| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
ARTICLE |
Department of Pharmacology (C.B.W.), University of Washington, Seattle, Washington 98195; and Department of Physiology and Pharmacology (D.M.D.), Oregon Health and Science University, Portland, Oregon 97201
Address all correspondence and requests for reprints to: Daniel M. Dorsa, Ph.D., Vice-President for Research, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Mail Code: L335, Portland, Oregon 97201-3098. E-mail: dorsad{at}ohsu.edu.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
and ERß are capable of activating the MAPK pathway in response to a low dose of 17ß-estradiol. In the present study, the ability of estrogen to act through both ER and ERß to increase CREB phosphorylation was evaluated in an immortalized hippocampal cell line stably expressing either receptor. Estrogen treatment promoted rapid CREB phosphorylation, reaching a maximum by 15 min. This activation is completely blocked by the antiestrogen ICI 182,780, suggesting an estrogen receptor-dependent mechanism. The addition of the mitogen/ERK kinase-1 inhibitor, PD98059, also blocked the ability of estrogen to signal to CREB phosphorylation. Estrogen also caused an increase in p90Rsk activity, a critical mediator of MAPK effects. Surprisingly, blockade of the protein kinase A pathway in cells treated with estrogen did not affect estrogen-mediated CREB phosphorylation. Thus, MAPK and p90Rsk appear to be the primary mediators of estrogen-induced gene transcription through ER and ERß. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
and ERß. The transcriptional effects are most commonly manifested via ER-binding ligand, dimerizing, and augmenting gene transcription at estrogen response elements. It has also been shown that an ER monomer can form a multimeric complex with fos and jun, which can regulate genes containing activator protein-1 elements. In addition to modulating gene transcription through these mechanisms, ligand-activated ERs can initiate numerous signal transduction cascades, all of which are known to modify the genomic output (1). It has recently been shown that an intact MAPK pathway is required for PRL gene expression (2), an effect of estrogen previously thought to be solely ERE mediated. Other recent work has shown that the rapid effects of estrogen may potentiate later genomic signaling (3). Estrogen can also rapidly affect a great number of other signaling pathways. Among these are changes in intracellular calcium (4), increases in cAMP (5, 6), modulation of neuronal calcium channels (7) and potassium channels (8), phosphorylation of cAMP response element-binding protein (CREB) (9, 10), activation of the protein kinase C (PKC) pathway (11), and activation of MAPK pathway members, ERK1 and ERK2 (12, 13, 14). Activation of the MAPK pathway appears to involve numerous upstream components, including hsp90, src, and B-raf, which form a multimeric complex with ligand-activated estrogen receptors (15).
Previous work from our laboratory has shown that blockade of estrogen rapid signaling inhibits gene transcription. In vivo and in SK-N-SH cells, we demonstrated that the cAMP/protein kinase A (PKA) pathway mediates estrogen-induced neurotensin expression (6). In this model, estrogen also increased CREB phosphorylation, which required activation of the PKA pathway. We have also shown that estrogen can differentially regulate gene expression in distinct brain regions by modulating the PKA and PKC pathways. In the ventromedial nucleus of the hypothalamus, activation of the PKC pathway by estrogen modulates oxytocin receptor expression, whereas in the central nucleus of the amygdala, genomic actions can be modulated by PKA (16). Together these data show that estrogen modulation of rapid signaling pathways can have profound effects on the genomic output.
The ability of estrogen to influence cAMP response element (CRE)-mediated gene transcription was first reported by Aronica et al. (5). Since then, numerous reports have established that estrogen treatment results in the rapid phosphorylation of CREB at Ser133 (9, 17, 18). A variety of mechanisms are capable of mediating this effect. Although most have assumed that this results from activation of PKA, previous reports have demonstrated that estrogen can activate the phosphatidylinositol 3-kinase (PI3K) pathway, which couples to CREB phosphorylation in primary cultures (10). Although estrogen has been shown to increase cAMP, it has been suggested that the cAMP/PKA pathway may not be involved in estrogen-mediated CREB phosphorylation in vivo (17).
To determine the role of ER and ERß in mediating estrogen rapid signaling, we chose to use a model system. In previous studies, we stably transfected the HT-22 murine hippocampal cell line with the cDNAs encoding ER or ERß to create the HTER and HTERß cell lines. In this system, we have demonstrated that estrogen is able to elicit MAPK phosphorylation in transfected HT-22 cells and this is required for neuroprotection (19). However, the mechanism by which MAPK activation might be neuroprotective is unclear. Activation of the Ras-MAPK pathway has been suggested to be an important factor in promoting cell survival. Activation of this pathway leads to the activation of the MAPK-activated p90 ribosomal S6 kinase family (Rsks), which mediate many of the effects of the MAPK pathway. This signaling pathway also results in CREB phosphorylation at Ser133 and subsequent gene transcription from CREs. Among the genes affected by this pathway are numerous antiapoptotic proteins, including Bcl-2 (20). Members of the Rsk family have also been shown to phosphorylate, and thereby inactivate, Bcl-2-associated death protein, contributing to cellular survival. Here we report that estrogen rapidly increases CREB phosphorylation in transfected HT-22 cells and this effect is mediated by the MAPK pathway. Activation of this pathway also elicits CRE-mediated gene transcription, which might play a role in estrogen-mediated neuroprotection.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Cell culture
HT-22 cells were grown on 100-mm tissue culture dishes and maintained in DMEM (Sigma) media supplemented to 5% fetal bovine serum and 1% Pen-Strep (Gem Cell, Woodland, CA) at 37 C in a 5% CO2 atmosphere. Cell density was maintained at 70% or less confluency as described previously (21). HT-22 cells, stably transfected with either human ER (HTER) or rat ERß (HTERß), were generated as previously described (19). Briefly, we stably transfected the cDNA clones encoding human ER or rat ERß into HT-22 cells. Single clones from each transfection were screened for estrogen-sensitive MAPK activation and ER expression. A single clone for each receptor subtype was then selected for further studies.
Immunoblotting
Cells were rinsed with ice-cold PBS buffer, scraped in immunoprecipitation buffer (2.5 mM HEPES, pH 7.5; 10% glycerol; 5 mM EDTA; 5 mM EGTA; 100 mM NaCl; 100 mM Na pyrophosphate; 50 mM NaF; 0.1 mM NaVO4; 1% Triton X-100; 1 mM benzamidine; 1 mM phenylmethylsulfonyl fluoride; 10 µg/ml leupeptin; 10 µg/ml aprotinin; 2 µg/ml pepstatin), and incubated on ice for at least 5 min. The samples were then sonicated for 2 min, followed by centrifugation at 15,000 rpm for 15 min. The supernatant was transferred to a new tube, and protein concentrations were determined using the BCA assay (Pierce Chemical Co., Rockford, IL). The protein samples were diluted in Laemmeli buffer and resolved by electrophoresis on 4–12% Bis-Tris precast gels (Invitrogen, Carlsbad, CA) in MES running buffer [50 mM MES (2-[N-morpholine] ethane sulfonic acid), 50 mM Tris base, 0.1% sodium dodecyl sulfate, 1 mM EDTA] as described by the manufacturer. The protein was transferred to polyvinylidene diflouride membrane and blocked in 5% nonfat dry milk in T-TBS (Tris-buffered saline containing 0.2% Tween 20) for 1 h at room temperature. The membrane was then placed in a 1:1000 dilution of the primary antibody in 5% nonfat dry milk/T-TBS overnight at 4 C with mild agitation. Membranes were then washed 3 x 5 min in T-TBS before incubation in a 1:2000 dilution of horseradish peroxidase-conjugated secondary antibody in 5% milk/T-TBS. The membranes were then washed again before proceeding to visualization by enhanced chemiluminescence (NEN Life Science Products, Boston, MA). The resulting film samples were scanned and analyzed with an image analysis program (NIH Image: Scion Corp., Frederick, MD).
Cell treatments
Cells were grown to 60–70% confluency on 100-mm plates. Eighteen hours before treatment the media was replaced with phenol red-free DMEM not supplemented with fetal bovine serum. Cells were treated with ethanol vehicle (0.1% final concentration), 17ß-estradiol (10 nM), PD98059 (50 µM), ICI 182,780 (1 µM), LY294002 (10 µM), or KT5720 (50 nM) for the indicated times. The media were removed, and the cells were harvested as described above. Immunoblotting was performed as previously described.
Transient transfections
HT-22, HTER, or HTERß cells were plated at a density of 5000 cells/well in a 24-well plate in phenol red-free DMEM containing 5% charcoal-stripped serum and pen-strep. The cells were then transfected with 0.25 µg/well CRE-luciferase (kindly provided by Dr. Daniel Storm, University of Washington) or the empty vector pCDNA3, using the Transfast transfection reagent (Promega Corp., Madison, WI) according to the manufacturer’s protocol. Then 0.3 µg pCH110, a ß-galactosidase reporter (Amersham Pharmacia Biotech, Uppsala, Sweden), was cotransfected to normalize for transfection efficiency. Twenty-four hours after transfection, cells were treated with 10 nM 17ß-estradiol for 12–16 h and harvested in reporter lysis buffer (Promega Corp.). Cell lysates were analyzed for ß-galactosidase or luciferase activity following the manufacturer’s protocol (Promega Corp.).
Statistical analysis
The significance of differences among groups was determined using one-way ANOVA followed by Tukey’s multiple comparison test. P of 0.05 or less was considered significant. Each treatment group consisted of 6–12 different samples. All values are expressed as mean ± SEM.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
and HTERß cell lines as previously reported (19), which stably express either ER or ERß, respectively. We used these cells to assess the capacity of each ER to signal to CREB phosphorylation by treating them with a 10-nM dose of 17ß-estradiol. This dose has been previously determined to provide near-maximal activation of the MAPK pathway in these cells (19). Using an antibody that detects the dual phosphorylation of ERK1/2 on Thr (202) and Tyr (204), which has been correlated with increased kinase activity (22), ERK1/2 phosphorylation was maximal at 10–20 min following estrogen treatment, and this activation dropped to basal levels by 30 min (Fig. 1
). CREB phosphorylation at Ser133 was also increased by estrogen, following a similar time course as that of ERK1/2 phosphorylation. Both ER and ERß were able to mediate increases in ERK1/2 phosphorylation and CREB phosphorylation, with ERß displaying slightly delayed kinetics, compared with ER. No increase in either CREB phosphorylation or ERK1/2 phosphorylation was observed following estrogen treatment of wild-type cells (Fig. 1C).
|
and HTERß cells for the indicated times (Fig. 2). 17ß-Estradiol caused an increase in phosphorylation of S6 riboprotein, indicating an increase in p90Rsk activity (23). The total levels of S6 protein did not change over the course of the experiment. Here also, both HTER and HTERß cells exhibited this increase in p90Rsk activity and followed a similar time course.
|
). When coadded with 10 nM estrogen to both HTER and HTERß cells, ICI 182,780 was able to completely block the increases in phospho-ERK1/2 and phospho-CREB previously observed. ICI 182,780 alone had no effect on CREB phosphorylation in either cell line (Fig. 3).
|
and HTERß cells with PD98059 (50 µM) before the addition of 10 nM estrogen (Fig. 3
). PD98059 was able to completely block the ability of estrogen to couple to phosphorylation of ERK1/2. Interestingly, PD98059 was also able to inhibit estrogen’s activation of CREB phosphorylation in both transfected cell lines, indicating that the MAPK pathway is primarily responsible for mediating estrogen’s effects on CREB phosphorylation in this system. In contrast, treatment of cells with the PI3K inhibitor, LY294002, failed to inhibit CREB phosphorylation by estrogen (Fig. 4).
|
and HTERß cells with KT5720 (50 nM) before the addition of estrogen (Fig. 5) at a dose that has been reported to specifically block PKA activity (24). The addition of KT5720 was not able to inhibit the ability of estrogen to couple to CREB phosphorylation.
|
, and HTERß cells and treated the cells with a low dose of estrogen (10 nM) for 24 h (Fig. 6). Forskolin produced a robust increase in luciferase activity, independent of the cell line used (HT-22, HTER, or HTERß). However, estrogen caused a significant increase in luciferase activity only in the HTER and HTERß cells, suggesting that an ER is required for this effect.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
or ERß (19). We chose this approach because it offers a unique opportunity to study the role of each receptor in estrogen rapid signaling. In this study, we examined the role of each ER subtype in coupling to CREB phosphorylation and CRE-mediated gene transcription. Cells were treated with 17ß-estradiol (10 nM) and assayed for changes in CREB phosphorylation at Ser133. This dose of estrogen increased the levels of phospho-CREB in the HTER and HTERß cell lines but had no effect on the untransfected cells. We also assayed these same cell lysates for any changes in the phosphorylation state of ERK1/2. As we previously reported, estrogen causes an increase in the dual-phosphorylation of ERK1/2. The time course of CREB phosphorylation by estrogen was similar to that for ERK1/2 phosphorylation. There was no detectable change in the levels of total CREB or total ERK2 protein during the time course of our experiments. Under the culture conditions used here and in our previous studies (19), neither ER nor ERß proteins were expressed in wild-type cells. Thus, it is the introduction of ER or ERß that confers sensitivity to nanomolar concentrations of estrogen for induction of CREB phosphorylation. One of the critical mediators of the effects of the MAPK pathway is the family of MAPK-activated protein kinases, of which p90Rsk is but one member. CREB is a known substrate of both p90Rsk and ERK1/2 (25). We sought to determine whether p90Rsk could play a role in mediating the effects of estrogen on CREB phosphorylation. To determine whether MAPK activation led to increased p90Rsk activation, we harvested cell lysates and probed for an increase in the phosphorylation of S6 riboprotein. This endogenous protein is a physiological substrate of p90Rsk and correlates closely with the kinase activity of p90Rsk. When our stably transfected cells were treated with a physiological dose of estrogen, we were able to observe a rapid increase in the phosphorylation of S6 riboprotein. Again, the total protein levels did not significantly change during the course of our experiment.
To further substantiate the requirement for transfected ERs to mediate the increase in CREB phosphorylation, we treated our cells with the selective ER modulator, ICI 182,780. Previously we have shown that, in Rat-2 cells, this compound acted as an ER antagonist for ER-mediated MAPK activation but did not block ERß (13). However, in this cell line, ICI 182,780 blocks both ER- and ERß-mediated MAPK phosphorylation. In a cotreatment experiment, ICI 182,780 was able to completely block the increase in CREB phosphorylation induced by estrogen. This suggests that either ER or ERß is required to mediate the effect of estrogen on CREB phosphorylation. However, it is also possible that a related, alternatively processed form of ER or ERß might be capable of mediating these effects. Recently an ER of different molecular weight, but that is immunoreactive to anti-ER antisera, has been reported (26).
The phosphorylation of CREB is often thought of as a coincidence detector, in that several different signal transduction pathways converge on CREB phosphorylation. Among these are the cAMP/PKA and MAPK pathways. We sought to pharmacologically determine the involvement of these pathways in mediating the effects of estrogen on CREB phosphorylation. We pretreated our cells with the mitogen/ERK kinase-1 inhibitor, PD98059 (50 µM), which effectively blocks MAPK phosphorylation. We found that inhibition of the MAPK signaling pathway completely blocked estrogen-mediated CREB phosphorylation. Although MAPK does not directly phosphorylate CREB, p90Rsk, which we have shown is activated by estrogen, is known to both phosphorylate and activate CREB (27). Thus, we have shown that the MAPK pathway is primarily responsible for mediating estrogen’s effects on CREB phosphorylation.
Surprisingly, when we treated our cells with the PKA inhibitor, KT5720, we did not see an effect on CREB phosphorylation. This led us to conclude that the cAMP/PKA pathway plays little role in mediating estrogen’s effects on CREB in this system. The pharmacologic inhibitor of PI3K, LY294002, also failed to inhibit estrogen’s effects on CREB phosphorylation.
The MAPK pathway, in addition to its role in regulating cell growth, also plays a critical role in neurons, in which it has been shown to be important in regulating the CREB/CRE pathway. CRE-mediated transcription has been shown to be important in memory consolidation and synaptic plasticity (28). In our system, we were able to show that estrogen robustly activated CRE-mediated transcription.
These studies clearly show that estrogen, acting through both ER and ERß, promotes MAPK-dependent CREB phosphorylation at Ser133. Both HTER and HTERß cells displayed an increase in phospho-CREB. Neither the PKA nor the PI3K pathway contributed significantly to estrogen’s ability to activate. The phosphorylation of CREB by estrogen also led to an increase in CRE-mediated transcription, measured 24 h following estrogen treatment. These results are the first that demonstrate a critical role for the MAPK pathway in mediating estrogen’s effects on the CREB/CRE pathway in a neuronal cell system. Our results indicate that, in addition to the recently reported ability of membrane-delimited estrogens to facilitate ERE-mediated transcription (3), estrogens may also promote CRE-dependent gene transcription by phosphorylating other transcription factors, such as CREB. It will be important to consider both modes of action in evaluating estrogen’s transcriptional effects.
Estrogen-induced activation of the CREB/CRE pathway could potentially play a role in estrogen-mediated neuroprotection. It has been shown that estrogen can increase cytoprotective genes such as Bcl-2 expression (29). Although the Bcl-2 promoter contains various response elements, a recent report in MCF-7 cells shows that estrogen-induced expression of the Bcl-2 gene is dependent in part on a CRE-related mechanism (30). Thus, estrogen modulation of Bcl-2 expression through CREB could contribute to neuroprotection against toxic insults.
|
Footnotes |
|---|
Abbreviations: CRE, cAMP response element; CREB, CRE-binding protein; ER, estrogen receptor; PI3K, phosphatidylinositol 3-kinase; PKA, protein kinase A; PKC, protein kinase C; Rsk, ribosomal S6 kinase; T-TBS, Tris-buffered saline containing Tween 20.
Received October 25, 2002.
Accepted for publication November 27, 2002.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
and estrogen receptor ß. Proc Natl Acad Sci USA 97:11603–11608 and ERß exhibit unique pharmacologic properties when coupled to activation of the mitogen-activated protein kinase pathway. Endocrinology 142:2336–2342 or ß and activation of the MAPK pathway. J Neurochem 82:674–682[CrossRef][Medline]
This article has been cited by other articles:
 |
|
 |
|
  P. Dewing, A. Christensen, G. Bondar, and P. Micevych Protein Kinase C Signaling in the Hypothalamic Arcuate Nucleus Regulates Sexual Receptivity in Female Rats Endocrinology, December 1, 2008; 149(12): 5934 - 5942. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Bake, L. Ma, and F. Sohrabji Estrogen Receptor-{alpha} Overexpression Suppresses 17{beta}-Estradiol-Mediated Vascular Endothelial Growth Factor Expression and Activation of Survival Kinases Endocrinology, August 1, 2008; 149(8): 3881 - 3889. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Titolo, C. M. Mayer, S. S. Dhillon, F. Cai, and D. D. Belsham Estrogen Facilitates both Phosphatidylinositol 3-Kinase/Akt and ERK1/2 Mitogen-Activated Protein Kinase Membrane Signaling Required for Long-Term Neuropeptide Y Transcriptional Regulation in Clonal, Immortalized Neurons J. Neurosci., June 18, 2008; 28(25): 6473 - 6482. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. I. Boulware, H. Kordasiewicz, and P. G. Mermelstein Caveolin Proteins Are Essential for Distinct Effects of Membrane Estrogen Receptors in Neurons J. Neurosci., September 12, 2007; 27(37): 9941 - 9950. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Dewing, M. I. Boulware, K. Sinchak, A. Christensen, P. G. Mermelstein, and P. Micevych Membrane Estrogen Receptor-{alpha} Interactions with Metabotropic Glutamate Receptor 1a Modulate Female Sexual Receptivity in Rats J. Neurosci., August 29, 2007; 27(35): 9294 - 9300. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Dziennis, T. Jia, O. K. Ronnekleiv, P. D. Hurn, and N. J. Alkayed Role of Signal Transducer and Activator of Transcription-3 in Estradiol-Mediated Neuroprotection J. Neurosci., July 4, 2007; 27(27): 7268 - 7274. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Moriarty, K. H. Kim, and J. R. Bender Estrogen Receptor-Mediated Rapid Signaling Endocrinology, December 1, 2006; 147(12): 5557 - 5563. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Xu, W. Zhang, J. Klaus, J. Young, I. Koerner, L. C. Sheldahl, P. D. Hurn, F. Martinez-Murillo, and N. J. Alkayed Role of cocaine- and amphetamine-regulated transcript in estradiol-mediated neuroprotection PNAS, September 26, 2006; 103(39): 14489 - 14494. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Luo and M. C. Wiltbank Distinct Regulation by Steroids of Messenger RNAs for FSHR and CYP19A1 in Bovine Granulosa Cells Biol Reprod, August 1, 2006; 75(2): 217 - 225. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y.-C. Hsieh, M. A. Choudhry, H.-P. Yu, T. Shimizu, S. Yang, T. Suzuki, J. Chen, K. I. Bland, and I. H. Chaudry Inhibition of cardiac PGC-1{alpha} expression abolishes ER{beta} agonist-mediated cardioprotection following trauma-hemorrhage FASEB J, June 1, 2006; 20(8): 1109 - 1117. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. Hernandez-Gonzalez, I. Gonzalez-Robayna, M. Shimada, C. M. Wayne, S. A. Ochsner, L. White, and J. S. Richards Gene Expression Profiles of Cumulus Cell Oocyte Complexes during Ovulation Reveal Cumulus Cells Express Neuronal and Immune-Related Genes: Does this Expand Their Role in the Ovulation Process? Mol. Endocrinol., June 1, 2006; 20(6): 1300 - 1321. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Shimada, I. Hernandez-Gonzalez, I. Gonzalez-Robayna, and J. S. Richards Paracrine and Autocrine Regulation of Epidermal Growth Factor-Like Factors in Cumulus Oocyte Complexes and Granulosa Cells: Key Roles for Prostaglandin Synthase 2 and Progesterone Receptor Mol. Endocrinol., June 1, 2006; 20(6): 1352 - 1365. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Mhyre, R. A. Shapiro, and D. M. Dorsa Estradiol Reduces Nonclassical Transcription at Cyclic Adenosine 3',5'-Monophosphate Response Elements in Glioma Cells Expressing Estrogen Receptor Alpha Endocrinology, April 1, 2006; 147(4): 1796 - 1804. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. A Orihuela, A. Parada-Bustamante, L. M Zuniga, and H. B Croxatto Inositol triphosphate participates in an oestradiol nongenomic signalling pathway involved in accelerated oviductal transport in cycling rats. J. Endocrinol., March 1, 2006; 188(3): 579 - 588. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z. T. Ruiz-Cortes, S. Kimmins, L. Monaco, K. H. Burns, P. Sassone-Corsi, and B. D. Murphy Estrogen Mediates Phosphorylation of Histone H3 in Ovarian Follicle and Mammary Epithelial Tumor Cells via the Mitotic Kinase, Aurora B Mol. Endocrinol., December 1, 2005; 19(12): 2991 - 3000. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Sedej, T. Rose, and M. Rupnik cAMP increases Ca2+-dependent exocytosis through both PKA and Epac2 in mouse melanotrophs from pituitary tissue slices J. Physiol., September 15, 2005; 567(3): 799 - 813. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. Arreguin-Arevalo and T. M. Nett A Nongenomic Action of 17{beta}-Estradiol as the Mechanism Underlying the Acute Suppression of Secretion of Luteinizing Hormone Biol Reprod, July 1, 2005; 73(1): 115 - 122. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. I. Boulware, J. P. Weick, B. R. Becklund, S. P. Kuo, R. D. Groth, and P. G. Mermelstein Estradiol Activates Group I and II Metabotropic Glutamate Receptor Signaling, Leading to Opposing Influences on cAMP Response Element-Binding Protein J. Neurosci., May 18, 2005; 25(20): 5066 - 5078. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. T. Papadeas, B. L. Blake, D. J. Knapp, and G. R. Breese Sustained Extracellular Signal-Regulated Kinase 1/2 Phosphorylation in Neonate 6-Hydroxydopamine-Lesioned Rats after Repeated D1-Dopamine Receptor Agonist Administration: Implications for NMDA Receptor Involvement J. Neurosci., June 30, 2004; 24(26): 5863 - 5876. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. D. Toran-Allerand Minireview: A Plethora of Estrogen Receptors in the Brain: Where Will It End? Endocrinology, March 1, 2004; 145(3): 1069 - 1074. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Nilsen and R. D. Brinton Divergent impact of progesterone and medroxyprogesterone acetate (Provera) on nuclear mitogen-activated protein kinase signaling PNAS, September 2, 2003; 100(18): 10506 - 10511. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
0.05, as determined by ANOVA.
