Download Activation of the hypothalamic pituitary adrenal axis is one

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Sex Differences in the ACTH Response to 24H Metyrapone in Depression.
Elizabeth A Young MD1, 2 and Saulo C Ribeiro MD1.
From The Department of Psychiatry1 and Molecular and Behavioral Neuroscience
Institute2 (EAY), the University of Michigan
Text word count: 4118
Abstract word count: 199
Corresponding Author:
Elizabeth A Young
Molecular and Behavioral Neurosciences Institute (MBNI)
205 Zina Pitcher Place
Ann Arbor MI 48109-0720
[email protected]
Fax: 734-647-4130
2
Abstract
Increased hypothalamic-pituitary adrenal (HPA) axis activation has been observed in
major depression. Increased corticotropin-releasing hormone (CRH) is hypothesized to
drive corticotropin (ACTH) secretion leading to increased ACTH and cortisol secretion
throughout 24H. Contradicting data exist as to whether the increased drive is present
throughout the day or is restricted to the late afternoon and evening. To determine if
increased HPA axis activation occurs during a specific circadian phase or is found
throughout the 24H, we studied 26 healthy drug-free depressed patients and 26 healthy
age and sex matched control subjects under metyrapone inhibition of cortisol synthesis
for 24H beginning at 4PM. Blood was drawn every 10 minutes for 24H and assayed for
ACTH and cortisol. Gender differences in response to metyrapone were seen in both
patients and controls. Depressed women demonstrated increased ACTH concentrations
between 4PM and 10PM compared to control women. Maximal ACTH response over
time was identical between depressed and control women. Depressed men demonstrated
significantly decreased ACTH secretion between 4-10PM as well as decreased maximal
ACTH response compared to control men or depressed women. These data support a
circadian phase specific increase in CRH drive in depressed women, but overall
decreased CRH drive in depressed men.
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INTRODUCTION
Activation of the hypothalamic pituitary adrenal (HPA) axis is one of the most robust
findings in major depression. Studies examining 24H cortisol secretion have found that
25-33% of patients show elevated mean cortisol (Rubin et al, 1987; Halbreich et al, 1985;
Pfohl et al, 1985; Linkowski et al, 1985; Young et al, 2001). In addition, multiple studies
have demonstrated failure to suppress cortisol to dexamethasone challenge (Arana et al,
1985; Ribeiro et al, 1993; Carroll et al, 1981); this finding has been linked to elevated
mean cortisol basally (Poland et al, 1987). Failure to suppress pituitary -endorphin
secretion with dexamethasone challenge was also linked to increased basal cortisol
secretion (Young et al, 1993). This HPA axis hyperactivity is generally believed to
reflect increased central CRH and AVP secretion from the PVN. In support of this
hypothesis, increased CRH in the CSF of depressed patients has been demonstrated
(Nemeroff et al, 1984); furthermore, post-mortem studies have found increased CRH
mRNA levels and increased number of CRH and AVP co-expressing neurons in the PVN
of depressed patients (Raadsheer et al, 1994, 1995). Studies examining 24H secretion
have generally found cortisol secretion is higher in depressed patients than normal
subjects around the clock (Rubin et al 1987; Halbreich et al, 1985; Young et al, 2001.).
Other studies have suggested that the late afternoon is a particularly sensitive time to
detect cortisol increases (Halbreich et al, 1982). Early studies by Sachar et al (1973)
found late evening to show the maximum difference between depressed and control
patients in cortisol secretion. Likewise, late afternoon has been found to be the most
sensitive time to detect non-suppression of cortisol or  -endorphin to dexamethasone
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(Carroll et al, 1981; Young et al, 1993). We have found that administration of
metyrapone, a 11- hydroxylase inhibitor of cortisol synthesis, in the period between
4PM and 10PM, leads to increased -endorphin and ACTH secretion in depressed
patients compared to matched controls (Young et al, 1994, 2004) while administration of
metyrapone in the morning (8AM to 2PM) leads to increased ACTH secretion in both
patients and normal subjects equally (Young et al, 1997). Consequently, our previous
metyrapone studies suggest a specific circadian time of increased activation of basal
secretion – 4PM and 10PM (Young et al, 1994, 1997, 2004). However, our own 24H
studies undertaken in depressed women under basal condition suggested increased ACTH
and cortisol were found around the clock (Young et al, 2001). Our previous studies of
morning and evening metyrapone blockade were conducted in separate groups of patients
and controls, and we did not assess overnight ACTH secretion with metyrapone blockade
of cortisol synthesis. Thus, the current studies were undertaken to test the following
alternative hypotheses: 1) that while blocking cortisol synthesis and feedback with
metyrapone, we would observe increased ACTH secretion (reflecting increased CRH and
AVP drive) across the 24H or 2) that under the influence of metyrapone, we would
observed increased secretion of ACTH at a specific circadian phase only – from 4PM
until 10PM in the evening.
METHODS
Subjects: We studied 52 subjects in total, 26 depressed patients and 26 age and sex
matched control subjects. All subjects were recruited by advertising and were untreated
for the current episode of depression at the time of recruitment. After initial telephone
screening, patients were administered the Structured Clinical Interview for DSM-IV by
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our trained research nurse and all met criteria for current major depression as determined
by the SCID and confirmation by a psychiatrist (EAY or SCR). All subjects were
physically healthy as determined by screening blood work and physical exam and were
on no other medications. Four depressed women and four control women were post
menopausal. The remaining women were studied at random phases of the menstrual
cycle, since our previous studies comparing ACTH response to metyrapone in control
women at follicular and luteal phase showed no menstrual cycle effect (Altemus et al., in
press). By cycle day estimates, 4 patients were studied in the follicular phase and 9 in the
luteal phase; 4 controls were studied in the follicular phase, 5 in the luteal phase and for 4
controls cycle phase is unknown. All subjects were untreated for their current episode of
depression and on no medications of any type including herbal supplements. No
minimum severity level was required other than meeting MDD by SCID. All subjects
signed an informed consent and were free to withdraw at any time.
Procedure: The study was approved by the University of Michigan Health system IRB.
All subjects were admitted to the General Clinical Research Center at 2:30PM and given
a snack at this time. An intravenous catheter for blood drawing was inserted at 3:00 and
the first dose of metyrapone was administered at 4:00PM immediately following the first
blood sample. The starting time of 4PM was chosen to replicate our previous study of
increased ACTH response to metyrapone in depressed women (Young et al, 1004), and to
determine if this increased drive continued throughout the 24 hours. Blood was drawn
every 10 minutes for the next 24 hours (145 samples total). Metyrapone, 750 mg, was
administered every 4H from 4PM through noon the following day. Standardized meals
were given at 7:30PM, 7:30 AM, 11:30 AM and a snack at 3:30PM. The midnight and
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4AM doses of metyrapone were given with milk. All samples were drawn via syringe and
placed in polypropylene tubes with EDTA, then placed on ice until centrifuged and
separated, a maximum of 2 hours after collection. Following centrifugation, plasma was
separated and frozen on dry ice. Samples were stored at -80 C until assay.
Hormone Assay: All samples were assayed for ACTH and cortisol with the Diagnostic
Products Corporation (Los Angeles, CA) Immulite chemiluminescent based system. All
samples for each subject were run in one assay, and the matched pairs were assayed in
adjacent runs with the same assay kits. Intrassay variability was 4.8% for ACTH and 5%
for cortisol. Interassay variability for ACTH was 7% and 8% for low (30pg/ml) and high
(430pg/m) ACTH samples respectively; interassay variability was 7% and 9% for low
(4µg/dl) and high (34µg/dl) cortisol samples across assays. Minimum detection limit for
ACTH was 10 pg/ml and for cortisol was 1µg/dl.
Quiescent period onset and offset, secretory onset and circadian maximum;
The 24H profile of ACTH secretion did not follow the classical circadian rhythm since
ACTH levels were still greatly elevated at the end of the study (4PM, day2), as reported
previously (Veldhuis et al, 2001). To estimate periods of nocturnal quiescence and the
onset of the circadian secretory surge we adapted the procedures of Linkowski et al
(1985). We referenced all values to the mean plasma ACTH concentration from 1600h to
0400h in each individual and periods of at least 60 minutes duration in which all values
were below this reference mean were designated quiescent periods. Onset of the circadian
secretory ACTH surge was identified as the time from which all samples for at least a one
hour block were above the reference mean. Ultimately, this algorithm defined the point in
which all subsequent samples were above the reference mean for the duration of the
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study. Circadian maximum was defined using a moving average of 3 samples as the time
of the highest ACTH level. (Rubin et al, 1987)
Statistical analyses: Data were analyzed using a repeated measure analysis of variance
(RM-ANOVA) with time as one factor and group as a second factor. Because a
significant sex difference in response to metyrapone was observed in both control
subjects and depressed patients, data for men and women were also analyzed separately.
Some samples, particularly at the trough of the circadian rhythm, were below the
detection limit for ACTH assay (10pg/ml). These samples were set to the assay limit (10
pg/ml) for analysis; since average peak levels under metyrapone blockade were greater
than 400 pg/ml, the relative contribution of these extremely low levels was small.
Likewise, cortisol levels reading below 1µg/dl were set to 1. Cortisol was assayed to
assure that escape from metyrapone blockade did not occur. For the purpose of
determining adequate blockade of cortisol levels, actual values below 1µg/dl were not
needed. Finally, in order to include all subjects in the RM-ANOVA , missing values
were interpolated by taking the mean of the two adjacent samples for any subject with
missing values. Missing values were les than 1% of all samples.
RESULTS
Mean patient and control demographic data are presented in Table 1. As would be
expected by disease prevalence twice as many of the patients and controls were women.
The patients were moderately depressed as measured by the 17 item Hamilton Depression
Rating Scale (HDRS). Thirteen (9F, 4M) of the 26 patients met DSM-IV criteria for
melancholia and 14 patients (11F, 3M) were recurrent, while 12 patients (6F, 6M) were
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first episode. In two subjects, dysthymia preceded the onset of major depression. Four
patients had a history of anxiety disorders on the SCID (PTSD in two; social anxiety
disorder in three; two with panic disorder). In addition, five patients had a past history of
alcohol abuse which resolved 2, 8, 10, 17 and 18 years earlier. The mean episode length
was 15 ±18 months with a range of 1 month to 5 years. 15 of the patients were depressed
longer than 1 year.
Figure 1 shows the cortisol data for the patients and control subjects. The y-axis is set to
the usual circadian maximum, 20µg/dl. As can be observed, metyrapone successfully
blocked cortisol secretion to approximately 2 µg/dl throughout the 24 hours, although
small increases are observed immediately before each scheduled dose of metyrapone.
There was no difference between patients and controls in mean cortisol levels (F=0.45,
df=1/42, p=.5 for group and F=0.79, df=144/6048, p=.96 for interaction of group and
time). There were no significant sex differences in mean cortisol levels (F=0.19,
df=1/42, p=.66; interaction F=0.62, df=144/6048, p=.998); nor was there a significant sex
difference within the patients (F=.016, df=1/42, p=.9 for sex, interaction F=.858,
df=144/6048, p=.88) or controls (F=.557, df=1.42, p=.46 for sex, interaction F=.805,
df=144/6048, p=.95).
The ACTH response to this low cortisol feedback is shown in Figure 2. Following the
steep reduction of cortisol levels after 4 PM, no major secretory rise of ACTH was
observed. Beginning at around 4:00 to 4:30 AM, the circadian surge of ACTH
commenced. Under the prevailing low feedback condition, this expected circadian ACTH
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secretory phase was exaggerated (peak values > 400 pg/ml) and prolonged to around
noon (see Table 2), in agreement with Veldhuis et al (2001). Initial analyses of the
ACTH time series demonstrated no significant difference between patients and controls
(F=.27, df=1/42, p=.6), but a significant effect of gender in both patients and normal
subjects (F = 5.08, df = 1/42, p = .029 for gender for all subjects; F = 5.37, df = 1/20, p =
.03 for gender in patients (F>M); F = 0.8, df = 1/20, p = .36 for gender in controls, but a
significant interaction between gender and time in controls F = 1.977, df = 144/2880, p =
.0001(F>M)). Subsequent analyses of patients vs. controls were conducted separately by
sex.
In women, there was no significant difference in the ACTH response to 24H metyrapone
(Fig 2a) (F = .0002, df = 1/30, p = .98 for group; F = 108, df = 144, p = .0001 for time
and F = .76, df=144/4320, p = .98 for interaction). In contrast, depressed men showed a
significantly smaller maximal response to 24H metyrapone blockade then their matched
controls (Fig 2b) (F = 3.13, df = 1/10, p = .09 for group; F = 40.93, df = 144, p = .0001
for time and F = 3.268, df = 144/1440, p = .0001 for interaction of group with time).
Since our previous studies had shown an increased response to metyrapone in the 410PM time frame, we examined the data from the early time points (4-10 PM) to
determine if we had replicated the increased drive in the early evening in these patients.
If we had been unable to replicate this increased evening drive in these subjects, then the
demonstration of a normal maximal ACTH response to metyrapone could be due to
differences in the depressed patient populations studied. The data are shown in Fig 3. In
depressed women, (Fig 3a) we again observed a significant increase in ACTH secretion
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in the evening compared to these matched controls (F = 5.82, df = 1/32, p = .02 for
group; F = 10.79, df=12, p = .001 for time; no significant interaction). In contrast,
depressed men showed a significant decrease from their matched controls (F = 6.3, df =
1/16, p = .02 for group; F = 11.02, df=12, p = .0001 for time; F=2.42, df=12/192, p=.006
for interaction), (Fig 3b). We explored whether the subset of patients who met criteria
for melancholia showed greater HPA axis activation compared to controls but their
evening and 24H data looked the same as all patients (data not shown). Subjects were
asked to record their bedtime and awakening for four days prior to the study.
Comparison of group and sex differences in bedtime showed a significant effect of sex
(F=10.56, df=1/1, p=.002), but no significant difference between patients and controls
(F=1.04, df=1, p=.31) and no significant interaction (F=.65, df=1/40, p=.4). (Control
men=1:58±58min; control women=0:44±72min; depressed men=1:32±67min; depressed
women=0:39±83min.). The women were on average older (35±14.2) that the men
(27.7±9.4) although this difference was not significant (p=.18 unpaired t). There was a
significant negative correlation between age and average bedtime in patients (r=0.588,
F=10.6, df=1, p=.004) and controls (r=.56, F=9.67, p=.005). Consequently, the
significant sex difference in bedtime appeared to be a function of age differences between
men and women with more subjects over 40 in the female groups. Finally, since
depressed women showed increased ACTH response in the early evening, but a normal
ACTH response during the circadian maximum, we asked at what time the ACTH
secretion returned to normal in women. At 1AM the depressed women and control
women show equal ACTH response to metyrapone blockade.
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The ACTH data following metyrapone blockade do not show the classic circadian pattern
which looks like a cosine function, since the low levels of secretion continue from onset
for 12 hours or longer and then rise dramatically beginning around 4AM and are still near
maximal at the end of the study (Fig 2). Rather than using harmonic analysis, we defined
evening and overnight quiescent period onset and offset and secretory drive onset as
described in the methods. All controls met criteria for a quiescent period within an hour
of the initiation of sampling at 4PM. In all but 2 controls, this quiescent period was
interrupted prior to midnight. The average time of this initial quiescent period offset
(excluding 2 controls with offset after midnight) is shown in Table 2. Among patients, 6
did not demonstrate an initial quiescent period. For the remaining 20 patients the offset of
this period is shown in Table 2. In no patients did the initial quiescent period extend past
midnight. All subjects except one patient and one control showed at least one other
quiescent period with onset around midnight. The data for onset and offset of this
quiescent period are shown is shown in Table 2. Although there is a suggestion that
patients showed shorter initial and overnight quiescent periods because of wide
individual variations there are no significant differences. The ACTH secretory onset time
is also similar in patients and controls. This onset time was correlated with average
bedtime in controls (r=.475, F=6.1, p=.02) and in patients (r=.72, F=21.8, p=.0001). The
time of ACTH secretory onset was also correlated with age in controls (r=.643, F=16.95,
p=.0004) and patients (r=.73, f=27.2, p=.0001).
DISCUSSION
These studies were conducted to determine if HPA axis hyperactivity was present
throughout the 24H in major depression or was specific to the evening. We utilized
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metyrapone blockade for 24H beginning at 4PM in the evening – the time when we had
previously observed increased evening pituitary -endorphin (Young et al, 1994) and
ACTH (Young et al, 2004) response to metyrapone blockade. The answer to this
question was completely gender dependent. In women, we observed increased evening
ACTH secretion under metyrapone blockade, in agreement with our two previous studies,
one involving men and women and the other involving premenopausal women only
(Young et al, 1994, 2004). However, depressed women showed a normal maximal
response to metyrapone at the circadian acrophase (Fig 2a). This agrees with our
previous work looking at a 6 hour metyrapone challenge in the morning (8AM), which
showed normal ACTH secretion in depressed patients (Young et al, 1997). In contrast,
depressed men showed decreased ACTH drive in the evening (Fig 3b), and decreased
maximal ACTH response to metyrapone (Fig 2b). We have previously observed a
significant sex differences in the HPA axis in depressed men and women, including the
observation that depressed men did not show increased -endorphin/-LPH activation in
response to evening metyrapone (Young, 1995). Thus, these data replicate our previous
observations of a sex difference in response to evening metyrapone. We have also
observed that depressed men did not show evidence of basal cortisol hypersecretion
between 8AM- 10AM while depressed women did (Young 1995). However, we did not
expect that the depressed men would show a smaller ACTH response to metyrapone
blockade. This same pattern was observed in 6 of 9 men, so it was not due to one
individual only. Although our ACTH assay did not detect levels below 10pg/ml, this was
unlikely to affect the overall estimates of maximal response since the maximal ACTH
secretion was in the 300-400 pg/ml range for the depressed patients. Interestingly, a
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study by Rubin et al (1999) examining ACTH and cortisol responses to low dose
physostigmine challenge found an significantly greater response to the challenge in
depressed women compared to matched controls and significantly smaller response to the
physostigmine in depressed men compared the their matched control men. Their data
point to increased cholinergic sensitivity in depressed women and decreased sensitivity in
depressed men. Furthermore, the ACTH and cortisol responses to physostigmine
appeared to act through arginine vasopressin release (Rubin et al, 1999). Studies of the
ACTH response to vasopressin have predominantly demonstrated a normal response in
both depressed men and depressed women (Rubin et al, 1999; Carroll et al, 1993)
Despite the smaller ACTH response to metyrapone in depressed men, our data should not
be interpreted to suggest that depressed men show no HPA axis dysregulation, since
studies of melancholic depressed men have similarly shown elevated cortisol around the
clock. (Deuschle et al, 1997). In addition, we have found that younger depressed men
(<50) were more likely to show non-suppression of -endorphin to dexamethasone than
younger (< 50) depressed women (Young, 1995). Since only 4 of the depressed men met
criteria for melancholia, they may not have shown the classic HPA axis dysregulation
picture. In neither case do our data suggest that CRH drive is increased across the 24 H
in patients with major depression. Rather, the data support increased ACTH and CRH
drive during the evening only, and then only in women.
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Studies in rodents suggest that the circadian rhythm of CRH persists in the absence of
glucocorticoid negative feedback (Kwak et al, 1993), although data with metyrapone
support that cortisol feedback in the morning shifts the acrophase (Veldhuis et al, 2001) .
Our data suggest continued HPA axis activation in the evening in depressed women.
However, during the time of maximal circadian drive, the peak ACTH secretion was
normal. We do not know the mechanisms through which this increased evening secretion
is occurring. Although metyrapone successfully blocks cortisol secretion, it cannot
suppress cortisol below 2 µg/dl, a range in which mineralocorticoid receptors (MR) are
active. Similar to our finding, elevated cortisol immediately before sleep onset has been
found in adolescents with major depression (Rao et al, 1996; Forbes et al, 2006). We do
not know if MR dysfunction could be involved in the increased evening drive in women,
or if a different neural inhibitory pathway is not properly functioning in the depressed
women. One possibility is that there is just phase delay in the circadian nadir of ACTH in
depressed women, since the two groups eventually were equal by 1AM. However, we
found an earlier bedtime in women compared to men and no difference in bedtime
between patients and controls, so it is unlikely that phase delay can explain the findings.
Furthermore, using our definitions of quiescent period onset and offset, we found no
difference between patients and controls, although we did note that 6 patients but no
controls showed no quiescent period at the initiation of the study. Finally, a similar
pattern of elevated evening cortisol secretion has been found with advanced aging (Van
Cauter et al, 1996) and also following experimenter imposed partial sleep deprivation
(Leproult et al, 1997). It is possible that sleep loss played a role in the increased evening
activation seen in our depressed patients. However, based upon the HDRS administered
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on the day of the study, only 5 (4F, 1M) of the 26 patients had experienced middle or
terminal insomnia in the week of the study, which suggests that disturbed sleep does not
account for the increased drive seen in women.
With regards to depressed men, again we are unsure of the mechanism involved in the
smaller ACTH response to metyrapone. Although speculative, the findings of Rubin et al,
(1999) showing a smaller AVP response to physostigmine in depressed men may mean
that tonic AVP release under metyrapone is less in depressed men compared to depressed
women. Such a change would result in a smaller ACTH response under the open loop
system produced by metyrapone inhibition of cortisol synthesis and release, and would
account for our findings.
Several limitations are noted in this study. We attempted to recruit subjects that were as
representative of the general population of depression as possible, including twice as
many women as men and including premenopausal and postmenopausal women.
However, this results in limited ability to address issues of effects of menopause or
menstrual cycle on the HPA axis drive under metyrapone. With respect to menstrual
cycle phase we previously observed no menstrual cycle difference in 24H basal ACTH
and cortisol secretion in either depressed or control women (Young et al, 2001).
Furthermore, using a within subject design we observed no follicular luteal phase
differences in ACTH following metyrapone (Altemus et al., in press) administration. The
small number of men is a clear limitation and suggests separate studies focusing on men
should be undertaken. The mild nature of the depression and the few subjects with
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melancholia among the males may account for the absence of HPA axis activation in
depressed men. We do want to note that other studies have found significantly decreased
basal HPA axis activity (Posener et al, 2000; Geracioti et al, 1992) in non-psychotic
major depression, although neither study examined possible sex differences in their data.
While atypical depression has been proposed to show a pattern of reduced central drive,
we did not observe this in our previous 24 study of the HPA axis in depressed women
(Young, 2001) nor did any of the men meet criteria for atypical depression.
Another limitation was the need to awaken subjects at midnight and 4AM to administer
metyrapone. Obviously, this caused sleep disturbances that may have influenced the
HPA axis. The studies of Leproult et al (1997) showed that sleep disruption leads to
increased afternoon/evening cortisol. In addition, in order to collect samples for
pulsatility analysis, blood was drawn every 10 minutes, which may also cause sleep
disruption. While we do not know the degree to which sleep disruption contributed to the
HPA axis picture, we do not believe it would have contributed differentially between
groups. In our previous study of ACTH and cortisol pulsatility over 24H, which included
sampling every 10 minutes even while subjects were asleep, we were still able to observe
increased ACTH and cortisol in major depression. Furthermore, the mean cortisol in
control women was similar to mean cortisol in other studies using less frequent sampling.
Finally, in this study, the evening time period was evaluated before the possible sleep
disturbances induced by nighttime metyrapone administration and overnight blood
sampling.
17
In conclusion, the use metyrapone allowed us to examine the maximal secretion of
ACTH in the absence of glucocorticoid feedback. Our data suggest that metyrapone is
useful to determine the true timing and activity of central CRH systems of the HPA axis.
This strategy revealed unexpected findings with regards to depressed men. Future
analyses will address the pulsatile and ultradian rhythm of ACTH secretion in these
subjects. But, our data highlight the importance of gender in evaluating the HPA axis in
depression.
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Acknowledgements:
The authors acknowledge the support of MH 50030 (EAY), K05 MH 0193 to EAY and
MO1 RR00042 (General Clinical Research Center of the University of Michigan) and the
assistance of the nursing staff of the G-CRC in blood drawing, and Kathleen Singer RN
in recruiting and interviewing patients. We also acknowledge the contributions of our
consultant, Bernard J Carroll in the design of the study and helpful comments upon the
manuscript.
19
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Figure Legends
Figure 1. Mean cortisol levels in patients and control subjects over 24H following
metyrapone blockade of cortisol synthesis. The upper panel shows the data for women
and the lower panel for men. The first dose of metyrapone is given following drawing the
first blood sample at 4PM. Repeat doses are given every 4H and are indicated by arrows.
Following the initial dose of metyrapone, cortisol levels decline to approximately 2 µg/dl
and remain low and constant throughout the 24H. Small increases are seen near the end
of the 4 hours when the effects of metyrapone blockade is waning.
Figure 2. 24H ACTH profile following metyrapone blockade of cortisol synthesis in
depressed women (n=17, upper panel) and depressed men (n=9, lower panel) and their
matched controls (17, 9 respectively). Depressed women demonstrate a normal maximal
ACTH response to metyrapone blockade (upper panel) while depressed men demonstrate
a significantly smaller response than matched control subjects (lower panel).
Figure 3. Initial ACTH response to metyrapone blockade of cortisol synthesis between
4PM and 10 PM in depressed women (n=17, upper panel) and depressed men (n=9, lower
panel) and their matched controls (17, 9 respectively). Depressed women demonstrate
significantly greater ACTH secretion following metyrapone, while depressed men show
similar responses to metyrapone as their matched control subjects,
26
27
Table 1
Baseline Description of Patients and Controls (Mean ±SD)
Patients
Controls
Sex
17F; 9M
17F; 9M
Age
32.0 ± 13.5
31.8± 12.7
HDRS
17.3 ± 3.3 (range 9-24)
0.8 ± 1.1
Carroll Depression Rating
20.2 ± 5.6 (range 11-26)
0.8 ± 1.2
Melancholic
13
Atypical
4
Recurrent
14
28
Table 2
Circadian Secretory Parameters (Mean ±SD)
Controls
Patients
19:45±94 min
18:56±105min
23:15±85 min
23:50±100 min
Last Quiescent Offset
3:29±159 min
3:08±109 min
Secretory Drive Onset
4:25±106 min
4:08±80 min
Maximum Secretion
11:51±128min
10:55±129min
Initial Quiescent Period
Offset
Last Quiescent Period
Onset
29
Cortisol under Metyrapone in Depressed
Female Patients and Control Women
20
Patients
Depressed Women
Control Women
Controls
Cortisol, µg/dl
15
10
5
0
0
4PM
12
24
8PM
36
48
MN
60
72
84
4AM
Fig 1a
96
8AM
10 8
12 0
Noon
13 2
14 4
4PM
30
Cortisol under Metyrapone in Depressed
Male Patients and Control Men
20
Depre ssed men
Patients
Control m en
Controls
Cortisol, µg/dl
15
10
5
0
0
4PM
12
24
8PM
36
48
MN
60
72
4AM
84
96
8AM
Figure 1b
10 8
12 0
Noon
13 2
14 4
4PM
31
Response of Depressed Women and Their Matched
Controls to 24H Metyrapone Blockade
500
Patients
Depressed
Controls
Control
400
ACTH, pg/ml
300
200
100
0
0
4PM
12
24
8PM
36
48
MN
60
72
4AM
84
96
8AM
Figure 2a
10 8
12 0
Noon
13 2
14 4
4PM
32
Response of Depressed Men and Their Matched
Controls to 24H Metyrapone Blockade
500
Controls
Controls
Depressed
Patients
400
ACTH, pg/ml
300
200
100
0
0
4PM
12
24
8PM
36
48
MN
60
72
4AM
84
96
8AM
Figure 2b
10 8
12 0
Noon
13 2
14 4
4PM
33
Evening Metyrapone Challenge in Women
Depressed Patients and Matched Controls
35
Controls
Patients
Dinner
30
ACTH, pg/ml
25
20
15
10
5
0
2
4
6
8
Clock Time, PM
Figure 3a
10
12
34
Evening Metyrapone Challenge in Male
Depressed Patients and matched Controls
60
Controls
Patients
50
Dinner
ACTH, pg/ml
40
30
20
10
0
2
4
6
8
Clock Time, PM
Figure 3b
10
12
35
Response to Metyrapone in Depressed Women
and Matched Control Subjects Over 12 Hours
45
Controls
40
Patients
35
ACTH, pg/ml
30
25
20
15
10
5
0
2
4
4PM
6
6PM
8
8PM
Figure 4
10
10PM
12
MN
14
2AM
16
4AM