Chaotic and stochastic dynamics of epileptiform-like activities in sclerotic hippocampus resected from patients with pharmacoresistant epilepsy.

The types of epileptiform activity occurring in the sclerotic hippocampus with highest incidence are interictal-like events (II) and periodic ictal spiking (PIS). These activities are classified according to their event rates, but it is still unclear if these rate differences are consequences of underlying physiological mechanisms. Identifying new and more specific information related to these two activities may bring insights to a better understanding about the epileptogenic process and new diagnosis. We applied Poincaré map analysis and Recurrence Quantification Analysis (RQA) onto 35 in vitro electrophysiological signals recorded from slices of 12 hippocampal tissues surgically resected from patients with pharmacoresistant temporal lobe epilepsy. These analyzes showed that the II activity is related to chaotic dynamics, whereas the PIS activity is related to deterministic periodic dynamics. Additionally, it indicates that their different rates are consequence of different endogenous dynamics. Finally, by using two computational models we were able to simulate the transition between II and PIS activities. The RQA was applied to different periods of these simulations to compare the recurrences between artificial and real signals, showing that different ranges of regularity-chaoticity can be directly associated with the generation of PIS and II activities.

Plasma kallikrein-kinin system contributes to peripheral inflammation in temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is a chronic disease, characterized by severe and refractory seizures, triggered in the hippocampus and/or amygdala, disrupting the blood-brain barrier. This disruption can sustain, or aggravate, the epileptic condition. The aim of this study was to evaluate the activation of the kallikrein-kinin system in patients with TLE, as it relates to the maintenance of blood-brain barrier. Human hippocampal sclerotic tissues removed after surgery for seizure control, plasma, and serum were used in the following assays: immunostaining for white blood cells in the TLE hippocampus, C-reactive protein in serum, quantification of plasma kallikrein (PKal) and cathepsin B (CatB) activity in serum and plasma, quantification of C1-inhibitor, analysis of high-molecular-weight kininogen (H-kininogen) fragments, and activation of plasma prekallikrein for comparison with healthy controls. Infiltration of white blood cells in the sclerotic hippocampus and a significant increase in the neutrophil/lymphocyte ratio in the blood of TLE patients were observed. High levels of C-reactive protein (TLE = 1.4 ± 0.3 µg/mL), PKal (TLE = 5.4 ± 0.4 U/mL), and CatB (TLE = 4.9 ± 0.4 U/mL) were also evident in the serum of TLE patients comparing to controls. A strong linear correlation was observed between active CatB and PKal in the serum of TLE patients (r = 0.88). High levels of cleaved H-kininogen and free PKal, and low levels of C1-inhibitor (TLE = 188 ± 12 µg/mL) were observed in the serum of TLE patients. Our data demonstrated that the plasma kallikrein-kinin system is activated in patients with TLE. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

Fish oil provides protection against the oxidative stress in pilocarpine model of epilepsy.

Temporal lobe epilepsy (TLE), the most common form of epilepsy is often resistant to pharmacological treatment. Neuronal loss observed in epileptic brain may be result of an overproduction of free radicals (oxidative stress). Oxidative stress is characterized by an imbalance between antioxidant defenses and oxidizing agents (free radicals), which can lead to tissue injury. The n-3 PUFAs are important for the development and maintenance of central nervous system functions. Research by our group has shown that chronic treatment with fish oil, immediately after status epilepticus (SE), exhibits both neuroprotective effects and effects on neuroplasticity. The main purpose of this research was to evaluate if fish oil exhibits a protective effect against oxidative stress. Animals were subjected to TLE model by pilocarpine administration. After 3 h of SE they were randomly divided into the following groups: control animals treated daily with vehicle or with 85 mg/kg of fish oil and animals with epilepsy treated daily with vehicle or with 85 mg/kg of fish oil. After 90 days, superoxide anion production, enzymatic activity of superoxide dismutase (SOD) and catalase (CAT) and protein expression of NAD(P)H oxidase subunits (p47(PHOX) and gp91(PHOX)) were analyzed. Our results showed evidences that reactive oxygen species are increased in animals with epilepsy and that fish oil supplementation could counteract it. Fish oil supplementation promoted protection against oxidative stress by multiple ways, which involved the reduction of activity and expression of NAD(P)H oxidase subunits and increased the activity and expression of antioxidants enzymes, contributing to well-known neuroprotective effect in epilepsy.

c-FOS expression after hippocampal deep brain stimulation in normal rats.

OBJECTIVES: We studied the effects of Hip-deep brain stimulation (DBS) on the expression of the inducible transcription factor c-FOS in the brain of normal rats. MATERIALS AND METHODS: Ten Wistar rats were anesthetized, and nine were implanted with epidural and hippocampal electrodes for brain activity recording; one animal was used as sham. Bipolar stimulating electrodes were implanted in the left hippocampus. Three animals were used as control (implanted but not stimulated), one as sham (not implanted, not stimulated), and six as the study group. Stimulation was carried out using square wave pulses with 0.8V, 300 µsec, and 130 Hz (∼25µC/cm2) on the left hippocampus through the implanted bipolar hippocampal lead. Three animals were submitted to a one-hour and three to a six-hour stimulation session. Immunohistochemistry was employed to visualize c-FOS distribution in the rat's brain. The presence of seizures and electrocorticographic findings also were observed. RESULTS: In animals submitted to both one-hour or six-hour unilateral hippocampal stimulation sessions, there was a significant bilateral overexpression of c-FOS in the hippocampus proper, dentate gyrus, and hylus. In the CA1 and CA3 regions, although activation was bilateral, c-FOS hyperexpression prevailed at the stimulated side over time; this was not true for the hilar and dentate gyrus regions where a more symmetric activation occurred over time. A significant c-FOS activation occurred after one hour of Hip-DBS in the ipsilateral amygdala; there was no contralateral amygdala activation, and by six hours, no amygdala activation was noted. No c-FOS activation was noted in other brain areas. DISCUSSION: Our data showed that unilateral Hip-DBS was able to cause widespread and persistent bilateral activation of the normal rat limbic system, although in some, nuclei activation prevailed over the stimulated side. Cortical activation outside the limbic system was not noted. Our data represent a first approach to study the mechanistic paradigm involved in Hip-DBS.

Epileptic seizure suppression: A computational approach for identification and control using real data.

Epilepsy affects millions of people worldwide every year and remains an open subject for research. Current development on this field has focused on obtaining computational models to better understand its triggering mechanisms, attain realistic descriptions and study seizure suppression. Controllers have been successfully applied to mitigate epileptiform activity in dynamic models written in state-space notation, whose applicability is, however, restricted to signatures that are accurately described by them. Alternatively, autoregressive modeling (AR), a typical data-driven tool related to system identification (SI), can be directly applied to signals to generate more realistic models, and since it is inherently convertible into state-space representation, it can thus be used for the artificial reconstruction and attenuation of seizures as well. Considering this, the first objective of this work is to propose an SI approach using AR models to describe real epileptiform activity. The second objective is to provide a strategy for reconstructing and mitigating such activity artificially, considering non-hybrid and hybrid controllers - designed from ictal and interictal events, respectively. The results show that AR models of relatively low order represent epileptiform activities fairly well and both controllers are effective in attenuating the undesired activity while simultaneously driving the signal to an interictal condition. These findings may lead to customized models based on each signal, brain region or patient, from which it is possible to better define shape, frequency and duration of external stimuli that are necessary to attenuate seizures.

Sexual response in female rats with status epilepticus.

PURPOSE: Female sexual function is complex and may be disrupted by disease, in particular epilepsy. Chronic seizures in women can have adverse effects on reproductive function, but it has been difficult to dissociate the effects of epilepsy from those related to anticonvulsant medications. The purpose of this study was to evaluate sexual behavior in female rats submitted to pilocarpine-induced status epilepticus (SE). METHODS: Adult female Wistar rats were given saline or pilocarpine (350 mg/kg, i.p.) to induce SE. The groups were distributed according to the treatment or response to pilocarpine: CTRL (control rats maintained in the home-cage after saline administration); NSE (non-status epilepticus, rats that did not display convulsive and intermittent seizures after pilocarpine injection) and SE (status epilepticus, rats that displayed convulsive and intermittent seizures after pilocarpine injection). After 50 days, sexual receptivity in the female rats was artificially induced via administration of a combination of estradiol and progesterone. Sexual behavior was evaluated during three sessions in the presence of a sexually experienced male rat. Receptivity and proceptivity behaviors, as well as hormones concentrations, were monitored. KEY FINDINGS: Significant decreases in proceptivity and receptivity behaviors during the three tests were observed in SE female rats. The rejection response was significantly increased in SE rats compared with CTRL or NSE groups. Progesterone, testosterone, and corticosterone were unchanged between the groups. SIGNIFICANCE: The SE female rats showed lower sexual motivation and performance regardless of their steroid hormones levels.

Sudden unexpected death in epilepsy: from the lab to the clinic setting.

Sudden unexpected death in epilepsy (SUDEP) is defined as sudden, unexpected, witnessed or unwitnessed, non-traumatic, and non-drowning death in a patient with epilepsy. Sudden unexpected death in epilepsy is probably the most common cause of epilepsy-related deaths. Many predisposing and initiating factors may coexist and contribute to SUDEP, but the mechanisms are poorly understood. Cardiac and respiratory deregulation seems to have a major role in SUDEP. Here, we review several advances in understanding the mechanisms involved in SUDEP.

Sleep and epilepsy: exploring an intriguing relationship with a translational approach.

The relationship between sleep and epilepsy has been well established. There is a high prevalence of sleep disturbances in epilepsy, which are associated with a decreased quality of life of individuals with epilepsy. In view of this fact, preclinical research is necessary to address many gaps in knowledge. For instance, it is well known that sleep deprivation can trigger seizures; however, this is a complex pathophysiological event. In this context, there are many valuable animal models of epilepsy that reproduce clinical symptoms and can be used. Investigations using animal models that simulate clinical epilepsy are imperative. Furthermore, preclinical studies that reveal mechanisms related to sleep-epilepsy interactions are very important. Results of such studies can, in turn, improve the understanding of epilepsy itself and can be useful in developing new antiepileptic drugs and preventive measures to control seizures. Preclinical research should be performed using a translational framework with experimental designs that can lead to advances in the quality of life of individuals with epilepsy. In view of the fact that more than 50 million of people are affected by epilepsy around the world, understanding the relationship between sleep and epilepsy is imperative.

Omega-3 fatty acid supplementation reduces resting heart rate of rats with epilepsy.

Since cardiovascular dysfunction may contribute to sudden unexpected death in epilepsy (SUDEP), the consumption of omega-3 fatty acids (omega-3 FAs) might be beneficial as an adjunctive therapy for SUDEP prevention. It is well recognized that omega-3 FAs exert positive effects on the cardiovascular system including heart rate (HR) reduction, a major risk factor to sudden death. Thus, we evaluated the effects of chronic supplementation of omega-3 FAs on the HR of rats with epilepsy. In agreement with our previous investigations, this study also showed that the HR of animals with epilepsy is higher than that of the control group. Quite interestingly, chronic supplementation with omega-3 FAs restored the HR of rats with epilepsy toward control values. In conclusion, although further investigations are still required, our preliminary results showed a potential preventive effect of omega-3 FA supplementation against SUDEP.

Brain electrical activity after acute hippocampal stimulation in awake rats.

OBJECTIVE: We describe the electrocorticographic findings after hippocampal stimulation in normal awake rats. METHODS: Six male Wistar rats were implanted bilaterally with neocortical and hippocampal electrodes. The animals were submitted to hippocampal low- and high-frequency stimulation. RESULTS: Recruiting responses were seen in the ipsilateral hippocampus after unilateral low-frequency (6 Hz) hippocampal stimulation with low voltage (0.3 V). These recruiting responses could be seen at the contralateral hippocampus with slightly higher voltage (0.5 V) and over the ipsilateral neocortex with stimulation with 1.2 V. Bilateral neocortical recruiting responses were noted at stimuli voltage of 1.5 V. There were no recruiting responses after high-frequency stimulation (130 Hz). A dorsal column (DC) shift, characterized by baseline oscillation without brain activity modification, was noted in all animals after hippocampal stimulation with frequency higher than 60 Hz. The increase of stimulation frequency from 6 to 130 Hz (1.2 V, 300 µ sec) showed progressive reduction in the amplitude and disappearance of the time-locked recruiting responses, especially from around 60 Hz. CONCLUSIONS: Bilateral hippocampal and cortical recruiting responses were easily obtained in all animals after low-frequency hippocampal unilateral stimulation. High-frequency stimulation did not give rise to recruiting response, although a DC shift was noted. The fact that unilateral hippocampal stimulation might lead to bilateral limbic system modulation suggested that unilateral stimulation might be enough in many situations. Our findings suggested that high-frequency stimulation was more likely to be effective than low-frequency stimulation regarding the potential inactivation of the hippocampus. These findings might prove relevant to the determination of the adequate parameters for stimulation using hippocampal deep brain stimulation (DBS) in the future. An increase in our knowledge on the physiologic mechanisms underlying DBS might be translated into more rational clinical approaches.

Activation of D1/D5 dopamine receptors protects neurons from synapse dysfunction induced by amyloid-beta oligomers.

Soluble oligomers of the amyloid-ß peptide (AßOs) accumulate in the brains of Alzheimer disease (AD) patients and are implicated in synapse failure and early memory loss in AD. AßOs have been shown to impact synapse function by inhibiting long term potentiation, facilitating the induction of long term depression and inducing internalization of both AMPA and NMDA glutamate receptors, critical players in plasticity mechanisms. Because activation of dopamine D1/D5 receptors plays important roles in memory circuits by increasing the insertion of AMPA and NMDA receptors at synapses, we hypothesized that selective activation of D1/D5 receptors could protect synapses from the deleterious action of AßOs. We show that SKF81297, a selective D1/D5 receptor agonist, prevented the reduction in surface levels of AMPA and NMDA receptors induced by AßOs in hippocampal neurons in culture. Protection by SKF81297 was abrogated by the specific D1/D5 antagonist, SCH23390. Levels of AMPA receptor subunit GluR1 phosphorylated at Ser(845), which regulates AMPA receptor association with the plasma membrane, were reduced in a calcineurin-dependent manner in the presence of AßOs, and treatment with SKF81297 prevented this reduction. Establishing the functional relevance of these findings, SKF81297 blocked the impairment of long term potentiation induced by AßOs in hippocampal slices. Results suggest that D1/D5 receptors may be relevant targets for development of novel pharmacological approaches to prevent synapse failure in AD.

PDEI-5 for erectile dysfunction: a potential role in seizure susceptibility.

INTRODUCTION: There is a high prevalence of erectile dysfunction (ED) in men with epilepsy; however, few studies have been conducted concerning the treatment of ED in this neurological group. AIM: The main purpose of this review is to highlight the influence of phosphodiesterase type 5 inhibitor (PDEI-5) for ED on seizure susceptibility. METHODS: All available online articles with information pertaining to PDEI-5 and seizure susceptibility were included in this review. MAIN OUTCOME MEASURES: The main outcome assessed demonstrated the intriguing role of PDEI-5 and its metabolites on seizure susceptibility. RESULTS: Case reports in men without epilepsy described seizure occurrence and electrophysiological changes following sildenafil, tadalafil, or vardenafil treatment. Consistent with these findings, preclinical studies suggested a proconvulsant effect of PDEI-5 on models of seizure induction. CONCLUSIONS: Evidence suggests an influence of PDEI-5 on seizure susceptibility in humans. In addition, preclinical studies have demonstrated the role of nitric oxide metabolites in the facilitation of paroxysmal phenomenon. Although there are many causes of seizures, medical professionals should be aware of the possible influence of PDEI-5 on seizure susceptibility. Further investigation by physicians and scientists is required to improve our understanding of this important topic.

Impairment of sexual function in rats with epilepsy.

INTRODUCTION: Epilepsy is a chronic disease that affects men and women of all ages, with different levels of severity. Many individuals with epilepsy also suffer from impairments in sexual function. However, it is difficult to differentiate between the impact of the disease and the impact of antiepileptic drugs on sexual function in human subjects. AIMS: To evaluate sexual behavior in adult male rats submitted to chronic pilocarpine-induced epilepsy. METHODS: First, non-epileptic rats were exposed to nine training sessions to acquire sexual experience, and their baseline sexual performance was evaluated. Then, the same rats were given pilocarpine to induce status epilepticus followed by chronic epilepsy. Once the animals had developed spontaneous recurrent seizures, their sexual behavior was evaluated during three sessions. MAIN OUTCOME MEASURES: Examine changes in latencies to first mount, intromission, and ejaculation, and the total number of mounts, intromissions, and ejaculations. RESULTS: All outcome measures related to sexual motivation and sexual performance were markedly impaired during chronic epilepsy compared with the baseline and the control group. CONCLUSION: These findings will aid in understanding the interaction between sexual behavior and epilepsy, as well as encouraging further experimental studies in human patients with epilepsy suffering from sexual dysfunction.

Differences in Evolution of Epileptic Seizures and Topographical Distribution of Tissue Damage in Selected Limbic Structures Between Male and Female Rats Submitted to the Pilocarpine Model.

Epidemiological evidence shows that clinical features and comorbidities in temporal lobe epilepsy (TLE) may have different manifestations depending on the sex of patients. However, little is known about how sex-related mechanisms can interfere with the processes underlying the epileptic phenomenon. The findings of this study show that male rats with epilepsy in the pilocarpine model have longer-lasting and more severe epileptic seizures, while female rats have a higher frequency of epileptic seizures and a greater number of seizure clusters. Significant sex-linked pathological changes were also observed: epileptic brains of male and female rats showed differences in mass reduction of 41.8% in the amygdala and 18.2% in the olfactory bulb, while loss of neuronal cells was present in the hippocampus (12.3%), amygdala (18.1%), and olfactory bulb (7.5%). Another important sex-related finding was the changes in non-neuronal cells with increments for the hippocampus (36.1%), amygdala (14.7%), and olfactory bulb (37%). Taken together, our study suggests that these neuropathological changes may underlie the differences in the clinical features of epileptic seizures observed in male and female rats.

Melatonin administration after pilocarpine-induced status epilepticus: a new way to prevent or attenuate postlesion epilepsy?

OBJECTIVE: The goal of this study was to verify the effects of treatment with melatonin and N-acetylserotonin on the pilocarpine-induced epilepsy model. METHODS: The animals were divided into four groups: (1) animals treated with saline (Saline); (2) animals that received pilocarpine and exhibited SE (SE); (3) animals that exhibited SE and were treated with N-acetylserotonin (30 minutes and 1, 2, 4, 6, 12, 24, 36, and 48 hours) after SE onset (SE+NAS); (4) animals that exhibited SE and were treated with melatonin at the same time the SE+NAS group (SE+MEL). Behavioral (latency to first seizure, frequency of seizures, and mortality) and histological (Nissl and neo-Timm) parameters were analyzed. RESULTS: The animals treated with melatonin (SE+MEL) had a decreased number of spontaneous seizures during the chronic period (P<0.05), a reduction in mossy fiber sprouting, and less cell damage than the SE group. Animals treated with N-acetylserotonin did not exhibit any kind of significant change. CONCLUSION: Melatonin exerts an important neuroprotective effect by attenuating SE-induced postlesion and promoting a decrease in the number of seizures in epileptic rats. This suggests, for the first time, that melatonin could be used co-therapeutically in treatment of patients exhibiting SE to minimize associated injuries in these situations.

Repeated amygdala-kindled seizures induce ictal rebound tachycardia in rats.

It is thought that cardiovascular changes may contribute to sudden death in patients with epilepsy. To examine cardiovascular alterations that occur during epileptogenesis, we measured the heart rate of rats submitted to the electrical amygdala kindling model. Heart rate was recorded before, during, and after the induced seizures. Resting heart rate was increased in stages 1, 3, and 5 as compared with the unstimulated control condition. In the initial one third of the seizures, we observed bradycardia, which increased in intensity with increasing stage and was blocked by injecting methyl atropine. During stage 5 seizures, a rebound tachycardia was observed that also increased in intensity with increasing number of seizures. This study demonstrated the influence of seizure frequency on cardiac autonomic modulation, providing a basis for discussion of potential mechanisms that cause patients with epilepsy to die suddenly.

Challenges in the treatment of a chronic disease: A study of narratives of people with juvenile myoclonic epilepsy.

PURPOSE: The purpose of this study was to explore how people with juvenile myoclonic epilepsy perceive the impact of treatment. METHODS: We conducted 14 interviews of participants with juvenile myoclonic epilepsy recruited with the support of the Brazilian Association of Epilepsy in 2018 in São Paulo. Thematic analysis was carried out by two investigators who independently coded the transcripts and reviewed the coding results to check for agreement. RESULTS: Participants' (n = 14, 8 female) mean age was 31.4 years (SD ± 8.3) and their onset of seizures occurred at mean age 13.4 (SD ± 2.9). The answers to the interview questions revealed the paths of participants through life as they dealt with difficulties and challenges. Three interrelated themes and seven sub-themes emerged from the answers of the participants: seizure control, impact of epilepsy and attitude of others. CONCLUSION: This investigation may be useful in providing insights for the interventions of health providers in caring for people with JME. Themes and sub-themes that emerged from this study are connected to important aspects of treatment that go beyond focusing solely on seizures.

Gut-microbiota-directed strategies to treat epilepsy: clinical and experimental evidence.

A growing appreciation that the intestinal microbiota might exert changes on the central nervous system via the gut-brain has emerged as a new research frontier in neurological disorders. Moreover, new approaches for studying and manipulating the gut microbiome, including metabolomics and faecal microbiota transplantation, have highlighted the tremendous potential that microbes have on neuroinflammation, metabolic, and neuroendocrine signaling pathways. Despite the large proliferation of studies in animal models examining the linkage between microbial disequilibrium and epilepsy, intestinal profiles at a functional level in humans have remained scarce. We reviewed the scientific evidence on gut microbiota's role in epilepsy, both in clinical and experimental studies, to better understand how targeting the gut microbiota could serve as a diagnostic or prognostic research tool. Likewise, translating microbial molecular mechanisms to medical settings could fill the gaps related to alternative therapies for patients with epilepsy, mainly in cases with refractory phenotypes.