| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Original Studies |
Departments of Obstetrics and Gynecology (G.G., J.H., U.L., T.B.), Clinical Chemistry (M.S.), and Internal Medicine (C.B.), Akademiska Hospital, Uppsala University, S-751 85 Uppsala, Sweden; and the Department of Obstetrics and Gynecology, S. Anna Hospital, Torino University (M.M.), 10126 Torino, Italy
Address all correspondence and requests for reprints to: Dr. Gianluca Gennarelli, Department of Obstetrics and Gynecology, Akademiska Hospital, Uppsala University, S-751 85 Uppsala, Sweden.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
2
test, P < 0.05), resulting in a higher molar ratio
between the maximum increments of cortisol and ACTH [PCOS, 13.9
(8.7–19); controls, 8.8 (5.7–12); P < 0.05].
The women with PCOS did, however, show a more rapid decline in cortisol
levels than the controls (P < 0.05 at 120 and 180
min). The responses of the androgens and intermediate adrenal steroids
were similar in women with PCOS and controls. The findings suggest an
adaptation to increased adrenal reactivity to endogenous ACTH in women
with PCOS. Exposure to hypoglycemia as a model of stress was not
followed by hypersecretion of adrenal androgens and revealed no signs
of steroid enzyme disturbances in women with PCOS. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
-hydroxylase and 17,20-lyase,
in a substantial number of women with PCOS or functional ovarian
hyperandrogenism in both the ovary (3) and the adrenal (4) has been
suggested as a possible pathogenetic mechanism. Alternatively, the
adrenal disturbance may represent a general or less enzyme-specific
adrenal hyperresponsiveness, similar to what is found in children with
excessive adrenarche (5), a clinical condition with a high risk to
develop PCOS at puberty (6, 7). Indications of such an aberration in
PCOS are augmented suppression of plasma cortisol after dexamethasone
administration (8) and increased cortisol secretion in response to
Synacthen, CRH, or mental stress in hyperandrogenic women (9, 10, 11, 12). Increased cortisol secretion during stress could putatively play a role in the pathogenesis of insulin resistance in women with PCOS, both directly by insulin antagonism at the target organ level and indirectly by promoting accumulation of truncal-abdominal fat (13, 14). Recently, increased and prolonged cortisol secretion after mental and physical stress was found in women with abdominal fat distribution (15).
To investigate the reactivity of the pituitary-adrenal axis in PCOS, a group of women with PCOS was studied during acute insulin-induced hypoglycemia, representing a strong and reproducible form of stress (16). The primary aim was to compare the acute and prolonged ACTH and cortisol responses with those of a control group, and the secondary aim was to investigate the chain of the C19 and C21 intermediate and androgen steroids.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The study group included 18 women with PCOS enrolled at the
Department of Obstetrics and Gynecology of Uppsala University Hospital
(Uppsala, Sweden), and 17 healthy women, with similar age and body mass
index (Table 1
), selected among hospital
staff and medical students. The diagnosis of PCOS was based on the
ultrasonographic evidence of polycystic ovaries (17) in association
with a history of amenorrhea or menstrual irregularities. The controls
had regular menses and normal ovarian morphology according to
ultrasonography. The ultrasound examination was performed
transvaginally with an Acuson machine (5 MHz; Acuson 128/10, Acuson
Corp., Mountain View, CA). The ovarian volume was calculated from the
three maximum diameters (D1, D2, and D3) according to the formula
/6 x D1 x D2 x D3.
|
7). All of the women were in good physical condition, nondiabetic, and normotensive with normal levels of PRL and did not suffer from any other endocrine or metabolic disease. Congenital adrenal hyperplasia was excluded by a morning serum 17-hydroxyprogesterone concentration below 5 nmol/L.
The degree of physical activity, assessed by a questionnaire, was comparable in the groups. Seven women with PCOS and four controls smoked more than five cigarettes per day (P = NS). None of the subjects had been taking any drug known to affect carbohydrate metabolism or any hormonal medication for at least 3 months before the study. The metabolic and endocrine investigations were performed between the third and the eighth day of the menstrual cycle in women with oligomenorrhea or regular menstrual cycles. The protocol received the approval of the local human ethics committee of the medical faculty, and informed consent was obtained from all women.
Anthropometric variables
The waist and hip circumferences were measured as previously described (19), and the waist/hip ratio (WHR) was calculated.
Study protocol
The women were admitted to the hospital at 0700 h after an
overnight fast. After positioning an indwelling catheter in the
antecubital vein, the patient rested for 30 min. At -15 min, blood
samples were collected for basal hormone analysis. Hypoglycemia was
induced by a bolus of 0.15 IU/kg human insulin (Actrapid Human,
Novo Nordisk A/S, Copenhagen, Denmark). Samples for
glucose and hormone measurements were collected at different time
points, as shown in Table 2. At the same
time points, heart rate and blood pressure were measured. Glucose
concentrations were evaluated in capillary blood by a glucose oxidase
method. Blood was collected in plain Vacutainer tubes (Becton
Dickinson, Meylon Cedex, France) for the measurements of FSH, LH, ACTH,
androstenedione, testosterone, dehydroepiandrosterone (DHEA) sulfate
(DHEA-S), sex hormone-binding globulin (SHBG), insulin, C
peptide, cortisol, pregnenolone, progesterone,
17-hydroxypregnenolone, 17-hydroxyprogesterone, DHEA, and
androstenedione. Sera were stored at -70 C until measurement of the
respective hormones. Prechilled test tubes for the evaluation of ACTH
were stored in ice immediately after sampling and centrifuged at 4
C.
|
The following methods were used: FSH and LH, immunoperoxidase (Amerlite FSH and Amerlite LH-30, Johnson & Johnson Clinical Diagnostic Ltd., Amersham, UK); DHEA-S, RIA (Radioassay System Laboratories, Inc., Carson, CA); SHBG, fluoroimmunoassay (DELFIA SHBG, Wallac Oy, Turku, Finland); testosterone, RIA (Kabi Pharmacia Diagnostics AB, Uppsala, Sweden); insulin, RIA (Insulin RIA 100, Kabi Pharmacia Diagnostics AB); C peptide, RIA (RIA-gnost hC-Peptid, Svenska Hoechst AB, Goteborg, Sweden); and ACTH, RIA (Amersham, Arlington Heights, IL). The free androgen index (FAI) was calculated by the formula: (total testosterone/SHBG) x 100. The values for FSH and LH are expressed in international units per L, using the Second International Preparation of pituitary FSH/LH (78/549) and the Second International Standard for pituitary LH (80/552), respectively. For RIA of the steroids studied during hypoglycemia, [1,2,6,7-3H]progesterone and [1,2,6,7-3H]DHEA were purchased from New England Nuclear (Boston, MA); [1,2,6,7-3H]17-hydroxyprogesterone, [1,2,6,7-3H]androstenedione, and [1,2,6,7-3H]cortisol were obtained from the Radiochemical Center (Amersham, U.K.); and [7-3H]pregnenolone, [1,2-3H]17-hydroxypregnenolone, and antisera were purchased from ICN Biomedicals, Inc. (Carson, CA). Nonlabeled steroids were purchased from Sigma Chemical Co. (St. Louis, MO). Celite was purchased from Celite Corp. (Lompoc, CA), and Ready Safe Liquid Scintillation Cocktail was obtained from Beckman Instruments, Inc. (Fullerton, CA). Celite chromatography was performed as described previously (20) before immunoassay of 17-hydroxyprogesterone and 17-hydroxypregnenolone. The within- and between-assay coefficients of variation for all hormones were below 9% and 14%, respectively.
Statistics and calculations
In case of normality of distribution (checked by the
Kolmogorov-Smirnov test) before or after log transformation of the
data, comparison between the groups was performed by Student’s
t test for unpaired data (two-tailed). Otherwise,
Wilcoxon’s rank sum test was used. Pearson’s product moment
correlation was used to estimate linear relationships between
variables. For ACTH and single steroid responses, we calculated 1) the
maximum increment (change from baseline to peak; 
), 2) the overall
response as the area under the curve calculated by the trapezoidal rule
(AUC), and 3) -steroid/-ACTH and the AUC-steroid/AUC-ACTH.
Repeated measures ANOVA was also used to evaluate differences in
hormone responses over time. In the event of no hormone increment, as
observed in some cases, and AUC were set at zero for statistical
evaluation. The results are expressed as either arithmetic or geometric
means, with 95% confidence intervals.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
). Basal hormone and glucose concentrations
The women with PCOS had higher serum concentrations of LH,
DHEA-S, testosterone, and C peptide and higher LH/FSH
ratios and FAI than the normal women, whereas FSH, SHBG, and insulin
levels did not differ significantly between the groups (Table 3). The basal plasma concentrations of
ACTH, cortisol, pregnenolone, progesterone,
17-hydroxypregnenolone, and DHEA were similar (Fig. 1, a and b), whereas the women with PCOS had higher basal levels of
17-hydroxyprogesterone [mean (95% confidence interval): PCOS,
2.6 (2–3.3); controls, 1.1 (0.8–1.6) nmol/L; P
< 0.001] and androstenedione [PCOS, 12.9 (11.2–14.6); controls, 7.3
(5.8–8.7) nmol/L, P < 0.001] than controls. Fasting
blood glucose concentrations were similar in the women with PCOS and
the controls [PCOS, 4.24 (4.07–4.41); controls, 4.21 (3.98–4.44)
mmol/L; P = NS].
|
|
After the insulin bolus, blood glucose concentrations decreased, with similar slopes in both groups [PCOS, 0.15 (0.13–0.17); controls, 0.16 (0.14–0.17) mmol/L·min; P = NS], reaching 2 mmol/L or less at 30 min in all women [PCOS, 1.45 (1.23–1.67); controls, 1.4 (1.21–1.6) mmol/L; P = NS], i.e. well below the threshold for the stimulation of ACTH and cortisol release (21). All women experienced symptoms of hypoglycemia and significant changes in heart rate and blood pressure from baseline, without significant differences between the groups (data not shown). The recovery from hypoglycemia was complete within 180 min in all women (data not shown).
ACTH and cortisol responses
Plasma ACTH increased in all women, reaching peak levels at either
30 or 60 min, with no differences in time to peak between the groups
(by 2, P = NS; Fig. 1a). The -ACTH was lower in the women
with PCOS (P < 0.05; Table 4), independently from body mass
index, WHR, fasting insulin, and FAI. The -cortisol was the same in
both groups (Table 4 and Fig. 1a). A higher proportion of women with
PCOS (17 of 18) compared to the controls (11 of 17) reached cortisol
peak concentrations at the early time points (i.e. 30 or 60
min vs. 120 min; by 2, P
< 0.05). In accord, repeated measures ANOVA showed no group
differences in cortisol concentrations, but a significant impact of
group-time interaction (P < 0.05). The basal
cortisol/ACTH ratio did not differ between the groups [PCOS, 27.8
(19.1–32.4); controls, 32.9 (25.1–40.6); P = 0.3],
whereas the -cortisol/-ACTH was higher in the women with PCOS
than in the controls [PCOS, 13.9 (8.7–19); controls, 8.8 (5.7–12),
respectively; P < 0.05], and the -ACTH correlated
strongly with that of cortisol in both groups (PCOS: r = 0.73,
P < 0.01; controls: r = 0.63, P
< 0.01), i.e. -cortisol was greater in the PCOS group
over the entire range of the ACTH response (Fig. 2). The AUC-ACTH was lower in the
women with PCOS than in the control women [PCOS, 985.8 (474–1,497);
controls, 2,132.6 (1,206–3,058) pmol/L, respectively;
P < 0.05], whereas the AUC-cortisol was not
significantly different between the groups [PCOS, 11,483.2
(1,915–20,051); controls, 20,708 (5,059–26,286) nmol/L;
P = 0.3], nor was the AUC-cortisol/AUC-ACTH ratio
[PCOS, 6.8 (2–23.7); controls, 6.6 (2.8–15.4);
P = 0.9].
|
|
) who had lower cortisol concentrations at 120 and
180 min than in the controls (both P < 0.05). Responses of intermediate steroids and androgens
The responses of pregnenolone, progesterone, and
17-hydroxypregnenolone were comparable in the groups, as judged by
the maximum increments, ANOVA analyses, and AUCs (Table 4 and Fig. 1, a
and b). In 7 cases (6 PCOS and 1 control) no rise in
17-hydroxyprogesterone, in 4 cases (all PCOS) no rise in
DHEA, and in 11 cases (9 PCOS and 2 controls) no rise in
androstenedione was observed. The maximum increments are summarized in
Table 4. The -17-hydroxyprogesterone correlated positively with the
basal insulin levels in the women with PCOS (r = 0.71;
P < 0.01; Fig. 3). No
significant correlations were found between the -ACTH and those of
the other steroids studied during hypoglycemia. Furthermore, no
significant differences were noted for any other steroid studied in
either the -steroid/-ACTH or the AUC-steroid/AUC-ACTH (data not
shown).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
To our knowledge, this is the first study in women with PCOS in which the responses of ACTH, cortisol, and the steroids of the 5-ene and 4-ene pathways have been investigated during hypoglycemic stress. Activation of the hypothalamic-pituitary-adrenal axis plays a key role in the counterregulatory response to hypoglycemia (22). As judged from similar blood glucose decreases and similar increases in the other hormones of counterregulation (23), the hypoglycemic stress was comparable in the groups. For research purposes, this type of stimulus may have some advantages compared with the traditional Synacthen test, in which ACTH doses 500-fold greater than physiological levels provoke an adrenal response that may not be representative of daily life conditions (24) and which provides no information about the feedback relationship between the pituitary and the adrenal.
Apart from the lower ACTH release followed by normal acute cortisol
secretion, a larger number of women with PCOS reached peak cortisol
concentrations early (either 30 or 60 min) in the PCOS group, both
findings suggesting increased adrenal reactivity. However, the total
cortisol responsiveness to ACTH, expressed as the ratios between the
areas under the curves for cortisol and ACTH, was not increased in the
women with PCOS. This was largely due to a more rapid fall in cortisol
after the initial rise in the women with PCOS. One possible explanation
to this finding is a more active rapid negative cortisol feedback (25, 26) on the hypothalamic-pituitary axis (27), which may represent an
adaptation to increased adrenal sensitivity or reactivity. Another
plausible explanation for the more rapid decline in cortisol in the
women with PCOS is increased cortisol clearance from the circulation.
There are previous results suggesting that this may be the case in PCOS
due to either increased hepatic cortisol 5-reduction (28) or
increased conversion of cortisol to cortisone (29). Alternatively,
increased uptake into the enlarged depot of truncal-abdominal fat,
which is rich in cortisol receptors (30), could play a role in women
with PCOS.
Although our results support the idea of increased adrenal reactivity in women with PCOS, we failed to confirm an overall increased and prolonged cortisol response, which was previously found in women with PCOS (12) or abdominal obesity (15). The possibility remains that qualitatively different stimuli may elicit different types of responses, as those investigators used mental stress (12), physical stress, and Synacthen (15), respectively.
The androgen responses observed in the study are likely to represent a spillover from the adrenal activation, as the few available data (in primates) suggest that hypoglycemia has a suppressive effect on gonadotropins and, thus, ovarian steroidogenesis (31). In contrast to cortisol, the responses of the intermediate steroids and the androgens were not elevated in relation to ACTH in the women with PCOS. This might partly depend on the nature of hypoglycemic stress, which is likely to provoke a preferential response from the outer zone of the adrenal at the expense of the inner androgen-producing zone, the zones forming functionally distinct units (32, 33).
A substantial portion of the women showed no measurable responses at
various steps in the steroid chain, a finding that could well be
compatible with a lower activation of the inner zone of the adrenal
after this type of stress compared with the supraphysiological stimulus
of conventional Synacthen tests. The high number of nonresponding
intermediate steroids does not allow a straight comparison of the
results with those obtained with Synacthen tests, in which
precursor/product ratios usually form the basis for evaluation of
enzyme activities. However, enzyme abnormalities, such as dysregulation
of cytochrome P450–17 (4), presumably would have been detected if
they played a major role in the adrenal steroidogenesis during this
kind of adrenal stimulation. We did, however, see a strong association
between fasting insulin and the acute response of serum
17-hydroxyprogesterone in the women with PCOS, a finding that is
interesting in the light of results showing induction of
17-hydroxylase together with a lower increase in 17,20-lyase during
hyperinsulinemia in hyperandrogenic women (34).
In conclusion, we found indications of an altered hypothalamic-adrenal interplay in the women with PCOS compatible with increased adrenal reactivity to endogenous ACTH during hypoglycemic stress. The findings did not seem to be secondary to obesity, body fat distribution, or insulin or androgen levels. The hyperreactivity was restricted to the acute response of cortisol, which was higher over the entire range of ACTH response in the women with PCOS. However, our results could not confirm hypersecretion of cortisol in absolute terms in these women, suggesting an adaptation to increased adrenal responsiveness. Intermediate adrenal steroids and androgens did not show increased responses to endogenous ACTH, and there were no indications of specific enzyme alterations.
Received February 5, 1998.
Revised September 15, 1998.
Accepted October 6, 1998.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
as the cause of polycystic
ovarian syndrome. Fertil Steril. 53:785–791.[Medline]
5-steroid
dehydrogenase deficiency. J Clin Endocrinol Metab. 76:450–455.[Abstract]
-Reductase activity in polycystic ovary syndrome. Lancet. 335:431–433.[CrossRef][Medline]
-hydroxycorticosteroid intermediates
response to adrenocorticotropin in hyperandrogenic women: apparent
relative impairment of 17,20-lyase activity. J Clin Endocrinol
Metab. 81:881–886.[Abstract]
This article has been cited by other articles:
 |
|
 |
|
  R. Orvieto and Z. Ben-Rafael Polycystic ovary syndrome: a simplified approach based on the evolving set of symptoms Hum. Reprod., April 1, 2003; 18(4): 896 - 897. [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 |
) and controls (•).
Bars indicate standard error of the mean.
, dotted line; R = 0.73, P < 0.01) and
controls (
, solid line; R = 0.63, P <0.01). The groups
differ in cortisol response over the entire range of ACTH response
(P < 0.05; test for interaction NS).