Influence of sleep deprivation on neuroactive steroids in major depression

The emergence of antidepressant drugs targeting GABAA receptors: A concise review

Depression is among the most common psychiatric illnesses, which imposes a major socioeconomic burden on patients, caregivers, and the public health system. Treatment with classical antidepressants (e.g. tricyclic antidepressants and selective serotonine reuptake inhibitors), which primarily affect monoaminergic systems has several limitations, such as delayed onset of action and moderate efficacy in a relatively large proportion of depressed patients. Furthermore, depression is highly heterogeneus, and its different subtypes, including post-partum depression, involve distinct neurobiology, warranting a differential approach to pharmacotherapy. Given these shortcomings, the need for novel antidepressants that are superior in efficacy and faster in onset of action is fully justified. The development and market introduction of rapid-acting antidepressants has accelerated in recent years. Some of these new antidepressants act through the GABAergic system. In this review, we discuss the discovery, efficacy, and limitations of treatment with classic antidepressants. We provide a detailed discussion of GABAergic neurotransmission, with a special focus on GABAA receptors, and possible explanations for the mood-enhancing effects of GABAergic medications (in particular neurosteroids acting at GABAA receptors), and, ultimately, we present the most promising molecules belonging to this family which are currently used in clinical practice or are in late phases of clinical development.

Neurosteroids and translocator protein 18 kDa (TSPO) ligands as novel treatment options in depression

Recently, the gamma-aminobutyric acid (GABA) system has come into focus for the treatment of anxiety, postpartum depression, and major depressive disorder. Endogenous 3α-reduced steroids such as allopregnanolone are potent positive allosteric modulators of GABAA receptors and have been known for decades. Current industry developments and first approvals by the U.S. food and drug administration (FDA) for the treatment of postpartum depression with exogenous analogues of these steroids represent a major step forward in the field. 3α-reduced steroids target both synaptic and extrasynaptic GABAA receptors, unlike benzodiazepines, which bind to synaptic receptors. The first FDA-approved 3α-reduced steroid for postpartum depression is brexanolone, an intravenous formulation of allopregnanolone. It has been shown to provide rapid relief of depressive symptoms. An orally available 3α-reduced steroid is zuranolone, which also received FDA approval in 2023 for the treatment of postpartum depression. Although a number of studies have been conducted, the efficacy data were not sufficient to achieve approval of zuranolone in major depressive disorder by the FDA in 2023. The most prominent side effects of these 3α-reduced steroids are somnolence, dizziness and headache. In addition to the issue of efficacy, it should be noted that current data limit the use of these compounds to two weeks. An alternative to exogenous 3α-reduced steroids may be the use of substances that induce endogenous neurosteroidogenesis, such as the translocator protein 18 kDa (TSPO) ligand etifoxine. TSPO has been extensively studied for its role in steroidogenesis, in addition to other functions such as anti-inflammatory and neuroregenerative properties. Currently, etifoxine is the only clinically available TSPO ligand in France for the treatment of anxiety disorders. Studies are underway to evaluate its antidepressant potential. Hopefully, neurosteroid research will lead to the development of fast-acting antidepressants.

Changes in neuroactive steroids, neurotrophins and immunological biomarkers after monotherapy 8-week rTMS treatment and their relationship with neurocognitive functions in depression

Repetitive transcranial magnetic stimulation (rTMS) has proven effective in the treatment of major depression. The underlying mechanisms of action are still poorly understood. We aimed to evaluate the changes in the levels of neuroactive steroids, neurotrophins and immunological biomarkers before and after rTMS treatment and assess the relationship of this change between clinical response and cognitive functions after monotherapy rTMS treatment. Twenty-three patients with major depressive disorder (MDD) and 25 matched healthy controls were included in the study. The Hamilton Depression Rating Scale (HDRS), Trail Making Test A and B forms and Digit Span Test were administered. Biomarkers (BDNF, TNF-α, IL-1ß, NAS) were run in the peripheral blood at the end of the first month that rTMS was administered daily and at the end of the 2nd month when that rTMS was administered once a week. Appropriate conditions were provided so that the relevant biomarkers were not affected by the biorhythm. After rTMS monotherapy, an increase in BDNF and allopregnanolone, a decrease in TNF-α, IL-1ß, DHEA, and DHEA-S levels was found to be statistically significant. The scores on cognitive tests increased with the treatment. Positive significant correlations was found between BDNF levels and cognitive tests at the end of the first and second months. Our findings suggest that the effects of rTMS treatment may be related to the neuroendocrine, neurotrophin, and immunological mechanisms. rTMS treatment is found to have positive effects on cognitive functions in the short term.

Effects of paroxetine treatment and its withdrawal on neurosteroidogenesis

Selective serotonin reuptake inhibitors (SSRI) show high efficacy in treating depression, however during treatment side effects, like for instance sexual dysfunction, may appear, decreasing compliance. In some cases, this condition will last after drug discontinuation, leading to the so-called post-SSRI sexual dysfunction (PSSD). The etiology of PSSD is still unknown, however a role for neuroactive steroids may be hypothesized. Indeed, these molecules are key physiological regulators of the nervous system, and their alteration has been associated with several neuropathological conditions, including depression. Additionally, neuroactive steroids are also involved in the control of sexual function. Interestingly, sexual dysfunction induced by SSRI treatment has been also observed in animal models. On this basis, we have here evaluated whether a subchronic treatment with paroxetine for two weeks and/or its withdrawal (i.e., a month) may affect the levels of neuroactive steroids in brain areas (i.e., hippocampus, hypothalamus, and cerebral cortex) and/or in plasma and cerebrospinal fluid of male rats. Data obtained indicate that the SSRI treatment alters neuroactive steroid levels and the expression of key enzymes of the steroidogenesis in a brain tissue- and time-dependent manner. Indeed, these observations with the finding that plasma levels of neuroactive steroids are not affected suggest that the effect of paroxetine treatment is directly on neurosteroidogenesis. In particular, a negative impact on the expression of steroidogenic enzymes was observed at the withdrawal. Therefore, it is possible to hypothesize that altered neurosteroidogenesis may also occur in PSSD and consequently it may represent a possible pharmacological target for this disorder.

Prenatal resident-intruder stress decreases levels of allopregnanolone in the cortex, hypothalamus, and midbrain of males, and increases levels in the hippocampus and cerebellum of female, juvenile rat offspring

Prenatal stress (PNS) can influence behaviors associated with cognition, reward and emotional regulation, which are controlled by brain areas such as the cortex, hippocampus, hypothalamus, midbrain and cerebellum. Allopregnanolone in these regions modulates behavioral and parasympathetic effects. The current study tested whether exposing pregnant dams to 5 days of resident-intruder stress on prenatal days 15-20 for 10 min altered the levels of allopregnanolone in cortex, hypothalamus, hippocampus, midbrain, and cerebellum of male and female juvenile offspring. In cortex, hypothalamus, and midbrain of male rats exposed to prenatal stress, levels of allopregnanolone were significantly lower compared to all other groups. In the hippocampus and cerebellum, among females exposed to prenatal stress levels were significantly higher compared to all other groups. These differences in allopregnanolone levels varying by prenatal stress, sex and brain regions provide insight in potential mechanism of stress regulation and etiopathophysiology of stress-related disorders.

Chronotype, social jetlag and sleep loss in relation to sex steroids

Chronotype describes preferences for functioning at different times of the day. At the onset of puberty, a sharp shift towards eveningness starts, reaching its peak at the end of adolescence, followed by a steady shift towards morningness as the ageing process occurs. Puberty is also the time when sex differences appear, with men being more inclined to eveningness than women, which diminishes around menopause; the described pattern of changes in chronotype leads to the hypothesis that reproductive hormones may be the driving factor behind this conversion. In the present study, we aimed to verify this hypothesis by analysing participants' testosterone, progesterone and dehydroepiandrosterone (DHEA) levels in the three months, as indicated by assays in 3-cm hair strands from the scalp. Participants (n = 239) of both sexes also completed the Munich Chronotype Questionnaire. The results showed that in men higher testosterone levels were related to eveningness and less sleep loss, whereas greater sleep loss was associated with lower levels of DHEA. In women, no associations between chronotype and levels of the analysed hormones were found. The results support the hypothesis that testosterone levels play a role in shaping eveningness. We further hypothesised that a possible cause of the higher secretion level of testosterone in men with the evening chronotype is a mechanism to offset the negative consequences of sleep loss.

Investigating relations among stress, sleep and nail cortisol and DHEA

In the current study, we present data investigating the relationships among stress, sleep disturbance, self-control, and levels of cortisol (CORT) and dehydroepiandrosterone (DHEA) in fingernail clippings. Currently, hair CORT is the only routinely used noninvasive, validated, biomarker of chronic exposure to stress-related hormones. Nail clippings represent an important potential alternative sample matrix for assessing chronic hormone exposure, as it offers a different timeline of hormone incorporation than scalp hair, and may be obtainable from populations in which hair either is lacking or is unavailable for cultural reasons. Moreover, there is established precedent for using fingernail clippings to attain biomarker data. However, the value of nail hormone assessment for psychological research is currently unknown due to a paucity of information on the relations between nail hormone concentrations and environmental or psychological variables. In the present study, we collected data from a low income, minority population (N = 47; 97% African American) to demonstrate feasibility and acceptability of nail collection and analysis of the adrenal steroids CORT and DHEA. Participants reported on perceived stress, sleep and self-control abilities. Correlational analyses suggest that exposure to stressful events, disturbances in sleep and waking were associated with higher levels of nail DHEA, while self-control was associated with higher levels of nail CORT. We discuss the potential importance of this methodology for investigating biological, behavioral, and subjective indices of stress and well-being.

LC–MS/MS simultaneous analysis of allopregnanolone, epiallopregnanolone, pregnanolone, dehydroepiandrosterone and dehydroepiandrosterone 3-sulfate in human plasma

Aim: Several neuropsychopharmacological properties have been attributed to the 3α-reduced pregnane steroids, allopregnanolone and pregnanolone, as well as to dehydroepiandrosterone sulfate because of their ability to modulate γ-aminobutyric acid (GABAA) receptors in the CNS. In order to understand better their role in several mechanisms in CNS, a new methodology is proposed to monitor these compounds in human plasma. Methodology & results: The analytes were first derivatized with 2-hydrazinopyridine and extracted from plasma using SPE. Then, the compounds were separated and detected by LC–MS/MS. A mobile phase of formic acid (0.1%) in water and methanol through a gradient of composition and a flow rate of 0.3 ml min-1 resulted in good separations of the analytes. Linear responses in wide range of concentrations and LOQs ranging from 10 (dehydroepiandrosterone 3-sulfate) to 40 pg ml-1 (dehydroepiandrosterone) were obtained in <9 min. The method proposed has been validated and then applied to monitor these neurosteroids in plasma samples from ten volunteers. Conclusion: For the first time, a straightforward and reliable method for the chromatographic separation of allopregnanolone, epiallopregnanolone and pregnanolone, as well as of dehydroepiandrosterone and dehydroepiandrosterone 3-sulfate was carried out, with optimal accuracy, sensitivity and specificity.

Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society on the Recommended Amount of Sleep for a Healthy Adult: Methodology and Discussion

The American Academy of Sleep Medicine and Sleep Research Society recently released a Consensus Statement regarding the recommended amount of sleep to promote optimal health in adults. This paper describes the methodology, background literature, voting process, and voting results for the consensus statement. In addition, we address important assumptions and challenges encountered during the consensus process. Finally, we outline future directions that will advance our understanding of sleep need and place sleep duration in the broader context of sleep health.

Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society on the Recommended Amount of Sleep for a Healthy Adult: Methodology and Discussion

The American Academy of Sleep Medicine and Sleep Research Society recently released a Consensus Statement regarding the recommended amount of sleep to promote optimal health in adults. This paper describes the methodology, background literature, voting process, and voting results for the consensus statement. In addition, we address important assumptions and challenges encountered during the consensus process. Finally, we outline future directions that will advance our understanding of sleep need and place sleep duration in the broader context of sleep health.

GABAA receptor-acting neurosteroids: a role in the development and regulation of the stress response

Regulation of hypothalamic-pituitary-adrenocortical (HPA) axis activity by stress is a fundamental survival mechanism and HPA-dysfunction is implicated in psychiatric disorders. Adverse early life experiences, e.g. poor maternal care, negatively influence brain development and programs an abnormal stress response by encoding long-lasting molecular changes, which may extend to the next generation. How HPA-dysfunction leads to the development of affective disorders is complex, but may involve GABAA receptors (GABAARs), as they curtail stress-induced HPA axis activation. Of particular interest are endogenous neurosteroids that potently modulate the function of GABAARs and exhibit stress-protective properties. Importantly, neurosteroid levels rise rapidly during acute stress, are perturbed in chronic stress and are implicated in the behavioural changes associated with early-life adversity. We will appraise how GABAAR-active neurosteroids may impact on HPA axis development and the orchestration of the stress-evoked response. The significance of these actions will be discussed in the context of stress-associated mood disorders.

Effects of electroconvulsive therapy on plasma levels of neuroactive steroids in inpatients with major depression

OBJECTIVE

Neuroactive steroids (NAS) are neuroactive molecules that have been shown to be associated with various psychiatric disorders. There are some inconclusive findings about the alteration in neuroactive steroid levels after the treatment of depression and ECT is still one of the most effective treatment choices for treatment resistant depression. Thus, we aimed to investigate the alterations of several NAS in plasma after ECT in inpatients with treatment resistant depression.

METHODS

In this study we enrolled 19 consecutive patients, 12 female and 7 male inpatients with major depression, who were not responding to medication, for whom ECT was Indicated, and were not taking any antidepressant treatment for at least a week prior to enrolment. We measured plasma progesterone, testosterone, pregnenolone, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate, and estradiol levels before and after ECT.

RESULTS

The mean age of the participants was 38.3 ± 9.4 years. The mean plasma neuroactive steroid levels were insignificant between baseline and post ECT in patients with treatment resistant depression.

CONCLUSIONS

ECT does not seem to influence plasma neuroactive steroid levels in patients with treatment resistant depression. Additionally, plasma dehydroepiandrosterone and pregnenolone levels might be associated with improvement in depressive symptoms after ECT.

5α-reductase type I expression is downregulated in the prefrontal cortex/Brodmann's area 9 (BA9) of depressed patients

RATIONALE

The implications of the neurosteroid 3α-hydroxy-5α-pregnan-20-one [allopregnanolone (Allo)] in neuropsychiatric disorders have been highlighted in several recent clinical investigations. For instance, Allo levels are decreased in the cerebrospinal fluid (CSF) of patients with posttraumatic stress disorder (PTSD) and major unipolar depression. Neurosteroidogenic antidepressants [i.e., selective brain steroidogenic stimulants (SBSSs)], including fluoxetine and analogs, correct this decrease in a manner that correlates with improved depressive symptoms. Allo positively and allosterically modulates GABA action at postsynaptic and extrasynaptic GABAA receptors. It is synthesized in both the human and rodent brain cortices by principal glutamatergic pyramidal neurons from progesterone by the sequential action of 5α-reductase type I (5α-RI), which is the rate-limiting step enzyme in Allo biosynthesis, and 3α-hydroxysteroid dehydrogenase (3α-HSD), which converts 5α-dehydroprogesterone into Allo.

HYPOTHESIS

We thus hypothesized that decreased CSF levels of Allo in depressed patients could reflect a brain dysfunction of 5α-RI.

METHODS

In a pilot study of samples from six patients per group [six depressed patients and six nonpsychiatric subjects (NPS)], we studied the expression of 5α-RI messenger RNA (mRNA) in prefrontal cortex Brodmann's area 9 (BA9) and cerebellum from depressed patients obtained from the Maryland Brain Collection at the Maryland Psychiatric Research Center (Baltimore, MD) that were age-matched with NPS.

RESULTS

The levels of 5α-RI mRNA were decreased from 25 ± 5.8 in NPS to 9.1 ± 3.1 fmol/pmol neuronal specific enolase (NSE) (t1,10 = 2.7, P = 0.02) in depressed patients. These differences are absent in the cerebellum of the same patients. The levels of neurosteroids were determined in the prefrontal cortex BA9 of depressed patients obtained from the Stanley Foundation Brain Bank Neuropathology Consortium, Bethesda (MD). The BA9 levels of Allo in male depressed patients failed to reach statistical difference from the levels of NPS (1.63 ± 1.01 pg/mg, n = 8, in NPS and 0.82 ± 0.33 pg/mg, n = 5, in nontreated depressed patients). However, depressed patients who had received antidepressant treatment (three patients SSRI and one TCA) exhibited increased BA9 Allo levels (6.16 ± 2.5 pg/mg, n = 4, t1,9 = 2.4, P = 0.047) when compared with nontreated depressed patients.

CONCLUSIONS

Although in a small number of patients, this finding is in-line with previous reports in the field that have observed an increase of Allo levels in CSF and plasma of depressed patients following antidepressant treatment. Hence, the molecular mechanisms underlying major depression may include a GABAergic neurotransmission deficit caused by a brain Allo biosynthesis downregulation, which can be normalized by SBSSs.

Multifunctional aspects of allopregnanolone in stress and related disorders

Allopregnanolone (3α-hydroxy-5α-pregnan-20-one) is a major cholesterol-derived neurosteroid in the central nervous system and is synthesized from progesterone by steroidogenic enzymes, 5α-reductase (the rate-limiting enzyme) and 3α-hydroxysteroid dehydrogenase. The pathophysiological role of allopregnanolone in neuropsychiatric disorders has been highlighted in several investigations. The changes in neuroactive steroid levels are detected in stress and stress-related disorders including anxiety, panic and depression. The changes in allopregnanolone in response to acute stressor tend to restore the homeostasis by dampening the hyper-activated HPA axis. However, long standing stressors leading to development of neuropsychiatric disorders including depression and anxiety are associated with decrease in the allopregnanolone levels. GABAA receptor complex has been considered as the primary target of allopregnanolone and majority of its inhibitory actions are mediated through GABA potentiation or direct activation of GABA currents. The role of progesterone receptors in producing the late actions of allopregnanolone particularly in lordosis facilitation has also been described. Moreover, recent studies have also described the involvement of other multiple targets including brain-derived neurotrophic factor (BDNF), glutamate, dopamine, opioids, oxytocin, and calcium channels. The present review discusses the various aspects of allopregnanolone in stress and stress-related disorders including anxiety, depression and panic.

The role of allopregnanolone in depression and anxiety

Neuroactive steroids such as allopregnanolone do not only act as transcriptional factors in the regulation of gene expression after intracellular back-oxidation into the 5-α pregnane steroids but may also alter neuronal excitability through interactions with specific neurotransmitter receptors. In particular, certain 3α-reduced metabolites of progesterone such as 3α,5α-tetrahydroprogesterone (allopregnanolone) and 3α,5β-tetrahydroprogesterone (pregnanolone) are potent positive allosteric modulators of the GABA(A) receptor complex. During the last years, the downregulation of neurosteroid biosynthesis has been intensively discussed to be a possible contributor to the development of anxiety and depressive disorder. Reduced levels of allopregnanolone in the peripheral blood or cerebrospinal fluid were found to be associated with major depression, anxiety disorders, premenstrual dysphoric disorder, negative symptoms in schizophrenia, or impulsive aggression. The importance of allopregnanolone for the regulation of emotion and its therapeutical use in depression and anxiety may not only involve GABAergic mechanisms, but probably also includes enhancement of neurogenesis, myelination, neuroprotection, and regulatory effects on HPA axis function. Certain pharmacokinetic obstacles limit the therapeutic use of natural neurosteroids (low bioavailability, oxidation to the ketone). Until now synthetic neuroactive steroids could not be established in the treatment of anxiety disorders or depression. However, the translocator protein (18 kDa) (TSPO) which is important for neurosteroidogenesis has been identified as a potential novel target. TSPO ligands such as XBD 173 increase neurosteroidogenesis and have anxiolytic effects with a favorable side effect profile.

Effects and Mechanisms of 3α,5α,-THP on Emotion, Motivation, and Reward Functions Involving Pregnane Xenobiotic Receptor

Progestogens [progesterone (P(4)) and its products] play fundamental roles in the development and/or function of the central nervous system during pregnancy. We, and others, have investigated the role of pregnane neurosteroids for a plethora of functional effects beyond their pro-gestational processes. Emerging findings regarding the effects, mechanisms, and sources of neurosteroids have challenged traditional dogma about steroid action. How the P(4) metabolite and neurosteroid, 3α-hydroxy-5α-pregnan-20-one (3α,5α-THP), influences cellular functions and behavioral processes involved in emotion/affect, motivation, and reward, is the focus of the present review. To further understand these processes, we have utilized an animal model assessing the effects, mechanisms, and sources of 3α,5α-THP. In the ventral tegmental area (VTA), 3α,5α-THP has actions to facilitate affective, and motivated, social behaviors through non-traditional targets, such as GABA, glutamate, and dopamine receptors. 3α,5α-THP levels in the midbrain VTA both facilitate, and/or are enhanced by, affective and social behavior. The pregnane xenobiotic receptor (PXR) mediates the production of, and/or metabolism to, various neurobiological factors. PXR is localized to the midbrain VTA of rats. The role of PXR to influence 3α,5α-THP production from central biosynthesis, and/or metabolism of peripheral P(4), in the VTA, as well as its role to facilitate, or be increased by, affective/social behaviors is under investigation. Investigating novel behavioral functions of 3α,5α-THP extends our knowledge of the neurobiology of progestogens, relevant for affective/social behaviors, and their connections to systems that regulate affect and motivated processes, such as those important for stress regulation and neuropsychiatric disorders (anxiety, depression, schizophrenia, drug dependence). Thus, further understanding of 3α,5α-THP's role and mechanisms to enhance affective and motivated processes is essential.

Neurosteroids and GABA(A) Receptor Interactions: A Focus on Stress

Since the pioneering discovery of the rapid CNS depressant actions of steroids by the "father of stress," Hans Seyle 70 years ago, brain-derived "neurosteroids" have emerged as powerful endogenous modulators of neuronal excitability. The majority of the intervening research has focused on a class of naturally occurring steroids that are metabolites of progesterone and deoxycorticosterone, which act in a non-genomic manner to selectively augment signals mediated by the main inhibitory receptor in the CNS, the GABA(A) receptor. Abnormal levels of such neurosteroids associate with a variety of neurological and psychiatric disorders, suggesting that they serve important physiological and pathophysiological roles. A compelling case can be made to implicate neurosteroids in stress-related disturbances. Here we will critically appraise how brain-derived neurosteroids may impact on the stress response to acute and chronic challenges, both pre- and postnatally through to adulthood. The pathological implications of such actions in the development of psychiatric disturbances will be discussed, with an emphasis on the therapeutic potential of neurosteroids for the treatment of stress-associated disorders.

The GABAergic deficit hypothesis of major depressive disorder

Increasing evidence points to an association between major depressive disorders (MDDs) and diverse types of GABAergic deficits. In this review, we summarize clinical and preclinical evidence supporting a central and causal role of GABAergic deficits in the etiology of depressive disorders. Studies of depressed patients indicate that MDDs are accompanied by reduced brain concentration of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) and by alterations in the subunit composition of the principal receptors (GABA(A) receptors) mediating GABAergic inhibition. In addition, there is abundant evidence that suggests that GABA has a prominent role in the brain control of stress, the most important vulnerability factor in mood disorders. Furthermore, preclinical evidence suggests that currently used antidepressant drugs (ADs) designed to alter monoaminergic transmission and nonpharmacological therapies may ultimately act to counteract GABAergic deficits. In particular, GABAergic transmission has an important role in the control of hippocampal neurogenesis and neural maturation, which are now established as cellular substrates of most if not all antidepressant therapies. Finally, comparatively modest deficits in GABAergic transmission in GABA(A) receptor-deficient mice are sufficient to cause behavioral, cognitive, neuroanatomical and neuroendocrine phenotypes, as well as AD response characteristics expected of an animal model of MDD. The GABAergic hypothesis of MDD suggests that alterations in GABAergic transmission represent fundamentally important aspects of the etiological sequelae of MDDs that are reversed by monoaminergic AD action.

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.

Venlafaxine and mirtazapine treatment lowers serum concentrations of dehydroepiandrosterone-sulfate in depressed patients remitting during the course of treatment

OBJECTIVES

The adrenal androgen dehydroepiandrosterone-sulfate (DHEA-S) seems to be involved in the pathophysiology of depression, although its precise role in the etiology and remission of depression remains unclear. In the present study we intended to examine possible differential effects of venlafaxine and mirtazapine in a randomised open trial with regard to DHEA-S serum concentrations in patients suffering from major depressive episode compared to healthy controls.

METHODS

We assessed DHEA-S concentrations both at baseline and after a 4-week treatment period in 70 depressed patients (n=33 for venlafaxine and n=37 for mirtazapine) and 33 matched healthy controls.

RESULTS

We describe the decrease of DHEA-S levels in depressive patients who remitted after treatment with both venlafaxine or mirtazapine. Patients without remission of depression did not show a significant decline in DHEA-S concentrations.

CONCLUSIONS

Our results suggest an effect of treatment outcome upon DHEA-S concentrations rather than a direct drug effect. The change of plasma DHEA-S levels as a marker of treatment-response of depression warrant further investigation.

Neuroactive steroids after estrogen exposure in depressed postmenopausal women treated with sertraline and asymptomatic postmenopausal women

Neuroactive steroids (NAS) allopregnanolone (ALLO), Allotetrahydrodeoxycorticosterone (THDOC) and dehydroepiandrosterone (DHEA) are important in the regulation of mood and behavior. Knowledge about these steroids in postmenopausal depression and the effect of estrogen on NAS is lacking. We elected to determine if there were differences in NAS between postmenopausal depressed women and age matched controls. We also investigated the effect of estradiol on NAS in post menopausal depressed women receiving a selective serotonin reuptake inhibitor (SSRI), and in non-depressed postmenopausal controls. As part of a previously published double blind study on estrogen acceleration of antidepressant action, post menopausal women with major depression receiving sertraline and healthy non depressed controls were randomized to transdermal estrogen patch 0.1 mg or placebo. NAS were measured at baseline and after 10 weeks of treatment. Depressed subjects were treated with sertraline 50 mg/day to 100 mg/day for 9 weeks. At the baseline and after treatment ALLO and DHEA were significantly lower in depressed women compared to controls. Although all depressed subjects experienced a positive clinical response, estrogen administration was not associated with changes in NAS in either the depressed or the asymptomatic postmenopausal women. The lower ALLO and DHEA in postmenopausal depressed women suggests that symptoms of depression may be influenced by the synthesis or fluctuation of these NAS. Estradiol exposure did not alter ALLO, DHEA, or THDOC, implying these NAS are unlikely to play a role in any mood changes in post menopausal women given estrogen therapy.

Studies of pharmacokinetic and pharmacodynamic properties of isoallopregnanolone in healthy women

RATIONALE

The pharmacokinetics and behavioral effects of isoallopregnanolone (3beta-hydoxy-5alpha-pregnan-20-one) in women are not known.

OBJECTIVES

Allopregnanolone (3alpha-hydoxy-5alpha-pregnan-20-one) is a well-known neurosteroid, acting via the GABA(A) receptor in the human brain. The naturally occurring progesterone metabolite isoallopregnanolone is the 3beta-stereoisomer of allopregnanolone. Prior studies have concluded that isoallopregnanolone has no effect on the GABA(A) receptor. However, an antagonistic effect of isoallopregnanolone to allopregnanolone on the GABA(A) receptor has been shown in animal and in vitro studies. The purpose of this study was to evaluate the pharmacokinetics and behavioral effects of isoallopregnanolone in humans.

MATERIALS AND METHODS

Six healthy women were given three increasing doses of isoallopregnanolone intravenously in the follicular phase. Repeated blood samples for analyses of isoallopregnanolone and allopregnanolone concentrations were drawn. Saccadic eye movement variables, self-rated sedation, and mood rating scales were used during the test day. A Likert scale for prospective symptoms was used to measure daily fluctuations during the ongoing menstrual cycle.

RESULTS

Exogenously administered isoallopregnanolone produced a dose-dependent increase in the serum concentration of isoallopregnanolone. In parallel, there was also a rise in the allopregnanolone concentration. There was a decrease in saccadic eye movement variables, but no effect was found on self-rated sedation or mood and no changes were seen in prospective symptoms during the menstrual cycle.

CONCLUSIONS

After administration of isoallopregnanolone at a cumulative dose of 0.20 mg/kg, no adverse effects were observed. There is a metabolism of isoallopregnanolone to allopregnanolone, most likely explaining the effects on the saccadic eye movements.

Effects of mirtazapine on dehydroepiandrosterone-sulfate and cortisol plasma concentrations in depressed patients

BACKGROUND

Among the neuroactive steroids, dehydroepiandrosterone sulfate (DHEA-S) is at least in part produced in the adrenal gland and is therefore under the control of the hypothalamic-pituitary-adrenocortical (HPA)-system. In the present study, the impact of mirtazapine on DHEA-S and cortisol (COR) levels was investigated in relation to clinical response in depressed patients.

METHODS

A total of 23 inpatients suffering from a major depressive episode (DSM-IV criteria) underwent 5-week treatment with mirtazapine (45 mg/day). Plasma samples were taken weekly at 0800 h and quantified for COR and DHEA-S levels.

RESULTS

Mirtazapine significantly reduced both COR and DHEA-S concentrations, but had no impact on the COR/DHEA-S ratio. The percentage decrease of DHEA-S, but not that of COR was significantly and positively correlated with the percentage reduction in the sum score of the Hamilton Depression Rating Scale at week 5, suggesting a relationship between DHEA-S reduction and clinical efficacy of mirtazapine. There was a significant positive correlation between the decline in COR and DHEA-S levels.

CONCLUSIONS

Apparently, the decrease in COR and DHEA-S concentrations conjointly reflects an attenuating impact of mirtazapine on HPA axis activity, thereby decreasing the adrenal secretion of COR and DHEA-S.

The complex roles of neurosteroids in depression and anxiety disorders

The role of neurosteroids in neuropsychiatric disorders has been thoroughly investigated in many research studies that have stressed their significant pathophysiological function in neuropsychiatry. In this review, we will focus mainly on the steroids active on the GABA(A) receptors studied in anxiety and depression. The aim is to discuss the controversial results reported in research on anxiety and depressive disorders. We suggest the combined use of biological parameters linked to psychopathological dimensions to make more homogeneous diagnoses and to develop more precise therapies for the treatment of depression and anxiety disorders. We discuss the role of neurosteroids in the pathophysiology and therapy of anxiety and depression. Finally, we consider the possibility of using quantification of mRNA expression of steroidogenic enzymes from peripheral sources in neuropsychiatry.

Effects of combination treatment with mood stabilizers and mirtazapine on plasma concentrations of neuroactive steroids in depressed patients

Antidepressants such as SSRIs or mirtazapine have been demonstrated to increase the concentrations of 3alpha-reduced neuroactive steroids throughout several weeks of treatment. However, no data are available on the impact of mood stabilizers such as lithium or carbamazepine on neuroactive steroid levels in depressed patients. Study 1 was performed in 26 drug-free depressed inpatients who were treated with either mirtazapine monotherapy (n=13) or combination therapy with mirtazapine and addition of lithium (n=13). Twenty drug-free depressed inpatients were included in study 2, receiving either mirtazapine monotherapy (n=10) or combination treatment with mirtazapine and carbamazepine (n=10). Plasma samples were taken weekly at 0800 h in the morning and quantified for neuroactive steroids by means of combined gas chromatography/mass spectrometry analysis. In study 1, the mirtazapine-induced rises in 3alpha,5alpha-tetrahydroprogesterone and 3alpha,5beta-tetrahydroprogesterone were abolished by additional lithium administration, as compared to mirtazapine monotherapy. In study 2, the mirtazapine-evoked increase in 3alpha,5alpha-tetrahydroprogesterone was reversed after additional administration of carbamazepine, presumably due to lowered mirtazapine levels after induction of cytochrome P450 enzymes. Apparently, the mood stabilizers lithium and carbamazepine do not enhance but rather reverse the increase in plasma concentrations of 3alpha-reduced neuroactive steroids in depressed patients pretreated with antidepressants such as mirtazapine.

GABA(A) receptor neurotransmission dysfunction in a mouse model of social isolation-induced stress: possible insights into a non-serotonergic mechanism of action of SSRIs in mood and anxiety disorders

Protracted social isolation in laboratory animals causes stress, which induces a variety of behavioral abnormalities including increased aggressiveness, anxiety-related behaviors, cognitive deficits and hyper locomotion. Many of these disorders are similar to the symptoms found in psychiatric disorders, such as depression, anxiety, premenstrual dysphoria and posttraumatic stress disorders (PTSD). Recent studies have demonstrated that male mice that have been socially isolated for more than 4 weeks show: (a) reduced responsiveness of GABA(A) receptors (GABA(A)-R) to the administrations of GABA mimetic drugs at GABA(A)-R; (b) downregulated biosynthesis of 3alpha,5alpha-tetrahydroprogesterone (3alpha,5alpha-THP) (allopregnanolone: ALLO), a neurosteroid with a potent positive allosteric modulatory effect on the action of GABA on GABA(A)-R; and (c) alterations in the expression of GABA(A)-R subunits (i.e. a decrease of alpha1/alpha2 and gamma2 subunits and an increase of alpha4 and alpha5 subunits). The selective serotonin reuptake inhibitor (SSRI) fluoxetine (FLX) and its congener norfluoxetine (Nor-FLX), when administered systemically at nmol/kg doses, normalize the reduced content of brain ALLO and the reduced responsiveness of GABA(A)-R to GABA mimetic drugs (i.e. pentobarbital) and also attenuate aggressive behavior in socially isolated mice in a stereospecific manner. Although these compounds inhibit ex vivo serotonin reuptake into brain tissue, their SSRI activities require high micromol/kg dose ranges and are not stereospecific. These studies suggest that in socially isolated mice, abnormalities of GABA(A)-R signal transduction are attributable to the downregulation of ALLO production and to a switch in heteropentameric GABA(A)-R subunit assembly composition. Hence, the normalization of ALLO biosynthesis may be a new target for the development of drugs effective for psychiatric disorders related to neurosteroid biosynthesis downregulation.

Neuroactive steroids and affective disorders

Neuroactive steroids modulate neurotransmission through modulation of specific neurotransmitter receptors such as gamma-aminobutyric acid type A (GABA(A)) receptors. Preclinical studies suggested that neuroactive steroids may modulate anxiety and depression-related behaviour and may contribute to the therapeutical effects of antidepressant drugs. Attenuations of such neuroactive steroids have been observed during major depression and in several anxiety disorders, suggesting a pathophysiological role in such psychiatric conditions. In panic disorder patients a dysequilibrium of neuroactive steroid composition has been observed, which may represent a counterregulatory mechanism against the occurrence of spontaneous panic attacks. Furthermore, alterations of 3alpha-reduced pregnane steroids during major depression were corrected by successful treatment with antidepressant drugs. However in contrast, non-pharmacological antidepressant treatment strategies did not affect neuroactive steroid composition. In addition, changes in neuroactive steroid concentrations after mirtazapine therapy occurred independently from the clinical response, thereby suggesting that changes in neuroactive steroid concentrations more likely reflect direct pharmacological effects of antidepressants rather than clinical improvement in general. Nevertheless, the effects of antidepressant pharmacotherapy on the composition of neuroactive steroids may contribute to the alleviation of certain depressive symptoms, such as amelioration of anxiety, inner tension or sleep disturbances. Moreover, first studies investigating the therapeutical effects of dehydroepiandrosterone revealed promising results in the treatment of major depression. In conclusion, neuroactive steroids are important endogenous modulators of depression and anxiety and may provide a basis for development of novel therapeutic agents in the treatment of affective disorders.

Difference in pre- and post-treatment plasma DHEA levels were significantly and positively correlated with difference in pre- and post-treatment Hamilton depression scores following successful therapy for major depression

OBJECTIVE

Clinical studies of endogenous concentrations of dehydroepiandrosterone (DHEA) and its relation to depression are limited. This study examined whether pre- and post-treatment changes in plasma DHEA levels are correlated with pre- and post-treatment differences in Hamilton depression scores following successful antidepressant therapy for major depression with venlafaxine XR.

METHOD

Thirty-four medication-free major depressive outpatients (Hamilton Rating Scale for Depression 17, HAM-D 17 score > or = 17) were treated with antidepressants. At baseline, plasma DHEA levels of all subjects were measured but only those who remitted (HAM-D 17 score < or = 7) before the end of this study had their plasma DHEA levels measured at remission-onset. Blood from subjects was drawn at 0900-1100 h. Depression severity was assessed with the HAM-D 17 scale at baseline, and on day 7, 14, 28, 56 and 84. Subjects were administered at minimum 75 mg/day venlafaxine XR until remission onset.

RESULTS

Fifteen patients remitted before the end of this study. Plasma DHEA levels decreased from baseline to remission was significant (P=0.017). After controlling for age and gender, pre- and post-treatment difference in Hamilton depression scores and the pre- and post-treatment difference in DHEA concentrations were significantly correlated (P=0.044).

CONCLUSION

This preliminary study provides the first clinical evidence identifying that difference in pre- and post-treatment plasma DHEA levels were significantly and positively correlated with difference in pre- and post-treatment Hamilton depression scores following successful therapy with venlafaxine XR for major depression in remitters; but non-remitters were not examined. It is not known if DHEA levels would show similar or dissimilar changes in non-remitters.

Neurosteroids, neuroactive steroids, and symptoms of affective disorders

Neurosteroids (NS) are steroids synthesized by the brain. Neuroactive steroids (NAS) refers to steroids that, independent of their origin, are capable of modifying neural activities. NAS bind and modulate different types of membrane receptors. The gamma amino butyric acid (GABA) and sigma receptor complexes have been the most extensively studied. Oxidized ring A reduced pregnanes, tetrahydroprogesterone (THP), and tetrahydrodeoxycorticosterone (THDOC) bind to the progesterone intracellular receptor (PR), and in this way can also regulate gene expression. Animal experimentation showed that salient symptoms of depression, viz., anxiety, sleep disturbances, and memory and sexual dysfunctions, are modulated by NAS. In turn, psychotropic drugs modulate NS and NAS levels. NS levels as well as NAS plasma concentrations change in patients with depression syndromes, the levels return to normal baseline with recovery, but normalization is not necessary for successful therapy. Results from current studies on the evolution of nervous systems, including evolutionary developmental biology as well as anatomical and physiological findings, almost preclude a categorical classification of the psychiatric ailments the human brain succumbs to. The persistence in maintaining such essentialist classifications may help to explain why up to now the search for biological markers in psychiatry has been an unrewarding effort. It is proposed that it would be more fruitful to focus on relationships between NAS and symptoms of psychiatric disorders, rather than with typologically defined disorders.

Neuroactive steroids as modulators of depression and anxiety

In addition to the well-known genomic effects of steroid molecules, certain neuroactive steroids control neurotransmission through the modulation of specific neurotransmitter receptors. Preclinical studies suggested that neuroactive steroids may modulate anxiety and depression-related behavior and may contribute to the therapeutic effects of antidepressant drugs. However, nonpharmacological antidepressant treatment strategies did not affect neuroactive steroid composition. These studies suggest that the changes in neuroactive steroids observed after antidepressant pharmacotherapy probably reflect distinct pharmacological properties of antidepressants, rather than the clinical response. Nevertheless, initial studies investigating the antidepressive effects of exogenously administered dehydroepiandosterone revealed promising results. In addition, in various anxiety disorders, alterations of neuroactive steroid levels have been observed. In conclusion, neuroactive steroids contribute to the pathophysiology of affective disorders and the mechanisms of action of antidepressants. They are important endogenous modulators of depression and anxiety and might offer new targets for the development of novel anxiolytic compounds.

Relevance of endogenous 3alpha-reduced neurosteroids to depression and antidepressant action

The naturally occurring 3alpha-reduced neurosteroids allopregnanolone and its isomer pregnanolone are among the most potent positive allosteric modulators of gamma-aminobutyric acid type A receptors. They play a critical role in the maintenance of physiological GABAergic tone and display a broad spectrum of neuropsychopharmacological properties. We have reviewed existing evidence implicating the relevance of endogenous 3alpha-reduced neuroactive steroids to depression and to the mechanism of action of antidepressants. A wide range of preclinical and clinical evidence suggesting the antidepressant potential of 3alpha-reduced neuroactive steroids and a possible involvement of a deficiency and a disequilibrium of neuroactive steroid levels in pathomechanisms underlying the etiology of major depressive disorder have emerged in recent years. Antidepressants elevate 3alpha-reduced neurosteroid levels in rodent brain, and clinically effective antidepressant pharmacotherapy is associated with normalization of plasma and cerebrospinal fluid (CSF) concentrations of endogenous neuroactive steroids in depressed patients, unveiling a possible contribution of neuroactive steroids to the mechanism of action of antidepressants. In contrast, recent studies using nonpharmacological antidepressant therapy suggest that changes in plasma neuroactive steroid levels may not be a general mandatory component of clinically effective antidepressant treatment per se, but may reflect distinct properties of pharmacotherapy only. While preclinical studies offer convincing evidence in support of an antidepressant-like effect of 3alpha-reduced neuroactive steroids in rodent models of depression, current clinical investigations are inconclusive of an involvement of neuroactive steroid deficiency in the pathophysiology of depression. Moreover, clinical evidence is merely suggestive of a role of neuroactive steroids in the mechanism of action of clinically effective antidepressant therapy. Additional clinical studies evaluating the impact of successful pharmacological and nonpharmacological antidepressant therapies on changes in neuroactive steroid levels in both plasma and CSF samples of the same patients are necessary in order to more accurately address the relevance of 3alpha-reduced neuroactive steroids to major depressive disorder. Finally, proof-of-concept studies with drugs that are known to selectively elevate brain neurosteroid levels may offer a direct assessment of an involvement of neurosteroids in the treatment of depressive symptomatology.

Neuropsychopharmacological properties of neuroactive steroids in depression and anxiety disorders

Neuroactive steroids modulate neurotransmission through modulation of specific neurotransmitter receptors such as gamma-aminobutyric acid type A (GABAA) receptors. Preclinical studies suggested that neuroactive steroids may modulate anxiety- and depression-related behaviour and may contribute to the therapeutical effects of antidepressant drugs. Attenuations of 3alpha-reduced neuroactive steroids have been observed during major depression. This disequilibrium can be corrected by successful treatment with antidepressant drugs. However, non-pharmacological antidepressant treatment strategies did not affect neuroactive steroid composition independently from the clinical response. Further research is needed to clarify whether enhancement of neuroactive steroid levels might represent a new therapeutical approach in the treatment of affective disorders. Nevertheless, the first studies investigating the therapeutical effects of exogenously administered dehydroepiandosterone revealed promising results in the treatment of major depression. In addition, in various anxiety disorders alterations of neuroactive steroid levels have been observed. In panic disorder, in the absence of panic attacks, neuroactive steroid composition is opposite to that seen in depression, which may represent counter-regulatory mechanisms against the occurrence of spontaneous panic attacks. However, during experimentally induced panic attacks, there was a pronounced decline in GABAergic neuroactive steroids, which might contribute to the pathophysiology of panic attacks. In conclusion, neuroactive steroids contribute to the pathophysiology of affective disorders and the mechanisms of action of antidepressants. They are important endogenous modulators of depression and anxiety and may provide a basis for the development of novel therapeutic agents in the treatment of affective disorders.

Neuroactive steroids as modulators of depression and anxiety

Certain neuroactive steroids modulate ligand-gated ion channels via non-genomic mechanisms. Especially 3alpha-reduced pregnane steroids are potent positive allosteric modulators of the GABA type A-receptor. During major depression there is a dysequilibrium of 3alpha-reduced neuroactive steroids, which is corrected by clinically effective pharmacological treatment. To investigate whether these alterations are a general principle of successful antidepressant treatment we studied the impact of non-pharmacological treatment options on neuroactive steroid concentrations during major depression. Neither partial sleep deprivation, transcranial magnetic stimulation nor electroconvulsive therapy affected neuroactive steroid levels irrespectively of the response to these treatments. These studies suggest that the changes in neuroactive steroids observed after antidepressant pharmacotherapy more likely reflect distinct pharmacological properties of antidepressants rather than the clinical response. In patients with panic disorder changes in neuroactive steroid composition have been observed opposite of those seen in depression. These changes may represent counterregulatory mechanisms against the occurrence of spontaneous panic attacks. However, during experimental panic induction with either cholecystokinin-tetrapeptide or sodium lactate there was a pronounced decline in the concentrations of 3alpha-reduced neuroactive steroids in patients with panic disorder, which might result in a decreased GABAergic tone. In contrast, no changes in neuroactive steroid concentrations could be observed in healthy controls with the exception of 3alpha, 5alpha-tetrahydrodeoxycorticosterone, allotetrahydrodeoxycorticosterone. The modulation of GABA type A-receptors by neuroactive steroids might contribute to the pathophysiology of depression and anxiety disorders and might offer new targets for the development of novel anxiolytic compounds.

Influence of mirtazapine on plasma concentrations of neuroactive steroids in major depression and on 3alpha-hydroxysteroid dehydrogenase activity

Concentrations of 3alpha-reduced neuroactive steroids are altered in depression and normalize after antidepressant pharmacotherapy with selective serotonin re-uptake inhibitors (SSRIs). We investigated the impact of mirtazapine on the activity of a key neurosteroidogenic enzyme, the 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD), and on the levels of neuroactive steroids in relation to clinical response. A total of 23 drug-free in-patients suffering from a major depressive episode (DSM-IV criteria) underwent 5-week treatment with mirtazapine (45 mg/day). Plasma samples were taken weekly at 0800 and quantified for neuroactive steroids by means of combined gas chromatography/mass spectrometry analysis. Enzyme activity was determined by assessment of steroid conversion rates. Irrespective of clinical outcome, there were significant increases in 3alpha,5alpha-tetrahydroprogesterone, 3alpha,5beta-tetrahydroprogesterone, 5alpha-dihydroprogesterone, and 5beta-dihydroprogesterone after mirtazapine treatment, whereas 3beta,5alpha-tetrahydroprogesterone levels were significantly decreased. In vitro investigations demonstrated a dose-dependent inhibitory effect of mirtazapine on the activity of the microsomal 3alpha-HSD in the oxidative direction (conversion of 3alpha,5alpha-tetrahydroprogesterone to 5alpha-dihydroprogesterone). Mirtazapine affects neuroactive steroid composition similarly as do SSRIs. The inhibition of the oxidative pathway catalyzed by the microsomal 3alpha-HSD is compatible with an enhanced formation of 3alpha-reduced neuroactive steroids. However, the changes in neuroactive steroid concentrations more likely reflect direct pharmacological effects of this antidepressant rather than clinical improvement in general.

Neuroactive steroids in depression and anxiety disorders: clinical studies

Certain neuroactive steroids modulate ligand-gated ion channels via non-genomic mechanisms. Especially 3alpha-reduced pregnane steroids are potent positive allosteric modulators of the gamma-aminobutyric acid type A (GABA(A)) receptor. During major depression, there is a disequilibrium of 3alpha-reduced neuroactive steroids, which is corrected by clinically effective pharmacological treatment. To investigate whether these alterations are a general principle of successful antidepressant treatment, we studied the impact of nonpharmacological treatment options on neuroactive steroid concentrations during major depression. Neither partial sleep deprivation, transcranial magnetic stimulation, nor electroconvulsive therapy affected neuroactive steroid levels irrespectively of the response to these treatments. These studies suggest that the changes in neuroactive steroid concentrations observed after antidepressant pharmacotherapy more likely reflect distinct pharmacological properties of antidepressants rather than the clinical response. In patients with panic disorder, changes in neuroactive steroid composition have been observed opposite to those seen in depression. However, during experimentally induced panic induction either with cholecystokinine-tetrapeptide or sodium lactate, there was a pronounced decline in the concentrations of 3alpha-reduced neuroactive steroids in patients with panic disorder, which might result in a decreased GABAergic tone. In contrast, no changes in neuroactive steroid concentrations could be observed in healthy controls with the exception of 3alpha,5alpha-tetrahydrodeoxycorticosterone. The modulation of GABA(A) receptors by neuroactive steroids might contribute to the pathophysiology of depression and anxiety disorders and might offer new targets for the development of novel anxiolytic compounds.

Plasma concentrations of neuroactive steroids before and after electroconvulsive therapy in major depression

There is evidence that both cerebrospinal fluid (CSF) and plasma concentrations of 3alpha-reduced neuroactive steroids are decreased in major depressive disorder. Successful antidepressant pharmacotherapy, for example, with selective serotonin reuptake inhibitors (SSRIs), over several weeks is accompanied by an increase in CSF and plasma concentrations of these neuroactive steroids. However, no such increase has been observed during nonpharmacological treatments such as partial sleep deprivation or repetitive transcranial magnetic stimulation. In order to investigate whether concentration changes in neuroactive steroids are an important component of clinically effective antidepressant treatment, we examined plasma concentrations of the neuroactive steroids 3alpha,5alpha-tetrahydroprogesterone, 3alpha,5beta-tetrahydroprogesterone, 3beta,5alpha-tetrahydroprogesterone, and their precursors progesterone, 5alpha-dihydroprogesterone, and 5beta-dihydroprogesterone in 31 pharmacotherapy-resistant depressed in-patients before and after unilateral electroconvulsive therapy (ECT) as a monotherapy over 4 weeks. Samples were quantified for neuroactive steroids by means of a highly sensitive and specific combined gas chromatography/mass spectrometry analysis. In all, 51.6% of the patients were treatment responders. There was no influence of ECT on the plasma concentrations of any neuroactive steroid studied. Moreover, neuroactive steroid levels did not differ between treatment responders and nonresponders. Our study shows that changes in neuroactive steroid plasma levels are not a mandatory factor for successful antidepressant treatment by ECT. Thus, the previously observed changes in plasma concentrations of neuroactive steroids following treatment with antidepressants such as SSRIs more likely reflect distinct pharmacological properties of these compounds rather than clinical improvement.

Steroids, neuroactive steroids and neurosteroids in psychopathology

The term "neurosteroid" (NS) was introduced by Baulieu in 1981 to name a steroid hormone, dehydroepiandrosterone sulfate (DHEAS), that was found at high levels in the brain long after gonadectomy and adrenalectomy, and shown later to be synthetized by the brain. Later, androstenedione, pregnenolone and their sulfates and lipid derivatives as well as tetrahydrometabolites of progesterone (P) and deoxycorticosterone (DOC) were identified as neurosteroids. The term "neuroactive steroid" (NAS) refers to steroids which, independent of their origin, are capable of modifying neural activities. NASs bind and modulate different types of membrane receptors. The GABA and sigma receptor complexes have been the most extensively studied, while glycine-activated chloride channels, nicotinic acetylcholine receptors, voltage-activated calcium channels, although less explored, are also modulated by NASs. Within the glutamate receptor family, N-methyl-d-aspartate (NMDA) receptors, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and kainate receptors have also been demonstrated to be a target for steroid modulation. Besides their membrane effects, once inside the neuron oxidation of Ring A reduced pregnanes, THP and THDOC, bind to the progesterone intracellular receptor and regulate gene expression through this path. The involvement of NASs on depression syndromes, anxiety disorders, stress responses to different stress stimuli, memory processes and related phenomena such as long-term potentiation are reviewed and critically evaluated. The importance of context for the interpretation of behavioral effects of hormones as well as for hormonal levels in body fluids is emphasized. Some suggestions for further research are given.

Neuroactive Steroids in Responders and Nonresponders to Sleep Deprivation

Evidence from preclinical and clinical studies indicates that concentrations of neuroactive steroids are altered in depression and normalize after antidepressant pharmacotherapy. However, data on the impact of sleep deprivation on concentrations of neuroactive steroids are not available. Therefore, 29 drug-free patients (12 men, 17 women) with major depression according to DSM-IV criteria were treated with partial sleep deprivation (PSD). Response to PSD was defined as a reduction of at least 30% according to the 6-item version of the Hamilton Depression Scale (6-HAMD). Plasma samples were taken the day before and the day after PSD (day 0 and 1) and after one night of recovery sleep (day 2) at 8:00 am. Samples were quantified for neuroactive steroids by means of a highly sensitive and specific combined gas chromatography/mass spectrometry analysis. PSD did not influence concentrations of neuroactive steroids in either PSD responders (n = 20) or nonresponders (n = 9). However, nonresponders showed significantly higher concentrations of 3alpha,5alpha-tetrahydroprogesterone, 3alpha,5beta-tetrahydroprogesterone, and dehydroepiandrosterone before or after PSD compared to responders. In contrast to antidepressant drugs which correct the dysequilibrium of neuroactive steroids in major depression within several weeks, PSD does not affect the concentrations of neuroactive steroids in either responders or nonresponders.

Antidepressant treatment and dehydroepiandrosterone sulfate: different effects of amitriptyline and paroxetine

BACKGROUND

There is evidence for activation of the hypothalamus-pituitary-adrenal system in depressed patients to be associated with increased secretion of adrenal androgens. However, there is only limited information about the effect of different classes of antidepressants on the course of adrenal androgens.

METHODS

Dehydroepiandrosterone sulfate (DHEA-S) serum concentrations were measured in 80 patients being treated with amitriptyline (AMI) or paroxetine (PAROX) for a period of 35 days.

RESULTS

Using analysis of variance with repeated measures, we found a significant effect of treatment upon DHEA-S serum concentrations that declined more in AMI-treated (before vs. after: 1.89+/-1.16 vs. 1.46 +/- 0.96 mg/l), compared to PAROX-treated patients (1.56+/-1.09 vs. 1.50+/-1.04 mg/l).

CONCLUSIONS

Our results show changes in DHEA-S serum concentrations during antidepressant treatment to depend on medication.

Effects of the active neurosteroid allotetrahydrodeoxycorticosterone on long-term potentiation in the rat hippocampus: implications for depression

We studied the effects of the active neurosteroid (ANS) allotetrahydrodeoxy corticosterone (ATHDOC) on long-term potentiation (LTP) in the dentate gyrus (DG) of intact, urethane anesthetized rats. Intravenous injection of the hormone at two doses, 0.1 and 0.5 mg/kg, produced a significant decrease in both components of the response: excitatory postsynaptic potentials (EPSP) and population spikes (PS). The effects were similar for the two doses. The results are discussed in terms of the potential mechanism by which ATHDOC modulates neural processes associated with symptoms present in depression syndromes.