Effect of age on the cortisol response to human corticotropin-releasing hormone in depressed patients pretreated with dexamethasone

Precision Psychiatry Approach to Treat Depression and Anxiety Targeting the Stress Hormone System - V1b-antagonists as a Case in Point

The future of depression pharmacotherapy lies in a precision medicine approach that recognizes that depression is a disease where different causalities drive symptoms. That approach calls for a departure from current diagnostic categories, which are broad enough to allow adherence to the "one-size-fits-all" paradigm, which is complementary to the routine use of "broad-spectrum" mono-amine antidepressants. Similar to oncology, narrowing the overinclusive diagnostic window by implementing laboratory tests, which guide specifically targeted treatments, will be a major step forward in overcoming the present drug discovery crisis.A substantial subgroup of patients presents with signs and symptoms of hypothalamic-pituitary-adrenocortical (HPA) overactivity. Therefore, this stress hormone system was considered to offer worthwhile targets. Some promising results emerged, but in sum, the results achieved by targeting corticosteroid receptors were mixed.More specific are non-peptidergic drugs that block stress-responsive neuropeptides, corticotropin-releasing hormone (CRH), and arginine vasopressin (AVP) in the brain by antagonizing their cognate CRHR1-and V1b-receptors. If a patient's depressive symptomatology is driven by overactive V1b-signaling then a V1b-receptor antagonist should be first-line treatment. To identify the patient having this V1b-receptor overactivity, a neuroendocrine test, the so-called dex/CRH-test, was developed, which indicates central AVP release but is too complicated to be routinely used. Therefore, this test was transformed into a gene-based "near-patient" test that allows immediate identification if a depressed patient's symptomatology is driven by overactive V1b-receptor signaling. We believe that this precision medicine approach will be the next major innovation in the pharmacotherapy of depression.

Blood mRNA expression levels of glucocorticoid receptors and FKBP5 are associated with depressive disorder and altered HPA axis

BACKGROUND

While depression has been associated with alterations in the hypothalamic-pituitary adrenal (HPA) axis function, there is still controversy regarding the nature and extent of the dysfunction, such as in the debate about hypercortisolism vs. hypocortisolism. It may therefore be necessary to understand whether and how HPA axis function in depression is linked to mRNA expression of key genes regulating this system.

METHODS

We studied 163 depressed outpatients, most of whom were chronically ill, and 181 healthy controls. Blood mRNA expression levels of NR3C1 (including GRα, GRβ, and GR-P isoforms), FKBP4, and FKBP5 were measured at baseline. HPA axis feedback sensitivity was measured by the dexamethasone (Dex)/corticotropin-releasing hormone (CRH) test. The association between mRNA expression levels and HPA axis feedback sensitivity was examined.

RESULTS

Compared to controls, patients showed significantly higher expression of GRα and lower expression of FKBP5, and higher post-Dex cortisol levels, even after controlling for age and sex. FKBP5 expression was significantly positively correlated with cortisol levels in patients, while GRα expression was significantly negatively correlated with cortisol levels in controls.

LIMITATIONS

Most patients were taking psychotropic medications. The large number of correlation tests may have caused type I errors.

CONCLUSIONS

The tripartite relationship between depression, mRNA expression of GR and FKBP5, and HPA axis function suggests that the altered gene expression affects HPA axis dysregulation and, as a result, impacts the development and/or illness course of depressive disorder. The combination of increased GRα expression and decreased FKBP5 expression may serve as a biomarker for chronic depression.

The Cortisol and ACTH Response to Dex/CRH Testing in Women With and Without Perimenopausal Depression

CONTEXT

Abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis are frequent accompaniments of depression, and studies have documented the role of stress and stressful life events in the ontogeny of perimenopausal depressions (PMD). Because HPA axis function in women is further modulated both by aging and ovarian steroids, it is possible that a dysregulated HPA axis contributes to the increased risk of PMD.

OBJECTIVE

We examined HPA axis function in perimenopausal women with and without depression using the combined dexamethasone-corticotropin-releasing hormone (Dex/CRH) test.

METHODS

Dex/CRH tests were performed on 20 women with PMD and 20 women who were also perimenopausal but without current or past depression (control women). Main outcome measures were plasma levels of cortisol and adrenocorticotropin (ACTH) and 24-hour urinary free cortisol (UFC). Five women took chronic stable medications, otherwise all women were medically healthy, and both groups were comparable with respect to reproductive stage and age. Standardized symptom rating scales were administered to each woman prior to Dex/CRH testing.

RESULTS

No group differences were present in either baseline or stimulated ACTH and cortisol secretion. Baseline plasma measures of estradiol, progesterone, and 24-hour UFC levels similarly did not differ in PMD and control women.

CONCLUSION

Despite reports of increased stress responsiveness in PMD, we observed no abnormalities of HPA axis activity associated with PMD compared with women without depression. These findings suggest that PMD is not uniformly associated with HPA dysregulation and could reflect underlying pathophysiologic processes that are distinct from women with nonreproductive-related depressions.

Are depression and denutrition good predictors of dexamethasone suppression test (DST) in anorexia nervosa?

This study was conducted to investigate the corticotropic axis in anorexia nervosa. In 93 female inpatients who met DSM-III-R criteria for anorexia nervosa, subsample (n = 64) with DSM-III criteria was also considered. Using stepwise regression analysis, this study examined the relationship between independent variables ie, age, body mass index, scores on depression scales and postdexamethasone serum cortisol, considered as a dependent variable. In patients who met DSM-III criteria, 16.7% of the variance of serum cortisol can be explained. The main predictors are depressive retardation, emaciation and age. Using stepwise logistic regression the main categorical predictors of the test suppression vs non suppression are of the same nature. The condition of realisation of DST are discussed.

Effect of Stress, Depression and Type D Personality on Immune System in the Incidence of Coronary Artery Disease

BACKGROUND:

Psychoneuroimmunology (PNI) is the study of the interaction between psychological processes and the nervous and immune systems of the human body. The impact of psychological factors on the immune system and the role of this system in Coronary Artery Disease (CAD) are confirmed. Coronary Heart Disease (CHD) is arisen due to the failure of blood and oxygen to the heart tissues.

AIM:

The present study aimed to describe psychoneuroimmunological processes which contribute to CAD and CHD progression.

METHOD:

Such psychological risk factors like stress, depression and type D personality were investigated here. Psychoneuroimmunological pathways of all three mentioned risk factors were described for CAD.

RESULTS:

The studies review indicated that stress could be accompanied with myocardial ischemia and help to rupture. The depression involves in the transfer of stable atherosclerotic plaque to unstable, and type D personality is effective in the initial stages of a CAD.

CONCLUSION:

As more information on cardiovascular immunity becomes available, this will provide a better understanding and thus act as the foundation for the potential development of new treatment strategies for treatment of cardiovascular disorders.

How to measure glucocorticoid receptor's sensitivity in patients with stress-related psychiatric disorders

Stress is a state of derailed homeostasis and a main environmental risk factor for psychiatric diseases. Chronic or uncontrollable stress may lead to a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which is a common feature of stress-related psychiatric disorders. One of the key mechanisms underlying a disturbed HPA axis is an impaired function of the glucocorticoid receptor (GR) with an enhanced or reduced feedback sensitivity for glucocorticoids and subsequently altered concentrations of peripheral cortisol. GR function is regulated by a multiprotein complex including the different expression of the hsp90 co-chaperone FK 506 binding protein 51 (FKBP5) that may be genetically determined or acquired in response to stressful stimuli. Specific patterns of a dysregulation of the HPA axis and GR function are found in different stress-related psychiatric entities e.g. major depression, job-related exhaustion or posttraumatic stress disorder. GR challenge tests like the dexamethasone-suppression test (DST), the dexamethasone-corticotropin-releasing hormone (dex-CRH) test or most recently the analysis of the dexamethasone-induced gene expression are employed to sensitively measure HPA axis activity in these disorders. They provide information for a stratification of phenotypic similar but neurobiological diverse psychiatric disorders. In this review we present a synopsis of GR challenge tests with a focus on the application of the DST, the CRH test and the dex-CRH test as well as the dexamethasone-induced gene expression in stress-related psychiatric entities.

Sex-related differential response to dexamethasone in endocrine and immune measures in depressed in-patients and healthy controls

Although sex differences in major depression have been reported repeatedly, the underlying mechanisms are still disputed. The rapidly changing gonadal steroid concentrations of the postpartum period or during menopause have been shown to be associated with depressive symptoms and to modulate the hypothalamic-pituitary-adrenal (HPA)-axis, which is implicated in depression. The sample comprised of 128 depressed in-patients (36.7% women) and 166 healthy controls (30.0% women). Blood was collected at baseline (at 6pm) and then 3 h as well as 21 h after ingestion of 1.5 mg dexamethasone for measurement of cortisol, ACTH and blood count. To further assess the function of the HPA-axis the dexamethasone/corticotrophin releasing hormone (Dex-CRH) test was performed in a subsample of 115 patients and 116 controls the following day. A significant interaction effect between sex, disease and ACTH concentrations over time after dexamethasone stimulation was observed, with men showing increased ACTH concentrations at baseline and after 21 h, while there was no difference after 3 h (p = .007). After separating for disease status this significant interaction effect was only observed in controls (p = .005). The cortisol response in the dex-CRH test was enhanced in female compared to male controls (p = .002). Leucocytes showed a stronger increase upon dexamethasone administration only in female compared to male controls (p = .023). These findings suggest a higher glucocorticoid receptor sensitivity following in-vivo glucocorticoid stimulation in healthy women that was absent in depressed patients. The sex-related differences in HPA-axis regulation and immune system function may contribute to the vulnerability of female sex to the development of depression.

Stress-Related Immune Markers in Depression: Implications for Treatment

Major depression is a serious psychiatric disorder; however, the precise biological basis of depression still remains elusive. A large body of evidence implicates a dysregulated endocrine and inflammatory response system in the pathogenesis of depression. Despite this, given the heterogeneity of depression, not all depressed patients exhibit dysregulation of the inflammatory and endocrine systems. Evidence suggests that inflammation is associated with depression in certain subgroups of patients and that those who have experienced stressful life events such as childhood trauma or bereavement may be at greater risk of developing depression. Consequently, prolonged exposure to stress is thought to be a key trigger for the onset of a depressive episode. This review assesses the relationship between stress and the immune system, with a particular interest in the mechanisms by which stress impacts immune function, and how altered immune functioning, in turn, may lead to a feed forward cascade of multiple systems dysregulation and the subsequent manifestation of depressive symptomology. The identification of stress-related immune markers and potential avenues for advances in therapeutic intervention is vital. Changes in specific biological markers may be used to characterize or differentiate depressive subtypes or specific symptoms and may predict treatment response, in turn facilitating a more effective, targeted, and fast-acting approach to treatment.

Early-life stress and HPA axis trigger recurrent adulthood depression

It is now broadly accepted that psychological stress may change the internal homeostatic state of an individual. During acute stress, adaptive physiological responses occur, which include hyperactivity of the HPA axis. Whenever there is an acute interruption of this balance, illness may result. The social and physical environments have an enormous impact on our physiology and behavior, and they influence the process of adaptation or 'allostasis'. It is correct to state that at the same time that our experiences change our brain and thoughts, namely, changing our mind, we are changing our neurobiology. Increased adrenocortical secretion of hormones, primarily cortisol in major depression, is one of the most consistent findings in neuropsychiatry. A significant percentage of patients with major depression have been shown to exhibit increased concentrations of cortisol, an exaggerated cortisol response to adrenocorticotropic hormone, and an enlargement of both the pituitary and adrenal glands. The maintenance of the internal homeostatic state of an individual is proposed to be based on the ability of circulating glucocorticoids to exert negative feedback on the secretion of hypothalamic-pituitary-adrenal (HPA) hormones through binding to mineralocorticoid (MR) and glucocorticoid (GR) receptors limiting the vulnerability to diseases related to psychological stress in genetically predisposed individuals. The HPA axis response to stress can be thought of as a mirror of the organism's response to stress: acute responses are generally adaptive, but excessive or prolonged responses can lead to deleterious effects. Evidence indicates that early-life stress can induce persistent changes in the ability of the HPA axis to respond to stress in adulthood. These abnormalities appear to be related to changes in the ability of hormones to bind to GR and MR receptors. First episodes may begin with an environmental stressor, but if the cycles continue or occur unchecked, the brain becomes kindled or sensitized, and future episodes of depression, hypomania, or mania will occur independently of an outside stimulus, with greater frequency and intensity. Generally, HPA axis changes appear in chronic depressive and more severe episodes. Moreover, HPA axis changes appear to be state-dependent, tending to improve upon resolution of the depressive syndrome. Interestingly, persistent HPA dysfunction has been associated with higher rates of relapse and chronicity.

Psychological coping in depressed outpatients: association with cortisol response to the combined dexamethasone/CRH test

BACKGROUND

Depression is associated with dysfunctional coping styles and dysregulated hypothalamic-pituitary-adrenal (HPA) axis function. Studies have shown that maladaptive coping strategies relate to abnormal HPA axis function; however, such a relationship has been under-studied in patients with depression. We aimed to examine whether dysfunctional coping styles in depression would be associated with abnormal cortisol reactivity.

METHODS

Seventy-four outpatients with major depressive disorder and 133 age- and sex-matched healthy individuals were recruited. Coping was assessed by the Ways of Coping Checklist. Psychological distress was assessed by the Hopkins Symptom Checklist. Cortisol reactivity was measured by the combined dexamethasone/corticotropin-releasing hormone test.

RESULTS

Compared to healthy individuals, depressed patients demonstrated significantly less use of problem-solving, positive reappraisal and social support coping styles and more use of self-blame and wishful thinking styles. Such a pattern of coping styles was significantly associated with patients' greater distress. Partial correlation analysis in patients, controlling for age and sex, revealed a significant correlation between more use of escape-avoidance coping and lower levels of reactive cortisol measures. A stepwise multiple regression analysis predicting cortisol reactivity from age, sex, distress, symptom severity and coping styles revealed that escape-avoidance coping was a significant predictor.

LIMITATIONS

The neuroendocrine challenge test was administered only once, based on a simple test protocol.

CONCLUSIONS

More use of escape-avoidance coping in depressed patients was associated with less cortisol reactivity. Our findings shed light on the heterogeneity of depression in terms of low and high levels of avoidance associated with exaggerated and blunted HPA axis reactivity, respectively.

Early Life Stress in Depressive Patients: HPA Axis Response to GR and MR Agonist

BACKGROUND

Evidence indicates that early life stress (ELS) can induce persistent changes in the hypothalamic-pituitary-adrenal (HPA) axis to respond to stress in the adult life that leads to depression. These appear to be related to the impairment of HPA hormones through binding to glucocorticoid (GR) and mineralocorticoid receptors (MR). The aim of this study was to evaluate the impact of ELS in HPA axis response to challenges with GR and MR agonists in depressed patients.

METHODS

We included 30 subjects, 20 patients with current major depression (HAM-D21 ≥ 17). Patients were recruited into two groups according to ELS history assessed by the Childhood Trauma Questionnaire (CTQ). The cortisol measures in the saliva and plasma were evaluated after using (at 10:00 p.m.) placebo, fludrocortisone (MR agonist), or dexamethasone (GR agonist).

RESULTS

Depressed patients showed a significantly lower salivary cortisol upon waking after placebo compared with controls. Moreover, cortisol awakening responses (CAR) after MR agonist were found to be lower in depressed patients than in controls. With CTQ scores, HAM-D21, body mass index and CAR after placebo, GR agonist, MR agonist we found in a Linear Regression model that depressive patients with ELS (p = 0.028) show differences between placebo vs. MR agonist (R = 0.51; p < 0.05) but not after GR agonist; in depressive patients, without ELS the data show differences between placebo vs. MR agonist (R = 0.69; p < 0.05); but now as well placebo vs. GR agonist (R = 0.53; p < 0.05).

CONCLUSION

Our findings indicate that MR activity is impaired in depressed patients compared with controls. Furthermore, in spite of the previous limitations described, in depressed patients with ELS, there was suppression by MR agonist, indicating that patients with ELS are sensitive to MR agonists. In contrast with depressed patients without ELS, we find suppression after both MR and GR agonist. These data suggested that in ELS an imbalance exists between MR and GR with MR dysfunction.

Combined dexamethasone suppression-corticotrophin-releasing hormone stimulation test in medication-free major depression and healthy volunteers

BACKGROUND

The hypothalamic-pituitary-adrenal (HPA) axis is dysfunctional in a subgroup of mood disorders.

METHODS

We compared cortisol and adrenocorticotropic hormone (ACTH) responses in major depression and healthy volunteers to the combined dexamethasone suppression-corticotrophin-releasing hormone stimulation (DEX-CRH) test. Unlike other published studies, the study patients were medication-free and the healthy volunteers did not have first-degree relatives with a mood or psychotic disorder. Demographics, DSM-IV diagnoses and other clinical parameters were evaluated in major depressive disorder (MDD) and healthy control groups. Participants received an oral dose of 1.5mg dexamethasone at 11 pm the day before CRH administration. On the following day, at 3 pm, 100 µg of ovine CRH was infused. Blood samples for determination of cortisol and ACTH were collected every 15 min from 3 pm to 4:15 pm. Cortisol and ACTH responses were calculated as areas under the curve.

RESULTS

Controlling for age, baseline (i.e., post-dexamethasone) ACTH levels were higher in depressed patients compared to controls (p=0.01). There was a trend for higher ACTH responses in depressed patients compared to the control group (p=0.08). In depressed patients, cortisol and ACTH responses correlated positively with age, duration of illness and number of hospitalizations.

LIMITATIONS

Because of the cross-sectional study design we can only evaluate the nature of potential HPA axis disturbances that were present in patients when they are acutely depressed.

CONCLUSIONS

Feedback inhibition of ACTH secretion by cortisol is compromised in MDD, and this is independent of an age effect on the HPA axis function.

Age-dependent and gender-dependent regulation of hypothalamic-adrenocorticotropic-adrenal axis

Tightly regulated output of glucocorticoids is critical to maintaining immune competence, the structure of neurons, muscle, and bone, blood pressure, glucose homeostasis, work capacity, and vitality in the human and experimental animal. Age, sex steroids, gender, stress, body composition, and disease govern glucocorticoid availability through incompletely understood mechanisms. According to an ensemble concept of neuroendocrine regulation, successful stress adaptations require repeated incremental signaling adjustments among hypothalamic corticotropin-releasing hormone and arginine vasopressin, pituitary adrenocorticotropic hormone, and adrenal corticosteroids. Signals are transduced via (positive) feedforward and (negative) feedback effects. Age and gonadal steroids strongly modulate stress-adaptive glucocorticoid secretion by such interlinked pathways.

Assessment of the hypothalamic-pituitary-adrenal axis activity: glucocorticoid receptor and mineralocorticoid receptor function in depression with early life stress - a systematic review

OBJECTIVE

The mechanisms involved in the dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, especially in the functioning of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) in depressed patients, are not well elucidated. The objective of this study was to conduct a systematic review of articles that assess the HPA axis activity from GR and MR in depressed patients and healthy controls with or without early life stress.

METHODS

We conducted a systematic review of articles in PubMed, SCOPUS and SciELO published between 2000 and 2011, using the following search terms: child abuse, depression, HPA axis, dexamethasone, prednisolone, fludrocortisone and spironolactone. Thirty-four papers were selected for this review.

RESULTS

Most studies identified in this review used the dexamethasone/corticotropin-releasing hormone test and dexamethasone suppression test. In these studies, hypercortisolaemia was associated with depression. We identified three studies with the Prednisolone suppression test, only one study with the use of fludrocortisone and one with spironolactone. This review found nine studies that evaluated the HPA axis in individuals with early life stress.

CONCLUSIONS

The majority of the studies assessed in this review show that early life stress leads to permanent changes in the HPA axis and may lead to development of depression in adults. The most consistent findings in the literature show increased activity of the HPA axis in depression associated with hypercortisolaemia and reduced inhibitory feedback. These findings suggest that this dysregulation of the HPA axis is partially attributable to an imbalance between GR and MR. Evidences have consistently showed that GR function is impaired in major depression, but few studies have assessed the activity of MR in depression and early life stress.

Impact of citalopram on the HPA system. A study of the combined DEX/CRH test in 30 unipolar depressed patients

BACKGROUND

Dysregulation of the hypothalamic-pituitary-adrenocortical (HPA) system is one of the best replicated pathophysiological findings in depression. However, studies on the influence of treatment on the HPA system have partly yielded inconsistent results.

OBJECTIVE

To assess the effects of citalopram monotherapy on the HPA system of mainly drug naïve patients with major depression by means of the combined DEX/CRH test.

METHODS

The DEX/CRH test was conducted twice in 30 patients (25 drug naïve for the index episode) with major depression (single episode or unipolar recurrent; SCID I- and II-confirmed): directly before the start of a citalopram monotherapy (day 0) and four weeks thereafter (day 28).

RESULTS

Twenty-three patients responded (≥50% reduction in the HDRS(21)-score), and 17 of them also reached criteria of remission (HDRS ≤ 7). Baseline (dexamethasone-suppressed) and CRH-stimulated ACTH concentrations significantly decreased from day 0 to day 28. CRH-stimulated cortisol concentrations also fell, although not significantly, but baseline cortisol concentrations exhibited a significant increase from day 0 to day 28.

CONCLUSIONS

The blunting of the ACTH response in the DEX/CRH test under citalopram is in line with what has been observed in most studies with antidepressants. However, the partial rise in cortisol concentrations indicates an increase in the sensitivity of the adrenal cortex to ACTH. State-dependent alterations in the volume and the ACTH responsiveness of the adrenal gland have repeatedly been reported in depressed subjects, which indicates the possibility that SSRIs such as citalopram might exhibit a direct or indirect effect on the adrenal cortex.

The stress hormone system in various sleep disorders

Hypothalamic-pituitary-adrenal (HPA)-system activity is regulated by the suprachiasmatic nucleus, the primary endogenous circadian pacemaker. In addition, sleep plays an important modulatory role. However, data on HPA-system activity in sleep disorders are quite conflicting. A sensitive challenge test to assess negative feedback sensitivity of the HPA-system like the dexamethasone/corticotropin-releasing-hormone (DEX/CRH)-test has never been used so far in sleep disorders. Therefore we studied 25 obstructive sleep apnea (OSA) patients, 18 restless legs syndrome (RLS) patients, 21 patients with primary insomnia and compared them to 33 healthy controls. The dynamic response of the HPA-system was assessed by the DEX/CRH-test which combines suppression (dexamethasone) and stimulation (CRH) of the stress hormone system. After HPA-axis suppression the number of non-suppressors did not differ among groups indicating normal negative feedback sensitivity. In RLS patients ACTH levels were slightly lower compared to controls while cortisol levels were similar between groups. Following CRH stimulation we did not detect differences in ACTH- or cortisol levels and adrenocortical responsitivity to ACTH was comparable between groups. These results for the first time document normal HPA-system feedback sensitivity in various sleep disorders and suggest that abnormalities of the stress hormone system in affective disorders are unlikely due to concomitant sleep problems.

Poor sleep is associated with exaggerated cortisol response to the combined dexamethasone/CRH test in a non-clinical population

Although sleep disturbance has been shown to be associated with psychological distress and the hypothalamic-pituitary-adrenal (HPA) axis function, the simultaneous relationship between sleep, distress and HPA axis function is less clear. Here we examined the relationship between sleep quality as assessed with the Pittsburgh Sleep Quality Index, psychological distress as assessed with the Hopkins Symptom Checklist, and cortisol responses to the dexamethasone (DEX)/corticotropin-releasing hormone (CRH) test in 139 non-clinical volunteers. Poor sleep was significantly correlated with greater cortisol response to the combined DEX/CRH challenge, but not with the cortisol level just before CRH challenge. When subjects were divided into three groups based on the suppression pattern of cortisol (i.e., incomplete-, moderate-, and enhanced-suppressors), poor sleep was significantly associated with the incomplete suppression in women while no significant association was found between sleep and the enhanced suppression. The association between poor sleep and exaggerated cortisol response to the CRH challenge became more clear in the regression analysis where the confounding effect of psychological distress was taken into consideration. These results indicate that poor sleep would be associated with exaggerated cortisol reactivity. The observed association of poor sleep with reactive cortisol indices to the CRH challenge, but not with the cortisol level after DEX administration alone, might add to the well-established evidence demonstrating the role of CRH in the regulation of sleep. Our findings further suggest that the mediation model would work better than the bivariate approach in investigating the relationship between sleep, distress and HPA axis reactivity.

Dopamine and oxytocin interactions underlying behaviors: potential contributions to behavioral disorders

Dopamine is an important neuromodulator that exerts widespread effects on the central nervous system (CNS) function. Disruption in dopaminergic neurotransmission can have profound effects on mood and behavior and as such is known to be implicated in various neuropsychiatric behavioral disorders including autism and depression. The subsequent effects on other neurocircuitries due to dysregulated dopamine function have yet to be fully explored. Due to the marked social deficits observed in psychiatric patients, the neuropeptide, oxytocin is emerging as one particular neural substrate that may be influenced by the altered dopamine levels subserving neuropathologic-related behavioral diseases. Oxytocin has a substantial role in social attachment, affiliation and sexual behavior. More recently, it has emerged that disturbances in peripheral and central oxytocin levels have been detected in some patients with dopamine-dependent disorders. Thus, oxytocin is proposed to be a key neural substrate that interacts with central dopamine systems. In addition to psychosocial improvement, oxytocin has recently been implicated in mediating mesolimbic dopamine pathways during drug addiction and withdrawal. This bi-directional role of dopamine has also been implicated during some components of sexual behavior. This review will discuss evidence for the existence dopamine/oxytocin positive interaction in social behavioral paradigms and associated disorders such as sexual dysfunction, autism, addiction, anorexia/bulimia, and depression. Preliminary findings suggest that whilst further rigorous testing has to be conducted to establish a dopamine/oxytocin link in human disorders, animal models seem to indicate the existence of broad and integrated brain circuits where dopamine and oxytocin interactions at least in part mediate socio-affiliative behaviors. A profound disruption to these pathways is likely to underpin associated behavioral disorders. Central oxytocin pathways may serve as a potential therapeutic target to improve mood and socio-affiliative behaviors in patients with profound social deficits and/or drug addiction.

The role of FKBP5, a co-chaperone of the glucocorticoid receptor in the pathogenesis and therapy of affective and anxiety disorders

FK506 binding protein 51 or FKBP5 is a co-chaperone of hsp90 which regulates glucocorticoid receptor (GR) sensitivity. When it is bound to the receptor complex, cortisol binds with lower affinity and nuclear translocation of the receptor is less efficient. FKBP5 mRNA and protein expression are induced by GR activation via intronic hormone response elements and this provides an ultra-short feedback loop for GR-sensitivity. Polymorphisms in the gene encoding this co-chaperone have been shown to associate with differential upregulation of FKBP5 following GR activation and differences in GR sensitivity and stress hormone system regulation. Alleles associated with enhanced expression of FKBP5 following GR activation, lead to an increased GR resistance and decreased efficiency of the negative feedback of the stress hormone axis in healthy controls. This results in a prolongation of stress hormone system activation following exposure to stress. This dysregulated stress response might be a risk factor for stress-related psychiatric disorders. In fact, the same alleles are over-represented in individuals with major depression, bipolar disorder and post-traumatic stress disorder. In addition, they are also associated with faster response to antidepressant treatment. FKBP5 might thus be an interesting therapeutic target for the prevention and treatment of stress-related psychiatric disorders.

The combined dexamethasone/CRH Test (DEX/CRH test) and prediction of acute treatment response in major depression

Background

In this study the predictive value of the combined dexamethasone/CRH test (DEX/CRH test) for acute antidepressant response was investigated.

Methodology/Principal Findings

In 114 depressed inpatients suffering from unipolar or bipolar depression (sample 1) the DEX/CRH test was performed at admission and shortly before discharge. During their stay in the hospital patients received different antidepressant treatment regimens. At admission, the rate of nonsuppression (basal cortisol levels >75.3 nmol/l) was 24.6% and was not related to the later therapeutic response. Moreover, 45 out of 114 (39.5%) patients showed an enhancement of HPA axis function at discharge in spite of clinical improvement. In a second sample, 40 depressed patients were treated either with reboxetine or mirtazapine for 5 weeks. The DEX/CRH test was performed before, after 1 week, and after 5 weeks of pharmacotherapy. Attenuation of HPA axis activity after 1 week was associated with a more pronounced alleviation of depressive symptoms after 5-week mirtazapine treatment, whereas downregulation of HPA system activity after 5 weeks was related to clinical response to reboxetine. However, early improvement of HPA axis dysregulation was not necessarily followed by a beneficial treatment outcome.

Conclusions/Significance

Taken together, performance of a single DEX/CRH test does not predict the therapeutic response. The best predictor for response seems to be an early attenuation of HPA axis activity within 1 or 2 weeks. However, early improvement of HPA system dysfunction is not a sufficient condition for a favourable response. Since a substantial part of depressive patients display a persistence of HPA axis hyperactivity at discharge, downregulation of HPA system function is not a necessary condition for acute clinical improvement either. Our data underline the importance of HPA axis dysregulation for treatment outcome in major depression, although restoration of HPA system dysfunction seems to be neither a necessary nor a sufficient determinant for acute treatment response.

Use of the dexamethasone-corticotrophin releasing hormone test to assess hypothalamic-pituitary-adrenal axis function in rheumatoid arthritis

Objectives. Hypothalamic-Pituitary-Adrenal axis function may be abnormal in rheumatoid arthritis (RA). A pilot study in 7 patients suggested impaired glucocorticoid feedback in some patients after the dexamethasone-corticotrophin releasing hormone (CRH) test. This study aimed to investigate the dexamethasone-corticotrophin releasing factor test in a larger group of patients and relate the results to characteristics of the disease. Methods. Outpatients with active RA (>/=3 swollen and tender joints and C-reactive protein > 10 mg/L) took dexamethasone (1.5 mg) at 23:00 hour in the evening. Next day, baseline saliva and plasma samples were collected, CRH was infused at 11:00 hour, and 4 serial blood and saliva samples were collected. Plasma samples were stored at -80 degrees C and a radioimmunoassay performed for saliva and plasma cortisol. Results. All 20 participants showed normal dexamethasone suppression and mounted no response to the CRH challenge. In samples with measurable cortisol, there was a strong correlation between saliva and plasma values (r = 0.876, n = 26, P < .01). Conclusion. No abnormalities were found in the Dexamethasone-CRH test in RA patients in contrast to a previous pilot study. Salivary cortisol measurement may offer an alternative noninvasive technique to plasma cortisol in RA patients in future studies.

Aging attenuates glucocorticoid negative feedback in rat brain

Aging is thought to be a risk factor to develop vulnerability of the neuroendocrine system, including the hypothalamic-pituitary-adrenal (HPA) axis, and dysregulation of this axis characterized by dexamethasone (DEX)-mediated negative feedback resistance is sometimes observed in elderly humans and animals. However, the influence of aging on the feedback system including an involvement of the brain is not fully understood. In the present study, we examined the suppressive effects of DEX by the systemic injection or the intracranial infusion into the prefrontal cortex (PFC), hippocampus, and hypothalamus on circulating corticosterone levels, and compared between young (3-month-old) and aged (24-month-old) rats. Moreover, we examined expression levels of glucocorticoid receptors (GRs) and their translocation from the cytoplasm to the nucleus using immunohistochemical and Western immunoblot techniques in the pituitary in addition to three brain regions. When DEX was injected systemically, the suppressive response was significantly enhanced in aged rats, compared with young rats. When DEX was infused into three brain regions, the suppressive response to DEX was abolished in aged rats. The immunohistochemical analysis revealed that the number of GR positive cells in the PFC, hippocampus, and hypothalamus was decreased, but that in the pituitary was increased, in aged rats, compared with young rats. The Western immunoblot analysis confirmed these results. Thus, basal expression levels of GRs in three brain regions were decreased, but those in the pituitary were increased, in aged rats. After the injection or infusion of DEX, the translocation of GRs in three brain regions was reduced, but that in the pituitary was enhanced, in aged rats. These results suggest that aging in rats enhances the feedback ability at the systemic level, which mainly involves the pituitary, but it attenuates the ability in the brain. These mechanisms may underlie the vulnerable neuroendocrine systems associated with aging.

Relationships of DEX/CRH and GHRH test results to the outcome of depression--preliminary results suggest the GHRH test may predict relapse after discharge

To explore and compare hypothalamic-pituitary-somatotropic (HPS) axis function and hypothalamic-pituitary-adrenocortical (HPA) axis function in depression, the dexamethasone (DEX)/CRH test and growth hormone releasing hormone (GHRH) test were prospectively performed on patients with depression at the time of admission and discharge. The patients who relapsed within six months after discharge exhibited significantly lower growth hormone (GH) responses to GHRH at the time of discharge than those who did not relapse. There were no significant correlations between GH response to GHRH and the results of DEX/CRH tests after controlling for age, sex, and body mass index. The findings of this study suggest that results of the GHRH test may be a predictor of future relapse in patients with depression.

Innovative approaches for the treatment of depression: targeting the HPA axis

Altered activity of the hypothalamic pituitary adrenal (HPA) axis is one of the most commonly observed neuroendocrine abnormalities in patients suffering from major depressive disorder (MDD). Altered cortisol secretion can be found in as many as 80% of depressed patients. This observation has led to intensive clinical and preclinical research aiming to better understand the molecular mechanisms which underlie the alteration of the HPA axis responsiveness in depressive illness. Dysfunctional glucocorticoid receptor (GR) mediated negative feedback regulation of cortisol levels and changes in arginine vasopressin (AVP)/vasopressin V1b receptor and corticotrophin-releasing factor/CRF1 receptor regulation of adrenocotricotrophin (ACTH) release have all been implicated in over-activity of the HPA axis. Agents that intervene with the mechanisms involved in (dys)regulation of cortisol synthesis and release are under investigation as possible therapeutic agents. The current status of some of these approaches is described in this review.

Intrahypothalamic neuroendocrine actions of corticotropin-releasing factor

Most studies of the neuroendocrine effects of corticotropin-releasing factor (CRF) have focused on its role in the regulation of the pituitary-adrenal axis; activation of this axis follows release of the peptide from CRF-containing terminals in the median eminence. However, a sizeable proportion of CRF fibres terminate within the hypothalamus itself, where synaptic contacts with other hypothalamic neuropeptidergic neurons (e.g. gonadotropin-releasing hormone-containing and opioidergic neurons) have been identified. Here, we summarize physiological and pharmacological data which provide insights into the nature and significance of these intrahypothalamic connections. It is now clear that CRF is a potent secretagogue of the three major endogenous opioid peptides (beta-endorphin, Met-enkephalin and dynorphin) and that it stimulates opioidergic neurons tonically. In the case of beta-endorphin, another hypothalamic peptide, arginine vasopressin, appears to be an essential mediator of CRF's effect, suggesting the occurrence of CRF synapses on, or in the vicinity of, vasopressin neurons; morphological support for this assumption is still wanting. Evidence for direct and indirect inhibitory effects of CRF on sexual behaviour and secretion of reproductive hormones is also presented; the indirect pathways include opioidergic neurons. An important conclusion from all these studies is that, in addition to its better known functions in producing adaptive responses during stressful situations, CRF might also contribute to the coordinated functioning of various components of the neuroendocrine system under basal conditions. Although feedback regulation of hypothalamic neuronal activity by peripheral steroids is a well-established tenet of endocrinology, data on modulation of the intrahypothalamic actions of CRF by adrenal and sex steroids are just emerging. Some of these newer findings may be useful in framing questions related to the mechanisms underlying disease states (such as depressive illness) in which CRF has been strongly implicated.

Combined dexamethasone/corticotropin releasing hormone test predicts treatment response in major depression - a potential biomarker?

BACKGROUND

Exaggerated corticotropin (ACTH) and cortisol response to the combined dexamethasone (DEX)/corticotropin releasing hormone (CRH) test, indicating impaired regulation of the hypothalamus-pituitary-adrenocortical (HPA) system, is frequently observed in depression. In the present study, we examined whether change in HPA system function during the first weeks of hospitalization predicts response to antidepressant treatment in major depression and thus constitutes a potential biomarker.

METHODS

We conducted the DEX/CRH test in 50 inpatients suffering from severe major depression, once after study inclusion and a second time 2 to 3 weeks later while under continuous antidepressant treatment.

RESULTS

We found increased ACTH and cortisol responses to the first DEX/CRH test compared with healthy control subjects. In the second DEX/CRH test 2 to 3 weeks later, 36 of the 50 patients showed an attenuated cortisol response, while 14 patients did not display improvement or exhibited even aggravation of the altered HPA system function. Improved HPA system regulation in the second DEX/CRH test was associated with beneficial treatment response after 5 weeks and a higher remission rate at the end of hospitalization.

CONCLUSIONS

The results suggest that change in HPA system regulation assessed with repeated DEX/CRH tests is a potential biomarker that may predict clinical outcome at follow-up. There is consensus that the drug development process could be improved, once reliable biomarkers become available that help to allow a judgement regarding the efficacy of a novel drug candidate. The combined DEX/CRH test seems to be a promising candidate for such a biomarker.

Glucocorticoid receptor transgenic mice as models for depression

In the era of mutant mice generated as molecular in vivo models for complex pathogenetic and therapeutic aspects of particular human diseases, glucocorticoid receptor transgenic mice represent an interesting and promising tool. Animals carrying mutations of this receptor show alterations in the hypothalamic-pituitary-adrenal (HPA)-system, which are comparable to those observed in depressed patients. Furthermore, similarities that may model the human disease have been described on the behavioral and pharmacological level, which increase the impact of such mutants. In this review we summarize different approaches used to alter or eliminate glucocorticoid receptor expression and function, and discuss their relevance as models for depression.

[Depression and stress: is there an endophenotype?]

OBJECTIVE

To review the new findings about stress, hypothalamic-pituitary-adrenal axis and depression trying to explain a possible endophenotype prone to depression.

METHOD

Nonsystematic review of the literature based on the endophenotype hypothesis.

RESULTS

Depression is linked to hypercortisolemia in many patients, but not all patients present these hypothalamic-pituitary-adrenal axis dysfunction. The dexamethasone suppression test is not the most accurate test to measure the hypothalamic-pituitary-adrenal axis function, and its use in the first studies published probably jeopardized the results. Hypercortisolemia frequently occurs in patients with severe depression, melancholic, either psychotic or nonpsychotic type; it is linked to the presence of a polymorphism in the promoter of the serotonin transporter gene, with a history of childhood abuse or neglect, or other significant stressful experiences like the loss of a parent during childhood and temperament leading to alterations in the response to stress.

CONCLUSIONS

The alterations of the hypothalamic-pituitary-adrenal axis depend on many factors like severity and type of depression, genotype, history of exposure to stress, temperament, and probably resilience. All these factors together result in an endophenotype thought to be prone to depression.

Immune-endocrine host response to endotoxin in major depression

OBJECTIVE

An impaired hypothalamic-pituitary-adrenocortical (HPA) function is a well-established finding in major depression (MD), but it is still unclear how this dysfunction affects immune responses in this disorder.

METHOD

To further examine the relationship between immune and endocrine responses in MD, 0.4ng/kg body weight endotoxin [LPS] or 100mug hCRH were sequentially applied to 12 patients with MD and to 12 age- and gender-matched healthy controls after pre-treatment with 1.5mg dexamethasone (DEX). Immune (TNF-alpha, IL-6, rectal temperature) and endocrine (ACTH, cortisol) parameters were examined as area under the curve (AUC) levels.

RESULTS

After pre-treatment with DEX, LPS evoked an immune response in all participants of the study with most immune parameters significantly related to the endotoxin challenge. However, only a marked immune response resulted in an additional endocrine reaction. Subsequently, the quantitative extent of the endocrine reaction was related to the extent of the immune response after DEX/LPS challenge. Pre-LPS AUC levels of cortisol, ACTH and post-LPS levels of IL-6 as well as the post-CRH AUC levels of cortisol and ACTH were related to the depressive symptomatology as measured by the Beck depression inventory (BDI). In depressive patients who showed increased cortisol plasma levels before LPS, the later increase in IL-6 was reduced.

CONCLUSIONS

The challenge with DEX/LPS did not reveal major impairments of evoked immune functions in MD. Only the endocrine parameters and the IL-6 response were related to the depressive symptomatology, suggesting a limited interaction between immune and endocrine dysfunctions in MD.

The DEX/CRH neuroendocrine test and the prediction of depressive relapse in remitted depressed outpatients

Hypothalamo-pituitary-adrenal (HPA) system dysfunction is the most characteristic biological alteration found in a majority of depressed patients. Accumulating evidence suggests that the combined dexamethasone (DEX)/corticotropin-releasing hormone (CRH) test is highly sensitive to detect HPA system abnormalities. The aim of this study was to evaluate whether the DEX/CRH test has a predictive value for the risk of depressive relapse in outpatients who are in clinical remission from a major depressive episode. Thirty-eight depressed outpatients (23 women, 15 men) in remission (MADRS score < or =8) underwent the DEX/CRH test and were followed up for 12 months regarding the occurrence of a new depressive episode. In parallel we recruited 24 controls (13 men and 11 women). The main result is a statistically significant difference concerning the delta and AUC numbers for cortisol plasmatic values between the group of patients who relapsed during the 1-year follow-up and control subjects, but not between the group of patients with prolonged remission and controls. These results suggest that in outpatients who are in clinical remission from a major depressive episode, high delta and AUC values in the DEX/CRH test compared to controls subjects can be associated with a higher risk of relapse.

Polymorphisms of the glucocorticoid receptor gene and major depression

BACKGROUND

The most consistent biological finding in patients with depression is a hyperactivity of the hypothalamic-pituitary-adrenal (HPA)-axis, which might be caused by impaired glucocorticoid signaling. Glucocorticoids act through the glucocorticoid receptor (GR) for which several polymorphisms have been described. The N363S and BclI polymorphisms have been associated with hypersensitivity to glucocorticoids, whereas the ER22/23EK polymorphism is related to glucocorticoid resistance.

METHODS

We studied whether the susceptibility to develop a depression is related to these polymorphisms by comparing depressive inpatients (n = 490) and healthy control subjects (n = 496). Among depressed patients, we also investigated the relation between GR variants and dysregulation of the HPA-axis, as measured by the combined dexamethasone suppression/corticotropin-releasing hormone (CRH)-stimulation test, clinical response to antidepressive treatment, and cognitive functioning.

RESULTS

Homozygous carriers of the BclI polymorphism and ER22/23EK-carriers had an increased risk of developing a major depressive episode. We found no genetic associations with functional HPA-axis measures in depressed patients. The ER22/23EK-carriers, however, showed a significantly faster clinical response to antidepressant therapy as well as a trend toward better cognitive functioning during depression.

CONCLUSIONS

The BclI and ER22/23EK polymorphisms were associated with susceptibility to develop major depression. In addition, the ER22/23EK polymorphism is associated with a faster clinical response to antidepressant treatment. These findings support the notion that variants of the GR gene might play a role in the pathophysiology of a major depression and can contribute to the variability of antidepressant response.

Assessment of the dexamethasone/CRH test as a state-dependent marker for hypothalamic-pituitary-adrenal (HPA) axis abnormalities in major depressive episode: a Multicenter Study

There is compelling evidence for the involvement of hypothalamic-pituitary-adrenal (HPA) axis abnormalities in depression. Growing evidence has suggested that the combined dexamethasone (DEX)/corticotropin-releasing hormone (CRH) test is highly sensitive to detect HPA axis abnormalities. We organized a multicenter study to assess the DEX/CRH test as a state-dependent marker for major depressive episode in the Japanese population. We conducted the DEX/CRH test in 61 inpatients with major depressive episode (Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-IV)) and 57 healthy subjects. In all, 35 patients were repeatedly assessed with the DEX/CRH test on admission and before discharge. The possible relationships between clinical variables and the DEX/CRH test were also examined. Significantly enhanced pituitary-adrenocortical responses to the DEX/CRH test were observed in patients on admission compared with controls. Such abnormalities in patients were significantly reduced after treatment, particularly in those who underwent electroconvulsive therapy (ECT) in addition to pharmacotherapy. Age and female gender were associated with enhanced hormonal responses to the DEX/CRH test. Severity of depression correlated with DEX/CRH test results, although this was explained, at least in part, by a positive correlation between age and severity in our patients. Medication per se was unrelated to DEX/CRH test results. These results suggest that the DEX/CRH test is a sensitive state-dependent marker to monitor HPA axis abnormalities in major depressive episode during treatment. Restoration from HPA axis abnormalities occurred with clinical responses to treatment, particularly in depressed patients who underwent ECT.

The combined dexamethasone/CRH test as a potential surrogate marker in depression

There is compelling evidence that impaired corticosteroid receptor function is the key mechanism in the pathogenesis of depression resulting in a dysfunctional stress hormone regulation, which can be most sensitively detected with the combined dexamethasone (dex)/corticotropin releasing hormone (CRH) test. Treatment with different kinds of antidepressants is associated with a reduction of the hormonal responses to the combined dex/CRH test suggesting normalization of impaired corticosteroid receptor signaling as the final common pathway of these drugs. Consequently, the combined dex/CRH test is suggested as a screening tool to decide whether new compounds designed as antidepressants provide sufficient efficacy to normalize corticoid receptor signaling in depressed patients. We summarize own data and findings from the literature suggesting that (1) the neuroendocrine response to the combined dex/CRH test is elevated during a major depressive episode, but (2) tends to normalize after successful treatment. (3) Favorable response to antidepressant treatment can be predicted by determining the dex suppresser status on admission. For optimal prediction of non-response to antidepressant treatment, however, the results of a second dex/CRH test are necessary. These findings, together with the fact that impaired corticosteroid receptor signaling is considered as key mechanism of the pathogenesis in depression, support the suitability of the combined dex/CHR test as a surrogate marker for treatment response in depression. In conclusion, the combined dex/CRH test is a promising candidate to serve as a screening tool for the antidepressive effects of new compounds in clinical drug trials. Furthermore, the test appears to be capable of predicting the individual likelihood to respond to a current antidepressant treatment. If a drug treatment fails to normalize the outcome of the combined dex/CRH test, a change of the treatment strategy is recommended. Further systematic research is required and already ongoing to confirm the suitability of the combined dex/CRH test as a surrogate marker in depression.

Type D personality: the heart, stress, and cortisol

Many studies have demonstrated the role of psychosocial and behavioural risk factors in the aetiology and pathogenesis of cardiovascular disorders. Recently, a new personality construct, the type D or 'distressed' personality, has been proposed. Type D behaviour is characterized by the joint tendency to experience negative emotions and to inhibit these emotions while avoiding social contacts with others. The observation that cardiac patients with type D personality are at increased risk for cardiovascular morbidity and mortality underlines the importance of examining both acute (e.g. major depression) and chronic (e.g. certain personality features) factors in patients at risk for coronary events. Both type D dimensions (negative affectivity and social inhibition) are associated with greater cortisol reactivity to stress. Elevated cortisol may be a mediating factor in the association between type D personality and the increased risk for coronary heart disease and, possibly, other medical disorders. Studies of the effect of age on hypothalamic-pituitary-adrenal (HPA) function in healthy humans have produced inconsistent results. This may relate to a different prevalence of type D individuals in study samples (i.e. some type D individuals may have alterations within the HPA axis that are similar to HPA axis changes in depressed patients). Further studies of the psychological and biological features of type D individuals may help develop treatment approaches to improve the psychological and physical health of individuals with type D personality.

Hypothalamus-pituitary-adrenal system regulation and suicidal behavior in depression

BACKGROUND

One of the most demanding tasks in psychiatry is to protect patients from suicidal attempts. Preventive strategies could be improved by increasing our knowledge on the pathophysiologic disturbances underlying this behavior. More than 70-80% of suicides occur in the context of depressive disorders, in which dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis is one of the most prominent neurobiological findings. So far data on the involvement of the HPA axis in the pathophysiology of suicidal behavior in depressed patients are controversial.

METHODS

In this retrospective study, we administered the combined dexamethasone-suppression/CRH stimulation (Dex/CRH) test to 310 patients with a depressive syndrome characterized at admission for acute and past suicidal behavior within the first 10 days after hospitalization.

RESULTS

Suicidal behavior in depressed patients, including past and recent suicide attempts as well as suicidal ideation, was associated with a lower adrenocorticotropin and cortisol response in the combined Dex/CRH test, with lowest hormone levels observed in patients with a recent suicide attempt.

DISCUSSION

The findings suggest that suicidal behavior may alter HPA axis regulation in depressed patients. Large-scale prospective studies assessing neuroendocrine changes may help to develop predictors for an early identification of patients at risk for committing suicide.

Endocrine disturbances in depression

Depression is one of the most common psychiatric disorders. For a long time, clinicians suspected a causal link between depression and the endocrine system. The most frequently occurring endocrine abnormality in depressed subjects is hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. CRH and AVP are likely to play a substantial role in the pathophysiology of this disorder, and their receptors appear to be a specific target for future antidepressant drugs. Depression also affects the hypothalamic-pituitary-GH (HPGH) and -thyroid (HPT) axes. Alterations in the reproductive system may also play a role in the pathology of depression. In addition, there is increasing evidence that leptin and neurosteroids, such as DHEA, are implicated in mood disorders.

Age effects on cortisol levels in depressed patients with and without comorbid post-traumatic stress disorder, and healthy volunteers

BACKGROUND

Post-traumatic stress disorder (PTSD) and major depression are frequently comorbid. Age and major depression are associated with higher cortisol levels and dexamethasone resistance, whereas PTSD is associated with lower cortisol and dexamethasone supersensitivity. Therefore, we examined the effect of age on the hypothalamic-pituitary-adrenal (HPA) system in depressed patients with and without PTSD.

METHODS

Thirty-one depressed patients without PTSD, 12 depressed patients with PTSD, and 23 healthy volunteers were studied on 2 days. Subjects received single-blind placebo on day 1 and fenfluramine on day 2. Cortisol levels were drawn before challenge and for 5 h thereafter.

RESULTS

Cortisol levels increase with age in depressed patients without PTSD but not in depressed patients with PTSD or in healthy volunteers. Number of previous major depressive episodes was a predictor of the cortisol response to fenfluramine administration in depressed patients without PTSD.

CONCLUSIONS

The results of our study highlight the importance of considering age in psychobiology. Further research is needed to fully delineate the role of age in abnormalities of the HPA axis found in major depression and PTSD.

[The hypothalamic pituitary adrenal axis, glucocorticoid receptor function and relevance to depression]

OBJECTIVES

Changes in the hypothalamic-pituitary-adrenocortical (HPA) system are characteristic of depression. Because the effects of glucocorticoids are mediated by intracellular receptors including, most notably, the glucocorticoid receptor (GR), several studies have examined the number and/or function of GRs in depressed patients.

METHODS

Review scientific evidences have consistently demonstrated that GR function is impaired in major depression, resulting in reduced GR-mediated negative feedback on the HPA axis and increased production and secretion of CRF in various brain regions postulated to be involved in the causality of depression.

RESULTS

This article summarizes the literature on GR in depression and on the impact of antidepressants on the GR in clinical and preclinical studies, and supports the concept that impaired GR signalling is a key mechanism in the pathogenesis of depression, in the absence of clear evidence of decreased GR expression. The data also indicate that antidepressants have direct effects on the GR, leading to enhanced GR function and increased GR expression. Although the effects of antidepressants on glucocorticoid hormones and their receptors are relevant for the therapeutic action of these drugs, the molecular mechanisms underlying these effects are unclear. We propose that antidepressants in humans could inhibit steroid transporters localised on the blood-brain barrier and in neurones, like the multidrug resistance p-glycoprotein, and thus increase the access of cortisol to the brain and the glucocorticoid-mediated negative feedback on the HPA axis.

CONCLUSION

Enhanced cortisol action in the brain might prove to be a successful approach to maximise therapeutic antidepressant effects. Hypotheses regarding the mechanism of these receptor changes involve non-steroid compounds that regulate GR function via second messenger pathways. Research in this field will lead to new insights into the pathophysiology and treatment of affective disorders.

Platelet serotonin and plasma prolactin and cortisol in healthy, depressed and schizophrenic women

Serotonin (5-hydroxytryptamine, 5-HT) is involved in the regulation of hypothalamic-pituitary-adrenal axis (HPA) activity and prolactin (PRL) secretion. The present study examined the relationship between platelet 5-HT and plasma cortisol and PRL concentrations in 20 schizophrenic, 25 depressed, and 25 healthy women. At the time of blood sampling, the schizophrenic and depressed patients had been drug-free for at least 7 days. Platelet 5-HT, plasma cortisol and PRL concentrations were determined by spectrofluorimetric, radioimmunoassay and immunoradiometric methods, respectively. Platelet 5-HT concentration was significantly higher in schizophrenic patients than in depressed patients or in healthy controls, while it was significantly lower in depressed patients than in healthy controls or in schizophrenic patients. Plasma cortisol levels were significantly increased both in schizophrenic and in depressed patients compared with values in healthy controls. Values of plasma PRL were similar across groups. A significant correlation was found between platelet 5-HT and plasma cortisol, and platelet 5-HT and plasma PRL concentrations in healthy controls, but not in schizophrenic or depressed patients. There was no significant relationship between plasma PRL and cortisol levels in any of the groups. Our data, although obtained on peripheral biochemical markers, indicate that depression and schizophrenia are characterized by disturbed 5-HT transmission and dysregulated HPA axis activity.

Combined DEX/CRH test among Japanese patients with major depression

There is compelling evidence for an important role of the hypothalamus-pituitary-adrenal (HPA) axis abnormalities in the pathophysiology of major depressive disorder. Growing evidence has suggested that the combined dexamethasone (DEX)/CRH test is much more sensitive than the conventional DEX suppression test in order to detect HPA axis abnormalities. However, little data is currently available on DEX/CRH results for Asian populations, which prompted us to examine the sensitivity of the DEX/CRH test among Japanese subjects with major depression. The DEX/CRH test was administered in 20 inpatients with major depressive episode and 30 healthy controls. Significantly increased cortisol responses were observed for the patients, compared to the controls. There was a substantial difference in the distribution of non-suppressor, intermediate suppressor, and suppressor, which were defined in terms of cortisol response, was observed between the patients and controls (10, 60, and 30% in the patients vs. 0, 27, and 73% in the controls, P<0.01). Responses of ACTH showed a trend in the same direction. Within the depressed patients, individuals with a history of attempted suicide, in particular, tended to have enhanced responses to the DEX/CRH test, compared to those without such a history. Our results confirmed that the DEX/CRH test is a sensitive test to detect HPA axis abnormalities among Japanese patients with major depression. In addition, a possible relationship between suicidal acts and enhanced HPA axis abnormalities was suggested.

Pharmacological and nonpharmacological factors influencing hypothalamic-pituitary-adrenocortical axis reactivity in acutely depressed psychiatric in-patients, measured by the Dex-CRH test

The most consistent biological findings in patients with depression are abnormalities in the hypothalamic-pituitary-adrenal (HPA)-axis, which can be measured using the combined dexamethasone-suppression/CRH-stimulation (Dex-CRH) test. The reactivity of the HPA-axis in this test, however, ranges over several orders of magnitude in depressed patients with comparable severity of symptoms. In this present study, we investigate which factors influence the magnitude of the response in the Dex-CRH test in 235 acutely depressed in-patients. We first examined the effects of common confounders shown to influence the HPA-axis, such as caffeine and nicotine consumption, acute stressors during the test, weight, gender, and age. Of all these variables, only female sex and nicotine consumption were positively correlated with the cortisol or ACTH response, respectively. As for the effects of psychopharmacological treatment, only the intake of carbamazepine and the fact of having relapsed under an established pharmacotherapy significantly increased the response in the Dex-CRH test, whereas the presence or absence of antidepressant treatment, the type of antidepressant treatment, or the number of ineffective antidepressant treatment trials during the index episode up to admission did not have any effect. We also found a positive correlation of the number of previous episodes, the overall HAM-D score and the severity of somatic/vegetative symptoms with the results in the Dex-CRH test. These results underline that in depressed patients this test is not majorly influenced by disease-unrelated factors. In addition, current antidepressant treatment does not appear to affect test outcome in the absence of clinical response. The influence of the number of previous episodes and relapse under pharmacotherapy suggests that HPA-axis reactivity may be altered by repetitive states of hypercortisolemia or continuous antidepressant treatment. Finally, more severe vegetative symptoms are associated with an enhanced HPA-axis activity.

Molecular mechanisms of glucocorticoid receptor sensitivity and relevance to affective disorders

Changes in the hypothalamic-pituitary-adrenocortical (HPA) system are characteristic of depression, and in the majority of these patients these result in HPA axis hyperactivity. This is further supported by the reduced sensitivity to the inhibitory effects of the glucocorticoid, dexamethasone (DEX), on the production of adrenocorticotropic hormone (ACTH) and cortisol, during the DEX suppression test and the DEX-corticotropin-releasing hormone (DEX/CRH) test. Because the effects of glucocorticoids are mediated by intracellular receptors including, most notably, the glucocorticoid receptor (GR), several studies have examined the number and/or function of GRs in depressed patients. These studies have consistently demonstrated that GR function is impaired in major depression, resulting in reduced GR-mediated negative feedback on the HPA axis and increased production and secretion of CRH in various brain regions postulated to be involved in the causality of depression. This article summarizes the literature on GR in depression and on the impact of antidepressants on the GR in clinical and preclinical studies, and supports the concept that impaired GR signaling is a key mechanism in the pathogenesis of depression, in the absence of clear evidence of decreased GR expression. The data also indicate that antidepressants have direct effects on the GR, leading to enhanced GR function and increased GR expression. Hypotheses regarding the mechanism of these receptor changes involve non-steroid compounds that regulate GR function via second messenger pathways, such as cytokines and neurotransmitters. Moreover, we present recent evidence suggesting that membrane steroid transporters such as the multidrug resistance (MDR) p-glycoprotein, which regulate access of glucocorticoids to the brain, could be a fundamental target of antidepressant treatment. Research in this field will lead to new insights into the pathophysiology and treatment of affective disorders.

Update on stress and depression: the role of the hypothalamic-pituitary-adrenal (HPA) axis

Over the past 50 years, relationships between stress and the neurobiological changes seen in psychiatric disorders have been well-documented. A major focus of investigations in this area has been the role of the hypothalamic-pituitary-adrenal (HPA) axis, both as a marker of stress response and as a mediator of additional downstream pathophysiologic changes. This review examines the emerging literature concerning the relationship between stress, HPA axis function, and depression, as well as the role of early life stress as an important risk factor for HPA axis dysregulation. The more recent studies reviewed suggest that the prominence of HPA axis hyperactivity in adults with depressive and anxiety disorders may constitute a link between the occurrence of adversity in childhood and the development of adult psychopathology.

Antidepressants differentially influence the transcriptional activity of the glucocorticoid receptor in vitro

Functional normalization of the hypothalamic-pituitary-adrenal axis in depressive patients by successful treatment with antidepressants is associated with increased efficiency of corticosteroid signal transduction. Accordingly, some antidepressants have been shown to influence the activity of the glucocorticoid receptor (GR) in cultured cells. It is not clear, however, whether this is a common principle for all antidepressants throughout all classes. Therefore, we screened a range of 18 antidepressants of different classes for their effect on GR signaling in a reporter gene assay using the mouse hippocampal cell line HT22. We evaluated GR-mediated gene transcription after short-time incubation (24 h) with different concentrations of each antidepressant (1 or 10 microM) in the presence or absence of the synthetic steroid dexamethasone (0.01 or 1 microM). The majority of antidepressants had a tendency to enhance steroid-induced GR-mediated gene transcription at high concentrations of antidepressant and low concentrations of steroid. Some antidepressants reduced the steroid-independent background activity of GR. This reduction was not due to unspecific inhibition of GR by oxidative stress, since no induction of intracellular peroxides was detectable in the concentration range of antidepressants used in our study. Furthermore, no significant change in GR activity was observed by concomitant treatment of HT22 cells with the antioxidant alpha-tocopherol (vitamin E). In conclusion, we report that many antidepressants enhance GR signaling in an in vitro neuronal system at clinically relevant concentrations. Those not showing an effect in vitro apparently use different mechanisms to influence GR activity that require an in vivo setting.

Characterization and functional significance of glucocorticoid receptors in patients with major depression: modulation by antidepressant treatment

Hyperactivity of the hypothalamic pituitary adrenal (HPA) axis in patients with major depression is one of the most consistent findings in biological psychiatry. Experimental data support the idea that glucocorticoid-mediated feedback via glucocorticoid receptors (GR) is impaired in major depression. The aim of the present work was to assess the putative changes in GR density of peripheral blood mononuclear cells (PBMCs) in a group of patients with major depression and to determine modulation of these GR sites by antidepressant treatment. In addition, susceptibility of PBMCs to glucocorticoid effects was also studied using a functional end-point analysis in vitro, such as cortisol inhibition of mitogen-induced lymphocyte proliferation. Cortisol levels were also measured before and after dexamethasone suppression test (DST). The results showed a decrease in GR density in depressed patients compared with healthy subjects, mainly in those patients that showed basal cortisol levels in the upper normal range and were refractory to DST. Regarding the functional significance of this variation, two representative groups emerged from our study: a) free-medication patients with GR function comparable to healthy controls, and b) patients showing diminished GR activity. These results suggest a lack of relationship between GR density and cortisol-induced inhibition of lymphocyte proliferation. Patients treated with different antidepressant drugs showed a marked increase in the number of GR sites per cell compared to non-treated. Interestingly, this increase was even higher than in normal subjects. Hence, restoration of GR density after an efficient antidepressant treatment could be an index of an effective modulatory action of drugs on GR expression and highlights the possibility that GR levels might be used as markers of a successful treatment.

The combined DEX-CRH test in treatment course and long-term outcome of major depression

Neuroendocrine studies strongly suggest that the hypothalamic-pituitary-adrenocortical (HPA) system plays a crucial role in the development and course of depression. The interaction between the disease process and HPA system function in long-term course, however, is unclear. Since improvement of HPA system deterioration has been demonstrated to be associated with treatment response, the question has arisen whether the course of therapy response as reflected by, for example, early improvement or response (after 1 or 2 weeks of therapy) is also based on HPA system dysfunction and whether the course of HPA regulation during treatment is only a state marker or has additional predictive implications for long-term outcome. In order to elucidate these questions a long-term study was carried out to investigate whether HPA system disturbance is associated (1) with the course of treatment response, predominantly early treatment response, during acute depression and (2) with the long-term course of depression, i.e. number of episodes. Twenty patients with affective disorders who participated in earlier controlled antidepressant treatment studies over 6 weeks were enrolled in an exploratory follow-up study. Using the combined DEX/CRH test it was demonstrated that (1) early improvement, early treatment response and beneficial treatment outcome after 6 weeks were associated with a lower HPA system activity and that (2) in long-term course of depression the HPA system deterioration increases in parallel with the number of previous episodes. These findings suggest that HPA system alterations are closely related to treatment response and long-term outcome of depression.