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Ren T, Lee PMY, Li F, Li J. Prenatal Carbamazepine Exposure and Academic Performance in Adolescents: A Population-Based Cohort Study. Neurology 2023; 100:e728-e738. [PMID: 36323520 PMCID: PMC9969917 DOI: 10.1212/wnl.0000000000201529] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 09/21/2022] [Indexed: 02/15/2023] Open
Abstract
BACKGROUND AND OBJECTIVES To investigate whether children born to mothers who used carbamazepine during pregnancy had worse academic performance in adolescence. METHODS This population-based cohort study included all live-born singletons in Denmark between 1996 and 2002 who participated in the national ninth-grade exit examination (n = 370,859). Those born to mothers with prescription of antiseizure medications other than carbamazepine during pregnancy were excluded. We examined the association of in utero exposure to maternal carbamazepine redeemed during pregnancy (n = 290) with academic performance of offspring, defined by the scores in Danish and mathematics in ninth-grade exit examination. We estimated mean z-score difference with linear regression adjusted for socioeconomic factors and potential indications, including epilepsy and medication for other psychiatric disorders. Additional analyses addressing confounding by indication included comparison between in utero exposed vs past exposed and between past exposed and never exposed. In utero exposure to valproate monotherapy was used as a positive control and in utero exposure to lamotrigine as a negative control. RESULTS At the age of 16.1 (SD 0.4) years, adolescents in utero exposed to maternal carbamazepine monotherapy had lower scores both in Danish and mathematics in ninth-grade exit examination (adjusted z-score difference, -0.14 [95% CI -0.24 to -0.05] and -0.17 [95% CI -0.28 to -0.07], respectively). In utero exposure to carbamazepine monotherapy was associated with lower scores than past exposure only (adjusted z-score difference, -0.24 [95% CI -0.41 to -0.06] for Danish and -0.25 [95% CI -0.44 to -0.06] for mathematics), while past exposure to carbamazepine was associated with minor decrease in offspring's academic performance (adjusted z-score difference, -0.02 [95% CI -0.09 to 0.06] for Danish and -0.07 [95% CI -0.16 to 0.01] for mathematics). The association was also observed for in utero exposure to valproate monotherapy, but not for in utero exposure to lamotrigine. DISCUSSION In utero exposure to carbamazepine was associated with poorer academic performance in adolescence, as represented by lower scores in ninth-grade exit examination in Danish and mathematics. Additional studies are needed to confirm these findings because of limitations in this study and variable findings in prior studies. CLASSIFICATION OF EVIDENCE This study provides Class III evidence that academic performance, as reflected in ninth-grade exit examinations in Danish and mathematics, was worse among those exposed to carbamazepine monotherapy in utero, compared with those without in utero exposure to antiseizure medications.
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Affiliation(s)
| | | | - Fei Li
- From the Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health (T.R., F.L.), Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, China; Department of Clinical Medicine-Department of Clinical Epidemiology (P.M.Y.L., J.L.), Aarhus University and Aarhus University Hospital, Denmark; and Department of Developmental and Behavioural Paediatric & Child Primary Care (F.L.), Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, China.
| | - Jiong Li
- From the Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health (T.R., F.L.), Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, China; Department of Clinical Medicine-Department of Clinical Epidemiology (P.M.Y.L., J.L.), Aarhus University and Aarhus University Hospital, Denmark; and Department of Developmental and Behavioural Paediatric & Child Primary Care (F.L.), Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, China.
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Lu Z, Guo Y, Xu D, Xiao H, Dai Y, Liu K, Chen L, Wang H. Developmental toxicity and programming alterations of multiple organs in offspring induced by medication during pregnancy. Acta Pharm Sin B 2023; 13:460-477. [PMID: 36873163 PMCID: PMC9978644 DOI: 10.1016/j.apsb.2022.05.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 05/05/2022] [Accepted: 05/25/2022] [Indexed: 11/29/2022] Open
Abstract
Medication during pregnancy is widespread, but there are few reports on its fetal safety. Recent studies suggest that medication during pregnancy can affect fetal morphological and functional development through multiple pathways, multiple organs, and multiple targets. Its mechanisms involve direct ways such as oxidative stress, epigenetic modification, and metabolic activation, and it may also be indirectly caused by placental dysfunction. Further studies have found that medication during pregnancy may also indirectly lead to multi-organ developmental programming, functional homeostasis changes, and susceptibility to related diseases in offspring by inducing fetal intrauterine exposure to too high or too low levels of maternal-derived glucocorticoids. The organ developmental toxicity and programming alterations caused by medication during pregnancy may also have gender differences and multi-generational genetic effects mediated by abnormal epigenetic modification. Combined with the latest research results of our laboratory, this paper reviews the latest research progress on the developmental toxicity and functional programming alterations of multiple organs in offspring induced by medication during pregnancy, which can provide a theoretical and experimental basis for rational medication during pregnancy and effective prevention and treatment of drug-related multiple fetal-originated diseases.
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Affiliation(s)
- Zhengjie Lu
- Department of Pharmacology, Wuhan University School of Basic Medical Science, Wuhan 430071, China.,Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Yu Guo
- Department of Pharmacology, Wuhan University School of Basic Medical Science, Wuhan 430071, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disorder, Wuhan 430071, China
| | - Dan Xu
- Department of Pharmacology, Wuhan University School of Basic Medical Science, Wuhan 430071, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disorder, Wuhan 430071, China
| | - Hao Xiao
- Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disorder, Wuhan 430071, China
| | - Yongguo Dai
- Department of Pharmacology, Wuhan University School of Basic Medical Science, Wuhan 430071, China
| | - Kexin Liu
- Department of Pharmacology, Wuhan University School of Basic Medical Science, Wuhan 430071, China
| | - Liaobin Chen
- Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disorder, Wuhan 430071, China
| | - Hui Wang
- Department of Pharmacology, Wuhan University School of Basic Medical Science, Wuhan 430071, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disorder, Wuhan 430071, China
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Tokariev A, Breakspear M, Videman M, Stjerna S, Scholtens LH, van den Heuvel MP, Cocchi L, Vanhatalo S. Impact of In Utero Exposure to Antiepileptic Drugs on Neonatal Brain Function. Cereb Cortex 2021; 32:2385-2397. [PMID: 34585721 PMCID: PMC9157298 DOI: 10.1093/cercor/bhab338] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/18/2021] [Accepted: 08/22/2021] [Indexed: 12/27/2022] Open
Abstract
In utero brain development underpins brain health across the lifespan but is vulnerable to physiological and pharmacological perturbation. Here, we show that antiepileptic medication during pregnancy impacts on cortical activity during neonatal sleep, a potent indicator of newborn brain health. These effects are evident in frequency-specific functional brain networks and carry prognostic information for later neurodevelopment. Notably, such effects differ between different antiepileptic drugs that suggest neurodevelopmental adversity from exposure to antiepileptic drugs and not maternal epilepsy per se. This work provides translatable bedside metrics of brain health that are sensitive to the effects of antiepileptic drugs on postnatal neurodevelopment and carry direct prognostic value.
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Affiliation(s)
- Anton Tokariev
- Baby Brain Activity Center (BABA), Department of Clinical Neurophysiology, New Children's Hospital, HUS Imaging, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.,Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Michael Breakspear
- School of Psychology, College of Engineering, Science and the Environment, University of Newcastle, Callaghan, New South Wales, Australia.,School of Medicine and Public Health, College of Health and Medicine, University of Newcastle, Callaghan, New South Wales, Australia
| | - Mari Videman
- Baby Brain Activity Center (BABA), Department of Clinical Neurophysiology, New Children's Hospital, HUS Imaging, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.,Department of Pediatric Neurology, New Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Susanna Stjerna
- Baby Brain Activity Center (BABA), Department of Clinical Neurophysiology, New Children's Hospital, HUS Imaging, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.,Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Lianne H Scholtens
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Martijn P van den Heuvel
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, the Netherlands.,Department of Child Psychiatry, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Luca Cocchi
- Department of Genetics and Computational Biology, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Sampsa Vanhatalo
- Baby Brain Activity Center (BABA), Department of Clinical Neurophysiology, New Children's Hospital, HUS Imaging, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.,Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
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González-Maciel A, Romero-Velázquez RM, Alfaro-Rodríguez A, Sanchez Aparicio P, Reynoso-Robles R. Prenatal exposure to oxcarbazepine increases hippocampal apoptosis in rat offspring. J Chem Neuroanat 2019; 103:101729. [PMID: 31794794 DOI: 10.1016/j.jchemneu.2019.101729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 11/29/2019] [Accepted: 11/29/2019] [Indexed: 01/18/2023]
Abstract
This study assessed apoptosis in the offspring of rats exposed to oxcarbazepine (OXC) from day 7 to 15 of gestation. Three groups of pregnant Wistar rats were used: 1) Control, treated with saline solution; 2) treated with 100 mg/kg OXC; 3) treated with 100 mg/kg of carbamazepine (CBZ, as a positive control for apoptosis); the route of administration was intragastric. Apoptosis was detected at three postnatal ages using the TUNEL technique in the CA1, and CA3 regions of the hippocampus and in the dentate gyrus (DG); neurogenesis was assessed in the DG using an antibody against doublecortin. The litter characteristics were recorded. OXC increased apoptosis in all regions (p < 0.01) at the three ages evaluated. Lamination disruption occurred in CA1 and CA3 due to the neuron absence and to ectopic neurons; there were also malformations in the dorsal lamina of the DG in 38% and 25% of the pups born from rats treated with OXC and CBZ respectively. CBZ also increased apoptosis. No clear effect on neurogenesis in the DG was observed. The size of the litter was smaller (p < 0.01) in the experimental groups. Nineteen-day OXC fetuses had low weight (p < 0.01), but 21 and 30 postnatal days old CBZ and OXC pups were overweight (p < 0.01). The results demonstrate that OXC administered during gestation is pro-apoptotic, alters the cytoarchitecture of the hippocampus, reduces litter size, and probably influences postnatal weight. We provide evidence of the proapoptotic effect of CBZ when administered early in gestation.
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Affiliation(s)
- A González-Maciel
- Laboratory of Cell and Tissue Morphology, Instituto Nacional de Pediatría, Secretaría de Salud, Insurgentes Sur No. 3700-C, Mexico City, C. P. 04530, Mexico.
| | - R M Romero-Velázquez
- Laboratory of Cell and Tissue Morphology, Instituto Nacional de Pediatría, Secretaría de Salud, Insurgentes Sur No. 3700-C, Mexico City, C. P. 04530, Mexico.
| | - A Alfaro-Rodríguez
- Division of Neurosciences, Instituto Nacional de Rehabilitación, "Luis Guillermo Ibarra Ibarra", Secretaría de Salud, Col. Arenal de Guadalupe, Mexico City, C.P. 14389, Mexico.
| | - P Sanchez Aparicio
- Faculty of Veterinary Medicine, Department of Pharmacology, Universidad Autónoma del Estado de México, Mexico
| | - R Reynoso-Robles
- Laboratory of Cell and Tissue Morphology, Instituto Nacional de Pediatría, Secretaría de Salud, Insurgentes Sur No. 3700-C, Mexico City, C. P. 04530, Mexico.
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Fujimura K, Mitsuhashi T, Takahashi T. Adverse effects of prenatal and early postnatal exposure to antiepileptic drugs: Validation from clinical and basic researches. Brain Dev 2017; 39:635-643. [PMID: 28450094 DOI: 10.1016/j.braindev.2017.03.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 03/19/2017] [Accepted: 03/28/2017] [Indexed: 12/20/2022]
Abstract
Epilepsy requires the long-term administration of antiepileptic drugs (AEDs), and thus, we must consider the effects of prenatal AED exposure on fetus when treating female patients of child bearing age. Large prospective clinical researches in humans have demonstrated the following: (1) prenatal exposure to valproic acid (VPA), carbamazepine, and phenobarbital increases the risk of congenital malformations in a dose-dependent manner and (2) prenatal exposure to VPA increases the risk of higher brain function impairments including intellectual disabilities and autistic spectrum disorders in the offspring. Furthermore, basic researches in animals have shown that prenatal exposure to specific AEDs causes microscopic structural abnormalities in the fetal brain. Specifically, prenatal exposure to VPA has been reported to inhibit the differentiation of neural progenitor cells during the early to middle phases of neuronogenesis, leading to increased number of projection neurons in the superficial layers of postnatal neocortices in mice. It is indispensable to prescribe AEDs that are associated with lower risk of congenital malformations and impairment of higher brain functions as well as to administer them at requisite minimum doses.
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Affiliation(s)
- Kimino Fujimura
- Department of Pediatrics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Takayuki Mitsuhashi
- Department of Pediatrics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Takao Takahashi
- Department of Pediatrics, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
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Zucker I. Risk mitigation for children exposed to drugs during gestation: A critical role for animal preclinical behavioral testing. Neurosci Biobehav Rev 2017; 77:107-121. [DOI: 10.1016/j.neubiorev.2017.03.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 03/08/2017] [Indexed: 12/13/2022]
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Ahmed RG, El-Gareib AW. Maternal carbamazepine alters fetal neuroendocrine-cytokines axis. Toxicology 2017; 382:59-66. [PMID: 28267586 DOI: 10.1016/j.tox.2017.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 02/14/2017] [Accepted: 03/02/2017] [Indexed: 12/15/2022]
Abstract
This study detected the impact of maternal carbamazepine (CBZ) on the fetal neuroendocrine-cytokines axis. 25 or 50mg/kg of CBZ was intraperitoneally administrated to pregnant albino rats from the gestation day (GD) 1 to 20. Both administrations of CBZ caused a hypothyroidism in dams and fetuses whereas the decreases in serum thyroxine (T4) and triiodothyronine (T3) and increases in serum thyrotropin (TSH) levels were highly significant (LSD; P <0.01) at GD 20 compared to untreated control dams. Also, both administrations had undesirable impacts on the maternofetal body weight, litter weight, survival of dams and fetuses, and their food consumption in comparison to the corresponding control. These administrations also elicited a reduction in fetal serum growth hormone (GH), interferon-γ (IFNγ), interleukins (IL-2 & 4) and prostaglandin E2 (PGE2) levels. Also, the elevation in fetal serum tumor necrosis factor-alpha (TNFα), transforming growth factor-beta (TGFβ), and interleukins (IL-1β & 17) levels was observed at embryonic day (ED) 20. Moreover, there were a cellular fragmentation, distortion, hyperemia, oedema and vacuolation in the fetal cerebellar cortex due to both maternal administrations. These developmental changes were dose-dependent. These novel results suggest that CBZ may act as a developmental immunoneuroendocrine disruptor.
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Affiliation(s)
- R G Ahmed
- Division of Anatomy and Embryology, Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
| | - A W El-Gareib
- Division of Anatomy and Embryology, Zoology Department, Faculty of Science, Cairo University, Egypt
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Evidence for spared attention to faces in 7-month-old infants after prenatal exposure to antiepileptic drugs. Epilepsy Behav 2016; 64:62-68. [PMID: 27732918 DOI: 10.1016/j.yebeh.2016.09.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 08/16/2016] [Accepted: 09/11/2016] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Prenatal antiepileptic drug (AED) exposure is associated with an increased risk of cognitive impairment and autism spectrum disorders detected mainly at the age of two to six years. We examined whether the developmental aberrations associated with prenatal AED exposure could be detected already in infancy and whether effects on visual attention can be observed at this early age. MATERIAL AND METHODS We compared a prospective cohort of infants with in utero exposure to AED (n=56) with infants without drug exposures (n=62). The assessments performed at the age of seven months included standardized neurodevelopmental scores (Griffiths Mental Developmental Scale and Hammersmith Infant Neurological Examination) as well as a novel eye-tracking-based test for visual attention and orienting to faces. Background information included prospective collection of AED exposure data, pregnancy outcome, neuropsychological evaluation of the mothers, and information on maternal epilepsy type. RESULTS Carbamazepine, oxcarbazepine, and valproate, but not lamotrigine or levetiracetam, were associated with impaired early language abilities at the age of seven months. The general speed of visuospatial orienting or attentional bias for faces measured by eye-tracker-based tests did not differ between AED-exposed and control infants. DISCUSSION Our findings support the idea that prenatal AED exposure may impair verbal abilities, and this effect may be detected already in infancy. In contrast, the early development of attention to faces was spared after in utero AED exposure.
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Gulec Suyen G, Isbil-Buyukcoskun N, Kahveci N, Sengun E, Ozluk K. Immediate and delayed treatment with gabapentin, carbamazepine and CNQX have almost similar impact on cognitive functions and behavior in the lithium-pilocarpine model in rats. Pharmacol Biochem Behav 2016; 148:128-35. [DOI: 10.1016/j.pbb.2016.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 06/15/2016] [Accepted: 07/13/2016] [Indexed: 02/06/2023]
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Cognitive outcomes of prenatal antiepileptic drug exposure. Epilepsy Res 2015; 114:89-97. [PMID: 26088891 DOI: 10.1016/j.eplepsyres.2015.04.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 04/13/2015] [Accepted: 04/23/2015] [Indexed: 01/18/2023]
Abstract
Antiepileptic drugs (AEDs) have been known to have teratogenic effects for a little over 50 years. While early reports focused on fetal malformations, there has been an increasing amount of data over the last few decades exploring the cognitive outcomes of offspring exposed to AEDs in utero. Although the challenges of confounding factors and varied methodologies have led to inconsistent results, the negative impact of some of the agents, such as valproate, have become clear. Further studies are needed to evaluate the cognitive effects of prenatal exposure to many AEDs which have not been tested, to clarify the effects of existing AEDs which have yielded mixed results, and to better understand the effects of polytherapy. Research in animal models is warranted to screen AEDs for their effects on cognition in exposed offspring and to further our understanding of the underlying mechanisms by which AEDs exert their harmful effects on the developing brain. And finally, new AEDs without these harmful effects and agents which can prevent or reverse the negative consequences imparted by AED therapy on cognition should be sought.
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Does in utero exposure of antiepileptic drugs lead to failure to reach full cognitive potential? Seizure 2015; 28:51-6. [DOI: 10.1016/j.seizure.2015.01.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 01/22/2015] [Indexed: 02/07/2023] Open
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Hyperthermia-Induced Febrile Seizures Have Moderate and Transient Effects on Spatial Learning in Immature Rats. Behav Neurol 2015; 2015:924303. [PMID: 26063965 PMCID: PMC4430674 DOI: 10.1155/2015/924303] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 03/31/2015] [Accepted: 04/07/2015] [Indexed: 11/17/2022] Open
Abstract
The aim of this study was to characterize a novel animal model hyperthermia-induced febrile seizure and to investigate the impacts of repetitive febrile seizures on spatial learning and memory performances in immature rats. Methods. Rats were subjected to hyperthermia exposure one, two, or three times in 10-day intervals during 30 min in a water bath warmed at 45–50°C and their behaviour was monitored. Morris water maze spatial learning and memory were examined for control and treated groups. Results showed that rats subjected to 30-minute hyperthermia hot water developed rapidly myoclonic jerks and then generalized seizures. After a single hyperthermia exposure, the time for generalised tonic-clonic seizures appearance was 16.08 ± 0.60 min and it decreased gradually with repetitive exposure to reach 12.46 ± 0.39 min by the third exposure. Febrile seizures altered the spatial learning and memory abilities in Morris water maze and increased the time spent to attain the platform after one or two exposures, while after a third exposure rats exhibited the same latency compared to controls. Similar results were obtained in probe test where rats, subjected to hyperthermia for one or two episodes, spent less time in the target quadrant compared to corresponding controls. Further, when platform was moved from northwest to southwest quadrant, memory transfer test indicated that after one or two hyperthermia exposures cognitive performances were slightly altered, while after a third exposure the latency to escape increased significantly compared to untreated group. It was concluded that 30 min of hyperthermia hot water was sufficient to induce febrile seizures in immature rats and an increase of susceptibility was observed with repetitive hyperthermia exposure. Hyperthermia treatment impaired cognitive performances but the effects were mostly transient and moderate.
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