| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Articles |
First Department of Internal Medicine, Nagoya University School of Medicine, Nagoya 466, Japan
Address all correspondence and requests for reprints to: Yasumasa Iwasaki, M.D. First Department of Internal Medicine, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466, Japan.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
-adrenergic,
agonist, suggesting the involvement of the ß-adrenergic receptor. The
combined effects of epinephrine and CRH were greater in all parameters
than those of CRH alone, and the effects of both hormones were
completely blocked by H89, an inhibitor of protein kinase A.
Vasopressin and angiotensin II showed minimal effects on POMC
expression. Our results suggest that 1) catecholamines, as well as CRH,
positively regulate the POMC gene at physiological concentrations; 2)
the cAMP-PKA system is the common intracellular signaling pathway
for CRH and catecholamines; and 3) vasopressin and angiotensin II also
have weak but significant stimulatory effects on POMC promoter
activity. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The regulatory mechanisms of ACTH secretion have been studied extensively both in vivo and in vitro (2, 3, 4). Among the secretagogues studied, the major role of CRH as a positive hypothalamic factor is well established (5). Furthermore, other factors such as arginine vasopressin, catecholamines, and angiotensin II, and some paracrine factors within the pituitary are shown to play modulatory roles on basal or CRH-induced ACTH secretion (2, 3, 4). On the other hand, glucocorticoids in the peripheral blood are known to be involved in the negative feedback regulation of both CRH and ACTH secretion. Recently, some other factors such as atrial natriuretic factor or adrenomedullin have also been suggested to be involved in the negative regulation (6, 7).
Most, but not all, of the secretagogues are supposed to be involved in the regulation of ACTH synthesis. The effects of these factors on the gene expression of POMC, which encodes ACTH and related peptides, have been under extensive investigation. However, the molecular mechanism of POMC gene regulation by each factor has not yet been fully characterized, partly because of the difficulty in assessing the dynamics of transcriptional events at the cellular level.
To elucidate the issue more precisely, we used the in vitro system with AtT20 mouse corticotroph tumor cells in which the rat POMC 5' promoter-luciferase fusion gene was stably incorporated. The AtT20 cell line is known to maintain many characteristics of the corticotroph such as CRH responsiveness or glucocorticoid suppressibility and has been widely used for studying ACTH synthesis and secretion (8), although it might lack some aspects of the original corticotroph (9). In this study, we found that, when we cultivated the cells with low serum medium for 4 days, the cells grew slowly and, at the same time, the responsiveness to CRH was markedly improved, implying that the characteristics of the cells seem to be closer to those of the original corticotroph. Using this system, we were able to evaluate the direct effects of various secretagogues on POMC gene expression as well as on ACTH secretion precisely and efficiently.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Cell culture
The murine corticotroph tumor cell line AtT20/D16v (AtT20) was
maintained in a T75 culture flask with DMEM (Life
Technologies, Grand Island, NY) supplemented with 10% FBS (Life
Technologies) and antibiotics (50 µU/ml penicillin and 50 µg/ml
streptomycin; Life Technologies) under a 5% CO2/95%
atmosphere at 37 C. Culture medium was changed twice a week, and the
cells were subcultured once a week.
During each experiment, the cells were plated in 3.5-cm diameter culture dishes with approximately 50% confluency. On the next day, the culture media were changed to DMEM supplemented with 1% FBS unless otherwise noted, and the cells were further cultured for 4 days, during which the culture media were changed every other day.
Plasmid constructions
An approximately 0.7 kb XmnI fragment of the rat POMC
gene 5' promoter (-708 to +64; +1 indicates the transcription start
site) (10) was isolated from a rat POMC gene (kindly provided by Dr.
Malcolm Low). Previous studies showed that the promoter sequence used
is enough for the tissue-specific and regulated expression of the POMC
gene in vivo (11, 12). After the HindIII linker
was ligated at both ends of the fragment, the promoter sequence was
inserted into the HindIII site of the pA3Luc plasmid (Fig. 1A
) (13), and the plasmid with the correct promoter
orientation was selected by restriction enzyme analysis.
|
Experiments
The AtT20PL cells were cultured with low serum medium (1% FBS)
for 4 days as mentioned above. On the day of the experiment, each of
the solutions for all the test reagents, in 1000x concentration, or
solvent alone, was added directly into the culture media of each dish,
and the cells were incubated for the defined time interval. All the
reagents were dissolved in sterile double distilled water except CRH,
which was dissolved in sterile 0.1% acetic acid solution. At the end
of incubation, the culture media were removed, and the cells were
harvested for the luciferase assay (see below). In the experiments in
which ACTH secretion and cAMP generation were studied, cells were
preincubated with IBMX (200 µM) 30 min before the
addition of the test reagents, and then the culture media were changed
to the serum-free media with the test reagent(s) and IBMX at the start
of the experiment. After the cells were incubated for the defined time
interval, culture media from each dish were collected for ACTH and cAMP
assay (see below).
Luciferase assay
Luciferase assay was performed as previously described (15) with
some modifications. At the end of each experiment, the cells were
washed two to three times with phosphate buffer saline without
Ca2+ and Mg2+, harvested with lysis buffer
containing 1% (vol/vol) Triton X-100 (Sigma), 25 mM
glycylglycine (Katayama Chemical, Osaka, Japan), pH 7.8, 15
mM MgSO4, 4 mM EGTA (Katayama
Chemical), and 1 mM dithiothreitol (DTT; Katayama
Chemical), and centrifuged 18,000 g for 30 min. For the
luciferase assay, 100 µl of each supernatant was added to 400 µl of
assay buffer containing 25 mM glycylglycine, pH 7.8, 15
mM MgSO4, 4 mM EGTA, 15
mM potassium phosphate buffer, pH 7.8, 2 mM
ATP, 1 mM DTT, and 0.5 mM coenzyme A (Wako Pure
Chemical, Osaka, Japan). The reactions were started by the injection of
200 µl of luciferin solution containing 0.2 mM
D-luciferin (Wako Pure Chemical), 25 mM glycylglycine, pH
7.8, 15 mM MgSO4, 4 mM EGTA, and 2
mM DTT. Light output was measured for 20 sec at room
temperature using a luminometer (Berthold Lumat LB9501, Postfach,
Germany).
ACTH and cAMP assays
ACTH in culture media were measured by radioimmunometric assay
(ACTH IRMA kit; Mitsubishi Chemical, Tokyo, Japan). cAMP in culture
media were determined by RIA (Yamasa Shoyu, Tokyo, Japan).
Data analyses
Samples in each group of the experiments were in triplicate or
quadruplicate. All data were expressed as mean ± SE.
When the statistical analyses were performed, data were compared by
one-way ANOVA with Duncan’s multiple range test, and P
values below 0.05 were considered significant.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
). Similar results were obtained
using other clones of the transfected cells. Since it has been known that tumor cells can be redifferentiated to some extent when the cells are cultured in serum-free or serum-reduced condition (16, 17), we examined the effects of low serum media on the CRH responsiveness by culturing the AtT20PL cells with medium containing 1% FBS or serum-free medium.
The responsiveness of the POMC 5' promoter activity to CRH (100
nM for 3 h) increased gradually during the cultivation
with the low serum culture medium (data not shown), and more than a
3-fold increase was observed 4 days after the start of incubation (Fig. 1B). Cultivation with serum-free medium for 4 days was not successful.
Therefore, we conducted all the subsequent studies under the
serum-reduced condition, i.e. after cultivation with medium
containing 1% FBS for 4 days.
The effect of CRH on POMC gene expression
Under the culture condition mentioned above, we examined the
effect of the major ACTH secretagogue, CRH, on the POMC 5' promoter
activity. As shown in Fig. 2, A and B, CRH potently
stimulated POMC gene expression in a time- and dose-related manner. The
time course study showed that the significant increase was found as
early as 1 h, and the maximal effect was observed 3–5 h after the
stimulation, with an approximately 3.5-fold increase compared with the
basal value. The dose response study showed that the significant
stimulatory effect of CRH was observed at 1 nM and was
maximal above 10 nM. These results indicate that CRH has an
acute stimulatory effect on POMC gene expression at the transcriptional
level.
|
and 4, epinephrine and
norepinephrine increased POMC gene expression in a time- and
dose-related manner, although the effects were much weaker than that of
CRH. Epinephrine (1 µM) elicited maximal increase 2–4 h
after the stimulation, and the significant effects (
30–50%
increase) were observed at and above 10 nM (Fig. 3).
Norepinephrine (1 µM) had a similar time-course effect as
epinephrine, but relatively high concentrations were needed (1
µM and above) to show significant effects (Fig. 4).
|
|
, 1-agonist phenylephrine (10 µM) and
2-agonist clonidine (1 µM) had no effect,
whereas ß-agonist isoproterenol (10 µM) showed a
significant positive effect, although again much less than that of CRH
(100 nM). These results suggest that the effects of
catecholamines on POMC gene expression are mediated through the
ß-adrenergic receptor subtype.
|
, both peptides showed
positive effects on POMC gene expression. The significant stimulatory
effects were observed 3–6 h in vasopressin and 5–6 h in angiotensin
II after the start of incubation. However, in both cases, the
increments were only approximately 10–15% of the basal values, at
least during the 6-h observation period. These results suggest that
vasopressin and angiotensin II have stimulatory effects on POMC gene
expression, although less markedly than the other secretagogues tested.
The dose-related effects were not examined in these experiments.
|
, maximally
effective dose of CRH (100 nM) significantly increased cAMP
efflux, ACTH secretion, and POMC gene expression. Epinephrine (100
nM) and norepinephrine (1 µM, data not shown)
showed similar stimulatory effects as CRH on all parameters, although
less potently. When CRH and epinephrine were simultaneously applied,
values were significantly higher in all parameters than those of CRH
alone.
|
, vasopressin (100 nM) significantly
stimulated ACTH secretion without increasing cAMP efflux. In this
particular 3-h experiment, vasopressin had no significant effect on
POMC gene expression. When both CRH and vasopressin were simultaneously
used, no additive effect was observed in any parameter. Similar effects
were obtained in the experiment using CRH and angiotensin II (Fig. 7C),
except for a weak but significant enhancing effect of angiotensin II on
CRH-induced POMC gene expression.
The effects of protein kinase A (PKA) inhibitor H89 on
CRH/epinephrine-induced POMC gene expression
Finally, to examine the relative role of the cAMP/PKA pathway in
the positive effects of CRH and catecholamines on POMC gene expression,
we carried out an experiment using H89, a specific inhibitor of PKA
(18). As shown in Fig. 8, CRH and epinephrine again
significantly increased the POMC 5' promoter activity, in agreement
with the previous experiments. In contrast, the stimulatory effects of
both hormones were completely abolished under the treatment with H89
(30 µM). The results suggest that the positive effects of
the hormones on the POMC gene are totally dependent on the cAMP/PKA
pathway.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
We found that catecholamines increase POMC 5' promoter activity. The
stimulatory effects of catecholamines on ACTH secretion in the rat are
well documented in vivo (19, 20, 21). The central
catecholaminergic system is involved in the regulation of ACTH
secretion and POMC gene expression through the
1-adrenergic receptor and CRH and/or vasopressin
secretion (21, 22). Catecholamines are also shown to stimulate ACTH
secretion in vitro at the pituitary level through
1- or ß-adrenergic receptors (23, 24, 25, 26, 27). On the other
hand, the effects of the hormones on the corticotroph POMC gene have
not been fully characterized, and in fact, this is the first report
using AtT20 cells. Previous studies using the rat anterior pituitary
cells in primary culture showed minimal or no direct effect of
-adrenergic agonists on the POMC messenger RNA (mRNA) level, and no
study has been carried out concerning the effect of ß-adrenergic
agonist (28, 29). In AtT20PL cells, we found dose- and time-related
acute increase in POMC 5' promoter activity during both epinephrine and
norepinephrine treatments. The minimal effective dose of epinephrine
was 10 nM, which seems to be a physiological concentration
under stress in vivo, whereas superphysiological doses
(above 1 µM) were needed for the significant effects with
norepinephrine. Furthermore, among the selective adrenergic agonists
tested, only the ß-adrenergic receptor agonist isoproterenol showed a
positive effect. These results indicate that, whereas ACTH secretion
appears to be stimulated through both 1- and
ß-adrenergic receptors, POMC gene expression is stimulated solely
through the ß-adrenergic receptor. This hypothesis is supported by
the facts that the effects of catecholamines are accompanied by the
increase in cAMP generation, and are abolished completely by the
pretreatment with PKA inhibitor H89, the latter implying that the
cAMP/PKA system is the sole intracellular signaling pathway of
catecholamines for the POMC gene. Thus, our results suggest that
blood-borne catecholamines, especially epinephrine released from the
adrenal medulla, may influence POMC gene expression at the pituitary
level during acute stress.
It is well established that CRH plays a major physiological role in regulating POMC gene expression as well as ACTH secretion (1, 2, 3, 4, 5, 8). We confirmed the effects of CRH such that concentrations of above 1 nM of the peptide potently stimulated POMC 5' promoter activity in a dose- and time-related manner. The onset of the effect was fairly rapid; a significant increase was observed 1 h after and the maximal effect 3–5 h after the start of incubation. This time course effect was much faster than that previously reported in AtT20 cells using Northern blot analysis (30), probably due to the shorter half life of luciferase protein than POMC mRNA. Thus, the rapid increase in the POMC 5' promoter activity suggests that CRH directly stimulates the corticotroph POMC gene, probably through the recently cloned CRH receptor in AtT20 cells (31). The CRH receptor is known to be coupled with adenylate cyclase, and the intracellular signal is transduced mainly through the cAMP/PKA pathway (32). A recent study indicates that PKA-independent pathways are also involved in the stimulatory effect of CRH on ACTH secretion (33). Regarding the effect on POMC gene expression, however, Reisine et al. (34) have shown that the positive effect of CRH on POMC mRNA was completely blocked by liposome-mediated insertion of PKA inhibitor in AtT20 cells. Our data that CRH treatment was accompanied by increased cAMP generation, and that the new PKA inhibitor H89 completely abolished the CRH-induced increase in POMC 5' promoter activity, support the previous concept that, like epinephrine, the CRH-stimulated increase in POMC expression depends entirely on the cAMP/PKA pathway.
Vasopressin is known to be a potent secretagogue for ACTH both in vivo and in vitro (35, 36). In this study, vasopressin slightly but significantly stimulated ACTH release in AtT20PL cells. This is noteworthy because previous studies using AtT20 cells have failed to show any positive effect of vasopressin on ACTH release, probably because of some intracellular signaling defect(s) of the cell line (9). The restoration of the responsiveness for vasopressin observed here may be caused by the redifferentiating effect of the cultivation with low serum medium, although the well-known potentiating effect of vasopressin on CRH-induced ACTH release and cAMP generation (37, 38) was still defective. Regarding the POMC gene, vasopressin unexpectedly stimulated the POMC 5' promoter activity, which is contradictory with the previous concept that vasopressin stimulates ACTH secretion but does not influence POMC expression. The degree of stimulation, however, was very weak, and thus may have not been detected by Northern blot analysis in the previous studies. A similar effect was observed with angiotensin II. Because both vasopressin and angiotensin II are known to activate the phospholipase C/PKC pathway (39, 40), and PKC may activate POMC promoter activity through its AP1 site (41), it is possible that vasopressin and angiotensin II can also positively regulate POMC promoter activity through the phospholipase C/PKC signaling system. The physiological role of the two hormones for ACTH synthesis, however, seems to be minimal because the degree of stimulation is much weaker than CRH (less than 10% of CRH effect), and ACTH synthesis is shown to be preserved in the homozygous Brattleboro rat, which lacks intrinsic vasopressin synthesis and secretion (42).
We found that the growth rate of the AtT20PL cells is much slower and the responsiveness of the POMC 5' promoter activity to CRH is markedly improved when the cells are cultured for 4 days with low serum medium (1% FBS) compared with serum-rich medium (10% FBS). In tumor cells, suppression of growth rate is usually followed by redifferentiation of the cells, with retrieval of some characteristics of the original cell type (16). In fact, CRH-induced ACTH secretion is shown to be much greater when cultured with serum-free medium (17), although it was not successful in our system. The improved responsiveness of the POMC gene to CRH, and the restored responsiveness of ACTH release to vasopressin, both found in our study, suggest that AtT20PL cells may be getting closer to the original corticotroph cells under the low-serum compared with regular serum-rich culture condition. Because AtT20PL is, unlike primary culture of the pituitary, a homogenous clonal cell line, this may be a good model to study the direct effects of various secretagogues or reagents on corticotroph function.
We used the POMC 5' promoter-luciferase fusion gene as a marker of the transcriptional regulation of the POMC gene. Northern blot analysis, which is theoretically beneficial in reflecting the overall changes of the mRNA amount, has been widely used to study the regulation of POMC gene expression in the previous studies. However, the procedure appears not to be suitable for monitoring the acute changes of the transcription because of the high basal activity and relatively long half life of the POMC mRNA in AtT20 cells. The capacity of quantitative analysis is also limited. Experiments using chloramphenicol acetyl transferase (CAT) reporter gene are not adequate for this purpose as well because of the long half life of the enzyme (50 h) (43). Detecting the changes in primary transcript level (heteronuclear RNA) seems to be ideal but is hampered by the complexity and low sensitivity of the procedure. In our experimental system, we found that the acute changes in the promoter activity can well be delineated by the luciferase activity, probably because of the short half-life of the luciferase protein (3 h) (43). Furthermore, the data reflect the transcriptional activity of the 5' promoter sequence incorporated and are not influenced by the changes in the rate of degradation of mRNA. Therefore, we believe that our experimental system using AtT20PL is a useful tool for studying molecular and cellular mechanisms of the secretagogue regulation of the POMC gene transcription as well as ACTH secretion.
|
Acknowledgments |
|---|
Received October 14, 1996.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
-adrenergic stimulation of adrenocorticotropin secretion in rat
anterior pituitary cells. Endocrinology 109:757–762This article has been cited by other articles:
 |
|
 |
|
  M. Perello, R. Stuart, and E. A. Nillni Prothyrotropin-releasing Hormone Targets Its Processing Products to Different Vesicles of the Secretory Pathway J. Biol. Chem., July 18, 2008; 283(29): 19936 - 19947. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Iwasaki, M. Nishiyama, T. Taguchi, M. Kambayashi, M. Asai, M. Yoshida, T. Nigawara, and K. Hashimoto Activation of AMP-activated protein kinase stimulates proopiomelanocortin gene transcription in AtT20 corticotroph cells Am J Physiol Endocrinol Metab, June 1, 2007; 292(6): E1899 - E1905. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. Murakami, S. Takeuchi, T. Kudo, S. Sutou, and S. Takahashi Corticotropin-releasing hormone or dexamethasone regulates rat proopiomelanocortin transcription through Tpit/Pitx-responsive element in its promoter J. Endocrinol., May 1, 2007; 193(2): 279 - 290. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Cao, C. L. Cetrulo, and T. C. Theoharides Corticotropin-Releasing Hormone Induces Vascular Endothelial Growth Factor Release from Human Mast Cells via the cAMP/Protein Kinase A/p38 Mitogen-Activated Protein Kinase Pathway Mol. Pharmacol., March 1, 2006; 69(3): 998 - 1006. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Nigawara, Y. Iwasaki, M. Asai, M. Yoshida, M. Kambayashi, H. Sashinami, K. Hashimoto, and T. Suda Inhibition of 11{beta}-Hydroxysteroid Dehydrogenase Eliminates Impaired Glucocorticoid Suppression and Induces Apoptosis in Corticotroph Tumor Cells Endocrinology, February 1, 2006; 147(2): 769 - 772. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. M. Soares, M. Thompson, and E. N. Chini Role of the Second-Messenger Cyclic-Adenosine 5'-Diphosphate-Ribose on Adrenocorticotropin Secretion from Pituitary Cells Endocrinology, May 1, 2005; 146(5): 2186 - 2192. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Ma, M. J. Shipston, D. Morilak, and J. A. Russell Reduced Hypothalamic Vasopressin Secretion Underlies Attenuated Adrenocorticotropin Stress Responses in Pregnant Rats Endocrinology, March 1, 2005; 146(3): 1626 - 1637. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E Yamamori, M Asai, M Yoshida, K Takano, K Itoi, Y Oiso, and Y Iwasaki Calcium/calmodulin kinase IV pathway is involved in the transcriptional regulation of the corticotropin-releasing hormone gene promoter in neuronal cells J. Mol. Endocrinol., December 1, 2004; 33(3): 639 - 649. [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]
|
|
|
|
|
|
K. Asaba, Y. Iwasaki, M. Yoshida, M. Asai, Y. Oiso, T. Murohara, and K. Hashimoto Attenuation by Reactive Oxygen Species of Glucocorticoid Suppression on Proopiomelanocortin Gene Expression in Pituitary Corticotroph Cells Endocrinology, January 1, 2004; 145(1): 39 - 42. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Yamamori, Y. Iwasaki, Y. Oki, M. Yoshida, M. Asai, M. Kambayashii, Y. Oiso, and N. Nakashima Possible Involvement of Ryanodine Receptor-Mediated Intracellular Calcium Release in the Effect of Corticotropin-Releasing Factor on Adrenocorticotropin Secretion Endocrinology, January 1, 2004; 145(1): 36 - 38. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Bousquet, V. Chesnokova, A. Kariagina, A. Ferrand, and S. Melmed cAMP Neuropeptide Agonists Induce Pituitary Suppressor of Cytokine Signaling-3: Novel Negative Feedback Mechanism for Corticotroph Cytokine Action Mol. Endocrinol., November 1, 2001; 15(11): 1880 - 1890. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Nomura, Y. Iwasaki, M. Saito, Y. Aoki, E. Yamamori, N. Ozaki, K. Tachikawa, N. Mutsuga, M. Morishita, M. Yoshida, et al. Involvement of upstream open reading frames in regulation of rat V1b vasopressin receptor expression Am J Physiol Endocrinol Metab, May 1, 2001; 280(5): E780 - E787. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Morishita, Y. Iwasaki, E. Yamamori, A. Nomura, N. Mutsuga, M. Yoshida, M. Asai, Y. Oiso, and H. Saito Antidiabetic Sulfonylurea Enhances Secretagogue-Induced Adrenocorticotropin Secretion and Proopiomelanocortin Gene Expression in Vitro Endocrinology, September 1, 2000; 141(9): 3313 - 3318. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Slominski, J. Wortsman, T. Luger, R. Paus, and S. Solomon Corticotropin Releasing Hormone and Proopiomelanocortin Involvement in the Cutaneous Response to Stress Physiol Rev, July 1, 2000; 80(3): 979 - 1020. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. J. Rossant, R. D. Pinnock, J. Hughes, M. D. Hall, and S. McNulty Corticotropin-Releasing Factor Type 1 and Type 2{alpha} Receptors Regulate Phosphorylation of Calcium/Cyclic Adenosine 3',5'-Monophosphate Response Element-Binding Protein and Activation of p42/p44 Mitogen-Activated Protein Kinase Endocrinology, April 1, 1999; 140(4): 1525 - 1536. [Abstract] [Full Text]
|
|
|
|
|
|
A. Niiori-Onishi, Y. Iwasaki, N. Mutsuga, Y. Oiso, K. Inoue, and H. Saito Molecular Mechanisms of the Negative Effect of Insulin-Like Growth Factor-I on Growth Hormone Gene Expression in MtT/S Somatotroph Cells Endocrinology, January 1, 1999; 140(1): 344 - 349. [Abstract] [Full Text]
|
|
|
|
|
|
C. J. Auernhammer, V. Chesnokova, and S. Melmed Leukemia Inhibitory Factor Modulates Interleukin-1{beta}-Induced Activation of the Hypothalamo-Pituitary-Adrenal Axis Endocrinology, May 1, 1998; 139(5): 2201 - 2208. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Katahira, Y. Iwasaki, Y. Aoki, Y. Oiso, and H. Saito Cytokine Regulation of the Rat Proopiomelanocortin Gene Expression in AtT-20 Cells Endocrinology, May 1, 1998; 139(5): 2414 - 2422. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Aoki, Y. Iwasaki, M. Katahira, Y. Oiso, and H. Saito Regulation of the Rat Proopiomelanocortin Gene Expression in AtT-20 cells. II: Effects of the Pituitary Adenylate Cyclase-Activating Polypeptide and Vasoactive Intestinal Polypeptide Endocrinology, May 1, 1997; 138(5): 1930 - 1934. [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 |
