The relationship between the effects of metyrapone treatment on depressed mood and urinary steroid profiles

Metyrapone Treatment Protects Low-Density Lipoprotein Receptor Knockout Mice against Hypercorticosteronemia Development without Changing Atherosclerosis Susceptibility

The steroid 11beta-hydroxylase inhibitor metyrapone is able to effectively reverse the hypercortisolemia detected in human Cushing's Syndrome patients. In this current preclinical study, we investigated whether metyrapone monotherapy can also reverse the hypercortisolemia-associated increase in atherosclerotic cardiovascular disease risk. In this instance, female low-density lipoprotein receptor knockout mice fed a cholic acid-containing high cholesterol/high fat diet to induce the development of hypercorticosteronemia and atherosclerotic lesions were treated twice daily with 100 mg/kg metyrapone for 4 weeks. Metyrapone effectively protected against hypercorticosteronemia development with endpoint plasma corticosterone levels remaining 43% lower than in controls (p < 0.01). Gene expression analysis in livers and adrenals validated that glucocorticoid receptor signaling was also reduced. Importantly, metyrapone treatment did not impact plasma cholesterol levels or alter atherosclerotic plaque areas or lesional collagen contents. However, metyrapone induced significant systemic lymphocytopenia as evident from marked decreases in splenic white pulp contents and thymus weights (-48% and -41%, respectively; p < 0.001). In conclusion, we have shown that treatment with metyrapone diminishes hypercorticosteronemia without affecting atherosclerosis susceptibility in cholic acid-containing high cholesterol/high fat diet-fed low-density lipoprotein receptor knockout mice. These preclinical findings highlight that restoring plasma glucocorticoid levels to normal is not necessarily sufficient to overcome the cardiovascular co-morbidities associated with human Cushing's disease.

Hormonal Treatments for Major Depressive Disorder: State of the Art

Major depressive disorder is a common psychiatric disorder associated with marked suffering, morbidity, mortality, and cost. The World Health Organization projects that by 2030, major depression will be the leading cause of disease burden worldwide. While numerous treatments for major depression exist, many patients do not respond adequately to traditional antidepressants. Thus, more effective treatments for major depression are needed, and targeting certain hormonal systems is a conceptually based approach that has shown promise in the treatment of this disorder. A number of hormones and hormone-manipulating compounds have been evaluated as monotherapies or adjunctive treatments for major depression, with therapeutic actions attributable not only to the modulation of endocrine systems in the periphery but also to the CNS effects of hormones on non-endocrine brain circuitry. The authors describe the physiology of the hypothalamic-pituitary-adrenal (HPA), hypothalamic-pituitary thyroid (HPT), and hypothalamic-pituitary-gonadal (HPG) axes and review the evidence for selected hormone-based interventions for the treatment of depression in order to provide an update on the state of this field for clinicians and researchers. The review focuses on the HPA axis-based interventions of corticotropin-releasing factor antagonists and the glucocorticoid receptor antagonist mifepristone, the HPT axis-based treatments of thyroid hormones (T₃ and T₄), and the HPG axis-based treatments of estrogen replacement therapy, the progesterone derivative allopregnanolone, and testosterone. While some treatments have largely failed to translate from preclinical studies, others have shown promising initial results and represent active fields of study in the search for novel effective treatments for major depression.

Baseline cortisol and the efficacy of antiglucocorticoid treatment in mood disorders: A meta-analysis

INTRODUCTION

Hyperactivity of the Hypothalamic-Pituitary-Adrenal (HPA) axis and high cortisol levels have been widely reported in patients with mood disorders but previous clinical trials investigating the efficacy of antiglucocorticoid treatment in this population have reported inconsistent findings. The inconsistencies among these studies may be because not all patients with mood disorders have increased HPA axis activity and therefore might not benefit from antiglucocorticoid treatment. The aim of this meta-analysis was to investigate whether baseline cortisol levels influence the efficacy of antiglucocorticoid drugs in patients with mood disorders.

METHODS

PubMed and Scopus databases were searched systematically up to October 2018. We included studies using metyrapone, ketoconazole or mifepristone in patients with major depressive disorder, bipolar disorder and major depressive disorder with psychotic symptoms. We tested for a difference in cortisol levels between responders (a reduction equal to or greater than 30% on depression scales following antiglucocorticoid treatment) and non-responders (a reduction of less than 30% on depression scales). We performed a meta-analysis to look specifically at differences in cortisol levels in the sample of patients treated with cortisol synthesis inhibitors (metyrapone and ketoconazole) and in those treated with glucocorticoid receptor (GR) antagonist (mifepristone).

RESULTS

We were able to retrieve data from 11 of the 16 selected studies and to include 9 studies in the meta-analysis. In the overall sample (N = 846), responders had similar baseline cortisol levels compared with non-responders (standardised mean difference, SMD = -0.03, 95% CI [-0.17, 0.12], p = 0.75). In the group of patients treated with cortisol synthesis inhibitors, responders (N = 109) had significantly higher peripheral baseline cortisol levels compared with non-responders (SMD = 0.42, 95% CI [0.01, 0.83], p = 0.047). In the group of patients treated with a GR antagonist (N = 737), both responders and non-responders had similar baseline cortisol levels (SMD = -0.09, 95% CI [-0.25, 0.07], p = 0.26).

CONCLUSION

Our data suggest that only patients with higher cortisol levels at baseline benefit from treatment with cortisol synthesis inhibitors and support a potential role for cortisol as a predictive biomarker for treatment with cortisol synthesis inhibitors in patients with mood disorders.

Cortisol and Major Depressive Disorder-Translating Findings From Humans to Animal Models and Back

Major depressive disorder (MDD) is a global problem for which current pharmacotherapies are not completely effective. Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has long been associated with MDD; however, the value of assessing cortisol as a biological benchmark of the pathophysiology or treatment of MDD is still debated. In this review, we critically evaluate the relationship between HPA axis dysfunction and cortisol level in relation to MDD subtype, stress, gender and treatment regime, as well as in rodent models. We find that an elevated cortisol response to stress is associated with acute and severe, but not mild or atypical, forms of MDD. Furthermore, the increased incidence of MDD in females is associated with greater cortisol response variability rather than higher baseline levels of cortisol. Despite almost all current MDD treatments influencing cortisol levels, we could find no convincing relationship between cortisol level and therapeutic response in either a clinical or preclinical setting. Thus, we argue that the absolute level of cortisol is unreliable for predicting the efficacy of antidepressant treatment. We propose that future preclinical models should reliably produce exaggerated HPA axis responses to acute or chronic stress a priori, which may, or may not, alter baseline cortisol levels, while also modelling the core symptoms of MDD that can be targeted for reversal. Combining genetic and environmental risk factors in such a model, together with the interrogation of the resultant molecular, cellular, and behavioral changes, promises a new mechanistic understanding of MDD and focused therapeutic strategies.

HPA Axis Interactions with Behavioral Systems

Perhaps the most salient behaviors that individuals engage in involve the avoidance of aversive experiences and the pursuit of pleasurable experiences. Engagement in these behaviors is regulated to a significant extent by an individual's hormonal milieu. For example, glucocorticoid hormones are produced by the hypothalamic-pituitary-adrenocortical (HPA) axis, and influence most aspects of behavior. In turn, many behaviors can influence HPA axis activity. These bidirectional interactions not only coordinate an individual's physiological and behavioral states to each other, but can also tune them to environmental conditions thereby optimizing survival. The present review details the influence of the HPA axis on many types of behavior, including appetitively-motivated behaviors (e.g., food intake and drug use), aversively-motivated behaviors (e.g., anxiety-related and depressive-like) and cognitive behaviors (e.g., learning and memory). Conversely, the manuscript also describes how engaging in various behaviors influences HPA axis activity. Our current understanding of the neuronal and/or hormonal mechanisms that underlie these interactions is also summarized. © 2016 American Physiological Society. Compr Physiol 6:1897-1934, 2016.

Antidepressant augmentation with metyrapone for treatment-resistant depression (the ADD study): a double-blind, randomised, placebo-controlled trial

BACKGROUND

Many patients with major depressive disorder have treatment-resistant depression, defined as no adequate response to two consecutive courses of antidepressants. Some evidence suggests that antiglucocorticoid augmentation of antidepressants might be efficacious in patients with major depressive disorder. We aimed to test the proof of concept of metyrapone for the augmentation of serotonergic antidepressants in the clinically relevant population of patients with treatment-resistant depression.

METHODS

This double-blind, randomised, placebo-controlled trial recruited patients from seven UK National Health Service (NHS) Mental Health Trusts from three areas (northeast England, northwest England, and the Leeds and Bradford area). Eligible patients were aged 18-65 years with treatment-resistant depression (Hamilton Depression Rating Scale 17-item score of ≥18 and a Massachusetts General Hospital Treatment-Resistant Depression staging score of 2-10) and taking a single-agent or combination antidepressant treatment that included a serotonergic drug. Patients were randomly assigned (1:1) through a centralised web-based system to metyrapone (500 mg twice daily) or placebo, in addition to their existing antidepressant regimen, for 21 days. Permuted block randomisation was done with a block size of two or four, stratified by centre and primary or secondary care setting. The primary outcome was improvement in Montgomery-Åsberg Depression Rating Scale (MADRS) score 5 weeks after randomisation, analysed in the modified intention-to-treat population of all randomly assigned patients that completed the MADRS assessment at week 5. The study has an International Standard Randomised Controlled Trial Number (ISRCTN45338259) and is registered with the EU Clinical Trial register, number 2009-015165-31.

FINDINGS

Between Feb 8, 2011, and Dec 10, 2012, 165 patients were recruited and randomly assigned (83 to metyrapone and 82 to placebo), with 143 (87%) completing the primary outcome assessment (69 [83%] in the metyrapone and 74 [90%] in the placebo group). At 5 weeks, MADRS score did not significantly differ between groups (21·7 points [95% CI 19·2-24·4] in the metyrapone group vs 22·6 points [20·1-24·8] in the placebo group; adjusted mean difference of -0·51 points [95% CI -3·48 to 2·46]; p=0·74). 12 serious adverse events were reported in four (5%) of 83 patients in the metyrapone group and six (7%) of 82 patients in the placebo group, none of which were related to study treatment. 134 adverse events occurred in 58 (70%) patients in the metyrapone group compared with 95 events in 45 (55%) patients in the placebo group, of which 11 (8%) events in the metyrapone group and four (4%) in the placebo group were judged by principle investigators at the time of occurrence to be probably related to the study drug.

INTERPRETATION

Metyrapone augmentation of antidepressants is not efficacious in a broadly representative population of patients with treatment-resistant depression within the NHS and therefore is not an option for patients with treatment-resistant depression in routine clinical practice at this time. Further research is needed to clarify if such augmentation might benefit subpopulations with demonstrable hypothalamic-pituitary-adrenal axis abnormalities.

FUNDING

Efficacy and Mechanism Evaluation (EME) programme, a UK Medical Research Council and National Institute for Health Research partnership.

Role of GABA-active neurosteroids in the efficacy of metyrapone against cocaine addiction

Previous research has demonstrated a complicated role for stress and HPA axis activation in potentiating various cocaine-related behaviors in preclinical models of drug dependence. However, the investigation of several antiglucocorticoid therapies has yielded equivocal results in reducing cocaine-related behaviors, possibly because of varying mechanisms of actions. Specifically, research suggests that metyrapone (a corticosterone synthesis inhibitor) may reduce cocaine self-administration in rats via a nongenomic, extra-adrenal mechanism without altering plasma corticosterone. In the current experiments, male rats were trained to self-administer cocaine infusions and food pellets in a multiple, alternating schedule of reinforcement. Metyrapone pretreatment dose-dependently decreased cocaine self-administration as demonstrated previously. Pharmacological inhibition of neurosteroid production by finasteride had significant effects on cocaine self-administration, regardless of metyrapone pretreatment. However, metyrapone's effects on cocaine self-administration were significantly attenuated with bicuculline pretreatment, suggesting a role for GABA-active neurosteroids in cocaine-reinforced behaviors. In vitro binding data also confirmed that metyrapone does not selectively bind to GABA-related proteins. The results of these experiments support the hypothesis that metyrapone may increase neurosteroidogenesis to produce effects on cocaine-related behaviors.

The extra-adrenal effects of metyrapone and oxazepam on ongoing cocaine self-administration

Investigation of the role of stress in cocaine addiction has yielded an efficacious combination of metyrapone and oxazepam, hypothesized to decrease relapse to cocaine use by reducing stress-induced craving. However, recent data suggest an extra-adrenal role for metyrapone in mediating stress- and addiction-related behaviors. The interactions between the physiological stress response and cocaine self-administration were characterized in rodents utilizing surgical adrenalectomy and pharmacological treatment. Male Wistar rats were trained to self-administer cocaine (0.25mg/kg/infusion) and food pellets under a concurrent alternating fixed-ratio schedule of reinforcement. Surgical removal of the adrenal glands resulted in a significant decrease in plasma corticosterone and a consequent increase in ACTH, as expected. However, adrenalectomy did not significantly affect ongoing cocaine self-administration. Pretreatment with metyrapone, oxazepam and their combinations in intact rats resulted in a significant decrease in cocaine-reinforced responses. These same pharmacological treatments were still effective in reducing cocaine- and food-reinforced responding in adrenalectomized rats. The results of these experiments demonstrate that adrenally-derived steroids are not necessary to maintain cocaine-reinforced responding in cocaine-experienced rats. These results also demonstrate that metyrapone may produce effects outside of the adrenal gland, presumably in the central nervous system, to affect cocaine-related behaviors.

The combination of metyrapone and oxazepam for the treatment of cocaine and other drug addictions

Although scientists have been investigating the neurobiology of psychomotor stimulant reward for many decades, there is still no FDA-approved treatment for cocaine or methamphetamine abuse. Research in our laboratory has focused on the relationship between stress, the subsequent activation of the hypothalamic-pituitary-adrenal (HPA) axis, and psychomotor stimulant reinforcement for almost 30 years. This research has led to the development of a combination of low doses of the cortisol synthesis inhibitor, metyrapone, and the benzodiazepine, oxazepam, as a potential pharmacological treatment for cocaine and other substance use disorders. In fact, we have conducted a pilot clinical trial that demonstrated that this combination can reduce cocaine craving and cocaine use. Our initial hypothesis underlying this effect was that the combination of metyrapone and oxazepam reduced cocaine seeking and taking by decreasing activity within the HPA axis. Even so, doses of the metyrapone and oxazepam combination that consistently reduced cocaine taking and seeking did not reliably alter plasma corticosterone (or cortisol in the pilot clinical trial). Furthermore, subsequent research has demonstrated that this drug combination is effective in adrenalectomized rats, suggesting that these effects must be mediated above the level of the adrenal gland. Our evolving hypothesis is that the combination of metyrapone and oxazepam produces its effects by increasing the levels of neuroactive steroids, most notably tetrahydrodeoxycorticosterone, in the medial prefrontal cortex and amygdala. Additional research will be necessary to confirm this hypothesis and may lead to the development of improved and specific pharmacotherapies for the treatment of psychomotor stimulant use.

Study protocol for the randomised controlled trial: antiglucocorticoid augmentation of anti-Depressants in Depression (The ADD Study)

BACKGROUND

Some patients with depression do not respond to first and second line conventional antidepressants and are therefore characterised as suffering from treatment refractory depression (TRD). On-going psychosocial stress and dysfunction of the hypothalamic-pituitary-adrenal axis are both associated with an attenuated clinical response to antidepressants. Preclinical data shows that co-administration of corticosteroids leads to a reduction in the ability of selective serotonin reuptake inhibitors to increase forebrain 5-hydroxytryptamine, while co-administration of antiglucocorticoids has the opposite effect. A Cochrane review suggests that antiglucocorticoid augmentation of antidepressants may be effective in treating TRD and includes a pilot study of the cortisol synthesis inhibitor, metyrapone. The Antiglucocorticoid augmentation of anti-Depressants in Depression (The ADD Study) is a multicentre randomised placebo controlled trial of metyrapone augmentation of serotonergic antidepressants in a large population of patients with TRD in the UK National Health Service.

METHODS/DESIGN

Patients with moderate to severe treatment refractory Major Depression aged 18 to 65 will be randomised to metyrapone 500 mg twice daily or placebo for three weeks, in addition to on-going conventional serotonergic antidepressants. The primary outcome will be improvement in Montgomery-Åsberg Depression Rating Scale score five weeks after randomisation (i.e. two weeks after trial medication discontinuation). Secondary outcomes will include the degree of persistence of treatment effect for up to 6 months, improvements in quality of life and also safety and tolerability of metyrapone. The ADD Study will also include a range of sub-studies investigating the potential mechanism of action of metyrapone.

DISCUSSION

Strengths of the ADD study include broad inclusion criteria meaning that the sample will be representative of patients with TRD treated within the UK National Health Service, longer follow up, which to our knowledge is longer than any previous study of antiglucocorticoid treatments in depression, and the range of mechanistic investigations being carried out. The data set acquired will be a rich resource for a range of research questions relating to both refractory depression and the use of antiglucocorticoid treatments.

TRIAL REGISTRATION

Current Controlled Trials: ISRCTN45338259; EudraCT Number: 2009-015165-31.

Metyrapone in treatment-resistant depression

Depression affects a significant proportion of the population, with 1-year and lifetime prevalence of 3-5% and 10-30% respectively. Full remission is achieved in only a third of patients following treatment with first-line antidepressant. There is a need for novel treatments for treatment-resistant depression (TRD). Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis has been described in patients with depression. There is persistent rise in the levels of cortisol (end product of the HPA axis) and impairment of the negative feedback inhibition mechanism of the HPA axis. Dysregulation of the HPA axis has been found to be linked to nonresponse to antidepressants and relapse following successful treatment. The efficacy of pharmacological agents that intervene with the mechanisms involved in dysregulation of cortisol synthesis and release are being explored in depression, particularly in TRD. Studies have been carried out with these drugs as augmenting agents for antidepressants or as monotherapy. The strongest evidence has come from studies using metyrapone, a cortisol synthesis inhibitor, and this has been described in detail in this review. The most robust evidence for its antidepressant efficacy in depression comes from a double-blind, randomized, placebo-controlled study of augmentation of serotonergic antidepressants with metyrapone. A 3-week augmentation of serotonergic antidepressants with 1 g metyrapone daily was shown to be superior to placebo in reducing the Montgomery-Asberg Depression Rating Scale by 50%, 5 weeks following initiation of treatment. The mechanism of the antidepressant action of metyrapone is not clear but the evidence for various potential mechanisms is discussed.

Neuroactive steroids in affective disorders: target for novel antidepressant or anxiolytic drugs?

In the past decades considerable evidence has emerged that so-called neuroactive steroids do not only act as transcriptional factors in the regulation of gene expression but may also alter neuronal excitability through interactions with specific neurotransmitter receptors such as the GABA(A) receptor. In particular, 3α-reduced neuroactive steroids such as allopregnanolone or allotetrahydrodeoxycorticosterone have been shown to act as positive allosteric modulators of the GABA(A) receptor and to play an important role in the pathophysiology of depression and anxiety. During depression, the concentrations of 3α,5α-tetrahydroprogesterone and 3α,5β-tetrahydroprogesterone are decreased, while the levels of 3β,5α-tetrahydroprogesterone, a stereoisomer of 3α,5α-tetrahydroprogesterone, which may act as an antagonist for GABAergic steroids, are increased. Antidepressant drugs such as selective serotonin reuptake inhibitors (SSRIs) or mirtazapine apparently have an impact on key enzymes of neurosteroidogenesis and have been shown to normalize the disequilibrium of neuroactive steroids in depression by increasing 3α-reduced pregnane steroids and decreasing 3β,5α-tetrahydroprogesterone. Moreover, 3α-reduced neuroactive steroids have been demonstrated to possess antidepressant- and anxiolytic-like effects both in animal and human studies for themselves. In addition, the translacator protein (18 kDa) (TSPO), previously called peripheral benzodiazepine receptor, is the key element of the mitochondrial import machinery supplying the substrate cholesterol to the first steroidogenic enzyme (P450scc), which transforms cholesterol into pregnenolone, the precursor of all neurosteroids. TSPO ligands increase neurosteroidogenesis and are a target of novel anxiolytic drugs producing anxiolytic effects without causing the side effects normally associated with conventional benzodiazepines such as sedation or tolerance. This article is part of a Special Issue entitled: Neuroactive Steroids: Focus on Human Brain.

Metyrapone blunts stress-induced hyperthermia and increased locomotor activity independently of glucocorticoids and neurosteroids

Metyrapone, a cytochrome P(450) inhibitor used to inhibit corticosterone synthesis, triggers biological markers of stress and also reduces stress-induced anxiety-like behaviors. To address these controversial effects, 6 separate investigations were carried out. In a first set of investigations, abdominal temperature (T(abd)), spontaneous locomotor activity (A(S)) and electroencephalogram (EEG) were recorded in freely moving rats treated with either saline or 150 mg kg(-1) metyrapone. An increase in T(abd) and A(S) occurred in saline rats, while, metyrapone rats exhibited an immediate decrease, both variables returning to basal values 5h later. Concomitantly, the EEG spectral power increased in the gamma and beta 2 bands and decreased in the alpha frequency band, and the EMG spectral power increased. This finding suggests that metyrapone depressed stress-induced physiological response while arousing the animal. In a second step, restraint stress was applied 5h after injection. Metyrapone significantly blunted the stress-induced T(abd) and A(S) rise, without affecting the brain c-fos mRNA increase. Corticosterone (5 and 40 mg kg(-1)) injected concomitantly to metyrapone failed to reverse the observed metyrapone-induced effects in T(abd) and A(S). Finasteride (50 mg kg(-1)), which blocks neurosteroid production, was also unable to block these effects. In conclusion, metyrapone acutely reduced stress-induced physiological response in freely behaving rats independently from glucocorticoids and neurosteroids.

Glucocorticoids. Mood, memory, and mechanisms

Elevated circulating levels of glucocorticoids are associated with psychiatric symptoms across several different conditions. It remains unknown if this hormonal abnormality is a cause or an effect of the psychiatric conditions. For example, the hypercortisolemia observed in a subset of patients with depression may have a direct impact on the symptoms of depression, but it is also possible that the hypercortisolemia merely reflects the stress associated with depression. Further, rather than causing depression, hypercortisolemia could represent a homeostatic attempt to overcome glucocorticoid resistance. Each of these possibilities will be considered, and correlational and causal evidence will be reviewed. This article will focus on the relationships between glucocorticoids and psychiatric symptoms in Cushing's syndrome, major depression, and steroid psychosis/steroid dementia, as well as the effects of exogenously administered glucocorticoids in normal volunteers. Similarities and differences in the relationship of glucocorticoid hormones to psychiatric symptoms in these conditions will be reviewed. Possible mediators of glucocorticoid effects on the brain and behavior, as well as possible "pro-aging" effects of glucocorticoids in certain cells of the body, will be reviewed. The article concludes with a conceptual model of glucocorticoid actions in the brain that may lead to novel therapeutic opportunities.

Reference intervals of urinary steroid metabolites using gas chromatography-mass spectrometry in Chinese adults

BACKGROUND

Urinary steroid profiling by GC or GC-MS are established clinical tools to complement other biochemical tests in the diagnosis and investigation of a wide range of adrenocortical disorders, but normative data on adults using the more specific GC-MS are lacking. Our objective was to set up the reference intervals of commonly detected urinary steroid metabolites as well as marker metabolites seen in disease states.

METHOD

Apparently healthy adult Chinese males and females were recruited by completing health questionnaires. A 24-h urine specimen was collected from all the participants for urinary steroid profiling by GC-MS in cyclic scan mode. The analyzer was calibrated by using authentic steroid standards. Statistical methods recommended by the National Committee for Clinical Laboratory Standards were followed for setting up the reference intervals of various steroid metabolites. After outliers were excluded, the data were tested for the necessity to partition into sex-, menopausal status- and age-specific reference intervals.

RESULTS

83 males and 89 females were recruited for the study. Necessity to partition into sex-specific reference intervals was demonstrated for almost all steroid metabolites. Menopausal status and age also had a significant impact on steroid metabolite excretion, making separate reference intervals necessary.

CONCLUSIONS

We have set up the normative data on the levels of urinary steroid metabolite excretion in Chinese adults for future reference in patient management and research in steroid metabolism.

Drug treatment of depression in the 2000s: An overview of achievements in the last 10 years and future possibilities

During the past 10 years our knowledge about the pharmacotherapy of depression has been consolidated, and a variety of very interesting new compounds launched onto the market. The pipeline of the pharmaceutical industry is still filled with an assortment of new developments and very promising new approaches towards the pharmacotherapy of depressive disorders. Future pharmacological treatments of depression will not only enhance serotonergic and noradrenergic neurotransmission: other systems, such as the melatonergic receptor system and the hypothalamus-pituitary-adrenal axis, are also the targets of newly developed and upcoming substances with putative antidepressant effects. The main advantages of the currently available newer pharmacotherapeutic options are the broadening of the spectrum of possible antidepressant treatments, which is of particular importance for the growing number of patients suffering from difficult-to-treat depression, and a far better tolerability profile in comparison to older compounds such as tricyclic antidepressants. Unresolved issues are the unacceptably high rate of non-responsiveness during antidepressant treatment, a latency of sometimes several weeks until clinical improvement and remission can be achieved, and a variety of possible side effects also present during treatment with modern compounds. This review mainly presents the development of antidepressant pharmacotherapies during the past 10 years, together with pharmacokinetic and pharmacodynamic information and a comparison of different pharmacological treatment principles evaluated in randomized controlled clinical trials. In addition, new pharmacological strategies that are not yet available on the market and strategies currently under development are reviewed in detail. The study of new treatment options is of major importance to provide better strategies for the clinical management of depression in the future, and is thus also of great socio-economic importance.

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.

Evaluation of GABAergic neuroactive steroid 3alpha-hydroxy-5alpha-pregnane-20-one as a neurobiological substrate for the anti-anxiety effect of ethanol in rats

RATIONALE

Acute systemic ethanol administration is known to elevate plasma and cerebral levels of neuroactive steroid 3alpha-hydroxy-5alpha-pregnane-20-one (3alpha, 5alpha-THP; allopregnanolone) to a concentration sufficient to potentiate GABA(A) receptors. We have earlier demonstrated that 3alpha, 5alpha-THP mediates the antidepressant-like effect of ethanol in Porsolt forced swim test.

OBJECTIVE

The aim of the present study is to explain the relationship between endogenous GABAergic neurosteroids and anxiolytic effect of ethanol in Sprague-Dawley rats.

METHOD

The mediation of 3alpha, 5alpha-THP in the anti-anxiety effect of ethanol was assessed by pharmacological interactions of ethanol with various endogenous neurosteroidal modulators and using simulated physiological conditions of altered neurosteroid content in elevated plus maze (EPM) test.

RESULTS

Pretreatment of 3alpha, 5alpha-THP (0.5-2.5 mug/rat, i.c.v.) or neurosteroidogenic agents such as 3alpha, 5alpha-THP precursor progesterone (5 or 10 mg/kg, i.p.), 11-beta hydroxylase inhibitor metyrapone (50 or 100 mg/kg, i.p.) or the GABA(A) receptor agonist muscimol (25 ng/rat, i.c.v.) significantly potentiated the anti-anxiety effect of ethanol (1 g/kg, i.p.). On the other hand, the GABAergic antagonistic neurosteroid dehydroepiandrosterone sulphate (DHEAS) (1 mg/kg, i.p.), the GABA(A) receptor blocker bicuculline (1 mg/kg, i.p.), the 5alpha-reductase inhibitor finasteride (50 x 2 mg/kg, s.c.) or the mitochondrial diazepam binding inhibitory receptor antagonist PK11195 (1 mg/kg, i.p.) reduced ethanol-induced preference of time spent and number of entries into open arms. Anti-anxiety effect of ethanol was abolished in adrenalectomized (ADX) rats as compared to sham-operated control. This ADX-induced blockade was restored by prior systemic injection of progesterone, signifying the contribution of peripheral steroidogenesis in ethanol anxiolysis. Socially isolated animals known to exhibit decreased brain 3alpha, 5alpha-THP and GABA(A) receptor functions displayed reduced sensitivity to the effects of ethanol and 3alpha, 5alpha-THP in EPM test.

CONCLUSIONS

Our results demonstrated the contributory role of neuroactive steroid 3alpha, 5alpha-THP in the anti-anxiety effect of ethanol. It is speculated that ethanol-induced modulation of endogenous GABAergic neurosteroids, especially 3alpha, 5alpha-THP, might be crucial pertinent to the etiology of 'trait' anxiety (tension reduction) and ethanol abuse.

Essentiality of central GABAergic neuroactive steroid allopregnanolone for anticonvulsant action of fluoxetine against pentylenetetrazole-induced seizures in mice

Fluoxetine, a selective serotonin reuptake inhibitor, is known to increase the cortical content of allopregnanolone (ALLO) without altering the level of other neurosteroids. In contrast to the proconvulsant effect of many antidepressants, fluoxetine exhibits anticonvulsant effects. The present study was undertaken to examine the role of ALLO in the anticonvulsant action of fluoxetine against pentylenetetrazole (PTZ)-induced seizures in mice. Prior administration of GABA(A) receptor agonist muscimol or neurosteroid ALLO or progesterone, a precursor of ALLO or neurosteroidogenic drugs like FGIN 1-27, an agonist at the mitochondrial diazepam binding inhibitor receptor (MDR) or metyrapone, an 11beta-hydroxylase inhibitor, significantly potentiated the anticonvulsant effect of fluoxetine. In contrast, the effect of fluoxetine was counteracted by inhibition of the neurosteroid biosynthesis using drugs like 5alpha-reductase inhibitor, finasteride; 3beta-hydroxysteroid dehydrogenase inhibitor, trilostane; 3alpha-hydroxysteroid dehydrogenase inhibitor, indomethacin; MDR antagonist, PK 11195; or the GABA(A) receptor antagonist, bicuculline. Further, bilateral adrenalectomy had no significant effect on the anticonvulsant action of fluoxetine, suggesting negligible contribution from peripheral steroidogenesis. The anticonvulsant effect of fluoxetine was partially abolished in 5,7-DHT treated mice, indicating that the effect may also, in part, be dependent on serotonergic transmission. Thus, our data indicate that increased synthesis of ALLO in CNS is a major factor that ultimately leads to anticonvulsant effects of fluoxetine against PTZ-induced seizures.

Emerging experimental therapeutics for bipolar disorder: clues from the molecular pathophysiology

Bipolar affective disorder (manic-depressive illness) is a common, severe, chronic, and often life-threatening illness, associated with significant comorbidity. The recognition of the significant morbidity and mortality of patients with bipolar disorder, as well as the growing appreciation that a high percentage of patients respond poorly to existing treatments, has made the task of discovering new therapeutic agents, that are both efficacious and have few side effects increasingly more important. Most recent agents introduced into the pharmacopeia for the treatment of bipolar disorder have been anticonvulsants and atypical antipsychotics. We propose that novel treatments developed specifically for bipolar disorder will arise from (1) understanding more precisely the molecular mechanisms of treatments that are clearly efficacious or (2) developing medications based on the knowledge obtained of the underlying pathophysiology of bipolar disorder. Knowledge with regard to the underlying pathophysiology of bipolar disorder is increasing at a rapid pace, including alterations in intracellular signaling cascades as well as impairments of cellular plasticity and resilience in critical neuronal circuits. We propose that therapeutics designed to enhance cellular plasticity and resilience and that counter maladaptive stress-responsive systems may have considerable utility for the treatment of bipolar disorder. Therapeutic strategies designed to address cellular resilience and plasticity include the regulation of neurotrophic pathways, glucocorticoid signaling, phosphodiesterase activity, and glutamatergic throughput and mitochondrial function. While the task of developing novel medications for bipolar disorder is truly daunting, these and similar approaches will ultimately lead to better medications for the millions who suffer from this devastating illness.

CRH, Stress, and Major Depression: A Psychobiological Interplay

Major depressive disorder (MDD) is a complex disease and is one of the leading causes of disability in our society. The provoking factors are multiple; acute and chronic psychological stress, severe early trauma experiences, somatic disease, and genetic factors all play a role. This review focuses on hyperdrive of corticotropin-releasing hormone (CRH) as the fundamental neurobiological correlate of MDD. CRH plays a key role in the adaptation to acute stress, but chronic CRH hyperdrive leads to a number of disadvantageous emotional and somatic effects. The evidence that the HPA axis is hyperactive in MDD, probably as a result of a primary hyperdrive of CRH, comes from multiple sources: biochemical studies, functional HPA axis tests, neuroimaging and postmortem studies, and clinical trials with HPA axis-related compounds. The liability to develop CRH hyperdrive is probably partly genetic. For a number of relevant genes, transgenic animal studies and human association studies indicate a role in HPA axis regulation and the liability to develop CRH hyperdrive. These data are reviewed. Finally, early adverse experience can produce a lasting effect on HPA axis regulation as well, probably leading to a lifelong tendency to develop chronic CRH hyperdrive in response to stress. This has been shown in a number of animal studies, and recently some data in humans with early trauma have become available as well. Taken together, these findings allow formulating an integrative hypothesis, with CRH hyperdrive at the core, bridging the old dichotomy between biology and psychology in our thinking about MDD.

Double-blind antiglucocorticoid treatment in schizophrenia and schizoaffective disorder: a pilot study

BACKGROUND

Antiglucocorticoids, such as ketoconazole, have been investigated as antidepressant agents in major depression and other conditions. Despite evidence that a significant number of patients with schizophrenia and schizoaffective disorder are both hypercortisolemic and depressed, the antidepressant effects of antiglucocorticoids have never been assessed in these populations.

METHODS

Fifteen symptomatic patients with diagnoses of schizophrenia or schizoaffective disorder, who were at least partially treatment-resistant, were treated with ketoconazole, up to 800 mg/day, (n = 8) or placebo (n = 7) for four weeks in a double-blind manner. The study medication was added to a pre-stabilized antipsychotic and/or antidepressant medication regimen.

RESULTS

Ketoconazole treatment, compared to placebo, was associated with significant improvements in observer-rated depression, but not in subjectively rated depression, positive or negative psychotic symptom ratings, or cognitive performance scores.

CONCLUSIONS

These pilot data partially support the hypothesis that antiglucocorticoids reduce depressive symptoms in patients with schizophrenia and schizoaffective disorder, although objective and subjective ratings may not be similarly affected during a four-week course of treatment. Further studies with larger sample sizes, more extensive endocrine assessments and longer duration of drug administration seem warranted.

Antiglucocorticoid drugs in the treatment of depression

A confluence of evidence indicates that prolonged elevation in gluco-corticoid level may result in disturbances of mood and cognition. In Cushing's syndrome, hypersecretion of cortisol is associated with a high incidence of depression, impairment in memory and hippocampal atrophy. Pharmacological usage of glucocorticoids is similarly productive of mood change and memory deficit. In patients with endogenous depression, hypercortisolaemia is associated with cognitive dysfunction and possibly a decrease in hippocampal volume. In each of these conditions, reduction of glucocorticoid level, either through discontinuation of steroid treatment or through usage of agents that block glucocorticoid synthesis, ameliorates the adverse behavioural effects. Traditional antidepressant agents may, in addition, stabilise mood through actions on the hypothalamic-pituitary adrenocortical (HPA) system. Although clinical usage of the currently available antiglucocorticoid drugs is limited by significant adverse side effect profiles, development of drugs specifically targeting the glucocorticoid receptor may lead to innovative strategies in the treatment of mood disorders.

Salivary cortisol measurements during a medically assisted alcohol withdrawal

Previous studies using plasma cortisol estimations have suggested that hypothalmo-pituitary-axis (HPA) activation occurs in alcohol-dependent patients during alcohol withdrawal. The present study set out to confirm this finding using salivary cortisol assays, which are a better indicator of plasma free cortisol, the fraction which exerts its physiological effects. Nine alcohol dependent patients provided four saliva samples (at 10 a.m., 2 p.m., 6 p.m. and 10 p.m.) on days 1, 3 and 7 of a medically assisted alcohol withdrawal (corresponding to 1, 3 and 7 days following the last drink, respectively).Withdrawal symptom severity, craving and mood disturbance were also measured. A group of non-alcohol-dependent individuals, without psychiatric or medical disorder, gave four samples at the same times on one day only. Mean daily cortisol levels in our alcohol-dependent population, as calculated by the area under the curve (AUC), decreased significantly over time (mean AUC (nmol/l/hour) on day 1 = 149, on day 7 = 85.7, p = 0.009) and were significantly higher than controls on each day (mean AUC in controls = 28.3, p = 0.001). The cortisol response showed a similar temporal trend to withdrawal symptom severity and mood disturbance. This is consistent with previous studies measuring plasma cortisol in alcohol withdrawal. However, the magnitude of the effect in our study was greater, and in contrast to some previous studies, levels were far from normal by day 7. The comparatively low cortisol response in our one mildly dependent patient suggests that there may be a relationship between dependence severity and the size of the cortisol response to withdrawal. Salivary cortisol sampling could prove to be a useful prognostic tool, with implications for subsequent withdrawal symptom severity, mood disturbances, risk of relapse and alcohol-related cognitive decline. There are implications for developing new treatments for alcohol withdrawal but more studies are needed.

Stress hormone-related psychopathology: pathophysiological and treatment implications

Stress is commonly associated with a variety of psychiatric conditions, including major depression, and with chronic medical conditions, including diabetes and insulin resistance. Whether stress causes these conditions is uncertain, but plausible mechanisms exist by which such effects might occur. To the extent stress-induced hormonal alterations (e.g., chronically elevated cortisol levels and lowered dehydroepiandrosterone [DHEA] levels) contribute to psychiatric and medical disease states, manipulations that normalize these hormonal aberrations should prove therapeutic. In this review, we discuss mechanisms by which hormonal imbalance (discussed in the frameworks of "allostatic load" and "anabolic balance") might contribute to illness. We then review certain clinical manifestations of such hormonal imbalances and discuss pharmacological and behavioural treatment strategies aimed at normalizing hormonal output and lessening psychiatric and physical pathology.

Quantitative aspects of stress-induced immunomodulation

Recent studies indicate that neuroendocrine-immune interactions can cause sufficient immunosuppression to adversely affect human health, but quantitative relationships between stress-related hormones or neurotransmitters and immune function have not been well documented. The mechanisms of stress-induced immunomodulation cannot be fully understood solely by identifying the hormones, neurotransmitters, and cytokines involved. Quantitative relationships and interactions must also be understood. Depending on the nature and duration of the stressor and the immunological parameter under investigation, stress responses can enhance, have no effect, or suppress immunological parameters. These quantitative relationships have implications with regard to safety assessment of drugs and chemicals and with regard to potential development of pharmacological interventions to ameliorate some of the immunosuppressive effects of stress. This review describes selected studies that relate the quantity and duration of exposure to stress-related neuroendocrine mediators to modulation of the immune system. These studies provide a useful starting point, but they also illustrate how much work remains to achieve a fully integrated qualitative and quantitative understanding of stress-induced immunomodulation.

Ketoconazole in bipolar patients with depressive symptoms: a case series and literature review

BACKGROUND

Data from several studies suggest that medications, such as ketoconazole, which lower cortisol levels, may be effective for major depressive disorder (MDD). As with MDD, the manic, depressive, and mixed phases of bipolar disorder are frequently associated with elevated cortisol levels. The literature on the use of cortisol-lowering strategies in mood disorders is reviewed, and a case series illustrating the use of ketoconazole in bipolar depression is presented.

METHODS

For the review, the MEDLINE and PSYCHINFO databases were searched, as were the bibliographies of pertinent articles to find papers on the use of cortisol-lowering agents in patients with mood disorders. In our open-label case series (n = 6), ketoconazole (up to 800 mg/day) as an add-on therapy was given to patients with treatment-resistant or intolerant bipolar I or II disorders with current symptoms of depression.

RESULTS

Several case reports and small open studies suggest that cortisol-lowering agents may be useful for patients with depression. Two recent placebo-controlled trials of ketoconazole on patients with MDD report conflicting results. In our case series, all three patients who received a dose of at least 400 mg/day had substantial reductions in depressive symptoms. None had significant increases in mania. However, cortisol levels were not lowered in any of the subjects.

CONCLUSIONS

The literature suggests that cortisol-lowering medications may be effective for a subset of depressed patients. Our preliminary findings suggest that ketoconazole may be useful in some patients with bipolar depression. Larger clinical trials are needed to confirm our observations.

Future therapeutic targets in mood disorders: the glucocorticoid receptor

BACKGROUND

The hypercortisolaemia and dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis associated with mood disorders have been attributed to a breakdown in the glucocorticoid-receptor-mediated negative feedback mechanism regulating HPA activity. Reinstating normal feedback may be therapeutic in mood disorders.

AIMS

To review the evidence for the involvement of the glucocorticoid receptor in the pathogenesis and treatment of mood disorders.

METHOD

Medline and hand searches were carried out, selecting literature relevant to psychiatrists and psychopharmacologists.

RESULTS

A dysfunction in glucocorticoid receptors is integral to the HPA abnormalities of mood disorders. Antidepressant and mood-stabilising drugs can up-regulate glucocorticoid receptors, restoring glucocorticoid function. Preliminary clinical studies targeting the glucocorticoid receptor are encouraging.

CONCLUSIONS

Drugs designed specifically to up-regulate glucocorticoid receptors may be integral to future strategies in treating mood disorders.

Antidepressant-like effect of the neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one in mice forced swim test

The present study aimed to examine the antidepressant-like effect of the neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha, 5alpha THP) using the forced swim test in mice. Intracerebroventricular (ICV, 1 or 2 microg/mouse) or intraperitoneal (IP, 0.5, 1, or 2 mg/kg) administration of 3alpha, 5alpha THP dose-dependently reduced the duration of immobility in forced swim test without accompanying changes in ambulatory or rearing behaviors in the open-field test. The antidepressant-like effect of 3alpha, 5alpha THP (1 microg/mouse, ICV) was potentiated by prior administration of the GABA(A) receptor agonist, muscimol (0. 5 mg/kg, IP) and blocked by prior administration of GABA(A) receptor antagonist, bicuculline (1 mg/kg, IP). Administration of the agonist at diazepam binding inhibitor receptors, 4'-chlorodiazepam (4'CD, 15 mg/kg, IP) or N,N-di-n-hexyl-2-(4-fluorophenyl)-indol-3-acetamide (FGIN 1-27, 1 or 2 microg/mouse, ICV), the 11beta-hydroxylase inhibitor, metyrapone (150 mg/kg, IP and 1 or 2 microg/mouse, ICV) and the selective serotonin reuptake inhibitor (SSRI), fluoxetine (20 mg/kg, IP), which are known to increase the endogenous level of neurosteroids, also reduced the duration of immobility in forced swim test. The tricyclic antidepressant, imipramine (20 mg/kg, IP), which does not increase the 3alpha, 5alpha THP in the brain, also reduced the immobility time. While the antidepressant-like effect of fluoxetine, which is known to selectively increase the brain content of 3alpha, 5alpha THP, was either blocked partially by bicuculline (1 mg/kg, IP) or potentiated by muscimol (0.5 mg/kg, IP), the antidepressant-like effect of imipramine was not modified by bicuculline. These results demonstrate the antidepressant-like effect of the neurosteroid 3alpha, 5alpha THP, and suggest further evaluation for its development as a new class of antidepressant drug.

Inhibition of microglial nitric oxide production by hydrocortisone and glucocorticoid precursors

Viral and bacterial infection in the central nervous system can induce nitric oxide production, which serves as a major host defense against invading microorganisms. Glucocorticoids secretion is enhanced and immune responses are diminished in stressed animals or in patients suffering depression. Using N9 microglial cells, this study tested the hypothesis that glucocorticoids and their precursors caused an impaired immune defense in animals because these compounds could inhibit microglial nitric oxide production. Results indicated that both hydrocortisone and the synthetic glucocorticoid, dexamethasone, were potent inhibitors of the microglial nitric oxide production. While glucocorticoid precursors were not as potent as hydrocortisone, the potency of these precursors increased linearly as they advanced on the biosynthesis pathway. Northern and Western blot analyses indicated that hydrocortisone and dexamethasone might interfere with the inducible nitric oxide synthase at either the transcription or at the post-translational level, depending on the concentrations used. These results suggest that glucocorticoids have the ability to block nitric oxide production by microgila, which could partially explain the impaired immune protection against infection in the central nervous system in stressed animals.

Treatment of depression with antiglucocorticoid drugs

OBJECTIVE

The theoretical and empirical rationales for the potential therapeutic use of antiglucocorticoid agents in the treatment of depression are reviewed.

METHOD

Individual case reports, case series, open-label, and double-blind, controlled trials of the usage of cortisol-lowering treatments in Cushing's syndrome and major depression are evaluated and critiqued.

RESULTS

In each of the 28 reports of antiglucocorticoid treatment of Cushing's syndrome, antidepressant effects were noted in some patients; the largest two series document a response rate of 70% to 73%. Full response, however, was at times erratic and delayed. Across the 11 studies of antiglucocorticoid treatment of major depression, some degree of antidepressant response was noted in 67% to 77% of patients. Antidepressant or antiobsessional effects of antiglucocorticoid augmentation of other psychotropic medications have also been noted in small studies of patients with treatment-resistant depression, obsessive-compulsive disorder, and schizoaffective disorder or schizophrenia.

CONCLUSIONS

These promising results with antiglucocorticoid treatment must be interpreted cautiously because of the small sample sizes and heterogeneity of the studies reviewed, the bias favoring publication of positive results, and the open-label nature of most of the studies. Although definitive controlled trials remain to be conducted, there is a consistent body of evidence indicating that cortisol-lowering treatments may be of clinical benefit in select individuals with major depression and other hypercortisolemic conditions.

Antiglucocorticoid treatment of depression: double-blind ketoconazole

BACKGROUND

Hypercortisolemia is frequently observed in major depression but its pathophysiologic significance is unknown. In patients in whom hypercortisolism contributes to depressive symptomatology, antiglucocorticoid agents should have antidepressant effects.

METHODS

Twenty medication-free depressed patients (eight of whom were hypercortisolemic and twelve of whom were not) received either the cortisol biosynthesis inhibitor, ketoconazole (400-800 mg/d p.o.) or placebo for 4 weeks in a double-blind manner, and behavioral ratings were performed weekly.

RESULTS

Ketoconazole, compared to placebo, was associated with improvements in depression ratings in the hypercortisolemic, but not in the non-hypercortisolemic patients. The hormonal changes seen (decreased dehydroepiandrosterone and testosterone levels and increased pregnenolone and pregnenolone-sulfate levels) are consistent with enzymatic blockade of C17,20-lyase, 11-hydroxylase, and 17-hydroxylase. Ketoconazole was generally well tolerated with no occurrence of significant side effects or laboratory abnormalities.

CONCLUSIONS

This small-scale double-blind study suggests that antiglucocorticoids have antidepressant activity in hypercortisolemic depressed patients. The data are consistent with a causal role of adrenocortical dysfunction in some depressed patients and suggest the need for larger-scale trials.

Neuroactive steroid concentrations following metyrapone administration in depressed patients and healthy volunteers

BACKGROUND

There is evidence that treatment with the 11 beta-hydroxylase inhibitor metyrapone may represent an alternative treatment strategy in major depression. As a consequence of inhibition of cortisol synthesis the overdrive of corticotropin leads to an accumulation of precursor steroids. However, the effects of metyrapone on the concentrations of endogenous neuroactive steroids that modulate ion channels, e.g., the GABAA receptor, have not yet been studied systematically.

METHODS

Therefore, we quantified the concentrations of an array of neuroactive steroids following administration of 1.5 g metyrapone before and after pretreatment with 1 mg dexamethasone in 19 patients suffering from severe depression in comparison to 13 healthy controls by means of a highly sensitive gas chromatography/mass spectrometry analysis.

RESULTS

The administration of metyrapone induced a pronounced increase in all neuroactive steroids studied both in patients and controls that was prevented by dexamethasone pretreatment.

CONCLUSIONS

Thus, the psychotropic properties of endogenous neuroactive steroids may contribute to the antidepressant properties of metyrapone in the treatment of major depression.

Metyrapone is a competitive inhibitor of 11beta-hydroxysteroid dehydrogenase type 1 reductase

The present study was designed to examine the effects of metyrapone in vitro on the activities of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) types 1 and 2, the two intracellular enzymes responsible for the metabolism of glucocorticoids. Enzymatic activities of 11beta-HSD1 and 2 were determined by a radiometric conversion assay using cortisol and cortisone as physiological substrates. The enzyme activity assays were carried out in the absence and presence of metyrapone using sheep liver and kidney microsomes as the source of 11beta-HSD1 and 2, respectively. It was found that metyrapone inhibited the reductase activity of 11beta-HSD1 in a dose-dependent manner with an apparent Ki of 30 microM. Moreover, this inhibition was competitive because the Km for cortisone was increased in the presence of metyrapone. In contrast, metyrapone showed biphasic effects on the dehydrogenase activity of 11beta-HSD1, in that it increased the activity at concentrations lower than 100 microM but decreased it at higher concentrations. However, under similar conditions, metyrapone had little effect on the unidirectional dehydrogenase activity of 11beta-HSD2. In conclusion, the present results provide the first direct evidence that metyrapone is a competitive inhibitor of 11beta-HSD1 reductase, and that it also exerts biphasic effects on 11beta-HSD1 dehydrogenase activity. These findings indicate that metyrapone influences peripheral glucocorticoid metabolism through its regulation of 11beta-HSD1 activity, in addition to its classic inhibitory effects on adrenal steroid biosynthesis. It is therefore imperative that this novel extra-adrenal effect of metyrapone be considered when this drug is used in the diagnosis and treatment of adrenocorticoid-related diseases.