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Sarkisova K, van Luijtelaar G. The impact of early-life environment on absence epilepsy and neuropsychiatric comorbidities. IBRO Neurosci Rep 2022; 13:436-468. [PMID: 36386598 PMCID: PMC9649966 DOI: 10.1016/j.ibneur.2022.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 11/11/2022] Open
Abstract
This review discusses the long-term effects of early-life environment on epileptogenesis, epilepsy, and neuropsychiatric comorbidities with an emphasis on the absence epilepsy. The WAG/Rij rat strain is a well-validated genetic model of absence epilepsy with mild depression-like (dysthymia) comorbidity. Although pathologic phenotype in WAG/Rij rats is genetically determined, convincing evidence presented in this review suggests that the absence epilepsy and depression-like comorbidity in WAG/Rij rats may be governed by early-life events, such as prenatal drug exposure, early-life stress, neonatal maternal separation, neonatal handling, maternal care, environmental enrichment, neonatal sensory impairments, neonatal tactile stimulation, and maternal diet. The data, as presented here, indicate that some early environmental events can promote and accelerate the development of absence seizures and their neuropsychiatric comorbidities, while others may exert anti-epileptogenic and disease-modifying effects. The early environment can lead to phenotypic alterations in offspring due to epigenetic modifications of gene expression, which may have maladaptive consequences or represent a therapeutic value. Targeting DNA methylation with a maternal methyl-enriched diet during the perinatal period appears to be a new preventive epigenetic anti-absence therapy. A number of caveats related to the maternal methyl-enriched diet and prospects for future research are discussed.
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Affiliation(s)
- Karine Sarkisova
- Institute of Higher Nervous Activity and Neurophysiology of Russian Academy of Sciences, Butlerova str. 5a, Moscow 117485, Russia
| | - Gilles van Luijtelaar
- Donders Institute for Brain, Cognition, and Behavior, Donders Center for Cognition, Radboud University, Nijmegen, PO Box 9104, 6500 HE Nijmegen, the Netherlands
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Al-Muhtasib N, Sepulveda-Rodriguez A, Vicini S, Forcelli PA. Neonatal phenobarbital exposure disrupts GABAergic synaptic maturation in rat CA1 neurons. Epilepsia 2018; 59:333-344. [PMID: 29315524 DOI: 10.1111/epi.13990] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2017] [Indexed: 01/24/2023]
Abstract
OBJECTIVE Phenobarbital is the most commonly utilized drug for the treatment of neonatal seizures. The use of phenobarbital continues despite growing evidence that it exerts suboptimal seizure control and is associated with long-term alterations in brain structure, function, and behavior. Alterations following neonatal phenobarbital exposure include acute induction of neuronal apoptosis, disruption of synaptic development in the striatum, and a host of behavioral deficits. These behavioral deficits include those in learning and memory mediated by the hippocampus. However, the synaptic changes caused by acute exposure to phenobarbital that lead to lasting effects on brain function and behavior remain understudied. METHODS Postnatal day (P)7 rat pups were treated with phenobarbital (75 mg/kg) or saline. On P13-14 or P29-37, acute slices were prepared and whole-cell patch-clamp recordings were made from CA1 pyramidal neurons. RESULTS At P14 we found an increase in miniature inhibitory postsynaptic current (mIPSC) frequency in the phenobarbital-exposed as compared to the saline-exposed group. In addition to this change in mIPSC frequency, the phenobarbital group displayed larger bicuculline-sensitive tonic currents, decreased capacitance and membrane time constant, and a surprising persistence of giant depolarizing potentials. At P29+, the frequency of mIPSCs in the saline-exposed group had increased significantly from the frequency at P14, typical of normal synaptic development; at this age the phenobarbital-exposed group displayed a lower mIPSC frequency than did the control group. Spontaneous inhibitory postsynaptic current (sIPSC) frequency was unaffected at either P14 or P29+. SIGNIFICANCE These neurophysiological alterations following phenobarbital exposure provide a potential mechanism by which acute phenobarbital exposure can have a long-lasting impact on brain development and behavior.
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Affiliation(s)
- Nour Al-Muhtasib
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA
| | - Alberto Sepulveda-Rodriguez
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA.,Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, USA
| | - Stefano Vicini
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA.,Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, USA.,Department of Neuroscience, Georgetown University, Washington, DC, USA
| | - Patrick A Forcelli
- Department of Pharmacology and Physiology, Georgetown University, Washington, DC, USA.,Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, USA.,Department of Neuroscience, Georgetown University, Washington, DC, USA
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Alpár A, Di Marzo V, Harkany T. At the Tip of an Iceberg: Prenatal Marijuana and Its Possible Relation to Neuropsychiatric Outcome in the Offspring. Biol Psychiatry 2016; 79:e33-45. [PMID: 26549491 DOI: 10.1016/j.biopsych.2015.09.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 08/26/2015] [Accepted: 09/14/2015] [Indexed: 12/11/2022]
Abstract
Endocannabinoids regulate brain development via modulating neural proliferation, migration, and the differentiation of lineage-committed cells. In the fetal nervous system, (endo)cannabinoid-sensing receptors and the enzymatic machinery of endocannabinoid metabolism exhibit a cellular distribution map different from that in the adult, implying distinct functions. Notably, cannabinoid receptors serve as molecular targets for the psychotropic plant-derived cannabis constituent Δ(9)-tetrahydrocannainol, as well as synthetic derivatives (designer drugs). Over 180 million people use cannabis for recreational or medical purposes globally. Recreational cannabis is recognized as a niche drug for adolescents and young adults. This review combines data from human and experimental studies to show that long-term and heavy cannabis use during pregnancy can impair brain maturation and predispose the offspring to neurodevelopmental disorders. By discussing the mechanisms of cannabinoid receptor-mediated signaling events at critical stages of fetal brain development, we organize histopathologic, biochemical, molecular, and behavioral findings into a logical hypothesis predicting neuronal vulnerability to and attenuated adaptation toward environmental challenges (stress, drug exposure, medication) in children affected by in utero cannabinoid exposure. Conversely, we suggest that endocannabinoid signaling can be an appealing druggable target to dampen neuronal activity if pre-existing pathologies associate with circuit hyperexcitability. Yet, we warn that the lack of critical data from longitudinal follow-up studies precludes valid conclusions on possible delayed and adverse side effects. Overall, our conclusion weighs in on the ongoing public debate on cannabis legalization, particularly in medical contexts.
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Affiliation(s)
- Alán Alpár
- MTA-SE NAP B Research Group of Experimental Neuroanatomy and Developmental Biology, Hungarian Academy of Sciences, Budapest, Hungary; Department of Anatomy, Semmelweis University, Budapest, Hungary
| | - Vincenzo Di Marzo
- Endocannabinoid Research Group, Instituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Pozzuoli, Naples, Italy
| | - Tibor Harkany
- Division of Molecular Neurosciences, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria.
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Models of cortical malformation--Chemical and physical. J Neurosci Methods 2015; 260:62-72. [PMID: 25850077 DOI: 10.1016/j.jneumeth.2015.03.034] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 03/27/2015] [Accepted: 03/30/2015] [Indexed: 11/21/2022]
Abstract
Pharmaco-resistant epilepsies, and also some neuropsychiatric disorders, are often associated with malformations in hippocampal and neocortical structures. The mechanisms leading to these cortical malformations causing an imbalance between the excitatory and inhibitory system are largely unknown. Animal models using chemical or physical manipulations reproduce different human pathologies by interfering with cell generation and neuronal migration. The model of in utero injection of methylazoxymethanol (MAM) acetate mimics periventricular nodular heterotopia. The freeze lesion model reproduces (poly)microgyria, focal heterotopia and schizencephaly. The in utero irradiation model causes microgyria and heterotopia. Intraperitoneal injections of carmustine 1-3-bis-chloroethyl-nitrosurea (BCNU) to pregnant rats produces laminar disorganization, heterotopias and cytomegalic neurons. The ibotenic acid model induces focal cortical malformations, which resemble human microgyria and ulegyria. Cortical dysplasia can be also observed following prenatal exposure to ethanol, cocaine or antiepileptic drugs. All these models of cortical malformations are characterized by a pronounced hyperexcitability, few of them also produce spontaneous epileptic seizures. This dysfunction results from an impairment in GABAergic inhibition and/or an increase in glutamatergic synaptic transmission. The cortical region initiating or contributing to this hyperexcitability may not necessarily correspond to the site of the focal malformation. In some models wide-spread molecular and functional changes can be observed in remote regions of the brain, where they cause pathophysiological activities. This paper gives an overview on different animal models of cortical malformations, which are mostly used in rodents and which mimic the pathology and to some extent the pathophysiology of neuronal migration disorders associated with epilepsy in humans.
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Bernášková K, Matějovská I, Šlamberová R. Postnatal challenge dose of methamphetamine amplifies anticonvulsant effects of prenatal methamphetamine exposure on epileptiform activity induced by electrical stimulation in adult male rats. Exp Neurol 2011; 229:282-7. [DOI: 10.1016/j.expneurol.2011.02.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 01/06/2011] [Accepted: 02/15/2011] [Indexed: 11/17/2022]
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Slamberová R, Hrubá L, Matějovská I, Bernášková K, Rokyta R. Increased seizure susceptibility induced by prenatal methamphetamine exposure in adult female rats is not affected by early postnatal cross-fostering. Epilepsy Behav 2011; 20:6-11. [PMID: 21067979 DOI: 10.1016/j.yebeh.2010.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 10/06/2010] [Accepted: 10/06/2010] [Indexed: 10/18/2022]
Abstract
Our previous studies repeatedly demonstrated that prenatal methamphetamine (MA) exposure alters seizure susceptibility in adult rats. Both the inhibitory GABA system and the excitatory NMDA system play a role in the effect of MA on epileptic seizures. On the basis of our previous behavioral results, the effect of cross-fostering on seizure susceptibility in adult female rats was examined in the present study. Bicuculline (GABA(A) receptor antagonist) and NMDA (NMDA receptor agonist) were used to induce seizures in adult female offspring exposed to MA in the prenatal and/or preweaning periods. Female dams were injected with MA (5mg/kg daily) or physiological saline (S) for approximately 9 weeks [about 3 weeks prior to impregnation, for the entire gestation period (22 days), and in the preweaning period (21 days)]. Absolute controls (C) did not receive any injections. On postnatal day 1, pups were cross-fostered so that each mother received pups from all three treatments. Thus, nine groups (based on the prenatal and postnatal drug exposures) of adult female rats were tested in each seizure test: C/C, C/S, C/MA, S/C, S/S, S/MA, MA/C, MA/S, MA/MA. The present study demonstrated that both the excitatory NMDA system and the inhibitory GABA system are involved in the proconvulsive effect of MA during prenatal and partially also postnatal development in female rats. However, because our results did not show any improvement in seizure susceptibility in prenatally MA-exposed animals that were fostered by control mothers (MA/C) relative to their siblings fostered by MA-treated mothers (MA/MA), our hypothesis of the cross-fostering effect seems to be incorrect in contrast to our behavioral studies.
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Affiliation(s)
- R Slamberová
- Department of Normal, Pathological, and Clinical Physiology, Prague, Third Faculty of Medicine, Charles University, Prague, Czech Republic.
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Slamberová R, Schutová B, Bernásková K, Matejovská I, Rokyta R. Challenge dose of methamphetamine affects kainic acid-induced seizures differently depending on prenatal methamphetamine exposure, sex, and estrous cycle. Epilepsy Behav 2010; 19:26-31. [PMID: 20708438 DOI: 10.1016/j.yebeh.2010.06.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 06/21/2010] [Accepted: 06/21/2010] [Indexed: 10/19/2022]
Abstract
Even though it is obvious that glutamate plays an important role in the effect of psychostimulants on seizures, the role of non-NMDA receptors remains uncertain. The aim of the present study was to determine whether acute methamphetamine (MA) administration changes sensitivity to seizures induced with kainic acid in prenatally MA-exposed adult rats. Adult male and female rats (prenatally MA exposed, prenatally saline exposed, and controls) were divided into groups that received a challenge dose (1mg/kg) of MA and groups that did not receive the MA challenge (saline injected). Systemic administration of 15 mg/kg kainic acid was used as a seizure model. Our results demonstrated that a single injection of MA (1mg/kg) affects kainic acid-induced seizures differently depending on prenatal exposure, sex, and female estrous cycle. Even though daily injections of MA (5mg/kg) in maternal rats did not have a long-term effect on susceptibility to seizures induced with kainic acid in adult progeny, sensitivity to the challenge dose of MA differed between the prenatal exposure groups.
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Affiliation(s)
- Romana Slamberová
- Department of Normal, Pathological and Clinical Physiology, Third Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
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Dcx reexpression reduces subcortical band heterotopia and seizure threshold in an animal model of neuronal migration disorder. Nat Med 2008; 15:84-90. [PMID: 19098909 PMCID: PMC2715867 DOI: 10.1038/nm.1897] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Accepted: 11/06/2008] [Indexed: 01/10/2023]
Abstract
Disorders of neuronal migration can lead to malformations of the cerebral neocortex that greatly increase the risk of seizures. It remains untested whether malformations caused by disorders in neuronal migration can be reduced by reactivating cellular migration, and whether such repair can decrease seizure risk. Here we show, in a rat model of subcortical band heterotopia (SBH) generated by in utero RNAi of Dcx, that aberrantly positioned neurons can be stimulated to migrate by re-expressing Dcx after birth. Re-starting migration in this way both reduces neocortical malformations and restores neuronal patterning. We find further that the capacity to reduce SBH has a critical period in early postnatal development. Moreover, intervention after birth reduces convulsant-induced seizure threshold to levels similar to that of malformation-free controls. These results suggest that disorders of neuronal migration may be eventually treatable by re-engaging developmental programs both to reduce the size of cortical malformations and to reduce seizure risk.
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Rao MS, Hattiangady B, Reddy DS, Shetty AK. Hippocampal neurodegeneration, spontaneous seizures, and mossy fiber sprouting in the F344 rat model of temporal lobe epilepsy. J Neurosci Res 2006; 83:1088-105. [PMID: 16493685 DOI: 10.1002/jnr.20802] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The links among the extent of hippocampal neurodegeneration, the frequency of spontaneous recurrent motor seizures (SRMS), and the degree of aberrant mossy fiber sprouting (MFS) in temporal lobe epilepsy (TLE) are a subject of contention because of variable findings in different animal models and human studies. To understand these issues further, we quantified these parameters at 3-5 months after graded injections of low doses of kainic acid (KA) in adult F344 rats. KA was administered every 1 hr for 4 hr, for a cumulative dose of 10.5 mg/kg bw, to induce continuous stages III-V motor seizures for >3 hr. At 4 days post-KA, the majority of rats (77%) exhibited moderate bilateral neurodegeneration in different regions of the hippocampus; however, 23% of rats exhibited massive neurodegeneration in all hippocampal regions. All KA-treated rats displayed robust SRMS at 3 months post-KA, and the severity of SRMS increased over time. Analyses of surviving neurons at 5 months post-KA revealed two subgroups of rats, one with moderate hippocampal injury (HI; 55% of rats) and another with widespread HI (45%). Rats with widespread HI exhibited greater loss of CA3 pyramidal neurons and robust aberrant MFS than rats with moderate HI. However, the frequency of SRMS (approximately 3/hr) was comparable between rats with moderate and widespread HI. Thus, in comparison with TLE model using Sprague-Dawley rats (Hellier et al. [1998] Epilepsy Res. 31:73-84), a much lower cumulative dose of KA leads to robust chronic epilepsy in F344 rats. Furthermore, the occurrence of SRMS in this model is always associated with considerable bilateral hippocampal neurodegeneration and aberrant MFS. However, more extensive hippocampal CA3 cell loss and aberrant MFS do not appear to increase the frequency of SRMS. Because most of the features are consistent with mesial TLE in humans, the F344 model appears ideal for testing the efficacy of potential treatment strategies for mesial TLE.
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Affiliation(s)
- Muddanna S Rao
- Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, North Carolina 27710, USA
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Slamberová R, Rokyta R. Occurrence of bicuculline-, NMDA- and kainic acid-induced seizures in prenatally methamphetamine-exposed adult male rats. Naunyn Schmiedebergs Arch Pharmacol 2005; 372:236-41. [PMID: 16247608 DOI: 10.1007/s00210-005-0016-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Accepted: 09/19/2005] [Indexed: 11/25/2022]
Abstract
Stimulant drugs are often associated with increased seizure susceptibility. Inhibitory gamma-aminobutyric acid (GABA) and excitatory N-methyl-D-aspartate (NMDA) systems play an important role in the effect of stimulants on epileptic seizures. No studies investigating the effect of prenatal methamphetamine (MA) exposure on seizures are available. In this study, bicuculline (GABAA receptor antagonist), NMDA (NMDA receptor agonist) and kainic acid (non-NMDA receptor agonist) were used to induce seizures in adult male rats. Three groups of animals were tested in each seizure test: prenatally MA- (5 mg/kg) exposed, prenatally saline-exposed, and absolute controls without any prenatal exposure. In bicuculline-induced seizures, the latency to onset of tonic-clonic seizures was shorter in MA-exposed rats than in controls, but it did not differ from saline-exposed rats. There were no differences in clonic seizure onset between groups. In NMDA-induced seizures, the latency to onset of clonic-tonic seizures was shorter in prenatally MA-exposed rats than in controls; however, the latency to onset of saline-exposed animals did not differ from either MA-exposed or from control rats. There were no differences in seizure susceptibility in kainic acid-induced clonic seizures. There were no differences in seizure incidences or stereotypical behavior in any seizure model. The question remains as to how much the present data demonstrate the effect of prenatal drug exposure on seizure susceptibility per se, and how much they may be explained by the effect of prenatal stress or by other mechanism(s).
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Affiliation(s)
- Romana Slamberová
- Department of Normal, Pathological and Clinical Physiology, 3rd Faculty of Medicine, Charles University, Ke Karlovu 4, 120 00, Praha 2, Czech Republic.
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Novikova SI, He F, Bai J, Lidow MS. Neuropathology of the cerebral cortex observed in a range of animal models of prenatal cocaine exposure may reflect alterations in genes involved in the Wnt and cadherin systems. Synapse 2005; 56:105-16. [PMID: 15729737 DOI: 10.1002/syn.20134] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Several recent reports show that the cerebral cortex in humans and animals with altered expressions of Wnt/cadherin network-associate molecules display cytoarchitectural abnormalities reminiscent of cortical dysplasias seen in some (mouse-, rat-, and monkey-based) animal models of prenatal cocaine exposure. Therefore, we employed oligo microarrays followed by real-time RT-PCR to compare expressions of genes involved in Wnt and cadherin systems in the cerebral wall of 18-day-old (E18) fetuses from cocaine-treated (20 mg/kg cocaine, s.c., b.i.d., E8-18) and drug-naive (saline, s.c.) mice. The pregnant mice chronically treated with cocaine in the above-described manner represent one of the animal models producing offspring with widespread cortical dysplasias. Out of more than 150 relevant genes in the arrays, 32 were upregulated and 9 were downregulated in cocaine-exposed fetuses. The majority of these genes (30 out of 41) were similarly affected in the frontal and occipital regions of the cerebral wall. We also used Western immunoblotting to examine the ability of cocaine to regulate the protein levels of beta-catenin, the key functional component of both Wnt and cadherin systems. While the total cell levels of beta-catenin were increased throughout the cerebral wall of cocaine-exposed fetuses, its nuclear (gene-transcription driving) levels remained unaltered. This suggests a transcription-unrelated role for cocaine-induced upregulation of this protein. Overall, our findings point to an intriguing possibility that that cerebral cortical dysplasias observed in several animal models of prenatal cocaine exposure may be at least in part related to alterations in the Wnt/cadherin molecular network.
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Affiliation(s)
- Svetlana I Novikova
- Department of Biomedical Sciences, and Program of Neuroscience, University of Maryland, Baltimore, Maryland 21201, USA
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Snyder-Keller A, Keller RW. Spatiotemporal analysis of Fos expression associated with cocaine- and PTZ-induced seizures in prenatally cocaine-treated rats. Exp Neurol 2001; 170:109-20. [PMID: 11421588 DOI: 10.1006/exnr.2001.7696] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously reported that prenatal cocaine exposure (40 mg/kg s.c., E10-E20) increased susceptibility to convulsant-induced seizures later in life, with female rats becoming more sensitive to seizures induced by cocaine and pentylenetetrazol (PTZ), and males more sensitive to PTZ-induced seizures (Snyder-Keller and Keller, 1995, 2000). In order to determine the locus of enhanced seizure susceptibility in the brains of prenatally cocaine-treated rats, we examined the distribution and density of Fos-immunoreactive cells after cocaine- and PTZ-induced seizures in mature rats. Subconvulsive cocaine doses induced c-fos in cortical areas as well as densely dopamine-innervated regions such as striatum and nucleus accumbens. Following cocaine-induced seizures, intense c-fos induction was observed in piriform cortex, amygdala, and hippocampus. Quantification of the number of Fos-immunoreactive cells in the brains of prenatally cocaine-treated versus prenatally saline-treated rats revealed differences in piriform cortex and amygdala that were indicative of a lower threshold in prenatally cocaine-treated female rats. Following PTZ-induced seizures, the same pattern of limbic structures were recruited with increasing seizure severity. Only females exhibited changes in the number of Fos-immunoreactive cells as a result of prenatal cocaine treatment. Pretreatment with the noncompetitive NMDA antagonist MK-801 blocked both cocaine- and PTZ-induced seizures, and Fos expression in limbic areas was also blocked. The dopamine D1 antagonist SCH 23390 blocked cocaine-induced seizures and associated c-fos induction, but not PTZ-induced seizures or Fos. Examination of the pattern of Fos expression at 15-20 min postseizure revealed that the initial site of c-fos induction associated with PTZ-induced seizures appeared to be the piriform cortex, whereas cocaine-induced seizures induced early expression in both piriform cortex and lateral amygdala. These findings suggest that neural alterations residing in the piriform cortex and amygdala are likely to account for the increased seizure susceptibility of prenatally cocaine-treated rats.
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Affiliation(s)
- A Snyder-Keller
- New York State Department of Health, Wadsworth Center, Albany, NY 12201, USA
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Snyder-Keller A, Sam C, Keller RW. Enhanced susceptibility to cocaine- and pentylenetetrazol-induced seizures in prenatally cocaine-treated rats. Neurotoxicol Teratol 2000; 22:231-6. [PMID: 10758352 DOI: 10.1016/s0892-0362(99)00061-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We previously reported that prenatal cocaine exposure increased susceptibility to cocaine-induced seizures later in life. Here we examine whether this enhanced susceptibility to seizures generalizes to other chemoconvulsants, and whether postnatal cocaine treatment similarly increases susceptibility. Following prenatal cocaine treatment (40 mg/kg; E10-20), both male and female rats were more likely to seize to a dose of 30 mg/kg pentylenetetrazol (PTZ) at 2 months of age, although the severity of the seizures observed was increased only in females. Daily cocaine injections (10-20 mg/kg SC) during the first 10 days after birth also produced effects that were dependent on the sex of the animal. Postnatally cocaine-treated female rats showed no greater incidence of seizures in response to an acute high dose of cocaine, but did exhibit an increased susceptibility to cocaine-kindled seizures. Male, but not female, postnatally cocaine-treated rats were more susceptible to PTZ-induced seizures. The increased susceptibility to seizures induced by two different chemoconvulsants after prenatal cocaine treatment suggests that developmental cocaine exposure, particularly during the second trimester equivalent, alters the balance between excitation and inhibition in the brain.
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Affiliation(s)
- A Snyder-Keller
- Wadsworth Center, New York State Department of Health, P.O. Box 509, Albany, NY 12201, USA.
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Chevassus-au-Louis N, Baraban SC, Gaïarsa JL, Ben-Ari Y. Cortical malformations and epilepsy: new insights from animal models. Epilepsia 1999; 40:811-21. [PMID: 10403203 DOI: 10.1111/j.1528-1157.1999.tb00786.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the last decade, the recognition of the high frequency of cortical malformations among patients with epilepsy especially children, has led to a renewed interest in the study of the pathophysiology of cortical development. This field has also been spurred by the recent development of several experimental genetic and non-genetic, primarily rodent, models of cortical malformations. Epileptiform activity in these animals can appear as spontaneous seizure activity in vivo, in vitro hyperexcitability, or reduced seizure susceptibility in vitro and in vivo. In the neonatal freeze lesion model, that mimics human microgyria, hyperexcitability is caused by a reorganization of the network in the borders of the malformation. In the prenatal methylazoxymethanol model, that causes a diffuse cortical malformation, hyperexcitability is associated with alteration of firing properties of discrete neuronal subpopulations together with the formation of bridges between normally unconnected structures. In agreement with clinical evidence, these experimental data suggest that cortical malformations can both form epileptogenic foci and alter brain development in a manner that causes a diffuse hyperexcitability of the cortical network.
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Penning DH, Dexter F, Henderson JL, Chestnut DH, Reynolds JD. Bolus maternal cocaine administration does not produce a large increase in fetal sheep cerebral cortical glutamate concentration. Neurotoxicol Teratol 1999; 21:177-80. [PMID: 10192278 DOI: 10.1016/s0892-0362(98)00050-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Human cocaine use during pregnancy may result in postnatal neurologic dysfunction and abnormal behavior. L-Glutamate, the major excitatory neurotransmitter in the brain, plays an important role in cerebral cortical development. An optimal level of glutamate is required for normal neuronal development. We tested whether acute cocaine exposure produces large increases in glutamate release in the intact cerebral cortex of the near-term fetal sheep. Cocaine 3.0 mg kg(-1) IV bolus produced the expected increase in maternal and fetal mean arterial pressure, increase in fetal heart rate, decrease in uterine blood flow, and decrease in fetal arterial blood pO2 (N = 5). The percentage increases in extracellular glutamate concentration in the fetal cerebral cortex measured by in utero microdialysis were 7%, 15%, 17%, 17%, and 43% in each fetus (upper 95% confidence bound for the median = 43%). We conclude that if cocaine increases glutamate concentration in the developing cerebral cortex, the increase in magnitude is small relative to the changes produced by other interventions such as ethanol or umbilical cord occlusion. Mechanisms other than increases in cerebral cortical glutamate concentration probably contribute to the neurologic injury associated with prenatal cocaine exposure.
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Affiliation(s)
- D H Penning
- Department of Anesthesiology, Duke University, Durham, NC, USA.
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