Neuroactive steroids and seizure susceptibility

Female sex steroids and epilepsy: Part 1. A review of reciprocal changes in reproductive systems, cycles, and seizures

Seizures, antiseizure medications, and the reproductive systems are reciprocally entwined. In Section 2 of this review, we outline how seizures may affect the hypothalamic-pituitary-gonadal axis, thereby altering sex steroids, and changes in sex steroids across the menstrual cycle and changes in pharmacokinetics during pregnancy may alter seizure susceptibility. The literature indicates that females with epilepsy experience increased rates of menstrual disturbances and reproductive endocrine disorders. The latter include polycystic ovary syndrome, especially for females on valproate. Studies of fertility have yielded mixed results. We aim to summarize and attempt to detangle the existing knowledge on these reciprocal interactions. The menstrual cycle causes changes in seizure intensity and frequency for many females. When this occurs perimenstrually, during ovulation, or in association with an inadequate luteal phase, it is termed catamenial epilepsy. There is a clear biophysiological rationale for how the key female reproductive neurosteroids interact with the brain to alter the seizure threshold, and Section 3 outlines this important relationship. Critically, what remains unknown is the specific pathophysiology of catamenial epilepsy that describes why not all females are affected. There is a need for mechanism-focused investigations in humans to uncover the complexity of the relationship between reproductive hormones, menstrual cycles, and the brain.

Changes of serum metabolomics and gut microbiota reveal specific characteristics of children with febrile seizures

BACKGROUND AND PURPOSE

Febrile seizures (FS) pose a severe threat to the neurological development of children. Probing the abnormality of host metabolism is essential for the prevention, diagnosis, and treatment of FS.

METHODS

Based on clinically collected serum and fecal samples, we used nontargeted metabolomics and 16S rDNA sequencing to explore the relationship of serum metabolite levels and gut microbiota community with the occurrence of FS.

RESULTS

Metabolomic analysis revealed abnormalities in multiple metabolic pathways in serum of FS patients, such as tryptophan metabolism and steroid hormone biosynthesis. Intestinal flora analysis indicated that the α-diversity of gut microbiota in FS patients was significantly reduced. In addition, the relative abundance of a variety of bacteria at the phylum level was remarkably changed in patients with FS, including decreased Firmicutes and Verrucomicrobia. Eleven serum metabolites were identified to be biomarker candidates for FS diagnosis. With the help of a panel biomarker strategy combining four biomarkers as a cluster, four bacteria (i.e., Rothia, Coprococcus, Lactobacillus, and Oscillospira) in a defined panel displayed perfect differentiation of subtypes of FS.

CONCLUSIONS

Combining metabolomic and intestinal flora analysis revealed specific characteristics of children with FS, and provided new clues for the diagnosis of FS and the classification of seizure types. In summary, these findings may provide new insights into revealing the significance of serum metabolites and gut microbiota in the pathogenesis of FS.

Effects of prenatal testosterone exposure on the development of autism-like behaviours in offspring of Wistar rats

BACKGROUND

A neurodevelopmental disease, autism spectrum disorder (ASD) occurs in males three times more commonly than girls. Higher prenatal testosterone exposure may result in autistic-like behaviour in boys, according to earlier research. It is unclear how fetal testosterone affects the development of autism. In this study, we tested the hypothesis that prenatal testosterone exposure in an animal model may result in autistic behaviours by modifying serotonin, dopamine, IGF-1 and oxytocin levels.

MATERIALS AND METHODS

Group 1 (control, n = 6) and Group 2 (testosterone undecanoate, n = 6) of female rats were randomly assigned. For 2-3 days during the oestrus cycle, female rats were housed with a reproductive male (three females/one male). On the 10th day of gestation, rats in Group 1 received 1 ml/kg% 0.9 NaCl saline, whereas rats in Group 2 received 250 mg/kg testosterone undecanoate. Until weaning on postnatal day 21 (P21), the mothers were permitted to care for their pups. On P21, 40 littermates-10 male and female for control and 10 male and female from mothers that exposed to testosterone-were arbitrarily split up and housed. On P50, these mature rats were tested for their behaviour. The rats were then sacrificed. The brain tissue was subjected to histological examinations as well as biochemical tests for homovanillic acid (HVA), 5-Hydroxyindoleacetic acid (5-HIAA), oxytocin and insulin-like growth factor-1 (IGF-1).

RESULTS

The groups differed significantly in the behavioural examinations (three-chamber social test, passive avoidance learning analysis, open field test), with the testosterone-exposed groups exhibiting autistic symptoms to a higher extent. When compared with the control groups, testosterone exposure caused significant histological changes in the hippocampus CA1 and CA3 areas, including gliosis and cell death of neurons. In the testosterone-exposed groups, HVA, 5-HIAA and IGF-1 tissue expressions in the brain elevated, whereas oxytocin levels reduced. These findings point to a potential connection between neurodevelopmental disorders like ASD and exposure to testosterone during gestation.

CONCLUSION

Overall, we revealed that prenatal testosterone exposure led to autistic traits by elevating serotonin, dopamine and IGF-1 levels while lowering oxytocin levels.

Epilepsy Care in Transgender Patients

PURPOSE OF REVIEW

The goal of this review is to outline the main considerations when treating transgender patients with epilepsy. Points to be addressed include the gender affirming hormone therapy regimens and how they interact with anti-seizure medications and seizure control, as well as common co-morbidities in the transgender epilepsy population.

RECENT FINDINGS

Gender affirming hormone therapy (GAHT) may affect seizure control directly, due to proconvulsant or anticonvulsant properties. GAHT may interact with anti-seizure medications; most notably, estrogen will decrease serum concentration of lamotrigine. Enzyme-inducing anti-seizure medications may decrease hormone levels, potentially interfering with goals of GAHT. Transgender epilepsy patients are at risk for co-morbidities such as decreased bone mineral density and depression. There are minimal direct studies on treatment or outcomes in the transgender epilepsy population. Providers must be knowledgeable about the bi-directional interactions between gender affirming hormone therapy and anti-seizure medications, as well as direct hormonal influences on seizure control. Future research should directly evaluate outcomes in transgender epilepsy patients with regard to seizure control, success of hormone therapy, and management of co-morbidities, to further educate providers and patients how to best manage their healthcare.

Steroid Sulfation in Neurodegenerative Diseases

Steroid sulfation and desulfation participates in the regulation of steroid bioactivity, metabolism and transport. The authors focused on sulfation and desulfation balance in three neurodegenerative diseases: Alzheimer´s disease (AD), Parkinson´s disease (PD), and multiple sclerosis (MS). Circulating steroid conjugates dominate their unconjugated counterparts, but unconjugated steroids outweigh their conjugated counterparts in the brain. Apart from the neurosteroid synthesis in the central nervous system (CNS), most brain steroids cross the blood-brain barrier (BBB) from the periphery and then may be further metabolized. Therefore, steroid levels in the periphery partly reflect the situation in the brain. The CNS steroids subsequently influence the neuronal excitability and have neuroprotective, neuroexcitatory, antidepressant and memory enhancing effects. They also exert anti-inflammatory and immunoprotective actions. Like the unconjugated steroids, the sulfated ones modulate various ligand-gated ion channels. Conjugation by sulfotransferases increases steroid water solubility and facilitates steroid transport. Steroid sulfates, having greater half-lives than their unconjugated counterparts, also serve as a steroid stock pool. Sulfotransferases are ubiquitous enzymes providing massive steroid sulfation in adrenal zona reticularis and zona fasciculata.. Steroid sulfatase hydrolyzing the steroid conjugates is exceedingly expressed in placenta but is ubiquitous in low amounts including brain capillaries of BBB which can rapidly hydrolyze the steroid sulfates coming across the BBB from the periphery. Lower dehydroepiandrosterone sulfate (DHEAS) plasma levels and reduced sulfotransferase activity are considered as risk factors in AD patients. The shifted balance towards unconjugated steroids can participate in the pathophysiology of PD and anti-inflammatory effects of DHEAS may counteract the MS.

Efficacy and prognosis of long-term, high-dose steroid therapy for Lennox-Gastaut syndrome

OBJECTIVE

Lennox-Gastaut syndrome (LGS) is a severe form of developmental and epileptic encephalopathy that is highly resistant to treatment with conventional anti-epileptic drugs and non-pharmacological therapies. In the present study, we aimed to investigate the efficacy of long-term, high-dose steroid therapy and its effect on prognosis in children with LGS.

METHODS

This prospective study included patients with LGS who received long-term, high-dose steroid therapy beginning in November 2016. Prednisolone (60 mg per day) was administered for 2 weeks, following which the dosage was reduced to 60 mg on alternate days for 12 weeks. The drug was then slowly tapered over the next 3 months. The primary outcome was a reduction in seizure frequency relative to baseline at 14 weeks. The secondary outcome was whether patients had become seizure-free at 1 year.

RESULTS

Among 44 patients, 30 (68.2%) experienced a reduction in seizure frequency of more than 50%, including 26 (59.1%) with complete seizure control who were classified as the responder group. The remaining 14 (31.8%) were classified as the non-responder group after 14 weeks of treatment. Twenty patients (45.5%, 20/44) remained seizure-free after 1 year of treatment. However, 10 patients (33.3%, 10/30) in the responder group relapsed within a year. Improvements in electroencephalography (EEG) findings tended to be consistent with seizure outcomes. All patients had side effects of weight gain and Cushing's face, but most adverse effects were mild and transient.

CONCLUSION

Long-term, high-dose steroid therapy can be considered an effective treatment option for children with intractable LGS.

Amygdaloid complex anatomopathological findings in animal models of status epilepticus

Temporal lobe epileptic seizures are one of the most common and well-characterized types of epilepsies. The current knowledge on the pathology of temporal lobe epilepsy relies strongly on studies of epileptogenesis caused by experimentally induced status epilepticus (SE). Although several temporal lobe structures have been implicated in the epileptogenic process, the hippocampal formation is the temporal lobe structure studied in the greatest amount and detail. However, studies in human patients and animal models of temporal lobe epilepsy indicate that the amygdaloid complex can be also an important seizure generator, and several pathological processes have been shown in the amygdala during epileptogenesis. Therefore, in the present review, we systematically selected, organized, described, and analyzed the current knowledge on anatomopathological data associated with the amygdaloid complex during SE-induced epileptogenesis. Amygdaloid complex participation in the epileptogenic process is evidenced, among others, by alterations in energy metabolism, circulatory, and fluid regulation, neurotransmission, immediate early genes expression, tissue damage, cell suffering, inflammation, and neuroprotection. We conclude that major efforts should be made in order to include the amygdaloid complex as an important target area for evaluation in future research on SE-induced epileptogenesis. This article is part of the Special Issue "NEWroscience 2018".

Therapeutic Targets for the Treatment of Comorbidities Associated with Epilepsy

One of the most common neurological disorders, which occurs among 1% of the population worldwide, is epilepsy. Therapeutic failure is common with epilepsy and nearly about 30% of patients fall in this category. Seizure suppression should not be the only goal while treating epilepsy but associated comorbidities, which can further worsen the condition, should also be considered. Treatment of such comorbidities such as depression, anxiety, cognition, attention deficit hyperactivity disorder and, various other disorders which co-exist with epilepsy or are caused due to epilepsy should also be treated. Novel targets or the existing targets are needed to be explored for the dual mechanism which can suppress both the disease and the comorbidity. New therapeutic targets such as IDO, nNOS, PAR1, NF-κb are being explored for their role in epilepsy and various comorbidities. This review explores recent therapeutic targets for the treatment of comorbidities associated with epilepsy.

Anxious Profile Influences Behavioral and Immunohistological Findings in the Pilocarpine Model of Epilepsy

Anxiety and epilepsy have a complex bidirectional relationship, where a depressive/anxious condition is a factor that can trigger seizures which in turn can aggravate the depressive/anxious condition. In addition, brain structures such as the hippocampus and amygdala might have a critical relevance in both epilepsy and anxiety. The aim of the present work was to investigate the influence of different anxious profiles to epileptogenesis. Initially, animals were screened through the elevated plus-maze anxiety test, and then seizure development was evaluated using the pilocarpine model of epilepsy. There were no differences in the susceptibility to status epilepticus, mortality rate or frequency of spontaneous recurrent seizures between animals characterized as anxious as compared to the non-anxious animals. Next, we evaluated immunohistological patterns related to seizures and anxiety in various related brain areas. Despite a decrease in the density of neuropeptide Y and parvalbumin expression in epileptic animals, those presenting greater neuropeptide Y immunoreactivity in various brain regions, also showed higher spontaneous recurrent seizures frequency. Differences on the anxious profile showed to interfere with some of these findings in some regions. In addition, animals that were injected with pilocarpine, but did not develop status epilepticus, had behavioral and neuroanatomical alterations as compared to control animals, indicating its importance as an additional tool for investigating the heterogeneity of the epileptogenic response after an initial insult. This study allowed to better understand the association between anxiety and temporal lobe epilepsy and might allow for therapeutic targets to be developed to minimize the negative impacts associated with it.

Serotonin Pretreatment Abolishes Sex-specific NMDA-induced Seizure Behavior in Developing Rats

Neuronal excitability and susceptibility to excitotoxic damage can be sex-specific, with neurons from males usually being more 'easily excitable' compared to neurons from females, especially during development. Increased excitability at an individual neuronal level can lead to the formation of hyperexcitable neuronal networks, which, consequently can make the brain more seizure prone. Both animal and clinical data suggest that males experience more frequent and severe seizures than do females. Serotonin (5-hydroxytryptamine; 5-HT) can mediate neuronal excitability and seizure behavior, often serving as an anticonvulsant. Importantly, 5-HT signaling during parts of the perinatal period is sexually dimorphic. Sex differences during development have been reported in both serotonin levels and receptor type (excitatory vs. inhibitory) expression in a manner that may leave the male brain more vulnerable to over-excitation. Thus, we aimed to determine if the anticonvulsant effects of 5-HT were sex- and/or age-dependent in juvenile animals. We report a baseline sex difference in N-methyl-d-aspartate (NMDA)-induced seizure behavior and hippocampal neuronal loss, with postnatal day (PND) 14 males exhibiting more severe seizure behavior compared to females. Pretreatment with the general 5-HT receptor agonist 5-methoxytryptamine (5-MT) abolishes baseline sex differences, providing an anticonvulsant effect for males only. These sex differences appear to be at least in part organized by testosterone, as females given neonatal androgen exhibit a seizure behavior profile in between that of males and females.

Dehydroepiandrosterone (DHEA) Serum Levels Indicate Cerebrospinal Fluid Levels of DHEA and Estradiol (E2) in Women at Term Pregnancy

Neuroactive steroids such as dehydroepiandrosterone (DHEA), estradiol (E2), and progesterone (P4) are associated with structural and functional changes in the central nervous system (CNS). Measurement of steroid levels in the CNS compartments is restricted in accessibility. Consequently, there is only limited human data on the distributional equilibrium for steroid levels between peripheral and central compartments. While some neuroactive steroids including DHEA and E2 have been reported to convey excitatory and proconvulsant properties, the opposite was demonstrated for P4. We aimed to elucidate the correlation between peripheral and central DHEA, E2, and P4 levels in women at term pregnancy. CSF and serum samples of 27 healthy pregnant women (22–39 years) at term pregnancy were collected simultaneously under combined spinal and epidural anesthesia and used for DHEA ELISA and E2, and P4 ECLIA. All three neuroactive steroids were detected at markedly lower levels in CSF compared to their corresponding serum concentrations (decrease, mean ± SD, 97.66 ± 0.83%). We found a strong correlation for DHEA between its serum and the corresponding CSF levels (r = 0.65, p = 0.003). Serum and CSF levels of E2 (r = 0.31, p = 0.12) appeared not to correlate in the investigated cohort. DHEA serum concentration correlated significantly with E2 (r = 0.58, p = 0.0016) in CSF. In addition, a strong correlation was found between DHEA and E2, both measured in CSF (r = 0.65, p = 0.0002). Peripheral DHEA levels might serve as an indicator for central nervous levels of the neuroactive steroids DHEA and E2 in pregnant women.

The intersections of stress, anxiety and epilepsy

Stress is ubiquitous in chronic medical conditions; however, the connections to psychiatric and neurologic conditions are not always clearly established. Epilepsy is a unique illness that is intimately intertwined with stress and anxiety not only as a result of the disease process but also as a cause of disease exacerbation. Anxiety and depression also involve stress management and often overlap with epilepsy. Anxiety symptoms themselves may be present as intrinsic aspects of seizure phenomena, either during the events or closely related to them. The pathways of stress and anxiety involve the hypothalamic pituitary adrenal (HPA) axis and explain at least in part how stress may lead to worsening seizure control. Ultimately, the study of stress, anxiety, and epilepsy offers insight into mind and body connections, and furthers understanding of neuropsychiatric illness.

Enriched environment attenuates behavioral seizures and depression in chronic temporal lobe epilepsy

OBJECTIVE

Temporal lobe epilepsy (TLE) is commonly associated with depression, anxiety, and cognitive impairment. Despite significant progress in our understanding of the pathophysiology of TLE, it remains the most common form of refractory epilepsy. Enriched environment (EE) has a beneficial effect in many neuropsychiatric disorders. However, the effect of EE on cognitive changes in chronic TLE has not been evaluated. Accordingly, the present study evaluated the effects of EE on chronic epilepsy-induced alterations in cognitive functions, electrophysiology, and cellular changes in the hippocampus.

METHODS

Status epilepticus (SE) was induced in 2-month-old male Wistar rats with lithium and pilocarpine. Six weeks' post SE, epileptic rats were either housed in their respective home cages or in an enrichment cage (6 h/day) for 14 days. Seizure behavior was video-monitored 2 weeks before and during exposure to EE. Depression-like behavior, anxiety-like behavior, and spatial learning and memory were assessed using the sucrose preference test (SPT), elevated plus maze (EPM), and Morris water maze (MWM), respectively. Delta and theta power in the CA1 region of hippocampus was assessed from recordings of local field potentials (LFPs). Cellular changes in hippocampus were assessed by histochemistry followed by unbiased stereologic analysis.

RESULTS

EE significantly reduced seizure episodes and seizure duration in epileptic rats. In addition, EE alleviated depression and hyperactivity, and restored delta and theta power of LFP in the hippocampal CA1 region. However, EE neither ameliorated epilepsy-induced spatial learning and memory deficits nor restored cell density in hippocampus.

SIGNIFICANCE

This is the first study that evaluates the role of EE in a chronic TLE model, where rats were exposed to EE after occurrence of spontaneous recurrent seizures (SRS). Given that 30% of TLE patients are refractory to drug treatment, therapeutic strategies that utilize components of EE could be designed to alleviate seizures and psychiatric comorbidities associated with TLE.

The Effects of Sex Hormonal Fluctuations during Menstrual Cycle on Cortical Excitability and Manual Dexterity (a Pilot Study)

AIM

To investigate whether hormonal fluctuations during the menstrual cycle affect corticospinal excitability, intracortical inhibition (ICI) or facilitation (ICF) in primary motor cortex, and also whether the hormonal fluctuations have any effect on manual dexterity in neurologically intact women.

MATERIALS AND METHODS

Twenty volunteers (10 Female, 10 Male) were included in this study. The levels of progesterone and estradiol were measured from saliva during the women's menstrual follicular, ovulation and mid-luteal phases. Motor evoked potentials were recorded from the right first dorsal interosseous muscle. Single and paired-pulse Transcranial Magnetic Stimulation (TMS) were delivered in a block of 20 stimuli. With paired-pulse technique, 3ms and 10ms inter-stimulus intervals were used to assess ICI and ICF, respectively. The Grooved Pegboard Test (GPT) was completed in each session before the TMS assessments. Male participants were tested at similar time intervals as female participants.

RESULTS

Mixed design ANOVA revealed that GPT score in female participants was significantly lower at the mid-luteal phase compared to the ovulation phase (p = 0.017). However, it was not correlated with progesterone or estrogen fluctuations during the menstrual cycle. The results also showed that the effect of phase, sex and the interaction of phase by sex for resting motor threshold, ICI or ICF were not significant (p > 0.05).

CONCLUSION

Manual dexterity performance fluctuates during the menstrual cycle in neurologically intact women, which might be due to the balance of the neuromodulatory effects of P4 and E2 in the motor cortex during different phases.

Epileptogenic effects of G protein-coupled estrogen receptor 1 in the rat pentylenetetrazole kindling model of epilepsy

BACKGROUND

G protein-coupled estrogen receptor 1 (GPER-1) has been demonstrated in several parts of the brain and may play an important role in estrogen downstream signaling pathway. However, the effects of this receptor on epileptic seizure are not clearly known. Therefore, the effects of GPER-1 agonist, G-1, GPER-1 antagonist, G-15 and the main estrogenic hormone, 17β-estradiol were investigated on seizures and brain tissue oxidative damages induced by pentylenetetrazole (PTZ) in rats.

METHODS

In this study, 30 adult male Wistar albino rats were used. Due to intraperitoneal (ip) injections of a subconvulsant dose of PTZ (35mg/kg) which was repeated 12 times every 48h, chemical kindling occurred and kindling seizure was recorded for 30min. The rats were injected with 17β-estradiol (5μg/kg, ip) or G-1 (5μg/kg, ip), G-15 (5μg/kg, ip), Saline, Ethanol and Dimethyl sulfoxide (DMSO) 30min before each dose of PTZ. Observed seizures were classified between the phase 0-5. Thirty minutes later when the last 12. PTZ administration, all rats were sacrificed and the brain cortex, hippocampus sections were removed and the tissue superoxide dismutase (SOD), malondialdehyde (MDA) and nitric oxide (NO) levels on these tissues were studied.

RESULTS

GPER1 agonist, G-1 and estrogenic hormone, 17β-estradiol significantly increased the development of PTZ kindling the seizures. However, GPER1 antagonist, G-15 did not change the development of PTZ kindling the seizures. In the cortex and hippocampus homogenates, the NO levels after G-1 administration had significantly increased (p<0.05) compared to the PTZ groups but SOD activities and MDA levels demonstrated no difference between the groups.

CONCLUSIONS

This is the first study that explores that GPER-1 receptors have epileptogenic effect on PTZ-induced kindling rat. GPER1 may mediate the epileptogenic effect of estrogens by changing the oxidative or anti-oxidative parameters in the brain.

Progesterone for neuroprotection in pediatric traumatic brain injury

OBJECTIVE

To provide an overview of the preclinical literature on progesterone for neuroprotection after traumatic brain injury and to describe unique features of developmental brain injury that should be considered when evaluating the therapeutic potential for progesterone treatment after pediatric traumatic brain injury.

DATA SOURCES

National Library of Medicine PubMed literature review.

STUDY SELECTION

The mechanisms of neuroprotection by progesterone are reviewed, and the preclinical literature using progesterone treatment in adult animal models of traumatic brain injury is summarized. Unique features of the developing brain that could either enhance or limit the efficacy of neuroprotection by progesterone are discussed, and the limited preclinical literature using progesterone after acute injury to the developing brain is described. Finally, the current status of clinical trials of progesterone for adult traumatic brain injury is reviewed.

DATA EXTRACTION AND DATA SYNTHESIS

Progesterone is a pleiotropic agent with beneficial effects on secondary injury cascades that occur after traumatic brain injury, including cerebral edema, neuroinflammation, oxidative stress, and excitotoxicity. More than 40 studies have used progesterone for treatment after traumatic brain injury in adult animal models, with results summarized in tabular form. However, very few studies have evaluated progesterone in pediatric animal models of brain injury. To date, two human phase II trials of progesterone for adult traumatic brain injury have been published, and two multicenter phase III trials are underway.

CONCLUSIONS

The unique features of the developing brain from that of a mature adult brain make it necessary to independently study progesterone in clinically relevant, immature animal models of traumatic brain injury. Additional preclinical studies could lead to the development of a novel neuroprotective therapy that could reduce the long-term disability in head-injured children and could potentially provide benefit in other forms of pediatric brain injury (global ischemia, stroke, and statue epilepticus).

Sex and the migraine brain

The brain responds differently to environmental and internal signals that relate to the stage of development of neural systems. While genetic and epigenetic factors contribute to a premorbid state, hormonal fluctuations in women may alter the set point of migraine. The cyclic surges of gonadal hormones may directly alter neuronal, glial and astrocyte function throughout the brain. Estrogen is mainly excitatory and progesterone inhibitory on brain neuronal systems. These changes contribute to the allostatic load of the migraine condition that most notably starts at puberty in girls.

Dehydroepiandrosterone's antiepileptic action in FeCl3-induced epileptogenesis involves upregulation of glutamate transporters

Dehydroepiandrosterone (DHEA), a neuroactive androgen steroid, has antiepileptic action in iron-induced experimental epilepsy (which models post-traumatic clinical epilepsy). In iron-induced epilepsy increased extracellular glutamate resulting from its reduced glial uptake due to the down-regulation (decreased expression) of transporters (glial and or neuronal) is active during epileptogenesis. The present study was aimed at determining whether the mechanism of antiepileptic action of DHEA involved upregulation (increased expression) of glutamate transporters. Iron-induced epileptogenesis was performed in rats by FeCl3 injection into the cerebral cortex. DHEA was administered intraperitoneally to the iron-induced epileptic rats for 7, 14 and 21 days. Levels of glutamate transporters mRNAs expression were measured using quantitative PCR in the hippocampus during the chronic phase of iron-induced epileptogenesis. There were significant reductions in the glutamate transporter mRNAs in epileptogenesis. DHEA treatment resulted in a significant elevation of glutamate transporters: GLT-1, GLAST and EACC-1 mRNA indicating that the DHEA treatment induced upregulation of these transporters. The results are of significance in respect of the mechanism of the antiepileptic action of neurosteroids and the glutamate transporters as therapeutic targets in glutamatergic epileptogenesis.

Sex and pain perception and analgesia

Sex is an important factor in painful experience modulation. Large volume of evidence shows that experience is different for males and females, as well as the answer to some classes of analgesics. Laboratory experiments suggest that women have a lower pain threshold than men related to pain from noxious stimuli such as heat, cold, pressure and electrical stimulation. Pain is a dynamic phenomenon under the influence of various mechanisms of excitatory and inhibitory control. The differences in pain perception related to sex may be associated with hyperalgesia in women, but also to the hypoactivity of the inhibitory system of pain in females. The purpose of this review besides showing some relationship for gonadal hormones, central nervous system and pain is to provide reference points for the discussion of one of the most intriguing aspects of the pathophysiology of pain: the differences in the presence of painful stimuli related to gender.

Stress and epilepsy: multiple models, multiple outcomes

Human studies show a link between stress and epilepsy, with stress causing an increase in seizure frequency and severity in patients with epilepsy. Many different animal model systems have been used to better understand this connection and the possible mechanisms involved. This review highlights the results of such studies relating stress and seizure susceptibility, with a focus on the hypothalamic-pituitary-adrenal axis and its relationship to seizure generation. The effects of hypothalamic-pituitary-adrenal axis mediators, acute stress, chronic stress, and early life stress on the seizure phenotype are summarized. Results suggest that stress has both anticonvulsive and proconvulsive properties, depending on the animal strain and the stress/seizure induction paradigm used. Attempts to interpret the stress-epilepsy literature must take these variables into account. The growing availability of genetically modified mice that carry either human epilepsy mutations or mutations in stress pathway genes now provide the opportunity to examine the relationship between stress and epilepsy more directly.

Estrogen modulation of peripheral pain signal transduction: involvement of P2X(3) receptors

There is evidence that gonadal hormones may affect the perception of painful stimulation, although the underlying mechanisms remain unclear. This investigation was undertaken to determine whether the adenosine 5'-triphosphate (ATP) receptor subunit, P2X(3), is involved in the modulatory action of estrogen in peripheral pain signal transduction in dorsal root ganglion (DRG). The mechanical pain behavior test, real-time quantitative reverse transcription-polymerase chain reaction analysis, and Western blot methods were used to determine the mean relative concentrations and functions of P2X(3) receptors in DRG in sham, ovariectomized (OVX), and estradiol replacement (OVX+E(2)) female rats and in sham and orchiectomized male rats. The mechanical hyperalgesia appeared after ovariectomy, which was subsequently reversed after estradiol replacement, whereas it was not observed after orchiectomy in male rats. Plantar injection of 2'(3')-O-(2,4,6-trinitrophenyl) ATP (TNP-ATP), a P2X(3) and P2X(2/3) receptor antagonist, resulted in an increase of the pain threshold force in OVX rats while had no effect on sham rats. Furthermore, A-317491, a selective P2X(3)/P2X(2/3) receptor antagonist, significantly reversed the hyperalgesia of OVX rats. Injection of ATP into the plantars also caused a significant increase of the paw withdrawal duration in OVX rats compared with that seen in the sham group, which became substantially attenuated by TNP-ATP. P2X(3) receptors expressed in DRG were significantly increased in both mRNA and protein levels after ovariectomy and then reversed after estrogen replacement, while a similar increase was not observed after orchiectomy in male rats. Furthermore, P2X(3) mRNA was significantly decreased 24 h after the application of 17β-estradiol in a concentration-dependent manner in cultured DRG neurons. ICI 182,780, an estrogen receptor antagonist, blocked the reduction in the protein level. These results suggest that the female gonadal hormone, 17β-estradiol, might participate in the control of peripheral pain signal transduction by modulating P2X(3) receptor-mediated events in primary sensory neurons, probably through genomic mechanisms.

Antiepileptic action of exogenous dehydroepiandrosterone in iron-induced epilepsy in rat brain

In the study described here, the antiepileptic effect of dehydroepiandrosterone (DHEA) treatment on iron-induced focal epileptiform activity in the rat brain was investigated. DHEA is a neuroactive corticosteroid hormone synthesized both in the adrenal cortex and in the brain. Its antioxidant properties are well known. As oxidative stress seems to play a major role in epileptogenesis in the iron-induced model of posttraumatic epilepsy, it was of interest to examine whether DHEA would exert antiepileptic activity. DHEA at a dose of 30 mg/kg/day administered intraperitoneally for 7, 14, and 21 days to iron-induced epileptic rats prevented epileptiform electrophysiological activity. Morris water maze and open-field tests on iron-induced epileptic rats revealed that DHEA also prevented behavioral alterations related to epileptiform activity. Thus, DHEA attenuated the cognitive defects produced by epileptic activity. Moreover, alterations in epileptogenesis-related biochemical parameters-lipid peroxidation, protein oxidation and Na(+), K(+)-ATPase (sodium pump) activity--were also countered by DHEA.

Effects of valproate and carbamazepine monotherapy on neuroactive steroids, their precursors and metabolites in adult men with epilepsy

Only limited data is available concerning the role of unconjugated Δ(5) C19-steroids and almost no data exists regarding the neuroactive C21 and C19 3α-hydroxy-5α/β-metabolites in men with epilepsy. To evaluate the alterations in serum neuroactive steroids and related substances in adult men with epilepsy on valproate and carbamazepine monotherapy, we have measured 26 unconjugated steroids, 18 steroid polar conjugates, gonadotropins and sex hormone binding globulin (SHBG) in 6 and 11 patients on valproate and carbamazepine monotherapy, respectively, and in 19 healthy adult men, using the GC-MS and immunoassays. Decreased testosterone, free androgen index, free testosterone, androstenediol, 5α-androstane-3α,17β-diol (androstanediol), androsterone, epiandrosterone, DHEA, 7β-hydroxy-DHEA, and DHEAS levels were associated with epilepsy per se. Valproate (VPA) therapy increased 5α-dihydrotestosterone, androsterone, epiandrosterone, DHEA, DHEAS, and 7β-hydroxy-DHEA levels. Decrease in pregnenolone and 17-hydroxypregnenolone were associated with epilepsy with no effect of antiepileptic drugs (AEDs). Alternatively, the increase in progesterone levels was linked to epilepsy and VPA further increased progesterone levels. Reduced steroid 20α-hydroxy-metabolites and cortisol were connected with epilepsy without an effect of AEDs. Carbamazepine induced only slight decrease in isopregnanolone, 5α,20α-tetrahydroprogesterone, and androstanediol levels.

Effects of progesterone on total brain tissue adenosine deaminase activity in experimental epilepsy

Single seizure and epilepsy is one of the most commonly encountered neurologic disorders in elderly individuals, arising as a result of complex and often multiple acquired underlying pathologies. Adenosine, acting at A1 receptors, exhibits anticonvulsant effects in experimental epilepsy and inhibits progression to status epilepticus. Adenosine deaminase is the enzyme for the regulation of adenosine levels. Therefore any change in adenosine deaminase levels will reflect to adenosine levels. Adenosine deaminase levels were decreased in the groups that were given progesterone. Progesterone may have an antiseizure effect with the additional finding decreased levels of adenosine deaminase that would have resulted in increased adenosine levels that exerts anticonvulsant effect via GABA-A receptors. Further studies are needed to evaluate the role of progesterone effects on adenosine deaminase levels and its mechanism(s) in the pathogenesis.

Role of nitric oxide in the anticonvulsive effect of progesterone

Described here is an investigation of the potential interaction of the nitric oxide signaling pathway with the anticonvulsant effects of progesterone. In ovariectomized Swiss mice, the threshold for seizures induced by intravenous infusion of pentylenetetrazole was determined after treatment with progesterone (25, 50, or 75 mg/kg, given subcutaneously 6h before seizure testing) or vehicle. Progesterone induced significant anticonvulsive activity at moderate (50 mg/kg) and high (75 mg/kg) doses. This effect of progesterone was abolished by the NO precursor compound L-arginine (200 mg/kg). Moreover, when subeffective doses of progesterone (25 mg/kg) and the NO synthase inhibitor N(omega)-nitro-L-arginine methyl ester (10 mg/kg) were injected, a strong anticonvulsant effect was observed. These findings suggest a potential role for NO signaling as an anticonvulsant target in females.

Gender and the injured brain

Anesthesiologists are frequently confronted with patients who are at risk for neurological complications due to perioperative stroke or prior traumatic brain injury. In this review, we address the growing and fascinating body of data that suggests gender and sex steroids influence the pathophysiology of injury and outcome for these patients. Cerebral ischemia, traumatic brain injury, and epilepsy are reviewed in the context of potential sex differences in mechanisms and outcomes of brain injury and the role of estrogen, progesterone, and androgens in shaping these processes. Lastly, implications for current and future perioperative and intensive care are identified.

Estrogen administration negatively alters mood following monoaminergic depletion and psychosocial stress in postmenopausal women

Differences in the rates of affective disorders between women and men may relate to gender differences in gonadal steroid levels such as estrogen that have effects on brain monoamines important to mood regulation. Changes in estrogen secretion patterns during the perimenopause and menopause may be relevant to the increased risk for affective symptoms at that time. This study examined whether 17beta-estradiol (E2) administration can modify the mood effects of experimental psychosocial stress following acute monoamine depletion in postmenopausal women. Subjects consisted of 15 normal postmenopausal women (PMW) (ages 67.1+/-11.2 years) blindly placed on either oral placebo or E2 (1 mg/day for 1 month, then 2 mg/day for 2 months). At the end of the 3-month treatment phase, subjects participated in three blinded depletion challenges in which they ingested each of three amino-acid mixtures: deficient in tryptophan, deficient in phenylalanine/tyrosine, or nutritionally balanced. After 5 h, subjects performed the Trier Social Stress Test (TSST), followed by mood and anxiety ratings. E2-treated subjects exhibited a significant increase in negative mood and anxiety after the TSST compared to placebo-treated women. These effects were independent of monoamine depletion and were not manifest before the TSST or at baseline. Exogenous estrogen administration in PMW may alter or modulate emotional reactivity to stressful events and may alter the sensitivity of emotional regulation. This modulation appears to be independent of alterations in monoaminergic neurotransmission. The dose of estrogen used after menopause may be important in determining the effects of gonadal steroids on emotional regulation.

Progesterone receptors: form and function in brain

Emerging data indicate that progesterone has multiple non-reproductive functions in the central nervous system to regulate cognition, mood, inflammation, mitochondrial function, neurogenesis and regeneration, myelination and recovery from traumatic brain injury. Progesterone-regulated neural responses are mediated by an array of progesterone receptors (PR) that include the classic nuclear PRA and PRB receptors and splice variants of each, the seven transmembrane domain 7TMPRbeta and the membrane-associated 25-Dx PR (PGRMC1). These PRs induce classic regulation of gene expression while also transducing signaling cascades that originate at the cell membrane and ultimately activate transcription factors. Remarkably, PRs are broadly expressed throughout the brain and can be detected in every neural cell type. The distribution of PRs beyond hypothalamic borders, suggests a much broader role of progesterone in regulating neural function. Despite the large body of evidence regarding progesterone regulation of reproductive behaviors and estrogen-inducible responses as well as effects of progesterone metabolite neurosteroids, much remains to be discovered regarding the functional outcomes resulting from activation of the complex array of PRs in brain by gonadally and/or glial derived progesterone. Moreover, the impact of clinically used progestogens and developing selective PR modulators for targeted outcomes in brain is a critical avenue of investigation as the non-reproductive functions of PRs have far-reaching implications for hormone therapy to maintain neurological health and function throughout menopausal aging.

Hyperestrogenemia simulating kennedy disease

A 71-year-old man developed clinical signs of Kennedy disease including dysarthria, dysphagia, palatal and oral mandibular fasciculations, lower-extremity weakness, gynecomastia, and testicular atrophy. Electrophysiologic studies showed sensory axonal polyneuropathy and chronic neurogenic changes of large-motor unit action potentials with decreased recruitment. Genetic analysis showed a normal 17-CAG repeat sequence. Laboratory studies showed an increased estrogen level of 180 to 220 pg/mL, probably related to his alcoholic fatty liver disease. Splenomegaly was present by ultrasound. The increased level of estrogen adversely affected estrogen-sensitive cells in breast, testicular, neuronal, and muscle cells, leading to the clinical phenotype.

Effects of anabolic androgenic steroids on sleep patterns of individuals practicing resistance exercise

Anabolic androgenic steroid (AAS) abuse has become a public health problem in many countries, and is associated with many psychiatric disorders. Epidemiological studies have also found increasing numbers of sleep disorders reported by individuals using AASs. The purpose of this study was to evaluate sleep patterns and disorders in anabolic androgenic users who practice resistance exercise. The sample comprised 58 males divided into three groups: (1) 20 current AAS users aged 26 +/- 1.2, (2) 21 controls with no history of AAS use, aged 26 +/- 1 and (3) 17 sedentary men with no sleep disorders aged 27.2 +/- 0.34. The volunteers spent a night in the sleep laboratory for polysomnography. Comparing the three groups, the user group showed reduced sleep efficiency and more wakings after sleep onset than the sedentary group (P = 0.001). The sedentary group showed a higher percentage of stage 4 than the non-users group. We suggest that using of anabolic steroids reduced sleep efficiency and alters sleep architecture.

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.

Steroidogenic acute regulatory protein expression and pregnenolone synthesis in rat astrocyte cultures

Neurosteroids are steroids synthesised by brain cells. The molecular mechanism of neurosteroidogenesis from cholesterol has not yet been revealed. We studied the potential role of the steroidogenic acute regulatory (StAR) protein in neurosterodogenesis by using rat brain astrocytes. The novelty of the study is that regulation of StAR is described in primary cultures from embryonic mesencephalon and cerebellum regions of the brain. Dibutyryl cyclic AMP (dbcAMP) treatment increased StAR protein expression in astrocyte cultures. This was observed in immunoblots of mitochondrial fractions and by immunocytochemistry. Dual-labelling showed that the cyclic AMP-induced increase in StAR immunofluorescence was localised to mitochondria. In addition, mitochondrial cytochrome P450-side chain cleavage enzyme was demonstrated with a specific antibody, indicating the potential for pregnenolone production in these cells. Radioimmunoassay on ether-extracted conditioned media of control and dbcAMP treated cells demonstrated pregnenolone production by mesencephalic and cerebellar astrocyte cultures. Furthermore, 24-h pregnenolone levels, in the presence of inhibitors of further pregnenolone metabolism, were significantly increased by dbcAMP exposure. A murine StAR promoter-luciferase fusion plasmid was activated by dbcAMP in transiently transfected mesencephalic and cerebellar astrocytes. These novel results indicate that cyclic AMP signalling can regulate StAR expression and pregnenolone production in brain astrocytes, and provide additional insight into the role of StAR in neurosteroidogenesis.

Pregnenolone sulfate in the brain: a controversial neurosteroid

Pregnenolone sulfate (PREGS) has been shown, either at high nanomolar or at micromolar concentrations, to increase neuronal activity by inhibiting GABAergic and by stimulating glutamatergic neurotransmission. PREGS is also a potent modulator of sigma type 1 (sigma1) receptors. It has been proposed that these actions of PREGS underlie its neuropharmacological effects, and in particular its influence on memory processes. On the other hand, the PREGS-mediated increase in neuronal excitability may become dangerous under particular conditions, for example in the case of excitotoxic stress or convulsions. However, the physiopathological significance of these observations has recently been put into question by the failure to detect significant levels of PREGS within the brain and plasma of rats and mice, either by direct analytical methods based on liquid chromatography/mass spectrometry (LC/MS) or enzyme linked immunosorbent assay (ELISA) with specific antibodies against PREGS, or by indirect gas chromatography/mass spectrometry (GC/MS) analysis with improved sample workup. These recent results have not come to the attention of a large number of neurobiologists interested in steroid sulfates. However, although available direct analytical methods have failed to detect levels of PREGS above 0.1-0.3 ng/g in brain tissue, it may be premature to completely exclude the local formation of biologically active PREGS within specific and limited compartments of the nervous system. In contrast to the situation in rodents, significant levels of sulfated 3beta-hydroxysteroids have been measured in human plasma and brain. Previous indirect measures of steroid sulfates by radioimmunoassays (RIA) or GC/MS had detected elevated levels of PREGS in rodent brain. The discrepancies between the results of different assay procedures have revealed the danger of indirect analysis of steroid sulfates. Indeed, PREGS must be solvolyzed/hydrolyzed prior to RIA or GC/MS analysis, and it is the released, unconjugated PREG which is then quantified. Extreme caution needs to be exercised during the preparation of samples for RIA or GC/MS analysis, because the fraction presumed to contain only steroid sulfates can be contaminated by nonpolar components from which PREG is generated by the solvolysis/hydrolysis/derivatization reactions.

Progesterone: Therapeutic opportunities for neuroprotection and myelin repair

Progesterone and its metabolites promote the viability of neurons in the brain and spinal cord. Their neuroprotective effects have been documented in different lesion models, including traumatic brain injury (TBI), experimentally induced ischemia, spinal cord lesions and a genetic model of motoneuron disease. Progesterone plays an important role in developmental myelination and in myelin repair, and the aging nervous system appears to remain sensitive to some of progesterone's beneficial effects. Thus, the hormone may promote neuroregeneration by several different actions by reducing inflammation, swelling and apoptosis, thereby increasing the survival of neurons, and by promoting the formation of new myelin sheaths. Recognition of the important pleiotropic effects of progesterone opens novel perspectives for the treatment of brain lesions and diseases of the nervous system. Over the last decade, there have been a growing number of studies showing that exogenous administration of progesterone or some of its metabolites can be successfully used to treat traumatic brain and spinal cord injury, as well as ischemic stroke. Progesterone can also be synthesized by neurons and by glial cells within the nervous system. This finding opens the way for a promising therapeutic strategy, the use of pharmacological agents, such as ligands of the translocator protein (18 kDa) (TSPO; the former peripheral benzodiazepine receptor or PBR), to locally increase the synthesis of steroids with neuroprotective and neuroregenerative properties. A concept is emerging that progesterone may exert different actions and use different signaling mechanisms in normal and injured neural tissue.

Diagnosis of rapid eye movement sleep disorder with electroencephalography and treatment with tricyclic antidepressants in a dog

A 9-month-old, female Labrador retriever mix was presented for two types of seizure-like episodes, one of which occurred only during sleep. The two types of episodes were morphologically distinct. An electroencephalogram (EEG) demonstrated that the sleep-associated episodes occurred during rapid eye movement (REM) sleep, supporting a diagnosis of a REM behavior disorder. Based on their morphology and response to antiseizure medications, the waking episodes were diagnosed as seizures. The animal was also diagnosed with an obsessive-compulsive and generalized anxiety disorder. The REM behavior disorder and anxiety-related behaviors improved with tricyclic antidepressant therapy.

Modified progesterone receptor expression in the hypothalamus of cysticercotic male mice

Progesterone participates in numerous developmental and behavioral processes in the mammalian brain. The intracellular (is this really intracellular? nuclear membrane?) progesterone receptor is expressed as two isoforms: a full-length form (PR-B) and the N-terminally truncated one (PR-A). Experimental intraperitoneal infections with Taenia crassiceps in mice exhibit the tendency of the parasites to develop more rapidly in females. Male mice undergo a feminization process characterized by their oestrogenisation, deandrogenisation and loss of sexual and aggressive patterns of behavior. Hence, we suspected that changes in PR expression in the brain could be involved in the feminization of the infected male mice and in the loss of the sexual and aggressive behaviors. We have studied the expression of PR isoforms in the normal and infected male mouse brain. Transcripts of both receptor isoforms (PR-A and -B) were readily detectable in normal and infected mice, but differentially regulated during infection depending on the area of the brain studied. Although the precise role of progesterone in mediating the behavioral changes noted during infection is not fully understood, our data implicate a role for PR signaling in the feminization process. CNS activity is potentially involved in the network that regulates the oestrogenisation and deandrogenisation observed in chronically infected male mice, as well as in the behavioral peculiarities observed in this parasitic infection.

Novel perspectives for progesterone in hormone replacement therapy, with special reference to the nervous system

The utility and safety of postmenopausal hormone replacement therapy has recently been put into question by large clinical trials. Their outcome has been extensively commented upon, but discussions have mainly been limited to the effects of estrogens. In fact, progestagens are generally only considered with respect to their usefulness in preventing estrogen stimulation of uterine hyperplasia and malignancy. In addition, various risks have been attributed to progestagens and their omission from hormone replacement therapy has been considered, but this may underestimate their potential benefits and therapeutic promises. A major reason for the controversial reputation of progestagens is that they are generally considered as a single class. Moreover, the term progesterone is often used as a generic one for the different types of both natural and synthetic progestagens. This is not appropriate because natural progesterone has properties very distinct from the synthetic progestins. Within the nervous system, the neuroprotective and promyelinating effects of progesterone are promising, not only for preventing but also for reversing age-dependent changes and dysfunctions. There is indeed strong evidence that the aging nervous system remains at least to some extent sensitive to these beneficial effects of progesterone. The actions of progesterone in peripheral target tissues including breast, blood vessels, and bones are less well understood, but there is evidence for the beneficial effects of progesterone. The variety of signaling mechanisms of progesterone offers exciting possibilities for the development of more selective, efficient, and safe progestagens. The recognition that progesterone is synthesized by neurons and glial cells requires a reevaluation of hormonal aging.

Dissociation of the immunoreactivity of synaptophysin and GAP-43 during the acute and latent phases of the lithium–pilocarpine model in the immature and adult rat

RATIONALE

Lithium-pilocarpine-induced status epilepticus (SE) generates neuronal lesions in the limbic forebrain, cerebral cortex and thalamus that lead to circuit reorganization and spontaneous recurrent seizures. The process of reorganization in regions with neuronal damage is not fully clarified.

METHODS

In the present study, we evaluated by immunohistochemistry the early reorganization during the latent period with two neuronal markers, synaptophysin and growth-associated protein 43 (GAP-43) in rats subjected to SE at PN21 and as adults.

RESULTS

Synaptophysin immunoreactivity increased between 24 h and 3 weeks post-SE in regions with severe and rapidly occurring neuronal loss, namely thalamus, amygdala, piriform and entorhinal cortices. GAP-43 expression decreased at 1 and 3 weeks in the same regions. The immunoreactivity of synaptophysin and GAP-43 increased in the inner molecular layer of dentate gyrus from 24 h after SE, and decreased in the outer molecular layer from 72 h after SE. These changes likely result from the death of hilar neurons and the reduction of the input from the entorhinal cortex. In 21-day-old rats that experience less SE-induced neuronal loss, increased immunoreactivity of synaptophysin was only found in piriform and entorhinal cortex while no changes occurred in GAP-43 expression.

CONCLUSION

These findings suggest that there is an age-related relation between the extent and rapidity of the process of neuronal death and the expression of these markers. Synaptophysin appears to be a more sensitive marker of plasticity induced by SE than GAP-43.

Neuroprotection by estradiol: A role of aromatase against spine synapse loss after blockade of GABAA receptors

Estrogen has been suggested to be pro-epileptic by reducing GABA synthesis, resulting in increased spine density and a decreased threshold for seizures in the hippocampus, which, once they occur, are characterized by a dramatic spine loss in the affected brain areas. As considerable amounts of estradiol are synthesized in the hippocampus, in this study we focused on aromatase, the rate-limiting enzyme in estrogen synthesis in order to examine the role of locally synthesized estrogens in epilepsy. To this end, we first examined the effects of letrozole, a potent aromatase inhibitor, on GABA metabolism in single interneurons of hippocampal dispersion cultures. Letrozole downregulated estradiol release into the medium, as well as glutamate decarboxylase (GAD) expression and GABA synthesis, and decreased the number of GAD positive cells in the cultures. Next, we counted spine synapses and measured estradiol release of hippocampal slice cultures, in which GABA(A) receptors had been blocked by bicuculline, in order to mimic epileptic activity. Treatment of slice cultures with bicuculline resulted in a dramatic decrease in the number of spine synapses and in a significant suppression of estrogen synthesis. The decrease in synapse number in response to bicuculline was restored by combined application of estradiol and bicuculline. Surprisingly, estradiol alone had no effect on either spine synapse number or on GAD expression and GABA synthesis. "Rescue" of synapse number in "epileptic slices" by estradiol and maintenance of GABA metabolism by hippocampus-derived estradiol points to a neuroprotective role of aromatase in epilepsy. Re-filling of estradiol stores after their depletion due to overexcitation may therefore add to therapeutical strategies in epilepsy.

The influence of gonadal hormones on neuronal excitability, seizures, and epilepsy in the female

It is clear from both clinical observations of women, and research in laboratory animals, that gonadal hormones exert a profound influence on neuronal excitability, seizures, and epilepsy. These studies have led to a focus on two of the primary ovarian steroid hormones, estrogen and progesterone, to clarify how gonadal hormones influence seizures in women with epilepsy. The prevailing view is that estrogen is proconvulsant, whereas progesterone is anticonvulsant. However, estrogen and progesterone may not be the only reproductive hormones to consider in evaluating excitability, seizures, or epilepsy in the female. It seems unlikely that estrogen and progesterone would exert single, uniform actions given our current understanding of their complex pharmacological and physiological relationships. Their modulatory effects are likely to depend on endocrine state, relative concentration, metabolism, and many other factors. Despite the challenges these issues raise to future research, some recent advances have helped clarify past confusion in the literature. In addition, testable hypotheses have developed for complex clinical problems such as "catamenial epilepsy." Clinical and animal research, designed with the relevant endocrinological and neurobiological issues in mind, will help advance this field in the future.

Role of androgens in epilepsy

Accumulating evidence suggests that both male- and/or female-typical sex steroids contribute to seizure susceptibility in epilepsy. Although there is rich literature regarding how female-typical sex steroids, such as progestins and estrogens, influence epilepsy, the role of androgens in seizure processes are just beginning to be understood. Given that some of the effects and mechanisms of androgen action on ictal activity may converge with that of progestins and/or estrogens, this review discusses what is known concerning the role of each of these sex steroids on seizures. Additionally, evidence that seizures and/or antiepileptic drugs can themselves influence steroid-dependent behaviors, such as affective, cognitive and reproductive function, is also reviewed. Considerations for therapeutic management and future directions for research and drug discovery are summarized.

Role of endothelial nitric oxide synthase in cerebral blood flow changes during kainate seizures: A genetic approach using knockout mice

The role of endothelial nitric oxide (NO) in the cerebrovascular response to partial seizures was investigated in mice deleted for the endothelial NO synthase gene (eNOS-/-) and in their paired wild-type (WT) congeners. Local cerebral blood flow (LCBF, quantitative [14C]iodoantipyrine method) was measured 3-6 h after unilateral kainate (KA) injection in the dorsal hippocampus; controls received saline. In WT mice, KA seizures induced a 22 to 50% LCBF increase restricted to the ipsilateral hippocampus, while significant LCBF decreases (15-33%) were noticed in 22% of the contralateral areas, i.e., the parietal cortex, amygdala and three basal ganglia areas, compared to saline-injected WT mice. In eNOS-/- mice, no LCBF increases were recorded within the epileptic focus and generalized contralateral LCBF decreases (22-46%) were noticed in 2/3 of the brain areas, compared to saline-injected eNOS-/- mice. Thus, endothelial NO is the mediator of the cerebrovascular response within the epileptic focus and participates in the maintenance of LCBF in distant areas.

Sex hormones, central nervous system and pain

The aim of the present review, which highlights some relationships between sex hormones, the CNS and pain, is to provide reference points for discussion on one of the most intriguing aspects of pain pathophysiology: the presence of sex differences in the response threshold to phasic painful stimuli and in the incidence of chronic pain syndromes. The first part of the review deals with sex steroids and their mechanisms of action. In the second part, the connections between sex steroids, the CNS and pain are illustrated to introduce possible areas of discussion in the study of sex differences in experimental and clinical pain.