Corticosteroid receptor mRNA expression in the brains of patients with epilepsy

Efficacy and Safety of Pulse Intravenous Methylprednisolone in Pediatric Epileptic Encephalopathies: Timing and Networks Consideration

Background: Epileptic encephalopathies (EE) are characterized by severe drug-resistant seizures, early onset, and unfavorable developmental outcomes. This article discusses the use of intravenous methylprednisolone (IVMP) pulse therapy in pediatric patients with EE to evaluate its efficacy and tolerability. Methods: This is a retrospective study from 2020 to 2023. Inclusion criteria were ≤18 years at the time of IVMP pulse therapy and at least 6 months of follow-up. Efficacy and outcome, defined as seizure reduction > 50% (responder rate), were evaluated at 6 and 9 months of therapy, and 6 months after therapy suspension; quality of life (QoL) was also assessed. Variables predicting positive post-IVMP outcomes were identified using statistical analysis. Results: The study included 21 patients, with a responder rate of 85.7% at 6 and 9 months of therapy, and 80.9% at 6 months after therapy suspension. Variables significantly predicting favorable outcome were etiology (p = 0.0475) and epilepsy type (p = 0.0475), with the best outcome achieved in patients with genetic epilepsy and those with encephalopathy related to electrical status epilepticus during slow-wave sleep (ESES). All patients evidenced improvements in QoL at the last follow-up, with no relevant adverse events reported. Conclusions: Our study confirmed the efficacy and high tolerability of IVMP pulse therapy in pediatric patients with EE. Genetic epilepsy and ESES were positive predictors of a favorable clinical outcome. QOL, EEG tracing, and postural-motor development showed an improving trend as well. IVMP pulse therapy should be considered earlier in patients with EE.

Comparative Effectiveness of Initial Treatment for Infantile Spasms in a Contemporary US Cohort

OBJECTIVE

To compare the effectiveness of initial treatment for infantile spasms.

METHODS

The National Infantile Spasms Consortium prospectively followed up children with new-onset infantile spasms that began at age 2 to 24 months at 23 US centers (2012-2018). Freedom from treatment failure at 60 days required no second treatment for infantile spasms and no clinical spasms after 30 days of treatment initiation. We managed treatment selection bias with propensity score weighting and within-center correlation with generalized estimating equations.

RESULTS

Freedom from treatment failure rates were as follows: adrenocorticotropic hormone (ACTH) 88 of 190 (46%), oral steroids 42 of 95 (44%), vigabatrin 32 of 87 (37%), and nonstandard therapy 4 of 51 (8%). Changing from oral steroids to ACTH was not estimated to affect response (observed 44% estimated to change to 44% [95% confidence interval 34%-54%]). Changing from nonstandard therapy to ACTH would improve response from 8% to 39% (17%-67%), and changing to oral steroids would improve response from 8% to 38% (15%-68%). There were large but not statistically significant estimated effects of changing from vigabatrin to ACTH (29% to 42% [15%-75%]), from vigabatrin to oral steroids (29% to 42% [28%-57%]), and from nonstandard therapy to vigabatrin (8% to 20% [6%-50%]). Among children treated with vigabatrin, those with tuberous sclerosis complex (TSC) responded more often than others (62% vs 29%; p < 0.05).

DISCUSSION

Compared to nonstandard therapy, ACTH and oral steroids are superior for initial treatment of infantile spasms. The estimated effectiveness of vigabatrin is between that of ACTH/oral steroids and nonstandard therapy, although the sample was underpowered for statistical confidence. When used, vigabatrin worked best for TSC.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for children with new-onset infantile spasms, ACTH or oral steroids were superior to nonstandard therapies.

Reduced expression of the glucocorticoid receptor in the hippocampus of patients with drug-resistant temporal lobe epilepsy and comorbid depression

Objective

Depressive disorders are common among about 50% of the patients with drug‐resistant temporal lobe epilepsy (TLE). The underlying etiology remains elusive, but hypothalamus‐pituitary‐adrenal (HPA) axis activation due to changes in glucocorticoid receptor (GR) protein expression could play an important role. Therefore, we set out to investigate expression of the GR in the hippocampus, an important brain region for HPA axis feedback, of patients with drug‐resistant TLE, with and without comorbid depression.

Methods

GR expression was studied using immunohistochemistry on hippocampal sections from well‐characterized TLE patients with depression (TLE + D, n = 14) and without depression (TLE − D, n = 12) who underwent surgery for drug‐resistant epilepsy, as well as on hippocampal sections from autopsy control cases (n = 9). Video–electroencephalography (EEG), magnetic resonance imaging (MRI), and psychiatric and memory assessments were performed prior to surgery.

Results

Abundant GR immunoreactivity was present in dentate gyrus granule cells and CA1 pyramidal cells of controls. In contrast, neuronal GR expression was lower in patients with TLE, particularly in the TLE + D group. Quantitative analysis showed a smaller GR+ area in TLE + D as compared to TLE − D patients and controls. Furthermore, the ratio between the number of GR+/NeuN+ cells was lower in patients with TLE + D as compared to TLE − D and correlated negatively with the depression severity based on psychiatric history. The expression of the GR was also lower in glial cells of TLE + D compared to TLE − D patients and correlated negatively to the severity of depression.

Significance

Reduced hippocampal GR expression may be involved in the etiology of depression in patients with TLE and could constitute a biological marker of depression in these patients.

Neurovascular glucocorticoid receptors and glucocorticoids: implications in health, neurological disorders and drug therapy

Glucocorticoid receptors (GRs) are ubiquitous transcription factors widely studied for their role in controlling events related to inflammation, stress and homeostasis. Recently, GRs have reemerged as crucial targets of investigation in neurological disorders, with a focus on pharmacological strategies to direct complex mechanistic GR regulation and improve therapy. In the brain, GRs control functions necessary for neurovascular integrity, including responses to stress, neurological changes mediated by the hypothalamic-pituitary-adrenal axis and brain-specific responses to corticosteroids. Therefore, this review will examine GR regulation at the neurovascular interface in normal and pathological conditions, pharmacological GR modulation and glucocorticoid insensitivity in neurological disorders.

Does cortisol modulate emotion recognition and empathy?

INTRODUCTION

Emotion recognition and empathy are important aspects in the interaction and understanding of other people's behaviors and feelings. The Human environment comprises of stressful situations that impact social interactions on a daily basis. Aim of the study was to examine the effects of the stress hormone cortisol on emotion recognition and empathy.

METHODS

In this placebo-controlled study, 40 healthy men and 40 healthy women (mean age 24.5 years) received either 10mg of hydrocortisone or placebo. We used the Multifaceted Empathy Test to measure emotional and cognitive empathy. Furthermore, we examined emotion recognition from facial expressions, which contained two emotions (anger and sadness) and two emotion intensities (40% and 80%).

RESULTS

We did not find a main effect for treatment or sex on either empathy or emotion recognition but a sex × emotion interaction on emotion recognition. The main result was a four-way-interaction on emotion recognition including treatment, sex, emotion and task difficulty. At 40% task difficulty, women recognized angry faces better than men in the placebo condition. Furthermore, in the placebo condition, men recognized sadness better than anger. At 80% task difficulty, men and women performed equally well in recognizing sad faces but men performed worse compared to women with regard to angry faces.

CONCLUSION

Apparently, our results did not support the hypothesis that increases in cortisol concentration alone influence empathy and emotion recognition in healthy young individuals. However, sex and task difficulty appear to be important variables in emotion recognition from facial expressions.

Effectiveness of a hybrid corticosteroid treatment regimen on refractory childhood seizures and a review of other corticosteroid treatments

BACKGROUND

Many different corticosteroid treatment schedules have been used in order to treat refractory epileptic seizures with encouraging effects on seizure reduction in many epileptic syndromes.

OBJECTIVE

The objective is to report our experience with a hybrid treatment regimen for refractory seizures in children with epilepsies other than West and Landau-Kleffner syndrome. We hypothesized that a pulse of corticosteroids effectively reduces seizures while low-dosage maintenance treatment reduces side effects. The results are compared with results from a review of reported corticosteroid and ACTH treatments.

METHODS

In this retrospective observational study, 26 children diagnosed with epilepsy with refractory seizures other than West syndrome and Landau-Kleffner syndrome were eligible for a treatment regimen consisting of three days intravenous methylprednisolone (20 mg per kilogram per day) followed by twelve weeks oral prednisolone (0.5 mg per kilogram on alternate days), concluded with a taper phase. Data on effectiveness and side effects were obtained. End-points were the percentages of patients who became seizure free or responded well.

RESULTS

Twenty-one patients received the study treatment. Nine (43%) responded well and 6 (29%) became seizure free. All but one patient had a relapse of seizures. Four patients had reversible adverse effects. Data extracted from the literature were consistent with a good response in 48% of 192 children treated with different corticosteroids and in 69% of 103 patients treated with ACTH.

CONCLUSION

This new hybrid therapy of a pulse of intravenous methylprednisolone and alternate day oral prednisolone is effective with a favourable side effect profile. Results on efficacy and safety justify a randomized controlled trial.

Corticosteroids including ACTH for childhood epilepsy other than epileptic spasms

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 1, 2007.Epilepsy is a disorder with recurrent epileptic seizures. Corticosteroids have been used in the treatment of children with epilepsy and have significant adverse effects. Their efficacy and tolerability have not been clearly established.

OBJECTIVES

To determine the efficacy, in terms of seizure control, improvements in cognition and in quality of life and tolerability of steroids compared to placebo or other antiepileptic drugs in children with epilepsy, excluding epileptic spasms.

SEARCH METHODS

We searched the following databases: The Cochrane Epilepsy Group Specialized Register (1 August 2014); CENTRAL, (The Cochrane Library Issue 7, July 2014); MEDLINE (1946 to 1 August 2014); EMBASE (1966 to December 2004); Database of Abstracts of Reviews of Effectiveness (DARE; Issue 3 of the database published in The Cochrane Library Issue 7, July 2014); ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform ICTRP (1 August 2014).We checked the reference lists of retrieved studies for additional reports of relevant studies.

SELECTION CRITERIA

All randomised controlled trials of administration of corticosteroids to children (less than 16 years) with epilepsy.

DATA COLLECTION AND ANALYSIS

For this update two review authors independently selected trials for inclusion and extracted data. Outcomes included cessation of seizures, reduction in seizure frequency, improvement in cognition, quality of life and adverse effects of steroids.

MAIN RESULTS

A single RCT was included that recruited five children in a double blind cross-over trial. One child was withdrawn prematurely from the study and another had infantile spasms and hence was excluded from further analysis. Adrenocorticotrophin hormone (ACTH 4-9) was administered. Of the three children analysed, one showed a reduction in seizures of 25% to 50% at both the low and higher doses of corticosteroids compared to placebo; one child showed a reduction in seizures at the higher dose only and one child showed no reduction in seizures at either dose. No adverse effects were reported.

AUTHORS' CONCLUSIONS

Since the last version of this review no new evidence has been found for the efficacy of corticosteroids in treating childhood epilepsies. Clinicians using steroids in childhood epilepsies, other than for epileptic spasms, should take this into account before using these agents.

Seizure occurrence and the circadian rhythm of cortisol: a systematic review

PURPOSE

Stress is the seizure precipitant most often reported by patients with epilepsy or their caregivers. The relation between stress and seizures is presumably mediated by stress hormones such as cortisol, affecting neuronal excitability. Endogenous cortisol is released in a circadian pattern. To gain insight into the relation between the circadian rhythm of cortisol and seizure occurrence, we systematically reviewed studies on the diurnal distribution of epileptic seizures in children and adults and linked the results to the circadian rhythm of cortisol.

METHODS

A structured literature search was conducted to identify relevant articles, combining the terms 'epilepsy' and 'circadian seizure distribution', plus synonyms. Articles were screened using predefined selection criteria. Data on 24-hour seizure occurrence were extracted, combined, and related to a standard circadian rhythm of cortisol.

RESULTS

Fifteen relevant articles were identified of which twelve could be used for data aggregation. Overall, seizure occurrence showed a sharp rise in the early morning, followed by a gradual decline, similar to cortisol rhythmicity. The occurrence of generalized seizures and focal seizures originating from the parietal lobe in particular followed the circadian rhythm of cortisol.

CONCLUSIONS

The diurnal occurrence of epileptic seizures shows similarities to the circadian rhythm of cortisol. These results support the hypothesis that circadian fluctuations in stress hormone level influence the occurrence of epileptic seizures.

Decreased hypothalamic functional connectivity with subgenual cortex in psychotic major depression

Hypothalamus communication with the rest of the brain and peripheral target tissues is critically important for many physiological and psychological functions. These functions include maintaining neuroendocrine circadian rhythms and managing affective processes. The hypothalamus maintains both direct neural connections within the brain and it also controls a variety of neuroendocrine processes that can influence target tissues throughout the body. Dysregulation of the hypothalamic pituitary adrenal axis and hyperactivity of the subgenual cortex are both frequently observed in depression. However, many details of how the hypothalamus, the hypothalamic pituitary adrenal (HPA) axis, and the subgenual cingulate interact with each other are unknown. We hypothesized that resting-state functional connectivity between the hypothalamus and the subgenual cortex would be associated with altered circadian rhythm in patients with depression and depressive symptoms. We also hypothesized that this would be most apparent in patients that have major depression with psychotic symptoms, who typically have the most robust HPA-axis dysregulation. Resting-state functional magnetic resonance imaging (fMRI) scans were collected to observe low-frequency resting-state functional connectivity patterns of the hypothalamus in 39 healthy participants, 39 patients with major depression, and 22 patients with major depression with psychotic symptoms. Hourly overnight measures of cortisol secretion and multiple measures of psychiatric symptom severity were also collected on all. Strong hypothalamic functional connectivity with the subgenual cortex was observed in healthy participants. This connectivity was significantly reduced in patients with psychotic major depression. Increased cortisol secretion during the circadian nadir and reduced connectivity were both associated with symptom severity. Reduced connectivity and high cortisol secretion during the circadian nadir are both useful for explaining a significant amount of variance in symptom severity that occurs between healthy participants and depressed patients. However, only cortisol secretion was useful for explaining the severity of symptoms within the depressed groups. This study suggests that the communication between the hypothalamus and the subgenual cortex is disrupted in patients with major depression with psychotic features. It also suggests that these disruptions are associated with increased symptom severity and may be a cause or a consequence of cortisol dysregulation.

Exogenous glucocorticoids decrease subgenual cingulate activity evoked by sadness

The glucocorticoid hormone cortisol is known to have wide-ranging effects on a variety of physiological systems, including the morphology and physiology of the amygdala and hippocampus. Disruptions of cortisol regulation and signaling are also linked with psychiatric disorders involving emotional disturbances. Although there is much evidence to suggest a relationship between cortisol signaling and the brain physiology underlying emotion, few studies have attempted to test for direct effects of cortisol on the neurophysiology of emotion. We administered exogenous synthetic cortisol (hydrocortisone, HCT) using two different dosing regimens (25 mg/day over 4 days, 100 mg single dose), in a double-blind placebo-controlled functional magnetic resonance imaging (fMRI) study. During fMRI scanning, healthy subjects viewed images designed to induce happy, sad, and neutral emotional states. Subjective emotional reactions were collected for each experimental stimulus after fMRI scanning. Mood ratings were also collected throughout the 4 days of the study. Both dose regimens of HCT resulted in decreased subgenual cingulate activation during sadness conditions. The 25 mg/day regimen also resulted in higher arousal ratings of sad stimuli. No effects of HCT were observed on any mood ratings. Few reliable effects of HCT were observed on brain activity patterns or subjective emotional responses to stimuli that were not sad. The inhibitory effects of cortisol on sadness-induced subgenual cingulate activity may have critical relevance to the pathophysiology of major depression, as both subgenual hyperactivity and decreased sensitivity to cortisol signaling have been documented in patients with depression.

Environmental stress and transposon transcription in the mammalian brain

We recently reported that acute stress causes a substantial upregulation of the epigenetic mark, Histone H3 Lysine 9 Trimethyl (H3K9me3) in the rat hippocampus within an hour of acute stress exposure. To determine the function of this change we used ChIP-sequencing to determine where this silencing mark was being localized. We found that it showed a strong bias toward localization at more active classes of retrotransposable elements and away from genes. Further, we showed that the change was functional in that it reduced transcription of some of these elements (notably the endogenous retrovirus IAP and the B2 SINE). In this commentary we examine these results, which appear to describe a selective genomic stress response and relate it to human health and disease, particularly stress related maladies such as Post-traumatic Stress Disorder, which have recently been shown to have both epigenetic elements in their causation as well as differences in epigenetic marking of retrotransposons in human patients.

Maternal early life experiences and parenting: the mediating role of cortisol and executive function

OBJECTIVE

Research suggests that early life adversity may affect subsequent parenting. Animal studies investigating mechanisms of transmission have focused on biological factors; whereas research in humans has emphasized cognitive and psychosocial factors. We hypothesized that neuropsychological and physiological factors would act as mediators between maternal retrospective reports of early life experiences (ELE) and current parenting.

METHOD

We recruited a community sample of 89 mothers and their infants (2-6 months of age). Maternal ELE consisted of self-reports of consistency of care and childhood maltreatment. Diurnal salivary cortisol samples were collected as the measure of hypothalamic-pituitary-adrenal (HPA) function. Executive function measures included attentional set-shifting and spatial working memory. Maternal sensitivity was assessed through videotapes of mothers interacting with their infants.

RESULTS

A series of path analyses indicated that maternal ELE was indirectly related to maternal sensitivity via two pathways: one through HPA function, and the other through HPA function and spatial working memory. There was no direct path between maternal ELE and parenting.

CONCLUSION

These findings provide support for the notion that mediators linking early life experiences to parenting in humans may be similar to physiological mechanisms found in animal models. As maternal care is associated with numerous infant outcomes, our findings may have broad relevance to understanding the risk associated with parenting and adverse outcomes in infants. A greater understanding of mechanism is important to informing interventions targeted at disrupting maladaptive trajectories of parenting.

Acute glucocorticoid effects on the multicomponent model of working memory

OBJECTIVE

In comparison with basal physiological levels, acute, high levels of cortisol affect learning and memory. Despite reports of cortisol-induced episodic memory effects, no study has used a comprehensive battery of tests to evaluate glucocorticoid effects on the multicomponent model of working memory. Here, we report the results of a double-blind, placebo-controlled, between-subjects study.

METHODS

Twenty healthy young men were randomly assigned to either acute cortisol (30 mg hydrocortisone) or placebo administration. Participants were subjected to an extensive cognitive test battery that evaluated all systems of the multicomponent model of working memory, including various executive domains (shifting, updating, inhibition, planning and access to long-term memory).

RESULTS

Compared with placebo, hydrocortisone administration increased cortisol blood levels and impaired working memory in storage of multimodal information in the episodic buffer and maintenance/reverberation of information in the phonological loop. Hydrocortisone also decreased performance in planning and inhibition tasks, the latter having been explained by changes in storage of information in working memory.

CONCLUSIONS

Thus, hydrocortisone acutely impairs various components of working memory, including executive functioning. This effect must be considered when administering similar drugs, which are widely used for the treatment of many clinical disorders.

Effects of acute psychosocial stress on working memory related brain activity in men

Acute psychosocial stress in humans triggers the release of glucocorticoids (GCs) and influences performance in declarative and working memory (WM) tasks. These memory systems rely on the hippocampus and prefrontal cortex (PFC), where GC-binding receptors are present. Previous studies revealed contradictory results regarding effects of acute stress on WM-related brain activity. We combined functional magnetic resonance imaging with a standardized psychosocial stress protocol to investigate the effects of acute mental stress on brain activity during encoding, maintenance, and retrieval of WM. Participants (41 healthy young men) underwent either a stress or a control procedure before performing a WM task. Stress increased salivary cortisol levels and tended to increase WM accuracy. Neurally, stress-induced increases in cortical activity were evident in PFC and posterior parietal cortex (PPC) during WM maintenance. Furthermore, hippocampal activity was modulated by stress during encoding and retrieval with increases in the right anterior hippocampus during WM encoding and decreases in the left posterior hippocampus during retrieval. Our study demonstrates that stress increases activity in PFC and PPC specifically during maintenance of items in WM, whereas effects on hippocampal activity are restricted to encoding and retrieval. The finding that psychosocial stress can increase and decrease activity in two different hippocampal areas may be relevant for understanding the often-reported phase-dependent opposing behavioral effects of stress on long-term memory.

Progesterone level predicts serotonin-1a receptor binding in the male human brain

BACKGROUND

Progesterone (P) is thought to influence mood and affective states. Alterations of the inhibitory serotonin-1A (5-HT(1A)) receptor distribution are associated with depression and anxiety. This study evaluates the influence of plasma P levels on the 5-HT(1A) receptor binding in healthy male subjects.

METHODS

Molecular neuroimaging of the 5-HT(1A) receptor distribution using positron emission tomography and hormone assays for total plasma P and cortisol were done in a sample of 18 healthy men.

RESULTS

Plasma P levels explained up to 65% of the variability in 5-HT(1A) receptor binding in limbic regions including the amygdala, orbitofrontal cortex and retrosplenial cortex. When controlling for cortisol in the model, there was an expected decline in explained variances of 5-HT(1A) binding attributed to P.

CONCLUSIONS

The results of this study provide further support for the effect of P on 5-HT(1A) receptor expression and raise the possibility that P mediates the vulnerability to mood disorders by affecting the serotonergic system.

The hypothalamic-pituitary-adrenal axis and serotonin abnormalities: a selective overview for the implications of suicide prevention

Suicidal behavior and mood disorders are one of the world's largest public health problems. The biological vulnerability for these problems includes genetic factors involved in the regulation of the serotonergic system and stress system. The hypothalamic-pituitary-adrenal (HPA) axis is a neuroendocrine system that regulates the body's response to stress and has complex interactions with brain serotonergic, noradrenergic and dopaminergic systems. Corticotropin-releasing hormone and vasopressin act synergistically to stimulate the secretion of ACTH that stimulates the biosynthesis of corticosteroids such as cortisol from cholesterol. Cortisol is a major stress hormone and has effects on many tissues, including on mineralocorticoid receptors and glucocorticoid receptors in the brain. Glucocorticoids produce behavioral changes, and one important target of glucocorticoids is the hypothalamus, which is a major controlling center of the HPA axis. Stress plays a major role in the various pathophysiological processes associated with mood disorders and suicidal behavior. Serotonergic dysfunction is a well-established substrate for mood disorders and suicidal behavior. Corticosteroids may play an important role in the relationship between stress, mood changes and perhaps suicidal behavior by interacting with 5-HT1A receptors. Abnormalities in the HPA axis in response to increased levels of stress are found to be associated with a dysregulation in the serotonergic system, both in subjects with mood disorders and those who engage in suicidal behavior. HPA over-activity may be a good predictor of mood disorders and perhaps suicidal behavior via abnormalities in the serotonergic system.

Prenatal psychosocial stress exposure is associated with subsequent working memory performance in young women

The aim of the present study was to examine the association between prenatal psychosocial stress exposure and subsequent prefrontal cortex-dependent working memory performance in human adults. Working memory performance was assessed using an item-recognition task under 10 mg hydrocortisone (cortisol) and placebo conditions in a sample of 32 healthy young women (mean age = 25 +/- 4.34 years) whose mothers experienced a major negative life event during their pregnancy (Prenatal Stress, PS group), and in a comparison group of 27 healthy young women (mean age = 24 +/- 3.4 years). The two groups did not differ in the placebo condition, however, subjects in the PS group showed longer reaction times after hydrocortisone administration compared with subjects in the comparison group (p = .02). These findings provide support for an association between prenatal stress exposure and the potential modulatory effect of cortisol on working memory performance in young adults, which may reflect compromised development of the prefrontal cortex in prenatal life.

Stress-induced changes in corticosteroid receptor expression in primate hippocampus and prefrontal cortex

Neurobiological studies of stress often focus on the hippocampus where cortisol binds with different affinities to two types of corticosteroid receptors, i.e., mineralocorticoid receptor (MR) and glucocorticoid receptor (GR). The hippocampus is involved in learning and memory, and regulates the neuroendocrine stress response, but other brain regions also play a role, especially prefrontal cortex. Here, we examine MR and GR expression in adult squirrel monkey prefrontal cortex and hippocampus after exposure to social stress in infancy or adulthood. In situ hybridization histochemistry with (35)S-labeled squirrel monkey riboprobes and quantitative film autoradiography were used to measure the relative distributions of MR and GR mRNA. Distinct cortical cell layer-specific patterns of MR expression differed from GR expression in three prefrontal regions. The relative distributions of MR and GR also differed in hippocampal Cornu Ammonis (CA) regions. In monkeys exposed to adult social stress compared to the no-stress control, GR expression was diminished in hippocampal CA1 (P=0.021), whereas MR was diminished in cell layer III of ventrolateral prefrontal cortex (P=0.049). In contrast, exposure to early life stress diminished GR but not MR expression in cell layers I and II of dorsolateral prefrontal cortex (P's<0.048). Similar reductions likewise occurred in ventrolateral prefrontal cortex, but the effects of early life stress on GR expression in this region were marginally not significant (P=0.053). These results provide new information on regional differences and the long-term effects of stress on MR and GR distributions in corticolimbic regions that control cognitive and neuroendocrine functions.

Enhanced effects of cortisol administration on episodic and working memory in aging veterans with PTSD

Though both glucocorticoid alterations and memory impairments have been noted in posttraumatic stress disorder (PTSD), it is not clear if these phenomena are causally linked. As there is emerging evidence that these domains become further altered in PTSD with increasing age, it is of interest to examine these relationships in an older cohort. Aging (mean age, 62.7+/-8.9; range, 52-81) combat veterans with (n=13) and without (n=17) PTSD received an intravenous bolus of 17.5 mg hydrocortisone (cortisol), a naturally occurring glucocorticoid, or placebo in a randomized, double-blind manner, on two mornings approximately 1-2 weeks apart. Neuropsychological testing to evaluate episodic and working memory performance was performed 75 min later. Cortisol enhanced episodic memory performance in both groups of subjects, but enhanced elements of working memory performance only in the PTSD+ group. The preferential effect of cortisol administration on working memory in PTSD may be related to the superimposition of PTSD and age, as cortisol had impairing effects on this task in a previously studied, younger cohort. The findings suggest that there may be opportunities for developing therapeutic strategies using glucocorticoids in the treatment of aging combat veterans.

Stress-induced changes in primate prefrontal profiles of gene expression

Stressful experiences that consistently increase cortisol levels appear to alter the expression of hundreds of genes in prefrontal limbic brain regions. Here, we investigate this hypothesis in monkeys exposed to intermittent social stress-induced episodes of hypercortisolism or a no-stress control condition. Prefrontal profiles of gene expression compiled from Affymetrix microarray data for monkeys randomized to the no-stress condition were consistent with microarray results published for healthy humans. In monkeys exposed to intermittent social stress, more genes than expected by chance appeared to be differentially expressed in ventromedial prefrontal cortex compared to monkeys not exposed to adult social stress. Most of these stress responsive candidate genes were modestly downregulated, including ubiquitin conjugation enzymes and ligases involved in synaptic plasticity, cell cycle progression and nuclear receptor signaling. Social stress did not affect gene expression beyond that expected by chance in dorsolateral prefrontal cortex or prefrontal white matter. Thirty four of 48 comparisons chosen for verification by quantitative real-time polymerase chain reaction (qPCR) were consistent with the microarray-predicted result. Furthermore, qPCR and microarray data were highly correlated. These results provide new insights on the regulation of gene expression in a prefrontal corticolimbic region involved in the pathophysiology of stress and major depression. Comparisons between these data from monkeys and those for ventromedial prefrontal cortex in humans with a history of major depression may help to distinguish the molecular signature of stress from other confounding factors in human postmortem brain research.

Stress and epilepsy: a population-based cohort study of epilepsy in parents who lost a child

OBJECTIVE

The goal of the study described here was to study the risk for epilepsy in parents exposed to severe stress caused by loss of a child.

METHODS

The risk of being diagnosed with epilepsy (Danish National Hospital Register) in a cohort of parents who had lost a child under the age of 18 was compared with the risk among parents who had not lost a child.

RESULTS

The adjusted relative risk (RR) of epilepsy in parents who had lost a child was 1.50 (95% CI: 1.21-1.86). The RR was modified by time since bereavement and was 2.46 (95% CI: 1.49-4.07) in mothers and 1.92 (95% CI: 1.09-3.36) in fathers within the first 3 years of loss of a child, and 2.10 (95% CI: 1.53-2.88) in mothers and 0.66 (95% CI: 0.41-1.06) in fathers 4 to 18 years after loss.

CONCLUSIONS

Stress was associated with a moderately increased risk of being diagnosed with epilepsy.

Mineralocorticoid receptor overexpression in forebrain decreases anxiety-like behavior and alters the stress response in mice

Although numerous stress-related molecules have been implicated in vulnerability to psychiatric illness, especially major depression and anxiety disorders, the role of the brain mineralocorticoid receptor (MR) in stress, depression, and affective function is not well defined. MR is a steroid hormone receptor that detects circulating glucocorticoids with high affinity and has been primarily implicated in controlling their basal level and circadian rhythm. To specifically address the role of MR in hypothalamic-pituitary-adrenal axis activity and anxiety-related behaviors, we generated transgenic mice with increased levels of MR in the forebrain (MRov mice) by using the forebrain-specific calcium/calmodulin-dependent protein kinase II alpha promoter to direct expression of MR cDNA. A mild but chronic elevation in forebrain MR results in decreased anxiety-like behavior in both male and female transgenic mice. Female MRov mice also exhibit a moderate suppression of the corticosterone response to restraint stress. Increased forebrain MR expression alters the expression of two genes associated with stress and anxiety, leading to a decrease in the hippocampal glucocorticoid receptor (GR) and an increase in serotonin receptor 5HT-1a, consistent with the decreased anxiety phenotype. These data suggest that the functions of forebrain MR may overlap with GR in hypothalamic-pituitary-adrenal axis regulation, but they dissociate significantly from GR in the modulation of affective responses, with GR overexpression increasing anxiety-like behavior and MR overexpression dampening it. These findings point to the importance of the MR:GR ratio in the control of emotional reactivity.

Individual differences in cortisol levels and performance on a test of executive function in men and women

Despite evidence for a high concentration of corticosteroid receptors in prefrontal cortex, little research has examined the relationship between cortisol and prefrontal cortical function other than working memory. We investigated the association between salivary cortisol levels and performance on the Wisconsin Card Sorting Test (WCST) of executive function and on a test of mental rotation (to test specificity of the relationship between cortisol and cognitive performance) in men and women (n=116, ages 17-22). Higher cortisol levels at the beginning of the test session were associated with more errors in women on the WCST and fewer errors in men. However, men's cortisol levels were lower than women's at this point in time. Cortisol levels were not associated with mental rotation scores. Our results suggest that individual differences in cortisol levels among participants upon arrival to a test situation influence performance on a task involving the prefrontal cortex.

Corticosteroids including ACTH for childhood epilepsy other than epileptic spasms

BACKGROUND

Epilepsy is a disorder with recurrent epileptic seizures. Corticosteroids have been used in the treatment of children with epilepsy and have significant adverse effects. Their efficacy and tolerability have not been not clearly established.

OBJECTIVES

To determine the efficacy of corticosteroids in terms of seizure control, improvements in cognition and in quality of life and tolerability of steroids compared to placebo or other antiepileptic drugs.

SEARCH STRATEGY

We searched the following databases: The Cochrane Epilepsy Group Specialized Register (September 2006); Cochrane Central Register of Controlled Trials (CENTRAL)(The Cochrane Library Issue 2, 2006); MEDLINE (1966 - April 2004); EMBASE (1966 - December 2004); Database of Abstracts of Reviews of Effectiveness (DARE) (December 2004). We checked the reference lists of retrieved studies for additional reports of relevant studies.

SELECTION CRITERIA

All randomized controlled trials of administration of corticosteroids to children (less than 16 years) with epilepsy.

DATA COLLECTION AND ANALYSIS

Three review authors independently selected trials for inclusion and extracted data. Outcomes included cessation of seizures, reduction in seizure frequency, improvement in cognition, quality of life and adverse effects of steroids.

MAIN RESULTS

A single RCT was included that recruited five patients in double blind crossover trial. One was withdrawn prematurely from the study and another had infantile spasms and hence was excluded from further analysis. ACTH 4-9 was administered. The overall reduction in seizure frequency of more than 25% and less than 50% occurred in one child at low dose and in two children at higher dose. One child did not show any reduction in seizure frequency. No adverse effects were reported.

AUTHORS' CONCLUSIONS

No evidence was found for the efficacy or safety of corticosteroids in treating childhood epilepsies. Clinicians using steroids in childhood epilepsies, other than for epileptic spasms, should take this into account before using these agents.

Drospirenone increases central and peripheral β-endorphin in ovariectomized female rats

OBJECTIVE

Drospirenone is the unique progestin derived from 17-spironolactone used for contraception and hormone therapy. Few data are available concerning the effects of drospirenone on the central nervous system and neuroendocrine milieu. The opioid beta-endorphin and the neurosteroid allopregnanolone are considered markers of neuroendocrine functions, and their synthesis and activity are regulated by gonadal steroids. The aim of the present study was to evaluate the effect of a 2-week oral treatment with drospirenone, estradiol valerate, and combined therapy of drospirenone + estradiol valerate on central and peripheral beta-endorphin and allopregnanolone levels in ovariectomized female rats.

DESIGN

Seven groups of Wistar ovariectomized rats received oral drospirenone (0.1, 0.5, and 1.0 mg/kg per day), estradiol valerate (0.05 mg/kg per day), or drospirenone (0.1, 0.5, and 1.0 mg/kg per day) + estradiol valerate (0.05 mg/kg per day). One group of fertile and one group of ovariectomized rats were used as controls. beta-endorphin levels were measured in frontal and parietal lobes, hippocampus, hypothalamus, anterior and neurointermediate pituitary, and plasma, and allopregnanolone content was assessed in frontal and parietal lobes, hippocampus, hypothalamus, anterior pituitary, adrenal glands, and serum.

RESULTS

Ovariectomy induced a significant decrease in beta-endorphin and allopregnanolone content in all brain areas analyzed and in circulating levels, whereas it increased allopregnanolone content in the adrenal gland. Estradiol valerate replacement increased beta-endorphin and allopregnanolone levels in all brain areas analyzed and in plasma/serum. Drospirenone treatment significantly increased beta-endorphin levels in all brain areas analyzed (with the only exception being the parietal lobe), whereas it produced no effect on allopregnanolone levels. The addition of drospirenone to estradiol valerate did not modify the effects of estradiol valerate on beta-endorphin or allopregnanolone levels. Drospirenone showed an additive and synergistic effect with estradiol in the neurointermediate lobe on beta-endorphin synthesis.

CONCLUSIONS

Drospirenone significantly increases central and circulating beta-endorphin levels and does not seem to interfere with allopregnanolone production.

Plasma cortisol levels, brain volumes and cognition in healthy elderly men

PURPOSE

In ageing animals, exposure to chronic high levels of glucocorticoids is associated with cognitive impairment and hippocampal atrophy. However, there are few studies examining relationships among glucocorticoids, brain volumes and cognitive function in healthy older humans. This study examined the hypotheses that higher plasma cortisol levels and altered sensitivity to glucocorticoids are associated with worse cognition and more brain atrophy in elderly men.

MATERIALS AND METHODS

Ninety-seven healthy men aged 65-70 had plasma cortisol measured at 09:00, 14:30 h, and post-dexamethasone (0.25mg, 09:00 h), and had dermal sensitivity to glucocorticoids measured. They also underwent cognitive testing, with scores adjusted for estimated prior mental ability, and had MRI measurements of intracranial area (a validated estimate of intracranial capacity), and hippocampus, temporal lobe and frontal lobe volumes.

RESULTS

Plasma cortisol levels at 09:00 h were significantly and negatively correlated with a summary General Cognitive Factor accounting for 51% of the variance of cognitive function (rho=-0.22, p=0.035), and specific cognitive tests: delayed paragraph recall (rho=-0.28, p=0.036) and processing speed (rho=-0.23, p=0.026). Regional brain volumes adjusted for intracranial area generally did not correlate with cortisol levels. Tissue glucocorticoid sensitivity did not correlate with any measure of cognition or brain volume.

CONCLUSIONS

In healthy older men, higher plasma cortisol levels are associated with worse ageing-related overall cognitive change but not ageing-related brain atrophy.

The stress system in the human brain in depression and neurodegeneration

Corticotropin-releasing hormone (CRH) plays a central role in the regulation of the hypothalamic-pituitary-adrenal (HPA)-axis, i.e., the final common pathway in the stress response. The action of CRH on ACTH release is strongly potentiated by vasopressin, that is co-produced in increasing amounts when the hypothalamic paraventricular neurons are chronically activated. Whereas vasopressin stimulates ACTH release in humans, oxytocin inhibits it. ACTH release results in the release of corticosteroids from the adrenal that, subsequently, through mineralocorticoid and glucocorticoid receptors, exert negative feedback on, among other things, the hippocampus, the pituitary and the hypothalamus. The most important glucocorticoid in humans is cortisol, present in higher levels in women than in men. During aging, the activation of the CRH neurons is modest compared to the extra activation observed in Alzheimer's disease (AD) and the even stronger increase in major depression. The HPA-axis is hyperactive in depression, due to genetic factors or due to aversive stimuli that may occur during early development or adult life. At least five interacting hypothalamic peptidergic systems are involved in the symptoms of major depression. Increased production of vasopressin in depression does not only occur in neurons that colocalize CRH, but also in neurons of the supraoptic nucleus (SON), which may lead to increased plasma levels of vasopressin, that have been related to an enhanced suicide risk. The increased activity of oxytocin neurons in the paraventricular nucleus (PVN) may be related to the eating disorders in depression. The suprachiasmatic nucleus (SCN), i.e., the biological clock of the brain, shows lower vasopressin production and a smaller circadian amplitude in depression, which may explain the sleeping problems in this disorder and may contribute to the strong CRH activation. The hypothalamo-pituitary thyroid (HPT)-axis is inhibited in depression. These hypothalamic peptidergic systems, i.e., the HPA-axis, the SCN, the SON and the HPT-axis, have many interactions with aminergic systems that are also implicated in depression. CRH neurons are strongly activated in depressed patients, and so is their HPA-axis, at all levels, but the individual variability is large. It is hypothesized that particularly a subgroup of CRH neurons that projects into the brain is activated in depression and induces the symptoms of this disorder. On the other hand, there is also a lot of evidence for a direct involvement of glucocorticoids in the etiology and symptoms of depression. Although there is a close association between cerebrospinal fluid (CSF) levels of CRH and alterations in the HPA-axis in depression, much of the CRH in CSF is likely to be derived from sources other than the PVN. Furthermore, a close interaction between the HPA-axis and the hypothalamic-pituitary-gonadal (HPG)-axis exists. Organizing effects during fetal life as well as activating effects of sex hormones on the HPA-axis have been reported. Such mechanisms may be a basis for the higher prevalence of mood disorders in women as compared to men. In addition, the stress system is affected by changing levels of sex hormones, as found, e.g., in the premenstrual period, ante- and postpartum, during the transition phase to the menopause and during the use of oral contraceptives. In depressed women, plasma levels of estrogen are usually lower and plasma levels of androgens are increased, while testosterone levels are decreased in depressed men. This is explained by the fact that both in depressed males and females the HPA-axis is increased in activity, parallel to a diminished HPG-axis, while the major source of androgens in women is the adrenal, whereas in men it is the testes. It is speculated, however, that in the etiology of depression the relative levels of sex hormones play a more important role than their absolute levels. Sex hormone replacement therapy indeed seems to improve mood in elderly people and AD patients. Studies of rats have shown that high levels of cumulative corticosteroid exposure and rather extreme chronic stress induce neuronal damage that selectively affects hippocampal structure. Studies performed under less extreme circumstances have so far provided conflicting data. The corticosteroid neurotoxicity hypothesis that evolved as a result of these initial observations is, however, not supported by clinical and experimental observations. In a few recent postmortem studies in patients treated with corticosteroids and patients who had been seriously and chronically depressed no indications for AD neuropathology, massive cell loss, or loss of plasticity could be found, while the incidence of apoptosis was extremely rare and only seen outside regions expected to be at risk for steroid overexposure. In addition, various recent experimental studies using good stereological methods failed to find massive cell loss in the hippocampus following exposure to stress or steroids, but rather showed adaptive and reversible changes in structural parameters after stress. Thus, the HPA-axis in AD is only moderately activated, possibly due to the initial (primary) hippocampal degeneration in this condition. There are no convincing arguments to presume a causal, primary role for cortisol in the pathogenesis of AD. Although cortisol and CRH may well be causally involved in the signs and symptoms of depression, there is so far no evidence for any major irreversible damage in the human hippocampus in this disorder.

Seizure Frequency and Cortisol and Dehydroepiandrosterone Sulfate (DHEAS) Levels in Women with Epilepsy Receiving Antiepileptic Drug Treatment

PURPOSE

Hormonal changes occur in epilepsy because of seizures themselves and of antiepileptic drug (AED) effects on steroid production, binding, and metabolism. Conversely, steroids may influence neuron activity and excitability by acting as neuroactive steroids. This cross-sectional observational study aimed to evaluating cortisol and dehydroepiandrosterone sulfate (DHEAS) levels in female epilepsy patients with different disease severity, as assessed by a seizure frequency score (SFS).

METHODS

Morning serum levels of cortisol and DHEAS were assayed in 113 consecutive women, aged 16 to 47 years, with varied epilepsy syndromes, receiving mono- or polytherapy with enzyme-inducing and/or noninducing antiepileptic drugs (AEDs). Hormonal data were correlated with clinical parameters (age, body mass index, epilepsy syndrome, disease onset and duration, SFS, AED therapy, and AED serum levels) and compared with those of 30 age-matched healthy women.

RESULTS

In epilepsy patients, cortisol levels and cortisol-to-DHEAS ratios (C/Dr) were significantly higher, whereas DHEAS levels were significantly lower than those in controls. Patients with more frequent seizures showed higher cortisol and C/Dr values and lower DHEAS levels than did those with rarer or absent seizures during the previous 6 months. SFS mainly explained the increase of cortisol levels and C/Dr in patients with more active disease. Changes in DHEAS levels correlated with SFS and epilepsy syndrome, as well as with AED treatments and ages.

CONCLUSIONS

Women with more frequent seizures had alterations of their adrenal steroids characterized by an increase of cortisol and a decrease of DHEAS levels. Such hormonal changes might be relevant in seizure control and in patient health.

Corticosteroid effect on Caco-2 cell lipids depends on cell differentiation

Previous studies from our laboratory have indicated that secondary hyperaldosteronism affects phospholipids of rat colonic enterocytes. To assess whether this represents a direct effect of mineralocorticoids on enterocytes, the role of aldosterone and dexamethasone in the regulation of lipid metabolism was examined in Caco-2 cells during development of their enterocyte phenotype. Differentiation of Caco-2 cells was associated with increased levels of triglycerides (TG) and cholesteryl esters (CE), a decreased content of cholesterol and phospholipids and changes in individual phospholipid classes. The phospholipids of differentiated cells had a higher content of n-6 polyunsaturated fatty acids (PUFA) and lower amounts of monounsaturated (MUFA) and saturated fatty acids than subconfluent undifferentiated cells. Differentiated cells exhibited a higher ability to incorporate [3H]arachidonic acid (AA) into cellular phospholipids and a lower ability for incorporation into TG and CE. Incubation of subconfluent undifferentiated cells with aldosterone or dexamethasone was without effect on the content of lipids, their fatty acids and [3H]AA incorporation. In contrast, aldosterone treatment of differentiated cells diminished the content of TG, increased the content of phospholipids and modulated their fatty acid composition. The percentage of n-6 and n-3 PUFA in phospholipids was increased and that of MUFA decreased, whereas no changes in TG were observed. The incorporation of [3H]AA into phospholipids was increased and into TG decreased and these changes were blocked by spironolactone. Treatment of differentiated cells with dexamethasone increased their CE content but no effect was identified upon other lipids, their fatty acid composition and on the incorporation of [3H]AA. As expected for the involvement of corticosteroid hormones the mineralocorticoid and glucocorticoid receptors were identified in Caco-2 cells by RT-PCR. The results suggest that aldosterone had a profound influence on lipid metabolism in enterocytes and that its effect depends on the stage of differentiation. The aldosterone-dependent changes occurring in phospholipids and their fatty acid composition may reflect a physiologically important phenomenon with long-term consequences for membrane structure and function.

Conception and pharmacodynamic profile of drospirenone

Progesterone is more than a progestin. Beyond functions in cycle and pregnancy, progesterone binds with high affinity to the mineralocorticoid receptor (MR) acting as an antagonist, with obvious significance for electrolyte homeostasis, an array of MR-related functions in the circulation as well as in the CNS. Progesterone induces natriuresis at physiological concentrations. Lack of antimineralocorticoid activity with conventional progestins may account for sodium and water retention, minor elevation of blood pressure and "pill hypertension" in susceptible women on oral contraceptives. Ethinylestradiol (EE) contributes to this problem by distinct activation of the renin-angiotensin-aldosterone (RAAS) system. Drospirenone (DRSP: 6beta,7beta,15beta,16beta-dimethylene-3-oxo 17alpha-pregn-4-ene-21,17 carbolactone) is the first synthetic progestin with antialdosterone activity. DRSP and progesterone bind to PR in uterine (affinity of both is about 30% of R5020) and MR in kidney cytosol (affinity about 230 and 100% of aldosterone, respectively). Intrauterine administration of DRSP in silastic tubes induced maximum local progestational effects in rabbits. At systemic subcutaneous (s.c.) administration (McPhail-assay) full endometrial transformation was obtained at 1mg per animal per day. At 1-3mg DRSP per animal per day subcutaneously, pregnancy maintenance after ovariectomy, antiovulatory activity, and antimineralocorticoid activity were seen in the respective assays in rats. The latter activity indicates about eight-fold higher potency than spironolactone. DRSP decreased blood pressure in male hypertensive rats, whereas an increase was noted under conventional progestins. DRSP also prevented hypertension and fetal growth retardation in pregnant rats after L-NAME, an inhibitor of nitric oxide synthase. DRSP has antiandrogenic activity. Feminizing effects were recorded during sexual differentiation in male fetuses at high doses. Powerful antiandrogenic effects were also seen in gonad intact and testosterone substituted castrated male rats. The antiandrogenic potency of DRSP is superior to that of spironolactone but below that of cyproterone acetate. Endometrial transformation, inhibition of ovulation, and antimineralocorticoid, i.e. natriuretic effects and mild antiandrogenic effects were recorded at the same range of oral doses (0.5-4 mg per day) in humans. Combined with EE (3 mg DRSP+30 microg EE), DRSP provides effective inhibition of ovulation and cycle control. Body weight compared to conventional oral contraceptives was reduced. DRSP (3 mg per day+15, 20, or 30 microg ethinyl estradiol per day) prevented the mild increase of blood pressure seen under a conventional levonorgestrel-containing contraceptive and even tended to reduce pretreatment blood pressure. Studies on modulation (i.e. inhibition) of glucocorticoid effects at the MR in the CNS remain an unexplored and interesting area for research.

Expression of glucocorticoid receptor alpha- and beta-isoforms in human cells and tissues

Alternative splicing of the human glucocorticoid receptor (GR) primary transcript generates two protein isoforms: GR-alpha and GR-beta. We investigated the expression of both GR isoforms in healthy human cells and tissues. GR-alpha mRNA abundance (x10(6) cDNA copies/microg total RNA) was as follows: brain (3.83 +/- 0.80) > skeletal muscle > macrophages > lung > kidney > liver > heart > eosinophils > peripheral blood mononuclear cells (PBMCs) > nasal mucosa > neutrophils > colon (0.33 +/- 0.04). GR-beta mRNA was much less expressed than GR-alpha mRNA. Its abundance (x10(3) cDNA copies/microg total RNA) was as follows: eosinophils (1.55 +/- 0.58) > PBMCs > liver > or = skeletal muscle > kidney > macrophages > lung > neutrophils > brain > or = nasal mucosa > heart (0.15 +/- 0.08). GR-beta mRNA was not found in colon. While GR-alpha protein was detected in all cells and tissues, GR-beta was not detected in any specimen. Our results suggest that, in physiological conditions, the default splicing pathway is the one leading to GR-alpha. The alternative splicing event leading to GR-beta is minimally activated.

Neuroactive steroids and seizure susceptibility

There is increasing clinical and experimental evidence that hormones, in particular sex steroid hormones, influence neuronal excitability and other brain functions. The term 'neuroactive steroids' has been coined for steroids that interact with neurotransmitter receptors. One of the best characterized actions of neuroactive steroids is the allosteric modulation of GABA(A)-receptor function via binding to a putative steroid-binding site. Since neuroactive steroids may interact with a variety of other membrane receptors, excitatory as well as inhibitory, they may have an impact on the excitability of specific brain regions. Neuronal excitability is enhanced by estrogen, whereas progesterone and its metabolites exert anticonvulsant effects. Testosterone and corticosteroids have less consistent effects on seizure susceptibility. Apart from these particular properties, neuroactive steroids may regulate gene expression via progesterone receptors. Based on their molecular properties, these compounds appear to have a promising therapeutical profile for the treatment of different neuropsychiatric diseases including epilepsy. This review focuses on the effects of neuroactive steroids on neuronal excitability and their putative impact on the physiology of epileptic disorders.