The plasma dexamethasone variable in depression: test-retest studies and early biophase kinetics

Systematic evaluation of 640 FDA drugs for their effect on CD4⁺Foxp3⁺ regulatory T cells using a novel cell-based high throughput screening assay

Regulatory T cells (Treg), which play a pivotal role in maintaining immune homeostasis by suppressing the proliferation of effector T cells, have great therapeutic potential for autoimmune diseases and transplantation. However, progress on their clinical application has been hampered by the lack of high throughput screening (HTS) strategies for the systematic and rapid evaluation of existing drugs and the identification of novel drug candidates. In this report, we present an innovative in vitro HTS assay using CD4⁺ T cells from Foxp3-GFP transgenic mice that specifically express the GFP signal in Foxp3⁺ Treg cells detectable by FACS analysis in a high throughput manner. Systematic evaluation of 640 FDA-approved drugs revealed that 70 drugs increased the number of Treg cells with suppression function only in the presence of TGFβ, 75 drugs increased Treg numbers even in the absence of TGFβ, and 32 drugs increased Treg numbers synergistically with TGFβ. The identified Treg-promoting drugs include those previously known to induce Treg (rapamycin and retinoic acid), statins, glucocorticoids and drugs in many other categories. Furthermore, Treg cells cultured with the identified drugs possess surface and intracellular markers characteristic of natural Treg cells and possess suppressive function. These results suggest that this Treg HTS assay can be used to screen compound libraries to identify novel chemical entities for Treg-based immune therapies.

Stability of the dexamethasone suppression test in borderline personality disorder with and without comorbid PTSD: a one-year follow-up study

Alterations in hypothalamic-pituitary-adrenal axis feedback regulation have been repeatedly reported in patients with borderline personality disorder (BPD). Due to the cross-sectional design of these studies, little is known about the longitudinal course of HPA axis functioning. In a sample of 13 patients with BPD, the dexamethasone suppression test (DST) has been used in a one-year follow-up study. There were no changes of cortisol concentrations before or after dexamethasone intake between baseline and follow-up examination. Patients with comorbid posttraumatic stress disorder (PTSD) showed more pronounced cortisol suppression compared to those without PTSD. The DST seems to be a stable marker of alterations in HPA axis feedback regulation in BPD, which is also reflected by substantial correlations between percentage of cortisol suppression at baseline and follow-up examination.

Impairment of inhibitory control of the hypothalamic pituitary adrenocortical system in epilepsy

Excess comorbidity between depression and epilepsy proposes common pathophysiological patterns in both disorders. Neuroendocrine abnormalities were often observed in depression as well as in epilepsy. Lack of inhibitory control of the hypothalamic pituitary adrenocortical (HPA) system is a core feature of depression; main relay stations of this system are located in the amygdala and hippocampus, which are key regions for both disorders. Therefore we explored the feedback mechanism of the HPA system in epilepsy. In order to control for the impact of depression we focused on epilepsies without depression. We compared patients with epilepsy (subdivided by medication with or without hepatic enzyme inducing antiepileptic medication) with 16 healthy controls and 16 patients with unipolar major depression but without epilepsy. We observed a lack of inhibitory control of the HPA system in patients with epilepsy, also in the absence of enzyme inducing medication. An impact of the temporal lobe location of the epileptic focus could not be observed. Thus, epilepsies share with depression the deficiencies in the feedback mechanism of the HPA system, proposing common pathophysiological features of up to now unknown nature.

A novel specific bioassay for the determination of glucocorticoid bioavailability in human serum

OBJECTIVE

Some patients develop side-effects even on relatively low doses of topically administered glucocorticoids (GCs), while others appear to be less sensitive to GCs. We have developed and validated a bioassay which can measure glucocorticoid bioavailability directly from small amounts of human serum to help elucidate underlying mechanisms.

METHODS

We have stably transfected the human embryonic kidney cell line HEK293 with a plasmid expressing the glucocorticoid receptor, and a plasmid containing the luciferase gene preceded by three concatenated steroid response elements, bringing luciferase expression under control of the liganded glucocorticoid receptor.

RESULTS

The assay, with an intra- and interassay coefficient of variance (CV) better than 10%, showed the expected difference in potency between different GCs (fluticasone propionate > budesonide > dexamethasone > hydrocortisone). No cross-reactivity was detected with other steroid hormones such as progesterone, testosterone and oestradiol. The bioassay easily detects the rise and subsequent fall of bioavailable GCs in human serum following ingestion of only 0.5 mg dexamethasone, and clearly reflects the diurnal cortisol rhythm. Moreover, systemic availability following inhalation of 2 x 250 micro g fluticasone propionate using a pressure dose inhaler could be demonstrated.

CONCLUSIONS

This assay can be used to determine levels of bioavailable GCs in serum, both endogenous and administered, and thus may help in optimizing treatment regimens. The small amount of serum needed to perform an analysis makes this assay applicable even to infants.

HPA hyperactivity with increased plasma cortisol affects dexamethasone metabolism and DST outcome

Data suggests that dexamethasone bioavailability or pharmacokinetic factors contribute importantly to the outcome of the dexamethasone suppression test, and a relationship between plasma cortisol and plasma dexamethasone levels has been shown. To evaluate these data further, we studied plasma dexamethasone pharmacokinetics in 24 patients with major depression (15 suppressors and nine nonsuppressors) who received a 1 mg IV dexamethasone bolus at 09:00 h with blood samples collected at intervals over the next 14 h. We found that nonsuppressors had significantly shorter plasma dexamethasone half-life (P = 0.003) as well as significantly lower dexamethasone levels 10 h (P = 0.02) following IV dexamethasone administration. Moreover, upon clinical improvement of patients, the shortened dexamethasone half-life and lower dexamethasone levels disappeared in the five patients who switched from nonsuppression to suppression and were restudied by IV bolus. These 10-h post IV plasma dexamethasone level findings paralleled the results of the 1 mg overnight oral DST performed in these depressed patients (N = 22) where we found significantly lower 10 h plasma dexamethasone levels in nonsuppressors on admission compared to suppressors (P = 0.002) and again at discharge (P = 0.007). Interestingly, in the few patients who switched from suppression to nonsuppression over the course of hospitalization, 10-h post dose plasma dexamethasone levels simultaneously dropped. No difference in dexamethasone half-life was observed in the patients studied by oral and IV dexamethasone administration. These findings support the concept that metabolism of dexamethasone is significantly related to the activity of the HPA axis (particularly by plasma cortisol levels), and that dexamethasone pharmacokinetics can be modified by state-dependent phenomena.

Hypercortisolemia decreases dexamethasone half-life in rabbit

The pharmacokinetics of dexamethasone have been found to be related to endogenous hypothalamic-pituitary-adrenal (HPA) axis activity. Lower plasma dexamethasone levels in psychiatric patients (especially depressed) who are dexamethasone suppression test (DST) nonsuppressors have previously been reported. Since DST nonsuppression is one measure of HPA axis hyperactivity and is usually associated with relatively increased plasma cortisol levels and lower post dose plasma dexamethasone levels, we hypothesized that hypercortisolemia can induce a more rapid disappearance of dexamethasone from plasma. We therefore studied the kinetics of dexamethasone in rabbits before and after a period of sustained hypercortisolemia produced by administration of IM hydrocortisone acetate, a slowly absorbed salt of cortisol. Mean dexamethasone half-life decreased significantly from baseline of 1.92 h on day zero in seven rabbits to 1.17 h on experimental day 17 of induced hypercortisolemia (P < 0.001), while there was no significant change in saline treated controls (n = 3). Dexamethasone half-life had returned to the baseline levels when retested 88 days later on experimental day 105. The results indicate that pronounced hypercortisolemia decreases dexamethasone half-life in rabbits, and support the concept that increased circulating cortisol levels induce hepatic enzymes that metabolize dexamethasone. Thus, the lower postdexamethasone plasma dexamethasone levels and decreased dexamethasone half-life in DST nonsuppressors may in part reflect the effect of prior or coincident hypercortisolemia.

Dexamethasone metabolism in dexamethasone suppression test suppressors and nonsuppressors

BACKGROUND

Variable dexamethasone kinetics is a possible confound in the dexamethasone suppression test. Modifications to include dexamethasone plasma levels and specific dexamethasone "windows" have been proposed. Our study aims to validate our proposed dexamethasone windows in an independent sample of 121 subjects.

METHODS

We performed dexamethasone suppression tests in 162 subjects with mixed psychiatric diagnoses. Dexamethasone levels and beta-phase half-life of dexamethasone were computed for suppressors and nonsuppressors.

RESULTS

Dexamethasone levels were lower in nonsuppressors than in suppressors. Dexamethasone levels correlated inversely with cortisol levels in the total sample, but were nonsignificant or weakly associated in those samples restricted to the windows. The beta-phase half-life of dexamethasone was shorter in nonsuppressors. The dexamethasone windows were validated at 3:00 PM and 10:00 PM. We propose 4.0 ng/mL as a revised upper limit of the 8:00 AM dexamethasone window.

CONCLUSIONS

The plasma dexamethasone level is confirmed as a confound in the dexamethasone suppression test through more rapid dexamethasone clearance in nonsuppressors. Application of dexamethasone windows will reduce this source of test variance.

The lower limits of dexamethasone window in Chinese depressives

BACKGROUND

Previous studies have shown wide variation in plasma dexamethasone (DEX) concentrations following a standard 1-mg dexamethasone suppression test (DST), and significantly lower DEX concentrations in DST nonsuppressors compared with suppressors, suggesting that DEX pharmacokinetics/bioavailability is an important variable associated with DST nonsuppression.

METHODS

To determine the effect of plasma DEX levels on the DST in Chinese depressives, we measured plasma DEX and post-DEX cortisol levels at 4:00 PM in a group of 50 depressed outpatients, 28 anxiety outpatients, and 33 normal subjects during the course of 1-mg oral overnight DST.

RESULTS

We found a significant difference in the plasma DEX levels between DST nonsuppressors and suppressors in the depression group and overall subject population, and a significant negative correlation between the plasma DEX and cortisol levels in the depression, anxiety, and total groups. Within a DEX "window", the DST performance was enhanced, whereas the relationships between plasma DEX and post-DEX cortisol levels remained equally strong.

CONCLUSIONS

Our findings support a relationship between plasma DEX and post-DEX cortisol levels, a relationship that might be superimposed on the hypothalamic-pituitary-adrenal axis. Comparing our "window" range with those of previous studies, we suggest that Chinese depressives may have lower limits of plasma DEX window, and that ethnicity may be an intervening variable in both DST response and pharmacokinetics of DEX.

Plasma dexamethasone concentration and cortisol response during manic episodes

BACKGROUND

Despite the widespread study of the dexamethasone suppression test (DST) in patients diagnosed with major depression, it has been less well studied during manic and mixed states of bipolar disorder.

METHODS

Cortisol response to the administration of 1 mg of dexamethasone was studied in 44 patients diagnosed bipolar disorder, manic (n = 37) or mixed (n = 7). Dexamethasone levels and cortisol responses were compared between these groups. Four patients initially meeting criteria for bipolar disorder, mixed, and 7 patients initially meeting criteria for bipolar disorder, manic, all of whom were characterized as DST nonsuppressors, were retested after remission.

RESULTS

Dexamethasone levels were lower and cortisol levels higher in those patients diagnosed bipolar disorder, mixed. An inverse correlation was found between log-transformed dexamethasone levels and log-transformed cortisol levels at 3 PM (r = -.619, p < or = .001) and 10 PM (r = -.501, p < or = .001). In those subjects retested after remission, dexamethasone levels were higher and cortisol levels lower than during the manic and mixed states.

CONCLUSIONS

Disturbances in the hypothalamic-pituitary-adrenal axis are observed frequently during mixed states of bipolar disorder, but are also not uncommon in purely manic episodes. These changes appear to be state dependent and revert with treatment.

Pharmacokinetics of dexamethasone and its relationship to dexamethasone suppression test outcome in depressed patients and healthy control subjects

The pharmacokinetics of dexamethasone (DEX) were studied in 9 drug-free melancholically depressed patients and 10 healthy control subjects matched by sex and age. Each subject received 1 mg of DEX administered orally and by the (i.v.) route at 11:00 PM and serial blood samples were collected over the next 17 hours until 4:00 PM. There were no significant differences between the diagnostic groups and DEX bioavailability, peak plasma level, time to maximum concentration, or in elimination half-life after oral administration. Bioavailability estimates indicated that DEX absorption was incomplete and variable mean = 61%, SD = 14) in controls as well as depressed patients. In both groups there was a wide interindividual variability in plasma DEX levels following both oral and i.v. routes of administration. This variability could not be reliably predicted by differences in age, sex, or weight between subjects. The factors that accounted for most the variability in 4:00 PM plasma DEX levels after oral administration were clearance, bioavailability, and time to reach maximum concentration. Plasma DEX levels were lower in 3 depressed nonsuppressors compared to 3 matched controls who suppressed. No single pharmacokinetic factor was shown to be responsible for the lower DEX levels in the depressed nonsuppressors. These results indicate that plasma DEX levels need to be measured in each individual during the DST procedure so that this information may be taken into consideration when interpreting DST results.

Depressive psychomotor disturbance, cortisol, and dexamethasone

We examine the dexamethasone suppression test as a biological correlate of melancholia as defined by the CORE system, a scale for rating objective signs of psychomotor disturbance. Postdexamethasone cortisol concentrations and rates of nonsuppression were higher in CORE, Newcastle, and DSM-III-R defined melancholic groups. These differences, however, were no longer significant after partialling out the combined effects of age, dexamethasone, and basal cortisol concentrations. There was a significant correlation between the CORE (but not the Newcastle) scale and 8:00 AM postdexamethasone cortisol levels, which persisted after partialling out those same three covariates. Dexamethasone concentrations themselves were lower in CORE- and Newcastle-defined melancholics, though these were no longer significant after covarying for cortisol concentrations. Dexamethasone levels were also significantly inversely correlated with CORE and Newcastle scales. A significant correlation between CORE (but not Newcastle) scores and dexamethasone levels at 4:00 PM persisted after partialling out the effects of age and cortisol. These findings indicate an intriguing relationship between the CORE system as a dimensional construct for rating psychomotor disturbance, and both postdexamethasone cortisol and dexamethasone concentrations.

Amitriptyline metabolism in elderly depressed patients and normal controls in relation to hypothalamic-pituitary-adrenal system function

The pharmacokinetics of amitriptyline (AMI) have been extensively studied, and a large interindividual variability between oral dose and concentration of the drug in plasma has been documented. The aim of this study was twofold: first, to compare AMI kinetics in depressed patients with those of healthy controls and, second, to describe the relationship between AMI levels in plasma and hypothalamic-pituitary-adrenal (HPA) system changes during depression. Thirty-eight patients with a DSM-III-R diagnosis of major depression and 13 healthy control persons received 75 mg of AMI daily for 6 weeks. Levels of AMI and nortriptyline in plasma were determined, and neuroendocrine testing with the combined dexamethasone-suppression/CRH-stimulation test (DST) was done before AMI administration and after weeks 1, 3, and 6 of medication. AMI levels in plasma were significantly higher in the patient group compared with controls during the entire treatment period, whereas nortriptyline levels did not differ between the two groups. Drug levels correlated significantly with age, but gender had no effect on the concentration of the drug in plasma. Twenty-two patients remitted after treatment. There was no difference in drug levels between responders and nonresponders. Fifteen patients were DST nonsuppressors before treatment; 23 patients and all controls suppressed cortisol after dexamethasone. DST suppressors had significantly higher AMI levels in plasma at weeks 3, 5, and 6 compared with DST nonsuppressors. In comparison to patients with high AMI levels in plasma, those with low drug concentration had higher postdexamethasone cortisol and adrenocorticotropic hormone levels and an increased hormone release after additional CRH.(ABSTRACT TRUNCATED AT 250 WORDS)

State specificity of DST abnormalities in geriatric depression

Pre-treatment and posttreatment dexamethasone suppression test (DST) results in physically healthy elderly major depressives without dementia demonstrated an association between treatment and DST normalization. Sixty percent of subjects were nonsuppressors at baseline compared to 17% after intensive treatment. DST results normalized in 75% of initial nonsuppressors; none of the initial suppressors converted to nonsuppression. A strong correlation between clinical improvement and decreases in afternoon cortisol levels was identified. Initial suppression status did not influence this association. There was a nonsignificant trend for very high (> 15 micrograms/dl) afternoon cortisol levels to be associated with delusional depression. The advantage of using continuous rather than categorical measures to assess the relationship between reversal of depression and DST results is discussed.

Inhibition of the pituitary-adrenal axis with dexamethasone and cortisol in depressed patients and healthy subjects: a dose-response study

Different doses dexamethasone (0.25, 0.5, and 1 mg) or cortisol (30, 60, and 120 mg) were administered PO at 2230h to 39 depressed patients and 20 healthy subjects on nonsuccessive days. The inhibiting capacity of the two steroids on hypothalamo-pituitary axis (HPA) function was evaluated by measuring the plasma levels of cortisol, ACTH, and beta-endorphin at 0900h and 1530h each day following treatment. Baseline levels of the hormones were measured before starting treatment. A dose-dependent suppressive effect of both steroids on the plasma levels of cortisol, ACTH, and beta-endorphin was found both in patients and controls, except for the 0900h levels of cortisol after cortisol treatment. The effects were most profound in the morning. Differences between patients and controls were observed after cortisol treatment, but not dexamethasone, with respect to cortisol, ACTH, and beta-endorphin plasma levels in the morning. Cortisol treatment discriminated dexamethasone nonsuppressors from suppressors (patients and controls) and patients categorized as dexamethasone suppressors from controls in a way that dexamethasone treatment could not. The data favour the idea of impaired corticosteroid feedback beyond the pituitary level as part of HPA dysfunction.

Do serum dexamethasone levels improve the DST?

Some investigators have reported that dexamethasone suppression test (DST) accuracy might be improved by incorporating dexamethasone concentrations ([dex]) into test results. Using receiver operating characteristic methods, we evaluated data from four studies in which cortisol and dexamethasone levels were measured simultaneously at one or more times after drug ingestion. We compared DST accuracy using cortisol alone with various diagnostic indices incorporating [dex]. In none of the 21 comparisons did the [dex] factor enhance diagnostic performance.

The effect of dexamethasone dosage upon plasma cortisol and dexamethasone during the DST

To investigate the effect of dexamethasone dosage upon the outcome of the dexamethasone suppression test (DST) and the role of concurrent plasma dexamethasone concentrations, four different dexamethasone dosages were administered to 119 hospitalized depressed patients (0.5 mg: n = 12; 1.0 mg: n = 30; 1.5 mg: n = 42; 2.0 mg: n = 35). Independent of the dosage, dexamethasone plasma concentrations at 4.00 p.m. were lower in DST non-suppressors than in suppressors, although differences were statistically significant only for the 1.5-mg and 2.0-mg dosages. Our findings confirm recent reports that the actual plasma concentration of dexamethasone at 4.00 p.m. does not determine DST outcome.

Plasma dexamethasone levels in children given the dexamethasone suppression test

To determine whether children who demonstrate dexamethasone suppression test (DST) nonsuppression have lower plasma dexamethasone levels than DST suppressors, we administered the DST to 73 patients ranging in age from 5-14 years. Plasma dexamethasone levels and postdexamethasone cortisol levels were measured at 4:00 PM on day 2. We found: (1) DST nonsuppressors had significantly lower plasma dexamethasone levels (p less than 0.03) than suppressors; similar trends were observed when the population was divided into depressed and nondepressed patients; (2) mg/m2 dose of dexamethasone was directly correlated with plasma dexamethasone (p less than 0.003) and inversely correlated with postdexamethasone plasma cortisol levels (p less than 0.04); and (3) a statistically significant inverse correlation between plasma dexamethasone levels and postdexamethasone cortisol levels (p less than 0.04). Our findings show that plasma dexamethasone levels are important in evaluating DST results in psychiatrically disturbed children and suggest that dexamethasone dosage for use in the DST in children might be better calculated in terms of body surface area.

Plasma dexamethasone concentrations and the dexamethasone suppression test

Altered bioavailability or altered pharmacokinetics of dexamethasone (dex) may contribute to a positive Dexamethasone Suppression Test (DST) in psychiatric patients. We measured plasma dex and plasma cortisol concentrations in 32 patients with primary major depressive disorder (MDD), 14 patients with other psychiatric disorders, and 16 normal controls. Cortisol was measured by the competitive protein binding (CPB) assay and dex by RIA (IgG Corp.). Additionally, cortisol was measured by a fluorescent polarization immunoassay (FPIA) available on the Abbott TDx analyzer in an attempt to validate this method for use in the DST. The agreement between FPIA and CPB cortisol results was excellent. Depressed nonsuppressors, by definition, had significantly higher mean plasma cortisol concentrations than depressed suppressors, psychiatric controls, and normal volunteers at 8:00 AM, 3:00 PM, and 10:00 PM postdex. When DST nonsuppressors and suppressors were compared regardless of diagnostic group, plasma dex concentrations were significantly lower (p less than 0.01) in the DST nonsuppressors. There was a significant negative correlation between plasma cortisol levels and plasma dex levels across all subjects at 8:00 AM (r = -0.365, n = 44, p less than 0.05). When the subjects were sorted by diagnostic category, there was a strong, but not statistically significant, trend toward lower plasma dex concentrations in the melancholic nonsuppressors versus the melancholic suppressors and between the psychiatric control non-suppressors and the corresponding suppressor group. These relationships disappeared when we restricted our analyses to an empirically derived middle range of plasma dex concentrations within which the DST results were considered to be valid. We conclude that bioavailability or pharmacokinetics of dex may significantly contribute to DST results. Further investigation is needed to determine whether or not the quantification of dex and its metabolites and their determination at which specific timepoints during the DST will enhance the predictive or interpretive value of the DST in psychiatric patients.

Dexamethasone kinetics in depressed patients before and after clinical response

Dexamethasone pharmacokinetics were measured in 19 depressed patients, 10 dexamethasone suppression test (DST) nonsuppressors and nine suppressors, following a 1 mg oral dose in tablet form at 2300 h. Median dexamethasone concentrations were significantly lower in the nonsuppressors from 3-16 hr post-administration. Nonsuppressors had a significantly lower area under the curve than suppressors, and plasma clearance was significantly faster in the nonsuppressors than in the suppressors. Eleven patients, six nonsuppressors and five suppressors, agreed to a repeat DST after clinical improvement when all six nonsuppressors had normal DST responses. There were no significant differences between the median dexamethasone concentrations, or any of the pharmacokinetic parameters measured, of the "normalising" nonsuppressors and the suppressors. Dexamethasone kinetics were altered in depressed nonsuppressors but became normal with remission of depressive symptoms and normalisation of the DST response.

The effect of age on cortisol and plasma dexamethasone concentrations in depressed patients and controls

The aim of this study was to identify any relationships between various patient factors such as age, gender and concurrent medication that may affect plasma cortisol or dexamethasone (DEX) concentrations. Multiple regression analysis was used to formulate an equation to predict plasma DEX levels to identify factors that may influence DEX bioavailability. Pre- and post-DST cortisol levels did not increase with age, but DEX levels were higher in elderly depressed patients. Neither gender nor psychotropic medication affected plasma cortisol or DEX levels. There was no indication that pre-DST cortisol levels influenced plasma DEX levels to account for the lower DEX values in non-suppressors. Age was the only significant factor found in this study to influence DEX levels and it could be argued that the dose of DEX should be lowered when administering the DST to elderly patients to reduce plasma DEX variability.

Psychiatric implications of altered limbic-hypothalamic-pituitary-adrenocortical activity

Hormones of the limbic-hypothalamic-pituitary-adrenocortical (LHPA) system are much involved in central nervous system regulation. The major LHPA neuropeptides, corticotropin-releasing hormone (CRH), vasopressin (AVP) and corticotropin (ACTH) do not only coordinate the neuroendocrine response to stress, but also induce behavioral adaptation. Transcription and post-translational processing of these neuropeptides is regulated by corticosteroids secreted from the adrenal cortex after stimulation by ACTH and other proopiomelanocortin derived peptides. These steroids play a key role as regulators of cell development, homeostatic maintenance and adaptation to environmental challenges. They execute vitally important actions through genomic effects resulting in altered gene expression and nongenomic effects leading to altered neuronal excitability. Since excessive secretory activity of this particular neuroendocrine system is part of an acute stress response or depressive symptom pattern, there is good reason to suspect that central actions of these steroids and peptides are involved in pathophysiology determining the clinical phenotype, drug response and relapse liability. This overview summarizes the clinical neuroendocrine investigations of the author and his collaborators, while they worked at the Department of Psychiatry in Mainz. The major conclusions from this work were: (1) aberrant hormonal responses to challenges with dexamethasone, ACTH or CRH are reflecting altered brain physiology in affective illness and related disorders; (2) hormones of the LHPA axis influence also nonendocrine behavioral systems such as sleep EEG; (3) physiologically significant interactions exist between LHPA hormones, the thyroid, growth hormone, gonadal and other neuroendocrine systems; (4) hormones of the LHPA axis constitute a bidirectional link between immunoregulation and brain activity; and (5) future psychiatric research topics such as molecular genetics of affective disorders, familial risk studies, drug response analysis and neurobiology of aging will benefit from extended knowledge of neural corticosteroid effects at a clinical, cellular, and molecular level.

Differential effects of scopolamine on nocturnal cortisol secretion, sleep architecture, and REM latency in normal volunteers: relation to sleep and cortisol abnormalities in depression

Scopolamine (SCOP) (3.0 mu/kg and 6.0 micrograms/kg) and saline were administered intramuscularly at 11:00 PM to eight normal male volunteers in a randomized design, and the effects on the sleep electroencephalogram (EEG) and nocturnal cortisol secretion (via blood sampling every 15 min) were evaluated. Compared to saline, SCOP produced a significant dose-related delay in rapid eye movement (REM) latency. In contrast, neither dose of SCOP significantly affected nocturnal plasma cortisol concentrations. These results suggest that the central cholinergic system that regulates the onset of REM sleep is more sensitive to dysregulation than the cholinergic system that controls the degree of nocturnal cortisol secretion. If central cholinergic overactivity is responsible for both the REM sleep latency and cortisol abnormalities in depressed patients, then our findings with SCOP might help explain why the incidences of these abnormalities are different.

Specific determination of plasma dexamethasone by HPLC and RIA--application to standard dexamethasone suppression test in psychiatric patients

Three radioimmunoassays (RIA), with or without preparative HPLC, were applied to the monitoring of plasma dexamethasone (DXM) levels during standard dexamethasone suppression test (DST) in psychiatric patients. Due to the robotic ease of the fully automated HPLC process, precision of the chromatographic assay was equivalent to that of the direct assays, but prepurification improved both sensitivity and specificity. These improvements allowed the elucidation of the following features: (1) half (36) of the patients (68) displayed infranormal DXM levels (less than or equal to 0.40 ng/ml) whatever the cortisol response; (2) 22% (15) patients (68) with DXM levels in the low control range showed a strong inhibition of cortisol suppression. These observations raise some doubts on the validity of the DST test and introduce the following questions. (1) What is the dependence of cortisol suppression upon DXM absorption and catabolism? (2) Does plasma DXM measurement several hours after its physiological action still reflect its effect on the hypothalamo-hypophyseal axis? (3) What is the reliability of DXM direct assays when measuring low DXM levels in the presence of high cortisol?

Triiodothyronine, thyroxine, and TSH response to dexamethasone in depressed patients and normal controls

In view of recent investigations concerning alterations of thyroid function in depression, the pre- and postdexamethasone levels of T3, T4, and TSH of 14 patients during depression and after recovery were studied, in addition to those of 27 healthy controls. A reduction of T3 and TSH levels was shown to be dependent on the depressive state, with a tendency to lower T4 levels after recovery. Dexamethasone had a pronounced suppressive effect on TSH levels in healthy controls and in patients after recovery, but not during the depressive episode. These results point to an inadequate suppressibility of the hypothalamo-pituitary-thyroid (HPT) axis to dexamethasone during depression. There are close interrelations between the hypothalamo-pituitary-adrenal (HPA) and the HPT axes that are possibly affected during depressive illness.

Gonadal steroid and gonadotropin response to dexamethasone: a study in sexual dysfunction and normal controls

Numerous investigations have reported an alteration of hormonal response to dexamethasone in depressive disorder. No such data are available in psychogenic sexual dysfunction. Pre- and postdexamethasone levels of testosterone, estradiol, LH and FSH were studied in 20 male patients with sexual dysfunction and 20 male healthy controls. Dexamethasone had no influence on testosterone, estradiol, LH and FSH in normal controls. The patients showed an increase in testosterone and LH but not in FSH levels in the morning after dexamethasone administration. When compared with basal levels, the increase in postdexamethasone levels in sexual dysfunction was significant for testosterone (delta T) but not for LH (delta LH). The altered gonadal steroid and gonadotropin response to dexamethasone in sexual dysfunction might be due to disturbances of dexamethasone metabolism and glucocorticoid receptor density comparable to similar findings in depressive disorder.

Judgement of the hypothalamic-pituitary-adrenocortical function in psychiatric patients by betamethasone-induced cortisol suppressibility

Betamethasone induced cortisol suppressibility was examined in 62 drug free consecutively admitted psychiatric inpatients. Betamethasone was choosen instead of the commonly used dexamethasone, because its double half-life compared to dexamethasone and its higher tissue availability. After a base-line evaluation with blood samples drawn at 8 a.m., 4 p.m., and 11 p.m., 0.5 mg or 1.0 mg betamethasone was given orally at 11 p.m. Postbetamethasone cortisol as well as betamethasone blood levels were then measured at the same time points as on the baseline day. In the groups receiving 1.0 mg betamethasone non-depressed patients had significantly (p less than 0.05) lower postbetamethasone cortisol levels than depressed patients for each time point measured whereas 0.5 mg betamethasone did not differentiate depressed from non-depressed patients. Patients with other depressions like schizoaffective psychosis-depressive subtype- or organic brain syndrome with depressive symptomatology demonstrated similar postbetamethasone cortisol profiles as the group of patients with major depression. Betamethasone plasma concentrations differed significantly (p less than 0.001) with respect to the oral dosage with higher values for the 1.0 mg betamethasone groups.

Cortisol suppression per nanogram per milliliter of plasma dexamethasone in depressive and normal subjects

It has been suggested that dexamethasone pharmacokinetics may affect cortisol suppression during the Dexamethasone Suppression Test (DST). In depressed patients the cortisol response has been shown to negatively correlate with dexamethasone plasma concentrations, which also influence the sensitivity and specificity of the DST. These findings have been interpreted as weakening the utility of the DST. However, the analysis of pre- and post-1 mg DST cortisol concentrations corrected for plasma dexamethasone concentrations suggest that compared with normals (n = 52), patients with major depressive disorder (MDD) as a group (n = 71) had less suppressibility of cortisol to the same plasma dexamethasone concentrations. Moreover, when the MDD patients were evaluated based on DST status, the suppressors had cortisol/dexamethasone ratios (micrograms/dl of cortisol per ng/ml of plasma dexamethasone) similar to the normal controls, whereas the nonsuppressors had ratios that were significantly higher. These data suggest that DST non-suppression, as well as sensitivity and specificity of the DST in depression, is not only attributable to altered dexamethasone disposition, but indeed, there is a genuine reduced sensitivity of cortisol to dexamethasone that still points to an abnormality of the delayed feedback mechanism of the hypothalamic-pituitary-adrenal system in some depressed patients.

Past and present strategies of research on the HPA-axis in psychiatry

Hypercortisolism in depression has been extensively studied during the last three decades. The main hypothesis regarding origin and clinical relevance of this phenomenon, however, has changed significantly. Up to the mid-seventies hypercortisolism was conceived as consequence of stress modified by the degree of unconscious defense mechanisms in different forms of depressive or non-depressive psychiatric disorders. At the end of the seventies this point of view changed considerably. Hypercortisolism was regarded as a biological statemarker of the endogenous subtype of depression with clinical differential-diagnostic relevance. An abnormal dexamethasone suppression test (DST) was assumed to be the best indication of increased activation of the cortisol system. These conclusions turned out to be wrong. DST results are not specific for melancholia and the test seems to be of limited value for measuring the function of the HPA-axis. Intervening variables, such as weight loss, drug and alcohol withdrawal or situational stress, influence the test results significantly, independent of the nosological classification. Additionally, interindividual differences in the susceptibility of the HPA-axis may decisively influence the the activation of the HPA-axis as well in healthy subjects under stress as in psychiatric patients.

Plasma dexamethasone and the dexamethasone suppression test. Initial and follow-up tests in depressed patients

Plasma dexamethasone concentrations following oral dexamethasone administration were examined in 78 patients with major depression prior to and during treatment. The test-retest stability of plasma dexamethasone levels within patients was satisfactory with an overall significant positive correlation between tests for each patient. However, significant variability was noted in individual patients. Change in pre-DST cortisol and plasma dexamethasone levels were the two variables, in that order of importance, contributing to change in DST status. In studies examining the clinical utility of serial dexamethasone suppression tests as a guide to recovery from depression, the effect of variability in plasma dexamethasone concentrations should be taken into account.

Serum dexamethasone concentrations in endogenous depressives before, during, and after treatment: preliminary observations

The 1.0-mg Dexamethasone (DEX) Suppression Test (DST) was performed in 10 endogenous depressives prior to treatment, during treatment, and again when the patients were medication- and symptom-free. Five of the 10 patients were DST escapers prior to treatment, and all 10 patients were DST suppressors following treatment. During treatment, 6 patients were DST escapers, 2 of them having been suppressors initially. There were no significant differences in serum DEX concentrations before, during, and after treatment in either the 5 DST escapers or the 5 DST suppressors. These results lend further support to the concept that reduced serum DEX concentrations are not the major factor underlying DST nonsuppression.

The dexamethasone suppression test and plasma dexamethasone in generalized anxiety disorder

A Dexamethasone Suppression Test nonsuppression rate of 27% was found in a group of 30 generalized anxiety disorder patients before treatment. The dexamethasone concentrations in the eight nonsuppressors were significantly lower than in eight suppressors matched by sex and age, but were similar to those in five nonsuppressors from a matched normal control group. The dexamethasone concentrations in the generalized anxiety disorder suppressors and a matched group of eight normal control suppressors were similar. After successful nondrug behavioral treatment, all generalized anxiety disorder patients were suppressors. Posttreatment dexamethasone concentrations in the initial nonsuppressor patients remained significantly lower than in the initial suppressors. The results suggest that low plasma dexamethasone concentrations after 1 mg oral dexamethasone may confer a vulnerability to nonsuppression that may be expressed in the presence of high state anxiety.

Plasma dexamethasone kinetics during the DST after oral and intravenous administration of the test drug

We compared early biophase kinetics of dexamethasone in 33 patients with a major depression who received a DST either by an oral (n = 20) or an intravenous (n = 13) route. After an oral DST, the dexamethasone kinetics between 14 suppressors and 6 nonsuppressors were indistinguishable during the early distribution phase. However, elimination of dexamethasone from the circulation was significantly enhanced in DST nonsuppressors, resulting in an association of decreased plasma dexamethasone with elevated post-DST cortisol levels. Following intravenous DST administration, we identified 5 nonsuppressors and 8 suppressors whose plasma dexamethasone kinetics were indistinguishable, and during the elimination phase, were in the same order of magnitude as those of nonsuppressors after an oral DST. We suggest that the actual plasma concentration at the conventional post-DST sampling times does not reflect the biopotency of the test drug to suppress the pituitary adrenocortical activity. Plasma dexamethasone concentrations after an oral DST that were associated with nonsuppressed cortisol seem to be coherent phenomena of the underlying endocrine disturbance, the precise nature of which deserves further study.

The dexamethasone suppression test: importance of dexamethasone concentrations

Plasma dexamethasone concentrations and cortisol response to dexamethasone were measured in 29 normal healthy volunteers, 23 depressed patients, and 10 patients with anorexia nervosa at 4:00 PM postdexamethasone. In each of the 3 groups, nonsuppressors had lower dexamethasone concentrations than suppressors. Of the subjects with plasma dexamethasone at or below 0.7 ng/ml, a significantly higher proportion (48%) were nonsuppressors compared to the proportion above 0.7 ng/ml (14%), all of whom were patients. Plasma dexamethasone concentrations in a subgroup of depressed nonsuppressors were high (mean 1.35 ng/ml), whereas the remainder were low (0.42 ng/ml) and were similar to the normal nonsuppressors (0.35 ng/ml), suggesting different mechanisms for nonsuppression in the subgroups. Plasma dexamethasone concentrations were similar in nonendogenous and endogenous depressives, in men and women, and in medicated and drug-free patients. None of the variables of age, weight, history of weight loss, Hamilton depression rating score, predexamethasone cortisol, or postdexamethasone cortisol were significantly correlated with plasma dexamethasone, except for body weight and a history of weight loss in the depressed group only. Mean plasma dexamethasone concentrations increased significantly from week 1 to week 2 in 7 depressed patients, whereas plasma cortisol decreased; however, the relationship between dexamethasone and cortisol varied considerably for individual patients.

Prolactin response to dexamethasone: a study on normal controls and depressed patients

Pre- and post-dexamethasone prolactin and cortisol levels of 40 endogenous and non-endogenous depressive patients and of 20 controls were studied. Dexamethasone had a suppressive effect on prolactin levels, which was expressed more in normal controls and in non-endogenous depressive patients than in endogenous depression. A "prolactin suppression test" by dexamethasone was constructed and provided comparable results to the usual DST. However, it failed to be a specific marker for endogenous depression. There are close relationships between various endocrine axes, which might be altered in depression.

Therapeutic drug monitoring of amitriptyline: impact of age, smoking and contraceptives on drug and metabolite levels in bulimic women

Concentrations of amitriptyline (AT), nortriptyline (NT) and E-10-hydroxynortriptyline (E-10-OH-NT) were measured in 18 women with bulimia receiving 100 mg AT/day for at least 6 wk. After onset of treatment between days 36 and 57 there is a decrease in AT and an increase in E-10-OH-NT concentrations, probably due to an autoinductive effect on hydroxylation. The estimated mean (+/- SD; range; n) elimination half-life time of AT was 14.0 (+/- 7.8 h; 7.5-38.5 h; 14). On day 36, AT concentrations in females using oral contraceptives (OC) were higher than in non-users of OC, which indicates inhibition of AT metabolism by OC. In all smokers the E-10-OH-NT concentrations on day 36 were lower than in non-smokers. Our findings suggest induction of N-demethylation and glucuronidation by smoke components.

Dexamethasone suppression test in severe schizophrenic illness: effects of plasma dexamethasone and caffeine levels

A dexamethasone suppression test (DST) was administered to 31 inpatients with a severe acute schizophrenic exacerbation 4 or 5 days following admission and repeated after 4 weeks or prior to discharge. We identified 15 patients (48%) who were nonsuppressors on the DST at the first test. To exclude major confounders of DST results we monitored weight constancy and plasma concentrations of dexamethasone. In a subgroup of patients also plasma caffeine contents were determined. Our results indicate that DST nonsuppression occurs frequently among patients with schizophrenic crisis. Since caffeine plasma levels were indistinguishable between suppressors and nonsuppressors we reject that excessive caffeine intake accounts for DST nonsuppression among individuals with schizophrenia. Nonsuppressors had lower plasma dexamethasone levels than suppressors and reversal of the DST status from nonsuppression to suppression was associated with an increase of plasma concentrations of the test drug.

Dexamethasone bioavailability: implications for DST research

The bioavailability of dexamethasone (DEX) has recently been demonstrated to be a critical factor in determining Dexamethasone Suppression Test (DST) status in psychiatric patients. This brief review focuses on several aspects of DEX bioavailability as they relate to the use of the DST in neuroendocrine research. Several methodologies, including radioimmunoassay, high-performance liquid chromatography, and gas chromatography-mass spectrometry are available for quantification of DEX in biological fluids, although few detailed comparisons between methods have been reported. Surprisingly, little systematic research on the metabolism of DEX has been reported, but it appears that hepatic rather than renal mechanisms are the major source of DEX elimination. The marked variability in serum DEX levels following oral administration in psychiatric patients is also observed in normal controls and patients with Cushing's syndrome. A variety of drugs can modify serum DEX levels and thereby after the effectiveness of DEX in suppressing serum cortisol levels. Simultaneous measurement of serum DEX and cortisol levels appears to be necessary for the appropriate evaluation of DST results. This procedure may help explain many of the inconsistencies in recent DST research.

Multisteroid analysis after DST in depressed patients--a controlled study

111 consecutively admitted in-patients with a depressive syndrome received a dexamethasone suppression test (DST) after all known factors which might confound the test results had been carefully excluded. Plasma concentrations of cortisol, corticosterone and dexamethasone were compared with several diagnostic evaluations (RDC, DSM-III, ICD-9) in a controlled study. The positive predictive value of nonsuppressed corticosteroid levels was only moderate for each diagnostic category. Diagnostic specificities were 84.6% for major depression, endogenous subtype (RDC), 71.2% for melancholia (DSM-III) and 86.8% for endogenous depression (IDC-9) when using a post-DST cortisol value above 50 ng/ml (5 micrograms/dl) as the referent value to define DST nonsuppression. Combined determination of cortisol and corticosterone as an index of dexamethasone-induced suppression raised the sensitivity rate considerably at the cost of the predictive value for major diagnostic categories. Dexamethasone plasma levels were reciprocally correlated with cortisol levels and neglect of samples with low plasma dexamethasone contents improved the diagnostic performance for endogenous depression according to RDC and ICD-9, but not for DSM-III melancholia. Although it would be speculative to suppose that the observed low dexamethasone levels are involved in DST nonsuppression, the present findings emphasize that multisteroid analysis which includes dexamethasone is important in future studies designed to explore the clinical utility of the DST.

Psychopathological correlates of plasma cortisol after dexamethasone suppression: a polydiagnostic approach

Seventy-seven consecutively admitted inpatients with depressive syndromes were examined with the Present State Examination and classified according to eight different operational diagnoses of endogenous depression. All patients received a 1.5 mg dexamethasone suppression test (DST). Sensitivity, specificity and the corrected predictive values of DST nonsuppression (50 or more ng/ml at 0800 hr, 1600 hr, or 2300 hr), adjusted to a 50% prevalence of endogenous and nonendogenous depression, varied considerably depending on the diagnostic definition used. The highest predictive value (89.9%) was found with the Taylor-Abrams criteria (sensitivity = 43.9%, specificity = 95.0%), and the lowest predictive value (53.3%) with DSM-III (sensitivity = 37.7%, specificity = 68.1%). Eliminating the patients with dexamethasone levels of less than 2000 pg/ml improved the diagnostic specificity of the DST for most of the eight definitions of endogenous depression. This further indicates that plasma dexamethasone levels should be analyzed in studies designed to explore the diagnostic utility of the DST. A significant, chance-corrected association between DST nonsuppression and the diagnosis of endogenous depression was found with clinical diagnosis (according to the International Classification of Diseases), and for four out of eight operational diagnoses (Newcastle Scale I, Newcastle Scale II, Taylor-Abrams Criteria, and Vienna Research Criteria). For the other diagnoses (Research Diagnostic Criteria, DSM-III, Michigan Discriminant Index, and Hamilton Endogenomorphy Index), no significant association was found. The RDC criterion "early or intermittent awakening" was the only one out of 28 diagnostic criteria tested which was significantly associated with DST nonsuppression.