| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Original Studies |
Service d’Endocrinologie et Maladies Métaboliques, CHU Rangueil (P.C., A.B.), 31054 Toulouse, France; Biologia Generale e Genetica Medica, Università di Pavia (S.I., G.C.), 27100 Pavia, Italy; Laboratoire de Biochimie, CHU La Grave (M.P.), and Service de Pédiatrie et Génétique Médicale, CHU Purpan (P.R.), Toulouse, France
Address all correspondence and requests for reprints to: Philippe Caron, M.D., Service d’Endocrinologie, CHU Rangueil, 1 avenue J. Poulhes, 31054 Toulouse Cedex, France. E-mail: caron.p{at}chu-toulouse.fr
 |
Abstract |
|---|
 Top Abstract IntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
-subunit (FAS) levels depicted erratic pulses, suggesting an
incomplete deficiency of hypothalamic GnRH secretion. During iv
pulsatile GnRH administration (10 µg/pulse every 90 min for 40
h), each GnRH pulse induced a LH response of low amplitude (0.54
± 0.05 UI/L), whereas mean LH (0.45 ± 0.01 IU/L) and FAS
(63 ± 8 mU/L) levels remained low. Amplitude of LH peaks
(0.83 ± 0.09 IU/L), mean LH (0.53 ± 0.02 IU/L), and FAS
(161 ± 18 mU/L) levels increased (P < 0.01),
whereas the T concentration remained low (0.75 nmol/L) when the
pulsatile GnRH regimen was raised to 20 µg/pulse for a 40-h period,
suggesting a partial pituitary resistance to GnRH. Thereafter, plasma T
levels remained in prepubertal value after three daily im injections of
5000 IU hCG (3.6 nmol/L) and after 1-yr treatment with weekly im
injections of 1500 IU hCG (1.2 nmol/L), implying Leydig cell resistance
to hCG. The patient had a growth spurt, bone maturation, progression of
genital and pubic hair stages, and normalization of plasma T level
(15.8 nmol/L) after a 12-month treatment with twice weekly injections
of hCG and human menopausal gonadotropin (75 IU International Reference
Preparation 2) preparations, suggesting that, in presence of FSH, a
Sertoli cell-secreted factor stimulated Leydig cell production of T. In
conclusion, we report a novel mutation in the DAX-1 gene
in patients with AHC and HH. Our results suggest that the hypogonadism
is due to a combined hypothalamic-pituitary-gonadal defect and imply
that the DAX-1 gene may play a critical role in human
testicular function. |
Introduction |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
|
Subjects and Methods |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
A 2-yr and 6-month-old boy (DB) was admitted for acute adrenal
insufficiency with clinical (extreme somnolence, increased cutaneous
pigmentation, and shock) and biochemical (hyponatremia, 107 mEq/L;
hyperkalemia, 7.0 mEq/L) symptoms of combined gluco- and
mineralocorticoid deficiency. The diagnosis of primary adrenal
insufficiency (low cortisol and 17-hydroxyprogesterone, increased
levels of plasma ACTH and PRA) was made, and replacement therapy with
gluco- and mineralocorticoids was rapidly initiated. The patient had
had an unaffected brother, but one first cousin (RR) was treated for
adrenal insufficiency, and his brother died because of adrenal crisis
at the age of 1 yr. A maternal grandmother had three brothers who died
in early childhood (Fig. 1
). The patient
had bilateral cryptorchidism, which was corrected surgically at the age
of 12 yr. At the age of 15 yr and 6 months, he was 153 cm tall with a
body mass index of 29.5 kg/m2. Despite regular
treatment with hydrocortisone (25 mg/day) and fludrocortisone (0.150
mg/day), he had delayed growth and bone maturation (bone age, 11.5
years) as well as failure of spontaneous puberty. The phallus and
testis (20 x 10 mm) were prepubertal in size. He had a normal
karyotype, normal olfaction, and a partially empty sella was visible on
magnetic resonance imaging. Hormonal evaluation established the
diagnosis of HH with undetectable plasma testosterone (T) concentration
(<0.30 nmol/L), low gonadotropin levels (LH, < 0.4 IU/L; FSH, 1.5
IU/L) not stimulated after iv injection of 100 µg GnRH. The patient
was treated with weekly im injections of 1500 IU hCG
(Organon, Saint Denis, France). During 1 yr of hCG
therapy, the T level remained low (1.2 nmol/L), and secondary sex
characteristics had not progressed. Then human menopausal gonadotropin
(hMG) preparation (75 IU International Reference Preparation 2,
Humegon, Organon) was twice weekly injected with hCG.
During the 18 months of hCG and hMG treatment, the patient had a growth
spurt, bone maturation, progression of genital and pubic hair stages, a
slight increase in testicular volume (30 x 15 mm), and
normalization of plasma T concentration (15.8 nmol/L). Subsequently, he
received therapy with a long acting T ester (monthly im injection of
200 mg T heptylate, Theramex, Monaco).
|
In vitro study
DNA analysis. DNA from patients DB and RR with AHC-HH and family members was extracted from peripheral blood lymphocytes after informed consent was obtained. Southern blot analysis was performed as described previously (1).
PCR
Each reaction contained 500 ng DNA, 2 mM each of the four deoxy-NTP, 1 U Taq polymerase (SuperTaq, HT Biotechnology Ltd., Cambridge, UK), 25 pmol each of the appropriate primers, 10 mM Tris (pH 9.0), 50 mM KCl, 1.5 mM MgCl2, 1% dimethylsulfoxide, and 0.1% Triton X-100 in a volume of 50 µl. The reaction mixture was submitted to amplification in a Perkin Elmer Corp. thermal cycler (Norwalk, CT) for 30 cycles of denaturation (1 min, 95 C), annealing (1 min, 58 C), and polymerization (1 min, 30 sec, 72 C) with a final extension at 72 C for 10 min. Amplified products were analyzed by electrophoresis on 1% (wt/vol) SeaKem GTG agarose gels (FMC, Rockland, ME) containing ethidium bromide run with 1 x TBE buffer (45 mM Tris-borate and 1 mM ethylenediamine tetraacetate).
The PCR products are overlapping segments covering almost the entire coding part of the DAX-1 gene and the exon-intron boundaries. Amplification was performed using a combination of 11 pairs of primers. Sequences of primers, identical (s) or complementary (a) to the coding strand, are indicated below; numbering is according to Zanaria et al. (1): 1s, 5'-gagctcccacgctgctgtt-3'; 296a, 5'-ttcgcgctcataagcatgtt-3'; 66s, 5'-aggtcatgggcgaacaca-3'; 350a, 5'-caacactgatccaccagccg-3'; 235s, 5'-atggcg-ggcgagaacca-3'; 533a, 5'-gtcgcctcgggcgccttcg-3; 494s, 5'-caaagcaaacgtacgcggca-3'; 687a, 5'-agtgagcaagctgtagagga-3'; 515s1 , 5-cgaaggcgccc-gaggcgac-3'; 799a, 5'-ctggtagcgcctctttacc-3'; 781s, 5'-ggtaaagaggcgc-taccag-3'; 971a, 5'-accggccgcagcgcaccagagga-3'; 949s, 5'-tcctctggtg-cgctgcggccggt-3'; 1198a, 5'-tgaggatcttctgcagcat-3'; 1180s, 5'-atgctg-cagaagatcctca-3'; inta, 5'-cgcccctagataggcactgcc-3'; ints, 5'-gctagcaaa-ggactctgtggtg-3'; 1663a, 5'-tgtggcccacatgact-3'; 760s, 5'-tacttcgcgc-agaggccag-3'; 1241a, 5'-acgggcagtggctcgttgc-3'; 1417s, 5'-cagtgcgtgaa-gtacattc-3'; and 1584a, 5'-cctgaagaacagttcagcaa-3'.
One long DNA fragment (fgt 515s-inta, 949 bp) and 16 short DNA fragments (from 115–533 bp long) were PCR amplified. The asterisk indicates primer 1AaF according to Zanaria et al. (1).
Direct DNA sequencing. The long PCR-amplified DNA fragment 515s-inta (949 bp) was purified by electrophoresis through a 1.5% (wt/vol) low melting point agarose gel (SeaPlaque GTG, FMC) run with 1 x TBE buffer and recovered by hot phenol extraction of the appropriate agarose slices followed by ethanol precipitation. PCR-purified products were subsequently sequenced using Ampli Cycle Sequencing kit (Perkin Elmer Corp.) according to the manufacturer’s instructions. The sequencing primer used was the forward internal primer 760s, listed above.
Restriction site analysis. About 250 ng of the PCR-amplified DNA fragment 515s-inta (946 bp) were digested for 4 h with 5 U RsaI restriction enzyme using the buffer and digestion temperature recommended by the manufacturer. Electrophoresis analysis of the restriction fragments was performed onto 1% (wt/vol) agarose (FMC) gel containing ethidium bromide, run in 1 x TBE buffer.
In vivo study
Protocol. After obtaining informed consent from the
20-yr-old patient (DB), baseline sex steroid and gonadotropin
concentrations were measured 9 weeks after the withdrawal of im
androgen replacement therapy. A catheter was placed in a forearm vein
of the patient, and 4-ml samples of blood were taken every 10 min for
8 h starting at 0800 h. The samples were collected in
ethylenediamine tetraacetate tubes and centrifuged, and the plasma was
stored at -20 C until assayed. Pulsatile GnRH was given using a closed
iv system (Zyklomat pulse, Lutrelef 3.2 mg, Ferring Pharmaceuticals Ltd. SA, Gentilly, France). GnRH pulses were
given every 90 min. The initial dose was 10 µg/pulse for 40 h,
and then a 20 µg/pulse regimen was subsequently administered for an
other 40-h period. The patterns of GnRH-induced LH and free -subunit
secretion were evaluated by serum sampling every 10 min for a 8-h
period during pulsatile GnRH administration. Plasma steroid (T and
17ß-estradiol), FSH, and inhibin concentrations were measured before
and after each regimen of pulsatile GnRH administration. The
gonadotropin (LH and FSH) response to GnRH was tested by iv injection
of 100 µg GnRH (Roussel Laboratory, Paris, France) before and after
each regimen of the pulsatile GnRH administration. Blood samples were
taken immediately before and 30 and 60 min after GnRH injection. Blood
was also drawn hourly from 0800–1600 h for cortisol evaluation during
gonadotropin cycles before and after administration of 10 and 20 µg
pulsatile GnRH while the patient was taking the usual substitution
therapy of 40 mg/day hydrocortisone (20 mg at breakfast, 10 mg at
lunch, and 10 mg at dinner) and 0.150 mg/day fludrocortisone. Four days
after completing pulsatile GnRH administration, serum levels of T and
inhibin B were measured before and every day for 5 days after three
daily im injections of 5000 IU hCG (Organon, Saint Denis,
France).
Assays. LH concentrations were determined using an
immunoradiometric assay ([125I]hLH Coatria,
BioMerieux, Marcy-l’Etoile, France). The between-assay coefficient of
variation (CV) was 5.2% when the mean LH was less than 7 IU/L. The
within-assay CV was less than 4.0%. The detection limit for LH was 0.4
IU/L. The LH concentration was expressed in terms of the International
Standard for LH immunoassay MRC 68/40. Free -subunit concentrations
were measured using an -subunit immunoradiometric assay
(Immunotech, Marseilles, France) with a between-assay CV
of less than 10.5% and a within-assay CV of less than 6.5%. The
cross-reactivity of LH and FSH in the -subunit assay was less than
0.1%. All samples from the patient were run in duplicate in the same
assay. FSH was determined by an immunoradiometric assay
([125I]human FSH Coatria, BioMerieux). The
between-assay CV was less than 4%; the within-assay CV was 2.8%. The
FSH concentration was expressed in terms of International Standard for
FSH immunoassay IRP 78/549. RIAs were used to measure T (Dina-testok,
Sorin Biomedica, Saluggia, Italy; within-assay CV, 9%; between-assay
CV, 10%; detection limit, 0.18 nmol/L; normal range in men, 9.7–28.4
nmol/L) and estradiol (Estradiol-2, Sorin Diagnostics, Antony, France;
within-assay CV, 4.2%; between-assay CV, 4.9%; detection limit, 18
pmol/L). Inhibin B was measured by an enzyme-linked immunosorbent assay
(Serotec, Oxford, UK). Inhibin A had 1% cross-reactivity
in this assay. Intraassay precision was 7.4% at 44 pg/mL and 4.2% at
225 pg/mL. The normal range is 70–330 pg/mL. Plasma cortisol
concentrations were measured by RIA (RIA kit, Immunotech,
Marseilles, France). The normal range of cortisol level at 0800 h
is 165–470 nmol/L.
LH pulse analysis. LH pulse analysis was performed using Cluster analysis with method 7, which calculates the SD as a power function of LH levels, based on series of duplicates. We selected the optimal parameter for LH male data (Veldhuis, J. D., correspondence of all users of Cluster analysis, 1988). These parameters are reported to give minimal false positive and false negative error rates (<5%). The half-life of immunoreactive LH was estimated using the Expfit program (version 1.6; Guardabasso, V., P. J. Munson, and D. Rodbard) applied to the downstroke of every significant pulse identified by the Cluster analysis algorithm. The Expfit program was run using one exponential term for each downstroke, which allowed us to calculate the rate constant (R). The half-life was determined as Ln2/R. The apparent half-life of LH was the mean of values for all identified LH pulses.
|
Results |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
The presence of gross rearrangements in the DAX-1 gene
of the patients (DB and RR) was excluded by Southern blot analysis
(data not shown). To identify small mutations in the coding portion of
the gene, the DAX-1 gene of the patients was amplified by
PCR and subjected to single strand conformation polymorphism analysis.
A DAX-1 genomic fragment exhibiting abnormal migration on
single strand conformation polymorphism (data not shown) was directly
sequenced, revealing a C to A transversion at position 825 in the first
exon of the DAX-1 gene (Fig. 2A). The mutation changes the TAC triplet
coding for Tyr197 to a TAA stop codon, thus
resulting in premature termination of the DAX-1 protein. The mutation
destroys an RsaI restriction site, allowing confirmation of
the carrier status of DB’s and RR’s mothers by restriction analysis
(Fig. 2, B and C).
|
Sex steroid and gonadotropin concentrations measured 9 weeks after withdrawal of androgen replacement therapy were similar to those observed at the time of diagnosis.
Endogenous pattern of LH and free -subunit secretions and their
responses to pulsatile GnRH administration (Fig. 3 and Table 1). In the basal condition, serum LH
and FSH concentrations were below the normal adult range. The
endogenous LH secretory pattern was apulsatile, with a complete lack of
any apparent LH pulse. The pattern of spontaneous free -subunit
revealed erratic pulses. Intravenous pulsatile GnRH administration at a
dose of 10 µg/pulse (i.e. 102 ng/kg·pulse) resulted in
the appearance of a pulsatile LH pattern; each exogenous GnRH pulse
induced a LH response of low amplitude (0.54 ± 0.05 IU/L). The
peak amplitude and mean LH concentration increased (P
< 0.01) when the GnRH dose was 20 µg/pulse (i.e. 204
ng/kg·pulse) every 90 min for 40 h. During 10 and 20 µg
pulsatile GnRH administrations, the immunoreactive LH half-lives were
at the lower limit of the normal range. A significant increase in the
free -subunit level was observed (P < 0.01) after
40 h of 204 ng/kg·pulse GnRH. The plasma T level did not change
significantly during pulsatile GnRH administration and remained at
prepubertal values.
|
|
During the baseline study of gonadotropin pulsatility, the serum cortisol level was at the upper limit of the normal range at 0800 h, with a progressive decline during the morning. Then, the cortisol level increased after the lunch and declined again during the early afternoon. The changes in cortisol levels were similar during pulsatile GnRH administration, and the mean cortisol level did not change significantly during 10 or 20 µg pulsatile GnRH administration compared to that at the baseline evaluation.
Response to acute hCG stimulation test and chronic hCG and hMG
treatment (Fig. 4). Before exogenous
hCG administration, the T concentration of the patient was
undetectable. After three daily im injections of 5000 IU hCG, the
plasma T level slightly increased (3.6 nmol/L), but it remained at the
prepubertal value. The inhibin B level did not vary significantly
during acute hCG stimulation (baseline, 25 pg/mL; after hCG, 30 pg/mL).
During chronic therapy with exogenous gonadotropins, the plasma T level
remained at the prepubertal value after 1-yr treatment with weekly im
injections of 1500 IU hCG, whereas it increased into the normal range
during im injections of hCG and hMG (75 IU International Reference
Preparation 2) preparations.
|
|
Discussion |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
The phenotypic spectrum of hypogonadism in patients with mutations in the DAX-1 gene seems also to be variable. Patients may present with unilateral or bilateral cryptorchidism (9, 13, 16, 17), implying that gonadotropin secretion has been deficient in utero. In other patients, hypogonadism is not diagnosed before the age of normal onset of puberty, when adequate adrenal steroid therapy has allowed patients to survive to adulthood. Furthermore, an active hypothalamic-pituitary-gonadal axis during the first months of life has been recently reported in other patients (16, 18). Interestingly, in generated Dax-1-deficient mice, gonadotropin secretion is normal, and T production during embryonic and early postnatal development seems to be sufficient for the formation of male internal and external genitalia, for testicular descent, and for the normal development of the T-sensitive seminal vesicles (19).
Although pharmacological doses of glucocorticoids suppress basal and stimulated LH release (20), patients with Addison’s disease receiving physiological replacement therapy have normal pubertal development and fertility (21, 22). These patients have also normal basal gonadotropin levels, and normal frequency and amplitude of spontaneous LH secretion (23). In this patient treated with adrenocortical replacement therapy, serum cortisol levels were within the normal range, and the mean cortisol levels did not change significantly during the study of baseline and GnRH-stimulated gonadotropin secretion. Therefore, hypogonadotropic hypogonadism of the patient is not related to the adrenocortical replacement therapy.
The site of the gonadotropin deficiency in hypogonadic patients with
AHC has not been definitively settled. Several reports, based upon lack
of gonadotropin response to prolonged pulsatile stimulation with
synthetic GnRH, have suggested pituitary gland dysfunction as the
primary defect (5, 6, 7). In contrast, Parstch (10) reported successful
induction of pubertal gonadotropins and sex steroid concentrations
after therapy with pulsatile GnRH, suggesting hypothalamic dysfunction
as the principal defect on the hypothalamic-pituitary axis. It is
possible that in clinical studies reported before the isolation of the
DAX-1 gene, some patients may have disorders others than
DAX-1 gene mutations. However, in patients with well
documented mutations in the DAX-1 gene, HH has been also
associated with dysfunctions either at the hypothalamic or at the
pituitary level (8, 16). The heterogeneity in the response to pulsatile
GnRH administration may be also related to the difference in the GnRH
regimen used. In this patient, baseline hormonal study revealed an
apulsatile pattern of LH secretion, whereas erratic pulses were
observed for free -subunit. This secretory profile has been reported
in a subset of GnRH-deficient men (24) and implies either an incomplete
deficiency of hypothalamic GnRH secretion or a different threshold of
gonadotrope sensitivity for secretion of LH and free -subunit to low
levels of GnRH. During pulsatile GnRH administration, each exogenous
GnRH pulse triggered a LH response of low amplitude, and immunoreactive
LH half-lives were at the lower limit of the normal range. Amplitude of
LH peaks, mean LH, and free -subunit concentrations increased when
the GnRH dose was raised to 20 µg/pulse, but the secretory profile of
gonadotropins remained different from that observed in men with
Kallmann’s syndrome after 2–3 days of physiological GnRH replacement
(6, 8, 25). Moreover, inhibin B levels did not vary significantly
during pulsatile GnRH administration, whereas they changed after short
term physiological GnRH replacement in GnRH-deficient men (26). In this
patient, the pattern of normal LH pulse frequency but decreased
amplitude during that regimen of pulsatile GnRH administration (204
ng/kg·pulse) is also suggestive of a partial pituitary resistance to
GnRH. Therefore, HH in this patient may be due to both deficient GnRH
secretion and partial resistance to GnRH, suggesting combined
hypothalamic and pituitary defects.
Spermatogenesis has been rarely restored by treatment (pulsatile GnRH, exogenous gonadotropins) in patients with DAX-1 gene mutations (27), and lack of the DAX-1 gene in mice causes progressive degeneration of the testicular germinal epithelium, resulting in male sterility (19). As the DAX-1 gene is expressed in human testicular cells (1, 2, 4, 28), mutations of the DAX-1 gene may also impair Leydig or Sertoli cell functions. Interestingly, targeted disruption of Dax-1 in mice causes hyperplasia of Leydig cells, suggesting either a primary defect due to loss of Dax-1 function in Leydig cells or a secondary Leydig cell response to the inactivation of Dax-1 in Sertoli cells (19). In the majority of hypogonadic patients with AHC or mutations of the DAX-1 gene (5, 6, 7, 8, 9, 10, 14, 15, 17, 21, 28, 29, 30, 31, 32), serum T levels respond to acute or prolonged stimulation with hCG, indicating preservation of Leydig cell function. In this patient, im injections of 5000 IU hCG for 3 consecutive days was associated with a negligible change in the plasma T level. Moreover, chronic hCG treatment did not induce the progression of pubertal stages or normalization of the plasma T concentration. A similar and poor response to prolonged hCG treatment has been reported (33, 34, 35), implying Leydig cell resistance to hCG in these hypogonadic patients. On the other hand, DAX-1 gene is expressed in Sertoli cells, and its expression is down-regulated by the pituitary gonadotropin FSH (36). Numerous factors secreted by Sertoli cells may modulate testicular function through autocrine, intracrine, and paracrine mechanisms (37). In particular, a nonsteroid factor, secreted by human Sertoli cells, may increase T production after administration of recombinant human FSH (38). In this patient, normalization of the serum T concentration and progression of genital and pubic hair stages observed during hCG and hMG treatment suggest that in the presence of FSH, a Sertoli cell-secreted factor stimulated Leydig cell production of T. Alternatively, the improved response to hCG might be related to induction of LH-hCG receptors by FSH. Further studies are required to elucidate the function of DAX-1 in Leydig cell steroidogenesis and Sertoli cell signaling.
In conclusion, we report a novel mutation in the DAX-1 gene in patients with AHC and HH. Our results suggest that hypogonadism is due to a combined hypothalamic-pituitary-gonadal defect and imply that the DAX-1 gene may play a critical role in human testicular function.
|
Acknowledgments |
|---|
-subunit kits, and
Ferring Pharmaceuticals Ltd. (Gentilly, France) for
supplying pulsatile GnRH (Lutrelef). |
Footnotes |
|---|
Received April 7, 1999.
Revised June 9, 1999.
Accepted June 17, 1999.
|
References |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
 |
|
 |
|
  C Russo, E J Davis, P R Betts, and J H Davies The importance of re-evaluation, re-investigation and follow-up of adrenal insufficiency Arch. Dis. Child. Ed. Pract., August 1, 2007; 92(4): ep109 - ep113. [Full Text] [PDF]
|
|
|
|
 |
|
 J. J. Meeks, T. A. Russell, B. Jeffs, I. Huhtaniemi, J. Weiss, and J. L. Jameson Leydig Cell-Specific Expression of DAX1 Improves Fertility of the Dax1-Deficient Mouse Biol Reprod, July 1, 2003; 69(1): 154 - 160. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Brown, G. A. Scobie, J. Townsend, R. A. L. Bayne, J. R. Seckl, P. T. K. Saunders, and R. A. Anderson Identification of a Novel Missense Mutation That Is as Damaging to DAX-1 Repressor Function as a Nonsense Mutation J. Clin. Endocrinol. Metab., March 1, 2003; 88(3): 1341 - 1349. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. J. Tremblay and R. S. Viger Nuclear Receptor Dax-1 Represses the Transcriptional Cooperation Between GATA-4 and SF-1 in Sertoli Cells Biol Reprod, April 1, 2001; 64(4): 1191 - 1199. [Abstract] [Full Text]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 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 |
