashima Dehydroepiandrosterone-Sulfate Inhibits Nuclear Factor-{kappa}B-Dependent Transcription in Hepatocytes, Possibly through Antioxidant Effect J. Clin. Endocrinol. Metab., July 1, 2004; 89(7): 3449 - 3454. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Littleton-Kearney and P. D. Hurn Testosterone as a Modulator of Vascular Behavior Biol Res Nurs, April 1, 2004; 5(4): 276 - 285. [Abstract] [PDF]
|
|
|
|
|
|
F. Pizzagalli, Z. Varga, R. D. Huber, G. Folkers, P. J. Meier, and M. V. St-Pierre Identification of Steroid Sulfate Transport Processes in the Human Mammary Gland J. Clin. Endocrinol. Metab., August 1, 2003; 88(8): 3902 - 3912. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Simoncini, P. Mannella, L. Fornari, G. Varone, A. Caruso, and A. R. Genazzani Dehydroepiandrosterone Modulates Endothelial Nitric Oxide Synthesis Via Direct Genomic and Nongenomic Mechanisms Endocrinology, August 1, 2003; 144(8): 3449 - 3455. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Kawano, H. Yasue, A. Kitagawa, N. Hirai, T. Yoshida, H. Soejima, S. Miyamoto, M. Nakano, and H. Ogawa Dehydroepiandrosterone Supplementation Improves Endothelial Function and Insulin Sensitivity in Men J. Clin. Endocrinol. Metab., July 1, 2003; 88(7): 3190 - 3195. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |
, Significant difference from the hormone-alone treatment.
