Fluoxetine decreases concentrations of 3 alpha, 5 alpha-tetrahydrodeoxycorticosterone (THDOC) in major depression

The adrenal steroid profile in adolescent depression: a valuable bio-readout?

There is preliminary evidence that adrenal steroids other than cortisol may be valuable biomarkers for major depressive disorder (MDD). So far, studies have been conducted in adults only, and conclusions are limited, mainly due to small sample sizes. Therefore, the present study assessed whether adrenal steroids serve as biomarkers for adolescent MDD. In 261 depressed adolescents (170 females) treated at a single psychiatric hospital, serum adrenal steroids (progesterone, 17-hydroxyprogesterone, 21-deoxycortisol, 11-deoxycortisol, cortisol, cortisone, deoxycorticosterone, corticosterone) were determined by liquid chromatography-tandem mass spectrometry. Findings were compared to that of an age- and sex-matched reference cohort (N = 255) by nonparametric analysis of variance. Nonparametric receiver operating characteristics (ROC) analyses were conducted to evaluate the diagnostic performance of single steroids and steroid ratios to classify depression status. Sensitivity analyses considered important confounders of adrenal functioning, and ROC results were verified by cross-validation. Compared to the reference cohort, levels of deoxycorticosterone and 21-deoxycortisol were decreased (P < 0.001). All other glucocorticoid- and mineralocorticoid-related steroids were increased (P < 0.001). The corticosterone to deoxycorticosterone ratio evidenced excellent classification characteristics, especially in females (AUC: 0.957; sensitivity: 0.902; specificity: 0.891). The adrenal steroid metabolome qualifies as a bio-readout reflecting adolescent MDD by a distinct steroid pattern that indicates dysfunction of the hypothalamus-pituitary-adrenal axis. Moreover, the corticosterone to deoxycorticosterone ratio may prospectively qualify to contribute to precision medicine in psychiatry by identifying those patients who might benefit from antiglucocorticoid treatment or those at risk for recurrence when adrenal dysfunction has not resolved.

The mechanisms of interactions of psychotropic drugs with liver and brain cytochrome P450 and their significance for drug effect and drug-drug interactions

Cytochrome P450 (CYP) plays an important role in psychopharmacology. While liver CYP enzymes are responsible for the biotransformation of psychotropic drugs, brain CYP enzymes are involved in the local metabolism of these drugs and endogenous neuroactive substances, such as neurosteroids, and in alternative pathways of neurotransmitter biosynthesis including dopamine and serotonin. Recent studies have revealed a relation between the brain nervous system and cytochrome P450, indicating that CYP enzymes metabolize endogenous neuroactive substances in the brain, while the brain nervous system is engaged in the central neuroendocrine and neuroimmune regulation of cytochrome P450 in the liver. Therefore, the effect of neuroactive drugs on cytochrome P450 should be investigated not only in vitro, but also at in vivo conditions, since only in vivo all mechanisms of drug-enzyme interaction can be observed, including neuroendocrine and neuroimmune modulation. Psychotropic drugs can potentially affect cytochrome P450 via a number of mechanisms operating at the level of the nervous, hormonal and immune systems, and the liver. Their effect on cytochrome P450 in the brain is often different than in the liver and region-dependent. Since psychotropic drugs can affect cytochrome P450 both in the liver and brain, they can modify their own pharmacological effect at both pharmacokinetic and pharmacodynamic level. The article describes the mechanisms by which psychotropic drugs can change the expression/activity of cytochrome P450 in the liver and brain, and discusses the significance of those mechanisms for drug action and drug-drug interactions. Moreover, the brain CYP2D6 is considered as a potential target for psychotropics.

Does Stress Trigger Seizures? Evidence from Experimental Models

This chapter describes the experimental evidence of stress modulation of epileptic seizures and the potential role of corticosteroids and neurosteroids in regulating stress-linked seizure vulnerability. Epilepsy is a chronic neurological disorder that is characterized by repeated seizures. There are many potential causes for epilepsy, including genetic predispositions, infections, brain injury, and neurotoxicity. Stress is a known precipitating factor for seizures in individuals suffering from epilepsy. Severe acute stress and persistent exposure to stress may increase susceptibility to seizures, thereby resulting in a higher frequency of seizures. This occurs through the stress-mediated release of cortisol, which has both excitatory and proconvulsant properties. Stress also causes the release of endogenous neurosteroids from central and adrenal sources. Neurosteroids such as allopregnanolone and THDOC, which are allosteric modulators of GABA-A receptors, are powerful anticonvulsants and neuroprotectants. Acute stress increases the release of neurosteroids, while chronic stress is associated with severe neurosteroid depletion and reduced inhibition in the brain. This diminished inhibition occurs largely as a result of neurosteroid deficiencies. Thus, exogenous administration of neurosteroids (neurosteroid replacement therapy) may offer neuroprotection in epilepsy. Synthetic neurosteroid could offer a rational approach to control neurosteroid-sensitive, stress-related epileptic seizures.

The engagement of brain cytochrome P450 in the metabolism of endogenous neuroactive substrates: a possible role in mental disorders

The current state of knowledge indicates that the cerebral cytochrome P450 (CYP) plays an important role in the endogenous metabolism in the brain. Different CYP isoenzymes mediate metabolism of many endogenous substrates such as monoaminergic neurotransmitters, neurosteroids, cholesterol, vitamins and arachidonic acid. Therefore, these enzymes may affect brain development, susceptibility to mental and neurodegenerative diseases and may contribute to their pathophysiology. In addition, they can modify the therapeutic effects of psychoactive drugs at the place of their target action in the brain, where the drugs can act by affecting the metabolism of endogenous substrates. The article focuses on the role of cerebral CYP isoforms in the metabolism of neurotransmitters, neurosteroids, and cholesterol, and their possible involvement in animal behavior, as well as in stress, depression, schizophrenia, cognitive processes, learning, and memory. CYP-mediated alternative pathways of dopamine and serotonin synthesis may have a significant role in the local production of these neurotransmitters in the brain regions where the disturbances of these neurotransmitter systems are observed in depression and schizophrenia. The local alternative synthesis of neurotransmitters may be of great importance in the brain, since dopamine and serotonin do not pass the blood-brain barrier and cannot be supplied from the periphery. In vitro studies indicate that human CYP2D6 catalyzing dopamine and serotonin synthesis is more efficient in these reactions than the rat CYP2D isoforms. It suggests that these alternative pathways may have much greater significance in the human brain but confirmation of these assumptions requires further studies.

Lower allopregnanolone during pregnancy predicts postpartum depression: An exploratory study

Current evidence is mixed on the role of progesterone and its metabolites in perinatal mood and anxiety disorders. We measured second and third trimester (T2 and T3) progesterone (PROG) and allopregnanolone (ALLO) levels by ELISA and postpartum depression (PPD) by clinician interview (DSM-IV criteria) in 60 pregnant women with a prior diagnosis of a mood disorder. Methods included multivariate and logistic regression with general linear mixed effect models. We found that, after adjustment, every additional ng/mL of T2 ALLO resulted in a 63% (95% CI 13% to 84%, p=0.022) reduction in the risk of developing PPD. Our findings extend previous work connecting ALLO and depression within pregnancy, and indicate that the relationship between pregnancy ALLO and PPD is worth further exploration in a larger sample.

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.

Environmental enrichment prevents anxiety-like behavior induced by progesterone withdrawal in two strains of rats

Stress vulnerability could influence the treatment response to anxiety associated with abrupt hormonal suppression. The present study explored the effects of different treatments on experimental anxiety induced by progesterone withdrawal (PW) in a stress-sensitive rat strain, Wistar Kyoto (WKY), in the burying behavior test (BBT). The following experimental series was conducted using independent groups of Wistar (control strain) and WKY ovariectomized rats: Experiment 1: Rats were treated for 5days with oil, a constant dose of progesterone (0.5mg/rat, s.c) or a combination of progesterone (0.5mg/rat, s.c) plus fluoxetine (10 mg/kg, i.p); on day 6, all rats were subjected to BBT. Experiment 2: Rats received corn oil or decreasing doses of progesterone (0.84, 0.67, 0.5, 0.33 and 0.17mg/rat; one dose daily); on day 6, the rats were subjected to BBT. Experiment 3: Rats were divided into two groups that were subjected to 30days of standard conditions or environmental enrichment (EE); from days 25 to 30, all rats received a fixed dose of progesterone (0.5mg/rat, s.c.) or vehicle. On day 31, the rats were tested with BBT. Results showed that PW increased anxiety in both strains, and fluoxetine prevented anxiety in WKY rats. In contrast, a gradual reduction of progesterone prevents the anxiety in Wistar but not in WKY. EE was preventive against the anxiety induced by PW in both strains of rats. Thus, the results suggest that anxiety induced by PW is prevented by EE while the anxiolytic effect of pharmacological treatments depends on stress vulnerability.

Analytical challenges for measuring steroid responses to stress, neurodegeneration and injury in the central nervous system

Levels of steroids in the adult central nervous system (CNS) show marked changes in response to stress, degenerative disorders and injury. However, their analysis in complex matrices such as fatty brain and spinal cord tissues, and even in plasma, requires accurate and precise analytical methods. Radioimmunoassays (RIA) and enzyme-linked immunosorbent assays, even with prepurification steps, do not provide sufficient specificity, and they are at the origin of many inconsistent results in the literature. The analysis of steroids by mass spectrometric methods has become the gold standard for accurate and sensitive steroid analysis. However, these technologies involve multiple purification steps prone to errors, and they only provide accurate reference values when combined with careful sample workup. In addition, the interpretation of changes in CNS steroid levels is not an easy task because of their multiple sources: the endocrine glands and the local synthesis by neural cells. In the CNS, decreased steroid levels may reflect alterations of their biosynthesis, as observed in the case of chronic stress, post-traumatic stress disorders or depressive episodes. In such cases, return to normalization by administering exogenous hormones or by stimulating their endogenous production may have beneficial effects. On the other hand, increases in CNS steroids in response to acute stress, degenerative processes or injury may be part of endogenous protective or rescue programs, contributing to the resistance of neural cells to stress and insults. The aim of this review is to encourage a more critical reading of the literature reporting steroid measures, and to draw attention to the absolute need for well-validated methods. We discuss reported findings concerning changing steroid levels in the nervous system by insisting on methodological issues. An important message is that even recent mass spectrometric methods have their limits, and they only become reliable tools if combined with careful sample preparation.

Role of brain cytochrome P450 (CYP2D) in the metabolism of monoaminergic neurotransmitters

This article focuses on recent research on the cytochrome P450 2D (CYP2D) catalyzed synthesis of the monoaminergic neurotransmitters dopamine and serotonin in the brain and on the influence of psychotropic drugs on the activity of brain CYP2D. Recent in vitro and in vivo studies performed in rodents indicate that dopamine and serotonin may be formed in the brain via alternative CYP2D-mediated pathways, i.e., tyramine hydroxylation and 5-methoxytryptamine O-demethylation, respectively. The contribution of these alternative pathways to the total synthesis of brain neurotransmitters may be higher in humans and may be significantly increased under specific conditions, such as tyrosine hydroxylase and amino acid decarboxylase or tryptophan hydroxylase deficiency. These alternative pathways of neurotransmitter synthesis may also become more efficient when the CYP2D enzyme is mutated or activated by inducers (e.g., alcohol, nicotine, psychotropics), which may be of importance in some neurodegenerative or psychiatric diseases. In addition to the previously observed influence of antidepressants and neuroleptics on CYP2D in the liver, the investigated drugs also produce an effect on CYP2D in the brain. However, their effect on brain CYP2D is different than that in the liver and is structure-dependent. The observed psychotropic drug-brain CYP2D interactions may be important for the metabolism of endogenous neuroactive substrates (e.g., monoaminergic neurotransmitters, neurosteroids) and for the local biotransformation of drugs. The results are discussed with regard to the contribution of CYP2D to the total synthesis of neurotransmitters in the brain in vivo as well as the possible significance of these alternative pathways in specific physiological and pathological conditions and in the pharmacological actions of psychotropic drugs.

Neurosteroid, GABAergic and hypothalamic pituitary adrenal (HPA) axis regulation: what is the current state of knowledge in humans?

RATIONALE

A robust epidemiological literature suggests an association between chronic stress and the development of affective disorders. However, the precise biological underpinnings of this relationship remain elusive. Central to the human response and adaptation to stress, activation and inhibition of the hypothalamic pituitary adrenal (HPA) axis involves a multi-level, multi-system, neurobiological stress response which is as comprehensive in its complexity as it is precarious. Dysregulation in this complex system has implications for human stress related illness.

OBJECTIVES

The pioneering research of Robert Purdy and colleagues has laid the groundwork for advancing our understanding of HPA axis regulation by stress-derived steroid hormones and their neuroactive metabolites (termed neurosteroids), which are potent allosteric modulators of GABAA receptor function in the central nervous system. This review will describe what is known about neurosteroid modulation of the HPA axis in response to both acute and chronic stress, particularly with respect to the current state of our knowledge of this process in humans.

RESULTS

Implications of this research to the development of human stress-related illness are discussed in the context of two human stress-related psychiatric disorders - major depressive disorder and premenstrual dysphoric disorder.

CONCLUSIONS

Neurosteroid-mediated HPA axis dysregulation is a potential pathophysiologic mechanism which may cross traditional psychiatric diagnostic classifications. Future research directions are identified.

Progesterone and its metabolites as therapeutic targets in psychiatric disorders

INTRODUCTION

Neurosteroids are molecules that regulate physiological functions of the CNS. There is increasing evidence suggesting that impaired neurosteroid biosynthesis has been associated with distinct psychiatric disorders. This review summarizes data from studies that have investigated the relationship between progesterone (PROG) and psychiatric disorders as well as the mechanisms potentially involved in PROG-induced neuroprotection.

AREAS COVERED

The review covers the role of PROG and its metabolites in psychiatric disorders, focusing on results from preclinical and some clinical studies that support the relationship between alterations on PROG levels and pathophysiology of psychiatric illness. We also discussed the main mechanisms underlying the neuroprotective effects of PROG metabolites.

EXPERT OPINION

Our review points out the possible relationship between PROG and its metabolites and the pathophysiology of psychiatric disorders. Furthermore, both preclinical and clinical studies show that certain treatments (antidepressants or antipsychotics) may normalize the levels of PROG, suggesting that the amelioration of psychiatric symptoms may occur due to upregulation of PROG metabolites. Therefore, these results give support to new possibilities of treatment for patients with psychiatric symptoms from anxiety- and depressive-like behaviors to aggressive behaviors.

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.

Synergistic effect of 5-HT1A and σ1 receptor activation on prefrontal dopaminergic transmission under circulating steroid deficiency

Serotonin (5-HT)1A and σ1 receptors have been implicated in psychiatric disorders. We previously found that combined 5-HT reuptake inhibition and σ1 receptor activation has a synergistic effect on prefrontal dopaminergic transmission in adrenalectomized/castrated mice lacking circulating steroid hormones. In the present study, we examined the mechanisms underlying this neurochemical synergism. Systemic administration of fluvoxamine, a selective 5-HT reuptake inhibitor with agonistic activity towards the σ1 receptor, increased prefrontal dopamine (DA) levels, and adrenalectomy/castration potentiated this fluvoxamine-induced increase in DA. This enhancement of DA release was blocked by WAY100635 (a 5-HT1A receptor antagonist), but not by ritanserin (a 5-HT2 receptor antagonist), azasetron (a 5-HT3 receptor antagonist) or SB269970 (a 5-HT7 receptor antagonist). Individually, osemozotan (a 5-HT1A receptor agonist) and (+)-SKF-10,047 (a σ1 receptor agonist) did not alter prefrontal monoamine levels in adrenalectomized/castrated and sham-operated mice differentially. In contrast, co-administration of these drugs increased prefrontal DA levels to a greater extent in adrenalectomized/castrated mice than in sham-operated animals. Furthermore, co-administration of osemozotan and (+)-SKF-10,047 increased expression of the neuronal activity marker c-Fos in the ventral tegmental area of adrenalectomized/castrated mice, but not in sham-operated animals. These findings suggest that combined activation of 5-HT1A and σ1 receptors has a synergistic effect on prefrontal dopaminergic transmission under circulating steroid deficiency, and that this interaction may play an important role in the regulation of the prefrontal DA system.

The role of steroids in the development of post-partum mental disorders

BACKGROUND

Unfavorable post-partum changes to mental well-being affect more than half of all women, and are a risk to the health of both mother and baby. Their effects place strains on health and social systems. Currently, no generally accepted theory exists of the causes and mechanisms of post-partum mental disorders.

METHODS

Literature search up to 2012, using PubMed and search words: neuroactive steroids, post-partum mental disorders, depression, corticotropin-releasing hormone and estrogens.

RESULTS

There are several theories for post-partum depression. One is that autoimmune diseases are involved. Others revolve around genes responsible or that lead to increased disposition to the disorder. It is likely however that the process is associated with the separation of the placenta and the fetal zone of fetal adrenal gland, the main sources of corticotropin-releasing hormone and sexual and neuroactive steroids during pregnancy, and the ability of the receptor system to adapt to these changes. The central nervous system is able to produce neurosteroids, but the drop in levels of peripheral steroids likely leads to a sudden deficit in neuroinhibitory steroids modulating ionotropic receptors in the brain.

CONCLUSIONS

Post-partum depression is a multifactorial disease with unknown etiology. It is probably associated with sudden changes in the production of hormones influencing the nervous system, and on the other hand the ability of the receptor system to adapt to these changes. When the relative changes in concentrations of hormones, rather than their absolute levels, is likely more important.

A history of depression in women is associated with an altered GABAergic neuroactive steroid profile

The 3α,5α- and 3α,5β-reduced metabolites of progesterone, deoxycorticosterone, and dehydroepiandrosterone (DHEA) have potent effects on neurotransmission mediated by GABA(A) receptors, and dysregulation of these receptors has been implicated in depression. Using gas chromatography-mass spectrometry, we compared neuroactive steroid concentrations in women with a history of depressive disorders, but who were in full remission at the time of testing (n=11) to never depressed women (n=17) both before and after a challenge with oral micronized progesterone (300 mg). Serum concentrations of the following were obtained: four progesterone-derived GABAergic neuroactive steroids, the precursor pregnenolone, androstenedione-derived neuroactive steroids, and the precursor DHEA. As an index of conversion of progesterone to neuroactive steroids, we also examined ratios of neuroactive steroids to progesterone following the oral progesterone challenge. Results indicated that both before and after oral progesterone, women with histories of depression showed lower concentrations of all GABAergic neuroactive steroids than never depressed women. Those with a history of depression also had lower cortisol concentrations. Because serum neuroactive steroids are mainly synthesized in the adrenals, we hypothesize that histories of depression may be associated with persistent adrenal suppression. Following the progesterone challenge, ratios of the progesterone-derived neuroactive steroids to plasma progesterone concentrations were elevated in women with depression histories, suggesting there may be an adaptive shift in the metabolism of progesterone that compensates for lower circulating neuroactive steroid concentrations.

The antidepressant-like effects of the 3β-hydroxysteroid dehydrogenase inhibitor trilostane in mice is related to changes in neuroactive steroid and monoamine levels

In the present study, we analyzed the effects of a systemic treatment with the competitive 3β-hydroxysteroid dehydrogenase (3β-HSD) inhibitor trilostane on: (i) neurosteroid and monoamine levels in the brain, and (ii) the antidepressant activity of steroids and antidepressants in the forced swimming test (FST). 3β-HSD converts pregnenolone (PREG) into progesterone (PROG) or dehydroepiandrosterone (DHEA) into androstenedione. These neuroactive steroids are known to regulate neurotransmitters effects in the brain, particularly glutamate, γ-aminobutyric acid (GABA) and serotonin (5-HT), with consequences on mood and depression. We previously reported that trilostane showed antidepressant-like properties in the FST and concomitantly regulated plasma adrenocorticotropin (ACTH) and corticosterone levels, markers of the stress-induced hypothalamus-pituitary-adrenal (HPA) axis activation. We here observed that adrenalectomy/castration blocked the trilostane effect, outlining the importance of peripheral steroid levels. Trilostane (25 mg/kg) decreased hippocampus PROG contents and paradoxically increased circulating PROG levels. It also increased PREG levels in the hippocampus and frontal cortex. In the FST, a co-treatment with trilostane facilitated DHEAS (5-20 mg/kg) antidepressant activity, but showed only an additive, not facilitative, effect with PREGS (10-40 mg/kg), PROG (10-40 mg/kg) or allopregnanolone (ALLO, 1-8 mg/kg). Trilostane (25 mg/kg) treatment significantly increased 5-HT and (-)-norepinephrine (NE) turnovers in the hippocampus, an effect likely related to its antidepressant action. In co-administration studies, trilostane further decreased immobility following fluoxetine (30-60 mg/kg), sertraline (20-40 mg/kg) and imipramine (20-40 mg/kg), but not desipramine (20-40 mg/kg), treatments. A significant additive effect was observed for the selective 5-HT reuptake inhibitors (SSRI) at their highest dose. This study confirmed that a systemic administration of trilostane directly affected peripheral and brain levels in neuroactive steroids and monoamine turnover, resulting in antidepressant activity. The drug could be proposed as a co-treatment with SSRI. This article is part of a Special Issue entitled 'Anxiety and Depression'.

Neuroendocrinological aspects of epilepsy: important issues and trends in future research

Neuroendocrine research in epilepsy focuses on the interface among neurology, endocrinology, gynecology/andrology and psychiatry as it pertains to epilepsy. There are clinically important reciprocal interactions between hormones and the brain such that neuroactive hormones can modulate neuronal excitability and seizure occurrence while epileptiform discharges can disrupt hormonal secretion and promote the development of reproductive disorders. An understanding of these interactions and their mechanisms is important to the comprehensive management of individuals with epilepsy. The interactions are relevant not only to the management of seizure disorder but also epilepsy comorbidities such as reproductive dysfunction, hyposexuality and emotional disorders. This review focuses on some of the established biological underpinnings of the relationship and their clinical relevance. It identifies gaps in our knowledge and areas of promising research. The research has led to ongoing clinical trials to develop hormonal therapies for the treatment of epilepsy. The review also focuses on complications of epilepsy treatment with antiepileptic drugs. Although antiepileptic drugs have been the mainstay of epilepsy treatment, they can also have some adverse effects on sexual and reproductive function as well as bone density. As longevity increases, the prevention, diagnosis and treatment of osteoporosis becomes an increasingly more important topic, especially for individuals with epilepsy. The differential effects of antiepileptic drugs on bone density and their various mechanisms of action are reviewed and some guidelines and future directions for prevention of osteoporosis and treatment are presented.

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.

Effect of fluoxetine on blood concentrations of serotonin, cortisol and dehydroepiandrosterone in canine aggression

Canine aggression directed towards people is the most frequent reason for referral to behaviour practices. The serotonergic system and the hypothalamic-pituitary-adrenal (HPA) axis are believed to play an important role in controlling aggression. The selective serotonin reuptake inhibitor fluoxetine is the most commonly used drug in canine aggression. The aim of the present study was to assess the effect of a 30-day-long fluoxetine treatment on the peripheral serotonergic system and the HPA axis in canine aggression. To this end, the concentrations of serum serotonin (5-HT) and plasma cortisol and dehydroepiandrosterone (DHEA) were analysed in a group of aggressive (n = 22) and nonaggressive dogs (n = 9) during pre- (day 0) and posttreatment (day 30) conditions. Treatment caused a significant decrease in 5-HT concentrations (46% in the aggressive group and 32% in the control group). There was a trend towards a rise of DHEA/cortisol ratio values after treatment both in the aggressive and the control group. The determination of blood 5-HT and the DHEA/cortisol ratio could have important clinical applications in the future for deciding which animals might benefit from a given treatment as well as for monitoring the response. Further large-scale studies with this aim should be carried out to obtain sound conclusions.

The effect of psychotropic drugs on cytochrome P450 2D (CYP2D) in rat brain

The aim of the study was to investigate the influence of selected antidepressants and neuroleptics on the protein level and activity of cytochrome P450 2D (CYP2D) in rat brain. The obtained results showed that imipramine, fluoxetine, nefazodone, thioridazine and perazine, added to brain microsomes of control rats, inhibited CYP2D activity to a lower extent (K(i)=255-485μM) than when added to liver microsomes (K(i)=1-45μM), which may result from their stronger affinity for liver CYP2D2 (K(i)=2.7 and 1.25μM for imipramine and fluoxetine, respectively) than for brain CYP2D4 (K(i)=25 and 10μM for imipramine and fluoxetine, respectively), as well as from their high non-specific binding in brain microsomes. Two-week treatment with fluoxetine evoked decreases in the level and activity of CYP2D in the striatum and the nucleus accumbens. In contrast, fluoxetine increased CYP2D expression in the cerebellum, while nefazodone considerably enhanced the activity (but not the protein level) of CYP2D in the truncus cerebri. Imipramine and mirtazapine (active in the liver) did not affect brain CYP2D. Chronic thioridazine decreased CYP2D activity in the substantia nigra and nucleus accumbens, but significantly increased that activity in the striatum and cerebellum. Clozapine significantly enhanced CYP2D activity in the truncus cerebri. In conclusion, psychotropics influence CYP2D in the brain, but their effect is different than in the liver and depends on the cerebral structure. The observed psychotropics-brain CYP2D interactions may be important for the metabolism of neurosteroids and monoaminergic neurotransmitters, and for the local biotransformation of drugs.

Neonatal exposure to estradiol in rats influences neuroactive steroid concentrations, GABAA receptor expression, and behavioral sensitivity to anxiolytic drugs

Gonadal steroids, in particular estradiol, exert important actions during pre- and perinatal periods in the regulation of sexual dimorphism and development of the nervous system. We have now examined the effects of neonatal estradiol administration in female rats on brain concentrations of the neuroactive steroids allopregnanolone and tetrahydrodeoxycorticosterone, expression of GABA(A) receptor subunits, and behavioral sensitivity to benzodiazepines and allopregnanolone. Administration of beta-estradiol 3-benzoate on the day of birth resulted in marked decreases in the concentrations of progesterone and allopregnanolone in the cerebral cortex at 21, 60, and 180 days after birth. The concentrations of tetrahydrodeoxycorticosterone, 17beta-estradiol, and dehydroepiandrosterone in the brain at 60 days were not affected by such treatment. Neonatal administration of beta-estradiol 3-benzoate also increased the cerebrocortical abundance of alpha(1), alpha(2), and gamma(2) subunits of the GABA(A) receptor without affecting that of alpha(3), alpha(4), alpha(5), or delta subunits. Diazepam induced a greater reduction in locomotor activity as well as a more pronounced anxiolytic-like effect in the elevated plus-maze test in rats subjected to neonatal treatment with beta-estradiol 3-benzoate than in vehicle-treated controls, while allopregnanolone induced a similar effect in both groups. These effects of estradiol suggest that it plays a major role in regulation both of GABAergic transmission and of the abundance of endogenous modulators of such transmission during development of the central nervous system.

Mirtazapine does not influence tetrahydrodeoxycorticosterone levels in depressed patients

BACKGROUND

Among the neuroactive steroids, 3alpha,5alpha-tetrahydrodeoxycorticosterone (3alpha,5alpha-THDOC) is at least in part produced in the adrenal gland and is therefore under the control of the hypothalamic-pituitary-adrenocortical (HPA) system. The antidepressant mirtazapine has been shown to attenuate HPA axis activity and to increase the concentrations of 3alpha-reduced metabolites of progesterone in depressed patients. In the present study, the impact of mirtazapine on 3alpha,5alpha-THDOC levels was investigated in relation to clinical response in depressed patients.

METHOD

A total of 23 drug-free 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 08:00 h and were quantified for 3alpha,5alpha-THDOC levels.

RESULTS

3alpha,5alpha-THDOC levels were not correlated with demographic and clinical parameters such as age and severity of depression. Moreover, 5-week treatment with mirtazapine did not influence the 3alpha,5alpha-THDOC in the depressed patients, neither in responders nor in non-responders.

CONCLUSION

Putative increasing effects of mirtazapine on 3alpha-reduced neuroactive steroids such as 3alpha,5alpha-THDOC which may be mediated via an impact on the neurosteroidogenic enzyme 3alpha-hydroxysteroid dehydrogenase seem to be counterbalanced by the mirtazapine-induced inhibition of ACTH secretion which directly influences the 3alpha,5alpha-THDOC release of the adrenal cortex.

Manipulation of GABAergic steroids: Sex differences in the effects on alcohol drinking- and withdrawal-related behaviors

Alcoholism is a complex disorder that represents an important contributor to health problems worldwide and that is difficult to encompass with a single preclinical model. Additionally, alcohol (ethanol) influences the function of many neurotransmitter systems, with the interaction at gamma-aminobutyric acid(A) (GABA(A)) receptors being integral for ethanol's reinforcing and several withdrawal-related effects. Given that some steroid derivatives exert rapid membrane actions as potent positive modulators of GABA(A) receptors and exhibit a similar pharmacological profile to that of ethanol, studies in the laboratory manipulated GABAergic steroid levels and determined the impact on ethanol's rewarding- and withdrawal-related effects. Manipulations focused on the progesterone metabolite allopregnanolone (ALLO), since it is the most potent endogenous GABAergic steroid identified. The underlying hypothesis is that fluctuations in GABAergic steroid levels (and the resultant change in GABAergic inhibitory tone) alter sensitivity to ethanol, leading to changes in the positive motivational or withdrawal-related effects of ethanol. This review describes results that emphasize sex differences in the effects of ALLO and the manipulation of its biosynthesis on alcohol reward-versus withdrawal-related behaviors, with females being less sensitive to the modulatory effects of ALLO on ethanol-drinking behaviors but more sensitive to some steroid manipulations on withdrawal-related behaviors. These findings imply the existence of sex differences in the sensitivity of GABA(A) receptors to GABAergic steroids within circuits relevant to alcohol reward versus withdrawal. Thus, sex differences in the modulation of GABAergic neurosteroids may be an important consideration in understanding and developing therapeutic interventions in alcoholics.

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.

Neurosteroids: endogenous role in the human brain and therapeutic potentials

This chapter provides an overview of neurosteroids, especially their impact on the brain, sex differences and their therapeutic potentials. Neurosteroids are synthesized within the brain and rapidly modulate neuronal excitability. They are classified as pregnane neurosteroids, such as allopregnanolone and allotetrahydrodeoxycorticosterone, androstane neurosteroids, such as androstanediol and etiocholanolone, and sulfated neurosteroids such as pregnenolone sulfate. Neurosteroids such as allopregnanolone are positive allosteric modulators of GABA-A receptors with powerful anti-seizure activity in diverse animal models. Neurosteroids increase both synaptic and tonic inhibition. They are endogenous regulators of seizure susceptibility, anxiety, and stress. Sulfated neurosteroids such as pregnenolone sulfate, which are negative GABA-A receptor modulators, are memory-enhancing agents. Sex differences in susceptibility to brain disorders could be due to neurosteroids and sexual dimorphism in specific structures of the human brain. Synthetic neurosteroids that exhibit better bioavailability and efficacy and drugs that enhance neurosteroid synthesis have therapeutic potential in anxiety, epilepsy, and other brain disorders. Clinical trials with the synthetic neurosteroid analog ganaxolone in the treatment of epilepsy have been encouraging. Neurosteroidogenic agents that lack benzodiazepine-like side effects show promise in the treatment of anxiety and depression.

Differential effects of ethanol on serum GABAergic 3alpha,5alpha/3alpha,5beta neuroactive steroids in mice, rats, cynomolgus monkeys, and humans

BACKGROUND

Acute ethanol administration increases plasma and brain levels of progesterone and deoxycorticosterone-derived neuroactive steroids (3alpha,5alpha)-3-hydroxypregnan-20-one (3alpha,5alpha-THP) and (3alpha,5alpha)-3,21-dihydroxypregnan-20-one (3alpha,5alpha-THDOC) in rats. However, little is known about ethanol effects on GABAergic neuroactive steroids in mice, nonhuman primates, or humans. We investigated the effects of ethanol on plasma levels of 3alpha,5alpha- and 3alpha,5beta-reduced GABAergic neuroactive steroids derived from progesterone, deoxycorticosterone, dehydroepiandrosterone, and testosterone using gas chromatography-mass spectrometry.

METHODS

Serum levels of GABAergic neuroactive steroids and pregnenolone were measured in male rats, C57BL/6J and DBA/2J mice, cynomolgus monkeys, and humans following ethanol administration. Rats and mice were injected with ethanol (0.8 to 2.0 g/kg), cynomolgus monkeys received ethanol (1.5 g/kg) intragastrically, and healthy men consumed a beverage containing 0.8 g/kg ethanol. Steroids were measured after 60 minutes in all species and also after 120 minutes in monkeys and humans.

RESULTS

Ethanol administration to rats increased levels of 3alpha,5alpha-THP, 3alpha,5alpha-THDOC, and pregnenolone at the doses of 1.5 g/kg (+228, +134, and +860%, respectively, p < 0.001) and 2.0 g/kg (+399, +174, and +1125%, respectively, p < 0.001), but not at the dose of 0.8 g/kg. Ethanol did not alter levels of the other neuroactive steroids. In contrast, C57BL/6J mice exhibited a 27% decrease in serum 3alpha,5alpha-THP levels (p < 0.01), while DBA/2J mice showed no significant effect of ethanol, although both mouse strains exhibited substantial increases in precursor steroids. Ethanol did not alter any of the neuroactive steroids in cynomolgus monkeys at doses comparable to those studied in rats. Finally, no effect of ethanol (0.8 g/kg) was observed in men.

CONCLUSIONS

These studies show clear species differences among rats, mice, and cynomolgus monkeys in the effects of ethanol administration on circulating neuroactive steroids. Rats are unique in their pronounced elevation of GABAergic neuroactive steroids, while this effect was not observed in mice or cynomolgus monkeys at comparable ethanol doses.

The role of neurosteroids in the pathophysiology and treatment of catamenial epilepsy

Catamenial epilepsy is a multifaceted neuroendocrine condition in which seizures are clustered around specific points in the menstrual cycle, most often around perimenstrual or periovulatory period. Generally, a twofold or greater increase in seizure frequency during a particular phase of the menstrual cycle could be considered as catamenial epilepsy. Based on this criteria, recent clinical studies indicate that catamenial epilepsy affects 31-60% of the women with epilepsy. Three types of catamenial seizures (perimenstrual, periovulatory and inadequate luteal) have been identified. However, there is no specific drug available today for catamenial epilepsy, which has not been successfully treated with conventional antiepileptic drugs. Elucidation of the pathophysiology of catamenial epilepsy is a prerequisite to develop specific targeted approaches for treatment or prevention of the disorder. Cyclical changes in the circulating levels of estrogens and progesterone play a central role in the development of catamenial epilepsy. There is emerging evidence that endogenous neurosteroids with anticonvulsant or proconvulsant effects could play a critical role in catamenial epilepsy. It is thought that perimenstrual catamenial epilepsy is associated with the withdrawal of anticonvulsant neurosteroids. Progesterone and other hormonal agents have been shown in limited trials to be moderately effective in catamenial epilepsy, but may cause endocrine side effects. Synthetic neurosteroids, which enhance the tonic GABA-A receptor function, might provide an effective approach for the catamenial epilepsy therapy without producing hormonal side effects.

The 3beta-hydroxysteroid dehydrogenase inhibitor trilostane shows antidepressant properties in mice

Changes in neuro(active)steroid levels are involved in depressive states and mood disorders. For instance, dehydroepiandrosterone or pregnenolone sulfate showed anti-stress and antidepressant activity in rodents and regulation of allopregnanolone levels appeared to be one of the consequence of an effective antidepressant therapy in patients. 4alpha,5-Epoxy-17beta-hydroxy-3-oxo-5alpha-androstane-2alpha-carbonitrile (trilostane) inhibits the activity of 3beta-hydroxysteroid dehydrogenase (3beta-HSD) that, in particular, converts pregnenolone into progesterone. We examined whether systemic administration of trilostane affects the response to stress and depression. An acute treatment with trilostane (6.3-50mg/kg SC injected twice -16 and -2h before the measure) increased 3beta-HSD mRNA levels in the hippocampus and adrenals, but had little effect on protein levels. The trilostane treatment failed to affect open-field, locomotor or exploratory behaviors, but significantly reduced the immobility duration in the forced swimming test, measuring antidepressant-like activity, and increased the time spent in open arm in the elevated plus-maze, measuring anxiety response. The antidepressant-like effect of trilostane was effective after a repeated treatment (2.5-20mg/kgSC twice-a-day during 7 days) or in mice submitted to a restraint stress during 21 days and showing several behavioral and physiological parameters of depression (decreased body weight, increased adrenal glands weight and anhaedonia). Trilostane also reduced stress-induced increase in plasma corticosterone and ACTH levels, showing direct effect on HPA axis activity. These observations suggest that the 3beta-HSD inhibitor trilostane present antidepressant-like activity, putatively by regulating brain and peripheral levels of neuroactive steroids.

A reproductive subtype of depression: conceptualizing models and moving toward etiology

The lifetime risk for major depression in women is well known to be twice the risk in men and is especially high during the reproductive years between menarche and menopause. A subset of reproductive-age women experience depressive episodes that are triggered by hormonal fluctuations. Such "reproductive depressions" involve episodes of depression that occur specifically during the premenstrual, postpartum, and perimenopausal phases in women. These reproductive subtypes of depression can be conceptualized as a specific biological response to the effects of hormonal fluctuations in the brain. The different types of reproductive depressions are associated with each other, have unique risk factors that are distinct from nonreproductive depression episodes, and respond to both hormonal and nonhormonal interventions. This review uses a PubMed search of relevant literature to discuss clinical, animal, and genetic evidence for reproductive depression as a specific subtype of major depression. Unique treatment options, such as hormonal interventions, are also discussed, and hypotheses regarding the underlying biology of reproductive depression-including interactions between the serotonergic system and estrogen, as well as specific effects on neurosteroids-are explored. This review will provide evidence supporting reproductive depression as a distinct clinical entity with specific treatment approaches and a unique biology that is separate from nonreproductive depression.

Reduced serum level of THDOC, an anticonvulsant steroid, in women with perimenstrual catamenial epilepsy

PURPOSE

Seizure exacerbation in catamenial epilepsy (CE) is associated with the decrease in progesterone secretion and increase in estradiol secretion during the premenstrual period. Moreover, experimental evidence suggests that tetrahydrodeoxycorticosterone (THDOC), a positive modulator of the type A receptor for gamma-aminobutyric acid (GABA), and dehydroepiandrosterone sulfate (DHEAS), a negative modulator of this receptor, might play a crucial role in modulating seizure frequency during the menstrual cycle. Following these studies it seems of interest to investigate possible variations, among other hormonal parameters, of THDOC and DHEAS in CE patients.

METHODS

The serum concentrations of progesterone (P4), pregnenolone, allopregnanolone (AP), THDOC, DHEAS, cortisol, and DHEAS/cortisol ratio were measured throughout the menstrual cycle at the 7th, 11th, 15th, 19th, 23rd, and 27th day from the onset of spontaneous menstrual blood loss in young premenopausal women with CE (n = 17) and age-matched controls (n = 13).

RESULTS

At each time of the study, the serum concentration of THDOC and the DHEAS/cortisol ratio were lower (p < 0.05) in women with CE than in control women. The concentrations of P4, pregnenolone, and AP did not differ between the two groups of subjects.

CONCLUSIONS

The reduced serum concentration of THDOC and the reduced DHEAS/cortisol ratio detected throughout the menstrual cycle in women with CE might play a role in CE. Moreover, the peculiar pattern of CE seizure exacerbation might suggest that these neuroendocrine variations are worth investigating in other epileptic syndromes, particularly in those characterized by relevant and uncontrolled variations in seizure frequency.

Endogenous steroid production in the spinal cord and potential involvement in neuropathic pain modulation

It has recently been demonstrated that the spinal cord (SC) is an active production center of neuroactive steroids including pregnenolone, dehydroepiandrosterone, progesterone and allopregnanolone. Indeed, anatomical, cellular and biochemical investigations have shown that the SC dorsal horn (DH), a pivotal structure in nociception, contains various active steroidogenic enzymes such as cytochrome P450side-chain-cleavage, cytochrome P450c17, 3beta-hydroxysteroid dehydrogenase, 5alpha-reductase and 3alpha-hydroxysteroid oxido-reductase. Reviewed here are several data obtained with in vitro and vivo experiments showing that endogenous steroids synthesized in the SC are involved in the modulation of nociceptive mechanisms. Various approaches were used as the real-time polymerase chain reaction after reverse transcription to determine the effects of neuropathic pain on the expression of genes encoding steroidogenic enzymes in the DH. Combination of the pulse-chase technique with high performance liquid chromatography and continuous flow scintillation detection allowed investigations of the impact of noxious signals on the activity of steroid-producing enzymes in the SC in vitro. Radioimmunological analyses of spinal tissue extracts contributed to determine the link between the painful state and endogenous steroid secretion in the SC in vivo. Finally, the physiological relevance of the modification of endogenous steroid formation in the SC during painful situation was discussed.

The relevance of neuroactive steroids in schizophrenia, depression, and anxiety disorders

1. Neuroactive steroids are steroid hormones that exert rapid, nongenomic effects at ligand-gated ion channels. There is increasing awareness of the possible role of these steroids in the pathology and manifestation of symptoms of psychiatric disorders. The aim of this paper is to review the current knowledge of neuroactive steroid functioning in the central nervous system, and to assess the role of neuroactive steroids in the pathophysiology and treatment of symptoms of schizophrenia, depression, and anxiety disorders. Particular emphasis will be placed on GABAA receptor modulation, given the extensive knowledge of the interactions between this receptor complex, neuroactive steroids, and psychiatric illness. 2. A brief description of neuroactive steroid metabolism is followed by a discussion of the interactions of neuroactive steroids with acute and chronic stress and the HPA axis. Preclinical and clinical studies related to psychiatric disorders that have been conducted on neuroactive steroids are also described. 3. Plasma concentrations of some neuroactive steroids are altered in individuals suffering from schizophrenia, depression, or anxiety disorders compared to values in healthy controls. Some drugs used to treat these disorders have been reported to alter plasma and brain concentrations in clinical and preclinical studies, respectively. 4. Further research is warranted into the role of neuroactive steroids in the pathophysiology of psychiatric illnesses and the possible role of these steroids in the successful treatment of these disorders.

Neurosteroids in the context of stress: implications for depressive disorders

Animal models indicate that the neuroactive steroids 3alpha,5alpha-THP (allopregnanolone) and 3alpha,5alpha-THDOC (allotetrahydroDOC) are stress responsive, serving as homeostatic mechanisms in restoring normal GABAergic and hypothalamic-pituitary-adrenal (HPA) function following stress. While neurosteroid increases to stress are adaptive in the short term, animal models of chronic stress and depression find lower brain and plasma neurosteroid concentrations and alterations in neurosteroid responses to acute stressors. It has been suggested that disruption in this homeostatic mechanism may play a pathogenic role in some psychiatric disorders related to stress. In humans, neurosteroid depletion is consistently documented in patients with current depression and may reflect their greater chronic stress. Women with the depressive disorder, premenstrual dysphoric disorder (PMDD), have greater daily stress and a greater rate of traumatic stress. While results on baseline concentrations of neuroactive steroids in PMDD are mixed, PMDD women have diminished functional sensitivity of GABA(A) receptors and our laboratory has found blunted allopregnanolone responses to mental stress relative to non-PMDD controls. Similarly, euthymic women with histories of clinical depression, which may represent a large proportion of PMDD women, show more severe dysphoric mood symptoms and blunted allopregnanolone responses to stress versus never-depressed women. It is suggested that failure to mount an appropriate allopregnanolone response to stress may reflect the price of repeated biological adaptations to the increased life stress that is well documented in depressive disorders and altered allopregnanolone stress responsivity may also contribute to the dysregulation seen in HPA axis function in depression.

Role of microsomal retinol/sterol dehydrogenase-like short-chain dehydrogenases/reductases in the oxidation and epimerization of 3alpha-hydroxysteroids in human tissues

Allopregnanolone (ALLO) and androsterone (ADT) are naturally occurring 3alpha-hydroxysteroids that act as positive allosteric regulators of gamma-aminobutyric acid type A receptors. In addition, ADT activates nuclear farnesoid X receptor and ALLO activates pregnane X receptor. At least with respect to gamma-aminobutyric acid type A receptors, the biological activity of ALLO and ADT depends on the 3alpha-hydroxyl group and is lost upon its conversion to either 3-ketosteroid or 3beta-hydroxyl epimer. Such strict structure-activity relationships suggest that the oxidation or epimerization of 3alpha-hydroxysteroids may serve as physiologically relevant mechanisms for the control of the local concentrations of bioactive 3alpha-hydroxysteroids. The exact enzymes responsible for the oxidation and epimerization of 3alpha-hydroxysteroids in vivo have not yet been identified, but our previous studies showed that microsomal nicotinamide adenine dinucleotide-dependent short-chain dehydrogenases/reductases (SDRs) with dual retinol/sterol dehydrogenase substrate specificity (RoDH-like group of SDRs) can oxidize and epimerize 3alpha-hydroxysteroids in vitro. Here, we present the first evidence that microsomal nicotinamide adenine dinucleotide-dependent 3alpha-hydroxysteroid dehydrogenase/epimerase activities are widely distributed in human tissues with the highest activity levels found in liver and testis and lower levels in lung, spleen, brain, kidney, and ovary. We demonstrate that RoDH-like SDRs contribute to the oxidation and epimerization of ALLO and ADT in living cells, and show that RoDH enzymes are expressed in tissues that have microsomal 3alpha-hydroxysteroid dehydrogenase/epimerase activities. Together, these results provide further support for the role of RoDH-like SDRs in human metabolism of 3alpha-hydroxysteroids and offer a new insight into the enzymology of ALLO and ADT inactivation.

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.

Associations of histories of depression and PMDD diagnosis with allopregnanolone concentrations following the oral administration of micronized progesterone

Twenty-three women with premenstrual dysphoric disorder (PMDD) and 29 non-PMDD controls were compared for plasma progesterone (P) and its neuroactive steroid metabolite allopregnanolone (ALLO), as well as the ALLO/P ratio following the double-blind, placebo controlled administration of 300 mg oral micronized progesterone. Approximately half of each group had prior depression (DEP) (13 PMDD, 12 non-PMDD), though all were free of current depression. Progesterone and ALLO were sampled 160, 190, 225, and 255 min after progesterone administration. Changes over time in plasma concentrations and the ALLO/P ratio were assessed using area under the curve analyses. Women with prior DEP had lower ALLO levels (p=0.05) and marginally lower P levels (p<0.07) following progesterone administration compared to never depressed women, and this was especially evident in the non-PMDD women (p<0.01). PMDD women with no prior DEP had higher pre-progesterone ALLO/P ratios than all other groups (Ps<0.05) and higher ratios than the never depressed, non-PMDD women following oral progesterone (p<0.05). Results could not be accounted for by group differences in steroid hormone binding protein concentrations. For all women, progesterone administration was associated with increased confusion, fatigue, and with reduced confidence (Ps<0.01), even after controlling for placebo-associated mood change. These results suggest a persistent effect of prior DEP on P and ALLO concentrations following oral progesterone and that PMDD women, especially those with no prior DEP, may have alterations in the metabolic pathways underlying the conversion of P to ALLO.

Relationship between omega-3 fatty acids and plasma neuroactive steroids in alcoholism, depression and controls

Deficiency in the long-chain omega-3 fatty acid, docosahexaenoic acid (DHA) has been associated with increased corticotropin releasing hormone and may contribute to hypothalamic pituitary axis (HPA) hyperactivity. Elevated levels of the neuroactive steroids, allopregnanolone (3alpha,5alpha-THP) and 3alpha,5alpha-tetrahydrodeoxycorticosterone (THDOC) appear to counter-regulate HPA hyperactivity. Plasma essential fatty acids and neurosteroids were assessed among 18 male healthy controls and among 34 male psychiatric patients with DSM-III alcoholism, depression, or both. Among all subjects, lower plasma DHA was correlated with higher plasma THDOC (r = -0.3, P < 0.05) and dihydroprogesterone (DHP) (r = -0.52, P < 0.05). Among psychiatric patients lower DHA was correlated with higher DHP (r = -0.60, P < 0.01), and among healthy controls lower plasma DHA was correlated with higher THDOC (r = -0.83, P < 0.01) and higher isopregnanolone (3beta,5alpha-THP) (r = -0.55, P < 0.05). In this pilot observational study, lower long-chain omega-3 essential fatty acid status was associated with higher neuroactive steroid concentrations, possibly indicating increased feedback inhibition of the HPA axis.

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.

Ethnic differences in allopregnanolone concentrations in women during rest and following mental stress

The neuroactive steroid allopregnanolone (ALLO) is stress sensitive, negatively modulates the HPA axis, and has been implicated in mood disorders. We examined ethnic differences in plasma ALLO at rest and following mental stress in African American (AA) men (n = 21) and women (n = 24) and non-Hispanic White men (n = 24) and women (n = 25). Overall, AA women had lower ALLO concentrations than non-Hispanic White women (p < .05), especially following mental stress (p < .01). Only 20% of AA women showed the expected stress-induced increase in ALLO compared with 59% of non-Hispanic White women (p < .01). No ethnic differences were seen in men. For both ethnic groups, poststress ALLO was negatively correlated with poststress cortisol (p < .05). Results are interpreted to reflect dysregulation in ALLO mechanisms in AA women and may have implications for ethnic differences in mood 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.

Decreased neuroactive steroids induced by combined oral contraceptive pills are not associated with mood changes

OBJECTIVE

To evaluate the effects of a low-dose combined oral contraceptive pill (OCP) on peripheral neuroactive steroid concentrations, precursors for neuroactive steroid synthesis, and mood in healthy women desiring contraception. These neuroactive steroids are gamma-aminobutyric acid receptor agonists and are important in the modulation of affect and adaptation to stress.

DESIGN

Prospective observational study.

SETTING

Human ambulatory patient study.

PATIENT(S)

Healthy OCP-naive women without current or history of affective disorder.

INTERVENTION(S)

A 0.020-mg ethinyl E2-0.1-mg levonorgestrel containing OCP for 3 months.

MAIN OUTCOME MEASURE(S)

Serum neuroactive steroids allopregnanolone, allotetrahydrodeoxycorticosterone, and DHEA; neuroactive steroid precursors P and pregnenolone; E2; and mood and anxiety as assessed by the Premenstrual Syndrome Daily Ratings Form, Beck Depression Inventory, Spielberger State-Trait Anxiety Inventory, and Profile of Mood States.

RESULT(S)

The combined OCP resulted in a decrease in neuroactive steroids and neuroactive steroid precursors as well as in E2. However, this decline was not associated with adverse mood changes on any of the well-validated assessment tools.

CONCLUSION(S)

Healthy women without underlying mood or anxiety disorder who were given a low-dose OCP did not experience adverse psychological symptoms despite a significant reduction in neuroactive steroids.

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.

Serotonergic 5-HT2A receptor stimulation induces steroid 5alpha-reductase gene expression in rat C6 glioma cells via transcription factor Egr-1

Selective serotonin reuptake inhibitors (SSRIs) are widely used for the treatment of depressive mood disorders and well known to inhibit the reuptake of neurotransmitter serotonin into nerve terminals. Thus, it seems conceivable that these drugs may induce the outflow of serotonin from the synapse as a consequence of inhibiting the reuptake, resulting in the stimulation of glial cells surrounding nerve terminals. On this hypothesis, the effect of serotonin on steroid 5alpha-reductase type 1 (5alpha-R) gene expression in rat C6 glioma cells was examined as one of the in vitro model experiments for investigating the indirect influence of SSRIs on glial cells. Serotonin elevated 5alpha-R mRNA and protein levels through the stimulation of serotonin 5-HT2A receptors, and also elevated Egr-1 mRNA and protein levels prior to 5alpha-R gene expression in the glioma cells. Furthermore, serotonin failed to significantly increase 5alpha-R mRNA levels in the cells preloaded with the antisense oligodeoxynucleotide targeted on Egr-1 gene. These results indicate that serotonin may stimulate 5alpha-R gene expression via transcription factor Egr-1 in glial cells, thus suggesting that serotonin flowing out of the serotonergic synapse may be implicated in SSRI-induced changes in neurosteroid metabolism in brain.

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.

Physiological role of adrenal deoxycorticosterone-derived neuroactive steroids in stress-sensitive conditions

Stress increases plasma and brain concentrations of corticosteroids and neuroactive steroids. Cortisol is the most important stress hormone in the hypothalamic pituitary adrenocortical system. However, significant amounts of the mineralocorticoid deoxycorticosterone are also released during stress. Deoxycorticosterone undergoes biotransformation to allotetrahydrodeoxycorticosterone, a neuroactive steroid with anxiolytic and anticonvulsant properties. Our studies indicate that the anticonvulsant activity of deoxycorticosterone is mediated by its conversion to allotetrahydrodeoxycorticosterone, which is a potent positive allosteric modulator of GABA(A) receptors. Although the role of allotetrahydrodeoxycorticosterone within the brain is undefined, recent studies indicate that stress induces increases in allotetrahydrodeoxycorticosterone to levels that can activate GABA(A) receptors. These results might have significant implications for human stress-sensitive conditions such as epilepsy, panic disorder, post-traumatic stress disorder, and major depression. In epilepsy, a role for adrenal allotetrahydrodeoxycorticosterone in seizure susceptibility has been suggested. Recent preclinical studies indicate a role of neuroactive steroids in ethanol actions. Although these studies provide a better understanding of the role of allotetrahydrodeoxycorticosterone and related neuroactive steroids in acute stress, further studies are clearly warranted to ascertain the specific role of neuroactive steroids in the pathophysiology of chronic stress and related brain conditions.