Papers by Luiz E.a.m. Mello
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There is currently no available drug to prevent the development of post-traumatic epilepsy. Precl... more There is currently no available drug to prevent the development of post-traumatic epilepsy. Preclinical studies support the potential use of anticholinergics. To evaluate whether treatment with biperiden has the potential to prevent post-traumatic epilepsy. Randomized, double-blind, placebo-controlled clinical trial, conducted between 2018- 2022. Adult patients with acute traumatic brain injury (TBI) following eligibility criteria were randomly assigned to placebo or biperiden groups. Biperiden or placebo was initiated within 12 h after trauma and repeated every 6 h for 10 days. Clinical evaluation was performed at 1, 3, 6, 12, 18, and 24 months after TBI to investigate seizures incidence. The primary outcome was a change in the incidence of post-traumatic epilepsy. Secondary outcomes included frequency of seizures, mortality and adverse events. Of 123 patients recruited, 1 declined and 1 was ineligible. After randomization, 11 (8.9%) participants were discontinued from the study. T...
PLOS ONE
Background Traumatic brain injury (TBI) is one of the most important causes of acquired structura... more Background Traumatic brain injury (TBI) is one of the most important causes of acquired structural epilepsy, post-traumatic epilepsy (PTE), however, efficient preventative measures and treatment are still not available to patients. Preclinical studies indicated biperiden, an anticholinergic drug, as a potential drug to modify the epileptogenic process. The main objective of this clinical trial is to evaluate the efficacy of biperiden as an antiepileptogenic agent in patients that suffered TBI. Methods This prospective multicenter (n = 10) interventional study will include 312 adult patients admitted to emergency care units with a diagnosis of moderate or severe TBI. Following inclusion and exclusion criteria, patients will be randomized, using block randomization, to receive double-blind treatment with placebo or biperiden for 10 days. Follow-up will occur at specific time windows up to 2 years. Main outcomes are incidence of PTE after TBI and occurrence of severe adverse events. Ot...
Hippocampus, 2000
Dentate granule cells are generally considered to be relatively resistant to excitotoxicity and h... more Dentate granule cells are generally considered to be relatively resistant to excitotoxicity and have been associated to robust synaptogenesis after neuronal damage. Synaptic reorganization of dentate granule cell axons, the mossy fibers, has been suggested to be relevant for hyperexcitability in human temporal lobe epilepsy and animal models. A recent hypothesis has suggested that mossy fiber sprouting is dependent on newly formed dentate granule cells. However, we have recently demonstrated that cycloheximide (CHX) can block the mossy fiber sprouting that would be otherwise induced by different epileptogenic agents and do not interfere with epileptogenesis in those models. Here, we investigated cell damage and neurogenesis in the dentate gyrus of pilocarpine-or kainate-treated animals with or without the co-administration of CHX. Dentate granule cells were highly vulnerable to pilocarpine induced-status epilepticus (SE), but hardly damaged by kainate induced-SE. CHX-pretreatment markedly reduced the number of injured neurons after pilocarpine-induced SE. Induction of SE dramatically increased the mitotic rate of KA and KA + CHX treated animals. Induction of SE in animals injected with pilocarpine alone led to increases of between two to sevenfold in the mitotic rate of dentate granule cells as compared to increases of between five and thirtyfold for pilocarpine+CHX animals. These observations indicate that in presence of cycloheximide the increase of the mitotic rate after pilocarpine-induced SE may be due to protection of a vulnerable precursor cell population that would otherwise degenerate. We further suggest that the mossy fiber sprouting and neurogenesis of granule cells are not necessarily related events.-(September 14, 1999) .
Neuroscience Letters, Mar 1, 2004
In this work, we show extensive phosphorylation of the alpha subunit of translation initiation fa... more In this work, we show extensive phosphorylation of the alpha subunit of translation initiation factor 2 (eIF2alpha) occurring in the brain of mice subjected to 30 min of status epilepticus induced by pilocarpine. eIF2alpha(P) immunoreactivity was detected in the hippocampal pyramidal layer CA1 and CA3, cortex layer V, thalamus and amygdala. After 2 h of recovery, there was a marked decrease in total brain eIF2alpha(P), with the cortex layer V showing the most pronounced loss of anti-eIF2alpha(P) labeling, whereas the CA1 subregion had a significant increase in eIF2alpha(P). These results indicate that inhibition of protein synthesis in experimental models of epilepsy might be due to low levels of eIF2-GTP caused by the phosphorylation of eIF2alpha, and suggest that translational control may contribute to cell fate in the affected areas.
NeuroReport, 2018
Background and purpose Among several cognitive advantages, meditation is thought to enhance pract... more Background and purpose Among several cognitive advantages, meditation is thought to enhance practitioners' capacity for sustained attention. In the present study, we explored this question by testing meditation practitioners (meditators) and nonpractitioners (nonmeditators) on a task that requires sustained attention, the Stroop Word-Color Task (SWCT), while using functional MRI. Participants and methods Participants were all righthanded and included 23 regular meditators as well as 17 nonmeditators. Participants viewed color words (i.e. 'red, ' 'blue, ' or 'green') presented one at a time on the screen that were written in either the same color (congruent condition) or a different color (incongruent condition) and were asked to indicate the color of the print. Participants also viewed noncolor words written in unrelated colors (neutral condition). Both groups completed the same two acquisition runs. Results Although both meditators and nonmeditators gave faster responses on run 2 than run 1 for both the neutral and incongruent trials, nonmeditators showed decreased activation and meditators showed increased activation in precuneus/posterior cingulate cortex. These regions were previously shown to be activated in the SWCT and belong to default mode network as well as to cognitive control network. Conclusion Attention to repetitive stimuli during two equal runs of SWCT is mediated by the precuneus/posterior cingulate cortex, and mental training through meditation may influence the activity of these regions during such tasks.
Seizure, 2014
Diseases such as temporal lobe epilepsy, brain trauma and stroke can induce endothelial cell prol... more Diseases such as temporal lobe epilepsy, brain trauma and stroke can induce endothelial cell proliferation and angiogenesis in specific brain areas. During status epilepticus (SE), bone marrowderived cells are able to infiltrate and proliferate, dramatically increasing at the site of injury. However, it is still unclear whether these cells directly participate in vascular changes induced by SE. Method: To investigate the possible role of bone marrow-derived cells in angiogenesis after seizures, we induced SE by pilocarpine injection in previously prepared chimeric mice. Mice were euthanized at 8 h, 7 d or 15 d after SE onset. Results: Our results indicated that SE modified hippocampal vascularization and induced angiogenesis. Further, bone marrow-derived GFP + cells penetrated through the parenchyma and participated in the formation of new vessels after SE. We detected bone marrow-derived cells closely associated with vessels in the hippocampus, increasing the density of blood vessels that had decreased immediately after pilocarpine-induced SE. Conclusion: We conclude that epileptic seizures directly affect vascularization in the hippocampus mediated by bone marrow-derived cells in a time-dependent manner.
Epilepsia, May 29, 2012
Purpose-Mossy fiber sprouting (MFS) is a frequent finding following status epilepticus (SE). The ... more Purpose-Mossy fiber sprouting (MFS) is a frequent finding following status epilepticus (SE). The present study aimed to test the feasibility of using manganese-enhanced magnetic resonance imaging (MEMRI) to detect MFS in the chronic phase of the well-established pilocarpine (Pilo) rat model of temporal lobe epilepsy (TLE). Methods-To modulate MFS, cycloheximide (CHX), a protein synthesis inhibitor, was coadministered with Pilo in a subgroup of animals. In vivo MEMRI was performed 3 months after induction of SE and compared to the neo-Timm histological labeling of zinc mossy fiber terminals in the dentate gyrus (DG). Key findings-Chronically epileptic rats displaying MFS as detected by neo-Timm histology had a hyperintense MEMRI signal in the DG, while chronically epileptic animals that did not display MFS had minimal MEMRI signal enhancement compared to non-epileptic control animals. A strong correlation (r = 0.81, P<0.001) was found between MEMRI signal enhancement and MFS. Significance-This study shows that MEMRI is an attractive non-invasive method to detect mossy fiber sprouting in vivo and can be used as an evaluation tool in testing therapeutic approaches to manage chronic epilepsy.
Epilepsy Research, Sep 1, 2012
Homer1a regulates expression of group I metabotropic glutamate receptors type I (mGluR1 and mGluR... more Homer1a regulates expression of group I metabotropic glutamate receptors type I (mGluR1 and mGluR5) and is involved in neuronal plasticity. It has been reported that Homer1a expression is upregulated in the kindling model and hypothesized to act as an anticonvulsant. In the present work, we investigated whether pilocarpine-induced status epilepticus (SE) would alter Homer1a and mGluR5 expression in hippocampus. Adult rats were subjected to pilocarpine-model and analyzed at 2h, 8h, 24h and 7 d following SE. mRNA analysis showed the highest expression of Homer1a at 8h after SE onset, while immunohistochemistry demonstrated that Homer1a protein expression was significantly increased in hippocampus, amygdala and piriform and entorhinal cortices at 24h after SE onset when compared to control animals. The increased Homer1a expression coincided with a significant decrease of mGluR5 protein expression in amygdala and piriform and entorhinal cortices. The data suggest that during the critical periods of epileptogenesis, overexpression of Homer1a occurs to counteract hyperexcitability and thus Homer1a may be a molecular target in the treatment of epilepsy.
Elsevier eBooks, 2009
Supragranular mossy fiber sprouting (MFS), aberrant axonal projections from dentate granule cells... more Supragranular mossy fiber sprouting (MFS), aberrant axonal projections from dentate granule cells to the area immediately above the granule cell layer, might be the best characterized form of aberrant synaptic plasticity in the mammalian brain. Starting with its initial description in epileptic tissue in 1985, a huge amount of information at all levels has been accumulated over the past two decades. Yet, despite this intense research effort, there is still important debate on the relative contribution of MFS to the hyperexcitability in temporal lobe epilepsy, and even less agreement about its role in seizure generation. Using cycloheximide to block the development of MFS after status epilepticus, we directly address some of the relevant issues in the field.
Frontiers in Neuroscience
This study aimed to determine whether preemptive fentanyl administration in neonatal rats reduces... more This study aimed to determine whether preemptive fentanyl administration in neonatal rats reduces the impact of a nociceptive stimulus initiated during the first day of life (P1) on hippocampal neurogenesis, behavior, and learning. At P1, Wistar rat pups received either a subcutaneous injection of fentanyl (F) before intraplantar injection of complete Freund’s adjuvant (CFA) (CFA + F group), an isolated injection of CFA (CFA group), or subcutaneous injection of fentanyl without CFA injection (F). Control animals received saline injections using the same route and volume as the treatment groups. Hippocampal neurogenesis was evaluated by 5′ –bromo-2′-deoxyuridine (BrdU) staining on P10 and P39 to assess neuronal proliferation and survival, respectively. Anxiety behavior in adulthood was assessed using an open field test (OF) and an elevated plus maze test (EPM). Spatial memory was assessed on a Morris water maze test (MWM), where the animals were trained for seven days, beginning on P...
International Journal of Developmental Neuroscience, 2021
Maternal separation and neonatal manipulation of pups produce changes in maternal behavior after ... more Maternal separation and neonatal manipulation of pups produce changes in maternal behavior after the dam–pup reunion. Here, we examined whether continuous versus alternating days of neonatal manipulation during the first 8 postnatal days produces differential changes in maternal and non‐maternal behaviors in rats. We found that both maternal separation protocols increased anogenital licking after dam–pup reunion, reflecting increased maternal care of pups.
Frontiers in Neuroscience
Interest in the use of anticholinergics to prevent the development of epilepsy after traumatic br... more Interest in the use of anticholinergics to prevent the development of epilepsy after traumatic brain injury (TBI) has grown since recent basic studies have shown their effectiveness in modifying the epileptogenic process. These studies demonstrated that treatment with anticholinergics, in the acute phase after brain injury, decreases seizure frequency, and severity, and the number of spontaneous recurrent seizures (SRS). Therefore, anticholinergics may reduce the risk of developing posttraumatic epilepsy (PTE). In this brief review, we summarize the role of the cholinergic system in epilepsy and the key findings from using anticholinergic drugs to prevent PTE in animal models and new clinical trial protocols. Furthermore, we discuss why treatment with anticholinergics is more likely to prevent PTE than treatment for other epilepsies.
Hippocampus, 2007
In the study of temporal lobe epilepsy (TLE) the characterization of genes expressed in the hippo... more In the study of temporal lobe epilepsy (TLE) the characterization of genes expressed in the hippocampus is of central importance for understanding their roles in epileptogenic mechanisms. Although several large-scale studies on TLE gene expression have been reported, precise assignment of individual genes associated with this syndrome is still debatable. Here we investigated differentially expressed genes by comparison of mRNAs from normal and epileptic rat hippocampus in the pilocarpine model of epilepsy. For this we used a powerful EST sequencing methodology, ORESTES (Open Reading frame Expressed Sequence Tags), which generates sequence datasets enriched for mRNAs open reading frames (ORFs) rather than simple 5 0 and 3 0 ends of mRNAs. Analysis of our sequences shows that ORESTES readily enables the identification of epilepsy associated ORFs. PFAM analysis of protein motifs present in our ORESTES epilepsy database revealed diverse important protein family domains, such as cytoskeletal, cell signaling and protein kinase domains, which could be involved in processes underlying epileptogenesis. More importantly, we show that the expression of homer 1a, known to be coupled to mGluR and NMDA synaptic transmission, is associated with pilocarpine induced status epilepticus (SE). The combined use of the pilocarpine model of epilepsy with the ORESTES technique can significantly contribute to the identification of specific genes and proteins related to TLE. This is the first study applying a large-scale method for rapid shotgun sequencing directed to ORFs in epilepsy research. V
Alcoholism: Clinical and Experimental Research, Aug 1, 2009
Background: Here we investigated the effects of electroacupuncture over locomotor sensitization i... more Background: Here we investigated the effects of electroacupuncture over locomotor sensitization induced by ethanol in mice. Methods: Adult male Swiss mice were daily injected with ethanol (2 g ⁄ kg, i.p.) or saline for 21 days (acquisition phase). After 4 days of withdrawal, all animals were challenged with ethanol (1.4 g ⁄ kg, i.p.). The locomotor activity during 30 minutes was accessed just after the ethanol challenge. Electroacupuncture at acquisition, expression, or maintenance phases of locomotor sensitization was provided over ST-36 (Zusanli) or PC-6 (Neiguan) as well as concomitantly over these 2 acupoints. One hour after the challenge with ethanol, the animals were decapitated, the hippocampus, striatum, and prefrontal cortex were dissected, and the expression of homer1A mRNA assessed by PCR. Results: Electroacupuncture provided simultaneously over ST-36 and PC-6 (but not to ST-36 or PC-6 alone) inhibited the acquisition, expression, and maintenance of ethanol-induced locomotor sensitization. In addition, electroacupuncture blocked the diminution of homer1A mRNA expression triggered by ethanol in the acquisition (striatum and prefrontal cortex), expression (hippocampus), and in the maintenance (hippocampus and prefrontal cortex) phases. Conclusion: Electroacupuncture provided concomitantly over ST-36 and PC-6 prevents the sensitization of the mesocorticolimbic pathway induced by ethanol in mice. In addition, these effects were accompanied by changes in the expression of homer1A. We suggest that electroacupuncture effects over ethanol-induced locomotor sensitization are associated to its ability to modulate homer1A expression and glutamatergic plasticity.
Epilepsia, Jul 1, 2005
GAP43 has been thought to be linked with mossy fiber sprouting (MFS) in various experimental mode... more GAP43 has been thought to be linked with mossy fiber sprouting (MFS) in various experimental models of epilepsy. To investigate how GAP43 expression (GAP43ir) correlates with MFS, we assessed the intensity (densitometry) and extension (width) of GAP43-ir in the inner molecular layer of the dentate gyrus (IML) of rats subject to status epilepticus induced by pilocarpine (Pilo), previously injected or not with cycloheximide (CHX), which has been shown to inhibit MFS. Methods: CHX was injected before the Pilo injection in adult Wistar rats. The Pilo group was injected with the same drugs, except for CHX. Animals were killed between 30 and 60 days later, and brain sections were processed for GAP43 immunohistochemistry. Results: Densitometry showed no significant difference regarding GAP43-ir in the IML between Pilo, CHX+Pilo, and control groups. However, the results of the width of the GAP43ir band in the IML showed that CHX+Pilo and control animals had a significantly larger band (p = 0.03) as compared with that in the Pilo group. Conclusions: Our current finding that animals in the CHX+Pilo group have a GAP43-ir band in the IML, similar to that of controls, reinforces prior data on the blockade of MFS in these animals. The change in GAP43-ir present in Pilotreated animals was a thinning of the band to a very narrow layer just above the granule cell layer that is likely to be associated with the loss of hilar cell projections that express GAP-43.
Cell Transplantation, Jul 1, 2013
The GABAergic system is critically involved in the modulation of anxiety levels, and dysfunction ... more The GABAergic system is critically involved in the modulation of anxiety levels, and dysfunction of GABAergic neurotransmission appears to be involved in the development of generalized anxiety disorder. Precursor cells from the medial ganglionic eminence (MGE) have the ability to migrate and differentiate into inhibitory GABAergic interneurons after being transplanted into the mouse brain. Thus, transplantation of interneuronal precursor cells derived from the MGE into a postnatal brain could modify the neuronal circuitry, increasing GABAergic tone and decreasing anxiety-like behavior in animals. Our aim was to verify the in vivo effects of transplanted MGE cells by evaluating anxiety-like behavior in mice. MGE cells from 14-day green fluorescent protein (GFP) embryos were transplanted into newborn mice. At 15, 30, and 60 days posttransplant, the animals were tested for anxiety behavior with the elevated plus maze (EPM) test. Our results show that transplanted cells from MGE were able to migrate to different regions of the brain parenchyma and to differentiate into inhibitory interneurons. The neuronal precursor cell transplanted animals had decreased levels of anxiety, indicating a specific function of these cells in vivo. We suggested that transplantation of MGE-derived neuronal precursors into neonate brain could strengthen the inhibitory function of the GABAergic neuronal circuitry related to anxiety-like behavior in mice.
Epilepsy Research, Nov 1, 1990
The effects of chronic etha~,,ol administration were studied in rats receiving amygdaloid kindlin... more The effects of chronic etha~,,ol administration were studied in rats receiving amygdaloid kindling. Daily ethanol administration 10 rain prior to kindling stimulation delayed acquisition of kindling without affecting the electrical afterdischarge. For the lowest tested dose of ethanol (0.5 g/kg), this delay was restricted to kindling stages 1 and 2. For the higher doses of ethanol (1.0 and 1.5 g/kg) this delay became more severe and stages 3 and 4 were blocked. Ethanol produced a clear dose-related anticonvulsant effect upon kindled seizures. After repeated exposure to kindling stimulation and ethanol this anticonvuisant effect vanished. After a 15-day interval without stimulation or ethanol application kindled animals were insensitive to ethanol's anticonvt~lsant eficct. In conclusion, it is suggested that the anticonvulsant effects of low ethanol doses are restricted to kindling stages 1 and 2 and thai anticonvulsant effects of high ethanol doses are limited by tolerance and by the level of consolidation of the kindled seizure. Finally, we suggest that the anticonvulsant properties of ethanol are not due to its general depressant effect but to some rather specific action.
Epilepsia, Jul 24, 2002
Mossy fiber sprouting (MFS) and synaptic reorganization in the dentate gyrus (DG) is considered o... more Mossy fiber sprouting (MFS) and synaptic reorganization in the dentate gyrus (DG) is considered one of the physiopathologic mechanisms in temporal lobe epilepsy. Supragranular MFS can be blocked by cycloheximide (CHX) without interfering with the genesis of spontaneous recurrent seizures. The aim of this study was to investigate electrophysiologic properties of the hippocampus in the CHX/pilocarpine (CHX/PILO) model as compared with the conventional PILO model. Methods: In vitro electrophysiology was performed 2 months after status epilepticus (SE) induction using extracellular recordings in hippocampal slices from PILO (n ס 8) and CHX/PILO animals (n ס 10). Field potential responses were evoked in the CA1 and DG regions during perfusion with normal artificial cerebrospinal fluid (aCSF) and aCSF containing 3.5, 5, or 8 mM K + without or with bicuculline added. Neo-Timm staining was used for the assessment of supragranular MFS. Results: Evoked potentials in PILO-and CHX/PILO-treated rats displayed small-amplitude polyspiking activity (epileptiform responses) in CA1 and an apparently normal isolated population spike in DG. More important, PILO and CHX/PILO animals did not differ regarding electrophysiologic abnormalities, even under high K + or high K + /bicuculline. Analysis of the neo-Timm staining revealed strong supragranular MFS in PILO-injected rats and significantly less staining in CHX/PILO rats. Thus, occurrence of abnormal stimulus responses and high K +-or high K + /bicuculline-induced epileptiform activities did not depend on the degree of MFS. Conclusions: We therefore suggest that other mechanisms such as anomalous intrinsic bursting and disinhibition rather than MFS might account for the increased hippocampal hyperexcitability in this model.
Epilepsia, Apr 8, 2010
The distribution of bone marrow cells in brain areas during the acute period after pilocarpine-in... more The distribution of bone marrow cells in brain areas during the acute period after pilocarpine-induced status epilepticus (SE) was investigated here. To achieve this, we generated chimeric mice by engrafting bone marrow cells from enhanced green fluorescent protein (eGFP) transgenic mice. GFP + bone marrow-derived cells were found throughout the brain, predominantly in the hippocampus. As expected, these cells exhibited the characteristics of microglia. The pattern of distribution, proliferation, and differentiation of GFP + cells changes as a function of intensity and time following SE. This pattern is also a consequence of the inflammatory response, which is followed by the progressive neuronal damage that is characteristic of the pilocarpine model.
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Papers by Luiz E.a.m. Mello