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Binder MS, Pranske ZJ, Hodges SL, Womble PD, Kwok EM, Quintero SI, Kim AD, Narvaiz DA, Lugo JN. Agomelatine Is Unable to Attenuate Kainic Acid-Induced Deficits in Early Life Communicative Behavior. Dev Psychobiol 2024; 66:e22543. [PMID: 39205500 PMCID: PMC11376987 DOI: 10.1002/dev.22543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 07/25/2024] [Accepted: 08/13/2024] [Indexed: 09/04/2024]
Abstract
Early life seizures are associated with a variety of behavioral comorbidities. Among the most prevalent of these are deficits in communication. Auditory communicative behaviors in mice, known as ultrasonic vocalizations (USVs), can be used to assess potential treatments. Agomelatine is a melatonin agonist that effectively reduces behavioral comorbidities of seizures in adults; however, its ability to attenuate seizure-induced communicative deficits in neonates is unknown. To address this, we administered C57 mice either saline or kainic acid (KA) on postnatal day (PD) 10. The mice then received either agomelatine or saline 1-h post-status epilepticus. On PD 11, we assessed the quantity of USVs produced, the duration, peak frequency, fundamental frequency, and amplitude of the vocalizations, as well as the call type utilization. We found that KA increased vocal production and reduced USV variability relative to controls. KA also increased USV duration and amplitude and significantly altered the types of calls produced. Agomelatine did not attenuate any of the deficits. Our study is the first to assess agomelatine's efficacy to correct USVs and thus provides an important point of context to the literature, indicating that despite its high therapeutic efficacy to attenuate other behavioral comorbidities of seizures, agomelatine's ability to correct neonatal communicative deficits is limited.
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Blandin KJ, Narvaiz DA, Sullens DG, Womble PD, Hodges SL, Binder MS, Faust A, Nguyen PH, Pranske ZJ, Lugo JN. A Two-Hit Approach Inducing Flurothyl Seizures in Fmr1 Knockout Mice Impacts Anxiety and Repetitive Behaviors. Brain Sci 2024; 14:892. [PMID: 39335388 PMCID: PMC11429635 DOI: 10.3390/brainsci14090892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2024] [Revised: 08/25/2024] [Accepted: 08/28/2024] [Indexed: 09/30/2024] Open
Abstract
BACKGROUND Fragile X Syndrome (FXS) is the leading monogenetic cause of autism spectrum disorder (ASD) and is associated with seizures. We examined the impact of repeated seizures on the behavioral and molecular changes in male Fmr1 knockout (KO) mice and wild-type (WT) mice. METHODS Seizures were induced by administering three flurothyl seizures per day across postnatal days (PD) 7-11, for a total of 15 seizures. In adulthood, mice were tested in a battery of behavioral tasks to assess long-term behavioral deficits. RESULTS The two-hit impact of a Fmr1 knockout and seizures resulted in decreased anxiety-like behavior in the elevated plus maze test and a longer latency to their first nose poke (repetitive behavior). Seizures resulted in decreased activity, decreased repetitive behavior (grooming and rearings), and decreased social behavior, while they also increased habituation to auditory stimuli and increased freezing in delayed fear conditioning in both KO and control mice. KO mice displayed increased repetitive behavior in the open field task (clockwise revolutions) and repeated nose pokes, and decreased anxiety in the open field test. No differences in mTOR signaling were found. CONCLUSIONS These findings further illuminate the long-term effects of synergistic impact of two hits on the developing brain.
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Santana-Coelho D, Pranske ZJ, Nolan SO, Hodges SL, Binder MS, Womble PD, Narvaiz DA, Muhammad I, Lugo JN. Neonatal immune stimulation results in sex-specific changes in ultrasonic vocalizations but does not affect seizure susceptibility in neonatal mice. Int J Dev Neurosci 2024; 84:381-391. [PMID: 38712612 DOI: 10.1002/jdn.10333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 04/15/2024] [Accepted: 04/19/2024] [Indexed: 05/08/2024] Open
Abstract
Neuroinflammation during the neonatal period has been linked to disorders such as autism and epilepsy. In this study, we investigated the early life behavioral consequences of a single injection of lipopolysaccharide (LPS) at postnatal day 10 (PD10) in mice. To assess deficits in communication, we performed the isolation-induced ultrasonic vocalizations (USVs) test at PD12. To determine if early life immune stimulus could alter seizure susceptibility, latency to flurothyl-induced generalized seizures was measured at 4 hours (hrs), 2 days, or 5 days after LPS injections. LPS had a sex-dependent effect on USV number. LPS-treated male mice presented significantly fewer USVs than LPS-treated female mice. However, the number of calls did not significantly differ between control and LPS for either sex. In male mice, we found that downward, short, and composite calls were significantly more prevalent in the LPS treatment group, while upward, chevron, and complex calls were less prevalent than in controls (p < 0.05). Female mice that received LPS presented a significantly higher proportion of short, frequency steps, two-syllable, and composite calls in their repertoire when compared with female control mice (p < 0.05). Seizure latency was not altered by early-life inflammation at any of the time points measured. Our findings suggest that early-life immune stimulation at PD10 disrupts vocal development but does not alter the susceptibility to flurothyl-induced seizures during the neonatal period. Additionally, the effect of inflammation in the disruption of vocalization is sex-dependent.
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Yuan Y, Lopez-Santiago L, Denomme N, Chen C, O'Malley HA, Hodges SL, Ji S, Han Z, Christiansen A, Isom LL. Antisense oligonucleotides restore excitability, GABA signalling and sodium current density in a Dravet syndrome model. Brain 2024; 147:1231-1246. [PMID: 37812817 PMCID: PMC10994531 DOI: 10.1093/brain/awad349] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/13/2023] [Accepted: 09/27/2023] [Indexed: 10/11/2023] Open
Abstract
Dravet syndrome is an intractable developmental and epileptic encephalopathy caused by de novo variants in SCN1A resulting in haploinsufficiency of the voltage-gated sodium channel Nav1.1. We showed previously that administration of the antisense oligonucleotide STK-001, also called ASO-22, generated using targeted augmentation of nuclear gene output technology to prevent inclusion of the nonsense-mediated decay, or poison, exon 20N in human SCN1A, increased productive Scn1a transcript and Nav1.1 expression and reduced the incidence of electrographic seizures and sudden unexpected death in epilepsy in a mouse model of Dravet syndrome. Here, we investigated the mechanism of action of ASO-84, a surrogate for ASO-22 that also targets splicing of SCN1A exon 20N, in Scn1a+/- Dravet syndrome mouse brain. Scn1a +/- Dravet syndrome and wild-type mice received a single intracerebroventricular injection of antisense oligonucleotide or vehicle at postnatal Day 2. We examined the electrophysiological properties of cortical pyramidal neurons and parvalbumin-positive fast-spiking interneurons in brain slices at postnatal Days 21-25 and measured sodium currents in parvalbumin-positive interneurons acutely dissociated from postnatal Day 21-25 brain slices. We show that, in untreated Dravet syndrome mice, intrinsic cortical pyramidal neuron excitability was unchanged while cortical parvalbumin-positive interneurons showed biphasic excitability with initial hyperexcitability followed by hypoexcitability and depolarization block. Dravet syndrome parvalbumin-positive interneuron sodium current density was decreased compared to wild-type. GABAergic signalling to cortical pyramidal neurons was reduced in Dravet syndrome mice, suggesting decreased GABA release from interneurons. ASO-84 treatment restored action potential firing, sodium current density and GABAergic signalling in Dravet syndrome parvalbumin-positive interneurons. Our work suggests that interneuron excitability is selectively affected by ASO-84. This new work provides critical insights into the mechanism of action of this antisense oligonucleotide and supports the potential of antisense oligonucleotide-mediated upregulation of Nav1.1 as a successful strategy to treat Dravet syndrome.
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Chen C, Ziobro J, Robinson-Cooper L, Hodges SL, Chen Y, Edokobi N, Lopez-Santiago L, Habig K, Moore C, Minton J, Bramson S, Scheuing C, Daddo N, Štěrbová K, Weckhuysen S, Parent JM, Isom LL. Epilepsy and sudden unexpected death in epilepsy in a mouse model of human SCN1B-linked developmental and epileptic encephalopathy. Brain Commun 2023; 5:fcad283. [PMID: 38425576 PMCID: PMC10903178 DOI: 10.1093/braincomms/fcad283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/13/2023] [Accepted: 10/18/2023] [Indexed: 03/02/2024] Open
Abstract
Voltage-gated sodium channel β1 subunits are essential proteins that regulate excitability. They modulate sodium and potassium currents, function as cell adhesion molecules and regulate gene transcription following regulated intramembrane proteolysis. Biallelic pathogenic variants in SCN1B, encoding β1, are linked to developmental and epileptic encephalopathy 52, with clinical features overlapping Dravet syndrome. A recessive variant, SCN1B-c.265C>T, predicting SCN1B-p.R89C, was homozygous in two children of a non-consanguineous family. One child was diagnosed with Dravet syndrome, while the other had a milder phenotype. We identified an unrelated biallelic SCN1B-c.265C>T patient with a clinically more severe phenotype than Dravet syndrome. We used CRISPR/Cas9 to knock-in SCN1B-p.R89C to the mouse Scn1b locus (Scn1bR89/C89). We then rederived the line on the C57BL/6J background to allow comparisons between Scn1bR89/R89 and Scn1bC89/C89 littermates with Scn1b+/+ and Scn1b-/- mice, which are congenic on C57BL/6J, to determine whether the SCN1B-c.265C>T variant results in loss-of-function. Scn1bC89/C89 mice have normal body weights and ∼20% premature mortality, compared with severely reduced body weight and 100% mortality in Scn1b-/- mice. β1-p.R89C polypeptides are expressed in brain at comparable levels to wild type. In heterologous cells, β1-p.R89C localizes to the plasma membrane and undergoes regulated intramembrane proteolysis similar to wild type. Heterologous expression of β1-p.R89C results in sodium channel α subunit subtype specific effects on sodium current. mRNA abundance of Scn2a, Scn3a, Scn5a and Scn1b was increased in Scn1bC89/C89 somatosensory cortex, with no changes in Scn1a. In contrast, Scn1b-/- mouse somatosensory cortex is haploinsufficient for Scn1a, suggesting an additive mechanism for the severity of the null model via disrupted regulation of another Dravet syndrome gene. Scn1bC89/C89 mice are more susceptible to hyperthermia-induced seizures at post-natal Day 15 compared with Scn1bR89/R89 littermates. EEG recordings detected epileptic discharges in young adult Scn1bC89/C89 mice that coincided with convulsive seizures and myoclonic jerks. We compared seizure frequency and duration in a subset of adult Scn1bC89/C89 mice that had been exposed to hyperthermia at post-natal Day 15 versus a subset that were not hyperthermia exposed. No differences in spontaneous seizures were detected between groups. For both groups, the spontaneous seizure pattern was diurnal, occurring with higher frequency during the dark cycle. This work suggests that the SCN1B-c.265C>T variant does not result in complete loss-of-function. Scn1bC89/C89 mice more accurately model SCN1B-linked variants with incomplete loss-of-function compared with Scn1b-/- mice, which model complete loss-of-function, and thus add to our understanding of disease mechanisms as well as our ability to develop new therapeutic strategies.
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Santana‐Coelho D, Hodges SL, Quintero SI, Womble PD, Sullens DG, Narvaiz DA, Herrera R, Sekeres MJ, Lugo JN. Lipopolysaccharide-induced sickness behavior is not altered in male Fmr1-deficient mice. Brain Behav 2023; 13:e3142. [PMID: 37407501 PMCID: PMC10454339 DOI: 10.1002/brb3.3142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 07/07/2023] Open
Abstract
OBJECTIVES Fragile X syndrome is the main monogenetic cause of intellectual disability and autism. Alterations in the immune system are commonly found in these developmental disorders. We and others have demonstrated that Fmr1 mutant mice present an altered response to immune stimuli. However, whether this altered immune response can influence the Fmr1 mutant behavioral outcomes in response to inflammation has not been fully investigated. MATERIALS AND METHODS In the current study, we examine the behavioral sickness response of male wildtype and knockout mice to the innate immune stimulus lipopolysaccharide (LPS) (0.1 mg/kg) to determine if Fmr1 mutants have altered sickness behavior. We used an enzyme-linked immunosorbent assay (ELISA) to measure changes in the cytokine interleukin-6 (IL-6) to determine that inflammation was induced in the mice. Sickness behavior was assessed in a wheel-running paradigm, and a tail suspension test was used to assess the depressive-like phenotype that follows sickness behavior in response to LPS. RESULTS The ELISA using blood serum confirmed a significant increase in IL-6 in mice that were treated with LPS. Treated Fmr1 mutants exhibited decreased distance traveled in the wheel running after LPS administration, similar to treated controls. Another cohort of animals treated with LPS were tested in the tail suspension test and exhibited no alterations in immobility time in response to LPS. CONCLUSION Together, our data suggest that Fmr1 mutant mice do not have altered sickness behavior in response to a low dose of LPS.
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Narvaiz DA, Kwok EM, Hodges SL, Binder MS, Nolan SO, Pranske ZJ, Senger S, Herrera R, Lugo JN. Vitamin D supplementation positively affects activity but impairs stimulus response behavior in an age and sex specific manner in C57BL/6 mice. Neurotoxicol Teratol 2023; 98:107180. [PMID: 37160210 DOI: 10.1016/j.ntt.2023.107180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 04/21/2023] [Accepted: 05/02/2023] [Indexed: 05/11/2023]
Abstract
Several studies have begun to demonstrate the possible cognitive and physiological benefits of a fortified vitamin D diet. However, the behavioral effects of a high vitamin D fortified diet during adolescence has not been fully explored. In the present study, a 4-week vitamin D fortified diet (20,000 IU/Kg) compared to controls (1500 IU/Kg) was administered during the juvenile (4 weeks old) or early adult period (8 weeks old) in C57BL/6 J mice to investigate the effects of fortification on cognition, behavior, and their bone phenotype. After 4 weeks on the diet, vitamin D-treated and control groups underwent a 4-week battery of behavioral tests while remaining on their respective diets. We found that a fortified diet affected behavior in both an age- and sex-specific manner. When vitamin D was administered to juveniles, both sexes displayed impaired habituation to a loud tone. However, females also presented with impaired prepulse inhibition compared to female controls. In the adult treated group, the fortified diet increased only time spent in the open field and had no effect on anxiety-like behavior in the elevated plus maze. Juvenile mice treated with a high vitamin D fortified diet showed a decrease in the total volume compared to the control group in the proximal metaphysis and midshaft region of their femur. There were no differences in bone measurements for mice treated during adulthood. Overall, our results suggest that the juvenile period is a more sensitive time point to the startle response and bone effects of a diet supplemented with high vitamin D, while adults exhibited alterations in locomotive behavior.
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Hodges SL, Bouza AA, Isom LL. Therapeutic Potential of Targeting Regulated Intramembrane Proteolysis Mechanisms of Voltage-Gated Ion Channel Subunits and Cell Adhesion Molecules. Pharmacol Rev 2022; 74:1028-1048. [PMID: 36113879 PMCID: PMC9553118 DOI: 10.1124/pharmrev.121.000340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/13/2022] [Indexed: 10/03/2023] Open
Abstract
Several integral membrane proteins undergo regulated intramembrane proteolysis (RIP), a tightly controlled process through which cells transmit information across and between intracellular compartments. RIP generates biologically active peptides by a series of proteolytic cleavage events carried out by two primary groups of enzymes: sheddases and intramembrane-cleaving proteases (iCLiPs). Following RIP, fragments of both pore-forming and non-pore-forming ion channel subunits, as well as immunoglobulin super family (IgSF) members, have been shown to translocate to the nucleus to function in transcriptional regulation. As an example, the voltage-gated sodium channel β1 subunit, which is also an IgSF-cell adhesion molecule (CAM), is a substrate for RIP. β1 RIP results in generation of a soluble intracellular domain, which can regulate gene expression in the nucleus. In this review, we discuss the proposed RIP mechanisms of voltage-gated sodium, potassium, and calcium channel subunits as well as the roles of their generated proteolytic products in the nucleus. We also discuss other RIP substrates that are cleaved by similar sheddases and iCLiPs, such as IgSF macromolecules, including CAMs, whose proteolytically generated fragments function in the nucleus. Importantly, dysfunctional RIP mechanisms are linked to human disease. Thus, we will also review how understanding RIP events and subsequent signaling processes involving ion channel subunits and IgSF proteins may lead to the discovery of novel therapeutic targets. SIGNIFICANCE STATEMENT: Several ion channel subunits and immunoglobulin superfamily molecules have been identified as substrates of regulated intramembrane proteolysis (RIP). This signal transduction mechanism, which generates polypeptide fragments that translocate to the nucleus, is an important regulator of gene transcription. RIP may impact diseases of excitability, including epilepsy, cardiac arrhythmia, and sudden death syndromes. A thorough understanding of the role of RIP in gene regulation is critical as it may reveal novel therapeutic strategies for the treatment of previously intractable diseases.
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Ramos-Mondragon R, Edokobi N, Hodges SL, Wang S, Bouza AA, Canugovi C, Scheuing C, Juratli L, Abel WR, Noujaim SF, Madamanchi NR, Runge MS, Lopez-Santiago LF, Isom LL. Neonatal Scn1b-null mice have sinoatrial node dysfunction, altered atrial structure, and atrial fibrillation. JCI Insight 2022; 7:152050. [PMID: 35603785 PMCID: PMC9220823 DOI: 10.1172/jci.insight.152050] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 04/12/2022] [Indexed: 11/17/2022] Open
Abstract
Loss-of-function (LOF) variants in SCN1B, encoding the voltage-gated sodium channel β1/β1B subunits, are linked to neurological and cardiovascular diseases. Scn1b-null mice have spontaneous seizures and ventricular arrhythmias and die by approximately 21 days after birth. β1/β1B Subunits play critical roles in regulating the excitability of ventricular cardiomyocytes and maintaining ventricular rhythmicity. However, whether they also regulate atrial excitability is unknown. We used neonatal Scn1b-null mice to model the effects of SCN1B LOF on atrial physiology in pediatric patients. Scn1b deletion resulted in altered expression of genes associated with atrial dysfunction. Scn1b-null hearts had a significant accumulation of atrial collagen, increased susceptibility to pacing induced atrial fibrillation (AF), sinoatrial node (SAN) dysfunction, and increased numbers of cholinergic neurons in ganglia that innervate the SAN. Atropine reduced the incidence of AF in null animals. Action potential duration was prolonged in null atrial myocytes, with increased late sodium current density and reduced L-type calcium current density. Scn1b LOF results in altered atrial structure and AF, demonstrating the critical role played by Scn1b in atrial physiology during early postnatal mouse development. Our results suggest that SCN1B LOF variants may significantly impact the developing pediatric heart.
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Nolan SO, Hodges SL, Binder MS, Smith GD, Okoh JT, Jefferson TS, Escobar B, Lugo JN. Dietary rescue of adult behavioral deficits in the Fmr1 knockout mouse. PLoS One 2022; 17:e0262916. [PMID: 35089938 PMCID: PMC8797197 DOI: 10.1371/journal.pone.0262916] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 01/09/2022] [Indexed: 11/21/2022] Open
Abstract
The current study aimed to further address important questions regarding the therapeutic efficacy of omega-3 fatty acids for various behavioral and neuroimmune aspects of the Fmr1 phenotype. To address these questions, our experimental design utilized two different omega-3 fatty acid administration timepoints, compared to both standard laboratory chow controls ("Standard") and a diet controlling for the increase in fat content ("Control Fat"). In the first paradigm, post-weaning supplementation (after postnatal day 21) with the omega-3 fatty acid diet ("Omega-3") reversed deficits in startle threshold, but not deficits in prepulse inhibition, and the effect on startle threshold was not specific to the Omega-3 diet. However, post-weaning supplementation with both experimental diets also impaired acquisition of a fear response, recall of the fear memory and contextual fear conditioning compared to the Standard diet. The post-weaning Omega-3 diet reduced hippocampal expression of IL-6 and this reduction of IL-6 was significantly associated with diminished performance in the fear conditioning task. In the perinatal experimental paradigm, the Omega-3 diet attenuated hyperactivity and acquisition of a fear response. Additionally, perinatal exposure to the Control Fat diet (similar to a "Western" diet) further diminished nonsocial anxiety in the Fmr1 knockout. This study provides significant evidence that dietary fatty acids throughout the lifespan can significantly impact the behavioral and neuroimmune phenotype of the Fmr1 knockout model.
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Nguyen PH, Narvaiz DA, Womble PD, Sullens DG, Binder MS, Hodges SL, Kwok E, Lugo JN. Multiple Early-Life Seizures Alters Neonatal Communicative Behavior in Fmr1 Knockout Mice. Dev Neurosci 2022; 44:478-486. [PMID: 35512644 DOI: 10.1159/000524898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/20/2022] [Indexed: 11/19/2022] Open
Abstract
Fragile X syndrome (FXS) is the leading monogenic cause of intellectual disability and a significant contributor to Autism Spectrum Disorder. Individuals with FXS are subject to developing numerous comorbidities, one of the most prevalent being seizures. In the present study, we investigated how seizures affected neonatal communicative behavior in the FXS mouse model. On postnatal day (PD) 7 through 11, we administered 3 flurothyl seizures per day to both Fmr1 knockout and wild-type C57BL/6J male mice. Ultrasonic vocalizations were recorded on PD12. Statistically significant alterations were found in both spectral and temporal measurements across seizure groups. We found that induction of seizures across PD7-11 resulted in an increased fundamental frequency (pitch) of ultrasonic vocalizations produced (p < 0.05), a longer duration of calls (p < 0.05), and a greater cumulative duration of calls (p < 0.05) in both genotypes. Induction of seizures across PD7-11 also resulted in a decreased latency to the first emitted vocalization (p < 0.05) and a decrease in mean power (loudness) for their vocalizations (p < 0.05). Early-life seizures also resulted in an increase in the number of downward and frequency step call types (p < 0.05). There was a significant increase in the number of chevron calls emitted from the Fmr1 knockout mice that received seizures compared to knockout control and wild-type seizure mice (p < 0.05). Overall, this study provides evidence that early-life seizures result in communication impairments and that superimposing seizures in Fmr1 knockout mice does produce an additional deficit in vocalization.
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Womble PD, Hodges SL, Nolan SO, Binder MS, Holley AJ, Herrera R, Senger S, Kwok E, Narviaz DA, Faust A, Hernandez-Zegada CJ, Kwon RY, Lugo JN. A vitamin D enriched diet attenuates sex-specific behavioral deficits, increases the lifespan, but does not rescue bone abnormalities in a mouse model of cortical dysplasia. Epilepsy Behav 2021; 124:108297. [PMID: 34509882 DOI: 10.1016/j.yebeh.2021.108297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/17/2021] [Accepted: 08/17/2021] [Indexed: 10/20/2022]
Abstract
Individuals who experience recurrent spontaneous seizures often show behavioral and physiological comorbidities. Those with epilepsy are at a high risk of bone fractures (independent of seizure-related falls) and show a higher rate of a diagnosis of Autism Spectrum Disorder. The neural subset-specific (NS) Pten knockout (KO) mouse has an epilepsy phenotype, has been characterized to show autistic-like deficits, and has an osteoporosis phenotype. The current study examined the effect of a vitamin D enriched diet (20,000 IU VD) in the NS-Pten KO and wildtype mice. Mice were placed onto a vitamin D enriched diet at 4 weeks of age and maintained on that diet throughout testing. Behavioral testing began at 6 weeks of age and included tests for general activity, anxiety, repetitive behaviors, social behaviors, and memory. Results indicated that a vitamin D diet attenuated hypoactivity levels in male KO mice (p < 0.05). In a social partition task, vitamin D increased sociability in male wildtype mice, (p < 0.05). Most significantly, vitamin D fortified diet increased percent survival in KO animals and decreased the level of microglia marker IBA-1 and mTOR (mammalian target of rapamycin) downstream targets pS6 and pAKT. A high vitamin D diet did not reverse bone deficits in male or female KO mice. Overall, these findings suggest that a vitamin D enriched diet had a significant impact on the behavioral phenotype of NS-Pten KO mice, suggesting that dietary manipulations could be a potential therapeutic option for autistic-like behavior.
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Hodges SL, Womble PD, Kwok EM, Darner AM, Senger SS, Binder MS, Faust AM, Condon SM, Nolan SO, Quintero SI, Lugo JN. Rapamycin, but not minocycline, significantly alters ultrasonic vocalization behavior in C57BL/6J pups in a flurothyl seizure model. Behav Brain Res 2021; 410:113317. [PMID: 33910029 DOI: 10.1016/j.bbr.2021.113317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 02/24/2021] [Accepted: 04/21/2021] [Indexed: 12/11/2022]
Abstract
Epilepsy is one of the most common neurological disorders, with individuals having an increased susceptibility of seizures in the first few years of life, making children at risk of developing a multitude of cognitive and behavioral comorbidities throughout development. The present study examined the role of PI3K/Akt/mTOR pathway activity and neuroinflammatory signaling in the development of autistic-like behavior following seizures in the neonatal period. Male and female C57BL/6J mice were administered 3 flurothyl seizures on postnatal (PD) 10, followed by administration of minocycline, the mTOR inhibitor rapamycin, or a combined treatment of both therapeutics. On PD12, isolation-induced ultrasonic vocalizations (USVs) of mice were examined to determine the impact of seizures and treatment on communicative behaviors, a component of the autistic-like phenotype. Seizures on PD10 increased the quantity of USVs in female mice and reduced the amount of complex call types emitted in males compared to controls. Inhibition of mTOR with rapamycin significantly reduced the quantity and duration of USVs in both sexes. Changes in USVs were associated with increases in mTOR and astrocyte levels in male mice, however, three PD10 seizures did not result in enhanced proinflammatory cytokine expression in either sex. Beyond inhibition of mTOR activity by rapamycin, both therapeutics did not demonstrate beneficial effects. These findings emphasize the importance of differences that may exist across preclinical seizure models, as three flurothyl seizures did not induce as drastic of changes in mTOR activity or inflammation as observed in other rodent models.
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Bouza AA, Edokobi N, Hodges SL, Pinsky AM, Offord J, Piao L, Zhao YT, Lopatin AN, Lopez-Santiago LF, Isom LL. Sodium channel β1 subunits participate in regulated intramembrane proteolysis-excitation coupling. JCI Insight 2021; 6:141776. [PMID: 33411695 PMCID: PMC7934843 DOI: 10.1172/jci.insight.141776] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 12/29/2020] [Indexed: 12/17/2022] Open
Abstract
Loss-of-function (LOF) variants in SCN1B, encoding voltage-gated sodium channel β1 subunits, are linked to human diseases with high risk of sudden death, including developmental and epileptic encephalopathy and cardiac arrhythmia. β1 Subunits modulate the cell-surface localization, gating, and kinetics of sodium channel pore-forming α subunits. They also participate in cell-cell and cell-matrix adhesion, resulting in intracellular signal transduction, promotion of cell migration, calcium handling, and regulation of cell morphology. Here, we investigated regulated intramembrane proteolysis (RIP) of β1 by BACE1 and γ-secretase and show that β1 subunits are substrates for sequential RIP by BACE1 and γ-secretase, resulting in the generation of a soluble intracellular domain (ICD) that is translocated to the nucleus. Using RNA sequencing, we identified a subset of genes that are downregulated by β1-ICD overexpression in heterologous cells but upregulated in Scn1b-null cardiac tissue, which lacks β1-ICD signaling, suggesting that the β1-ICD may normally function as a molecular brake on gene transcription in vivo. We propose that human disease variants resulting in SCN1B LOF cause transcriptional dysregulation that contributes to altered excitability. Moreover, these results provide important insights into the mechanism of SCN1B-linked channelopathies, adding RIP-excitation coupling to the multifunctionality of sodium channel β1 subunits.
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Nolan SO, Hodges SL, Okoh JT, Binder MS, Lugo JN. Prenatal High-Fat Diet Rescues Communication Deficits in Fmr1 Mutant Mice in a Sex-Specific Manner. Dev Neurosci 2021; 42:94-104. [PMID: 33395685 PMCID: PMC7864857 DOI: 10.1159/000509797] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 06/25/2020] [Indexed: 12/22/2022] Open
Abstract
Using high-throughput analysis methods, the present study sought to determine the impact of prenatal high-fat dietary manipulations on isolation-induced ultrasonic vocalization production in both male and female Fmr1mutants on postnatal day 9. Prior to breeding, male FVB/129 Fmr1 wildtype and female Fmr1 heterozygous breeding pairs were assigned to 1 of 3 diet conditions: standard lab chow, omega-3 fatty acid-enriched chow, and a diet controlling for the fat increase. Prenatal exposure to omega-3 fatty acids improved reductions in the number of calls produced by Fmr1heterozygotes females. Moreover, diminished spectral purity in the female Fmr1homozygous mouse was rescued by exposure to both high-fat diets, although these effects were not seen in the male Fmr1knockout. Prenatal dietary fat manipulation also influenced several other aspects of vocalization production, such as the number of calls produced and their fundamental frequency, aside from effects due to loss of Fmr1.Specifically, in males, regardless of genotype, prenatal exposure to high omega-3s increased the average fundamental frequency of calls. These data support the need for future preclinical and clinical work elucidating the full potential of prenatal high-fat diets as a novel therapeutic alternative forFragile X syndrome.
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Huebschman JL, Hodges SL, Reynolds CD, Nolan SO, Lugo JN. A single episode of early-life status epilepticus impacts neonatal ultrasonic vocalization behavior in the Fmr1 knockout mouse. Epilepsy Behav 2020; 111:107279. [PMID: 32693376 PMCID: PMC7541794 DOI: 10.1016/j.yebeh.2020.107279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 10/23/2022]
Abstract
Fragile X syndrome (FXS) is a genetic disorder caused by a trinucleotide (CGG) expansion mutation in the Fmr1 gene located on the X chromosome. It is characterized by hyperactivity, increased anxiety, repetitive-stereotyped behaviors, and impaired language development. Many children diagnosed with FXS also experience seizures during their lifetime. However, the underlying etiology of the relationship between FXS and epilepsy is not fully understood. Ultrasonic vocalizations (UVs) are one tool that may be used to measure early behavioral changes in mouse pups. In the present study, neonatal UVs were analyzed as a measure of communicative behavior in a mouse model of FXS, both with and without early-life seizures (ELSs). On postnatal day (PD) 10, status epilepticus (SE) was induced via intraperitoneal injections of 0.5% kainic acid (2.0 mg/kg) in male Fmr1 knockout (KO) and wild-type (WT) mice. On PD 12, all pups were temporarily isolated from their dam and UVs were recorded. Significant alterations were found in both spectral and temporal measures across genotype and seizure groups. Early-life seizure experience resulted in a significant increase in the quantity of UVs only in WT animals (p < 0.05). We also found that while there was no difference between genotypes in the total number of vocalizations made, calls produced by Fmr1 KO mice were significantly shorter and had a higher peak frequency compared with WT mice. Overall, these findings support the use of vocalization behavior as an early phenotypic marker and highlight the importance of utilizing double-hit models to better understand comorbid disorders.
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Hodges SL, Lugo JN. Therapeutic role of targeting mTOR signaling and neuroinflammation in epilepsy. Epilepsy Res 2020; 161:106282. [PMID: 32036255 DOI: 10.1016/j.eplepsyres.2020.106282] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/03/2020] [Accepted: 01/29/2020] [Indexed: 02/08/2023]
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Binder MS, Jones DG, Hodges SL, Lugo JN. NS-Pten adult knockout mice display both quantitative and qualitative changes in urine-induced ultrasonic vocalizations. Behav Brain Res 2020; 378:112189. [PMID: 31586563 PMCID: PMC7000110 DOI: 10.1016/j.bbr.2019.112189] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/31/2019] [Accepted: 08/28/2019] [Indexed: 01/28/2023]
Abstract
The NS-Pten knockout (KO) mouse exhibits hyperactivity of the mammalian target of rapamycin (mTOR) and is a model of autism spectrum disorder (ASD). ASD presents with marked deficits in communication which can be elucidated by investigating their counterpart in mice, ultrasonic vocalizations (USVs). While USVs have been found to be altered in NS-Pten KO pups, no study has assessed whether this communication deficit persists into adulthood. In the present study, we investigate female urine-induced USVs, scent marking behavior, and open field activity in NS-Pten KO and wildtype (WT) adult male mice. Results showed that there was no difference in the quantity of vocalizations produced between groups, however, there were extensive alterations in the spectral properties of USVs. KO mice emitted vocalizations of a lower peak frequency, shorter duration, and higher peak amplitude compared to WT mice. KO animals also emitted a significantly different distribution of call-types relative to controls, displaying increased complex and short calls, but fewer upward, chevron, frequency steps, and composite calls. No significant differences between groups were observed for scent marking behavior and there was no difference between groups in the amount of time spent near the female urine. Overall, this study demonstrated that mTOR hyperactivity contributes to communication deficits in adult mice.
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Hodges SL, Nolan SO, Tomac LA, Muhammad IDA, Binder MS, Taube JH, Lugo JN. Lipopolysaccharide-induced inflammation leads to acute elevations in pro-inflammatory cytokine expression in a mouse model of Fragile X syndrome. Physiol Behav 2019; 215:112776. [PMID: 31838149 DOI: 10.1016/j.physbeh.2019.112776] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/11/2019] [Accepted: 12/11/2019] [Indexed: 02/07/2023]
Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by a single genetic mutation in the Fmr1 gene, serving as the largest genetic cause of intellectual disability. Trinucleotide expansion mutations in Fmr1 result in silencing and hypermethylation of the gene, preventing synthesis of the RNA binding protein Fragile X mental retardation protein which functions as a translational repressor. Abnormal immune responses have been demonstrated to play a role in FXS pathophysiology, however, whether these alterations impact how those with FXS respond to an immune insult behaviorally is not entirely known. In the current study, we examine how Fmr1 knockout (KO) and wild type (WT) mice respond to the innate immune stimulus lipopolysaccharide (LPS), both on a molecular and behavioral level, to determine if Fmr1 mutations impact the normal physiological response to an immune insult. In response to LPS, Fmr1 KO mice had elevated hippocampal IL-1β and IL-6 mRNA levels 4 h post-treatment compared to WT mice, with no differences detected in any cytokines at baseline or between genotypes 24 h post-LPS administration. Fmr1 KO mice also had upregulated hippocampal BDNF gene expression 4 h post-treatment compared to WT mice, which was not dependent on LPS administration. There were no differences in hippocampal protein expression between genotypes in microglia (Iba1) or astrocyte (GFAP) reactivity. Further, both genotypes displayed the typical sickness response following LPS stimulation, demonstrated by a significant reduction in food burrowed by LPS-treated mice in a burrowing task. Additional investigation is critical to determine if the transient increases in cytokine expression could lead to long-term changes in downstream molecular signaling in FXS.
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Hodges SL, Reynolds CD, Nolan SO, Huebschman JL, Okoh JT, Binder MS, Lugo JN. A single early-life seizure results in long-term behavioral changes in the adult Fmr1 knockout mouse. Epilepsy Res 2019; 157:106193. [PMID: 31520894 PMCID: PMC6823160 DOI: 10.1016/j.eplepsyres.2019.106193] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/06/2019] [Accepted: 08/28/2019] [Indexed: 12/20/2022]
Abstract
Fragile X syndrome (FXS) is the leading cause of inherited intellectual disability and a significant genetic contributor to Autism spectrum disorder. In addition to autistic-like phenotypes, individuals with FXS are subject to developing numerous comorbidities, one of the most prevalent being seizures. In the present study, we investigated how a single early-life seizure superimposed on a genetic condition impacts the autistic-like behavioral phenotype of the mouse. We induced status epilepticus (SE) on postnatal day (PD) 10 in Fmr1 wild type (WT) and knockout (KO) mice. We then tested the mice in a battery of behavioral tests during adulthood (PD90) to examine the long-term impact of an early-life seizure. Our findings replicated prior work that reported a single instance of SE results in behavioral deficits, including increases in repetitive behavior, enhanced hippocampal-dependent learning, and reduced sociability and prepulse inhibition (p < 0.05). We also observed genotypic differences characteristic of the FXS phenotype in Fmr1 KO mice, such as enhanced prepulse inhibition and repetitive behavior, hyperactivity, and reduced startle responses (p < 0.05). Superimposing a seizure on deletion of Fmr1 significantly impacted repetitive behavior in a nosepoke task. Specifically, a single early-life seizure increased consecutive nose poking behavior in the task in WT mice (p < 0.05), yet seizures did not exacerbate the elevated stereotypy observed in Fmr1 KO mice (p > 0.05). Overall, these findings help to elucidate how seizures in a critical period of development can impact long-term behavioral manifestations caused by underlying gene mutations in Fmr1. Utilizing double-hit models, such as superimposing seizures on the Fmr1 mutation, can help to enhance our understanding of comorbidities in disease models.
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Nolan SO, Hodges SL, Lugo JN. High-throughput analysis of vocalizations reveals sex-specific changes in Fmr1 mutant pups. GENES BRAIN AND BEHAVIOR 2019; 19:e12611. [PMID: 31587487 DOI: 10.1111/gbb.12611] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 09/16/2019] [Accepted: 09/21/2019] [Indexed: 12/11/2022]
Abstract
There have been several reports that individuals with Fragile X syndrome (FXS) and animal models of FXS have communication deficits. The present study utilized two different call classification taxonomies to examine the sex-specificity of ultrasonic vocalization (USV) production on postnatal day (PD8) in the FVB strain of Fmr1 knockout (KO) mice. One classification protocol requires the investigator to score each call by hand, while the other protocol uses an automated algorithm. Results using the hand-scoring protocol indicated that male Fmr1 KO mice exhibited longer calls (P = .03) than wild types on PD8. Male KOs also produced fewer complex, composite, downward, short and two-syllable call-types, as well as more frequency steps and chevron call-types. Female heterozygotes exhibited no significant changes in acoustic or temporal aspects of calls, yet showed significant changes in call-type production proportions across two different classification taxonomies (P < .001). They exhibited increased production of harmonic and frequency steps calls, as well as fewer chevron, downward and short calls. According to the second high-throughput analysis, female heterozygotes produced significantly fewer single-type and more multiple-type syllables, unlike male KOs that showed no changes in these aspects of syllable production. Finally, we correlated both scoring methods and found a high level of correlation between the two methods. These results contribute further knowledge of sex differences in USV calling behavior for Fmr1 heterozygote and KO mice and provide a foundation for the use of high-throughput analysis of neonatal USVs.
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Nolan SO, Hodges SL, Condon SM, Muhammed I, Tomac L, Binder MS, Reynolds CD, Lugo JN. High seizure load during sensitive periods of development leads to broad shifts in ultrasonic vocalization behavior in neonatal male and female C57BL/6J mice. Epilepsy Behav 2019; 95:26-33. [PMID: 31022661 PMCID: PMC6546518 DOI: 10.1016/j.yebeh.2019.03.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 03/20/2019] [Accepted: 03/20/2019] [Indexed: 10/27/2022]
Abstract
There is increasing evidence that seizures during early development can impact ultrasonic vocalizations (USVs) emitted from neonatal mice. However, most of the effects of early-life seizures have been reported using chemoconvulsants that produce continuous seizures (status epilepticus). In the present study, we evaluated the impact of different seizure frequency loads during early-life vocalization development in C57BL/6J male and female mice. For the high seizure load (HSL) paradigm, we administered 3 flurothyl seizures to mice on postnatal day (PD) 7 through PD11, and recorded USVs on PD12. We found that the induction of seizures across PD7-11 resulted in increased average duration (P < 0.05) and cumulative duration (P < 0.05) of USVs across both sexes. Call-type analyses indicated several call-type changes, including reduced production of complex call-types from males' HSL condition. For the low seizure load (LSL) paradigm, we induced 3 flurothyl seizures only on PD10 and recorded USVs on PD12. We found no change in any spectral or temporal features of USVs. However, call-type production analyses indicated that both male and female animals from the LSL paradigm also produced changes in call-types. This study provides evidence that the magnitude of communication impairment following seizures is significantly impacted by seizure frequency load early in development.
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Holley AJ, Hodges SL, Nolan SO, Binder M, Okoh JT, Ackerman K, Tomac LA, Lugo JN. A single seizure selectively impairs hippocampal-dependent memory and is associated with alterations in PI3K/Akt/mTOR and FMRP signaling. Epilepsia Open 2018; 3:511-523. [PMID: 30525120 PMCID: PMC6276778 DOI: 10.1002/epi4.12273] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2018] [Indexed: 02/03/2023] Open
Abstract
Objective A single brief seizure before learning leads to spatial and contextual memory impairment in rodents without chronic epilepsy. These results suggest that memory can be impacted by seizure activity in the absence of epilepsy pathology. In this study, we investigated the types of memory affected by a seizure and the time course of impairment. We also examined alterations to mammalian target of rapamycin (mTOR) and fragile X mental retardation protein (FMRP) signaling, which modulate elements of the synapse and may underlie impairment. Methods We induced a single seizure and investigated hippocampal and nonhippocampal memory using trace fear conditioning, novel object recognition (NOR), and accelerating rotarod to determine the specificity of impairment in mice. We used western blot analysis to examine for changes to cellular signaling and synaptic proteins 1 h, 24 h, and 1 week after a seizure. We also included a histologic examination to determine if cell loss or gross lesions might alternatively explain memory deficits. Results Behavioral results indicated that a seizure before learning leads to impairment of trace fear memory that worsens over time. In contrast, nonhippocampal memory was unaffected by a seizure in the NOR and rotarod tasks. Western analysis indicated increased hippocampal phospho‐S6 and total FMRP 1 h following a seizure. Tissue taken 24 h after a seizure indicated increased hippocampal GluA1, suggesting increased α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptor expression. Histologic analysis indicated that neither cell loss nor lesions are present after a single seizure. Significance The presence of memory impairment in the absence of damage suggests that memory impairment caused by seizure activity differs from general memory impairment in epilepsy. Instead, memory impairment after a single seizure is associated with alterations to mTOR and FMRP signaling, which leads to a disruption of synaptic proteins involved in consolidation of long‐term memory. These results have implications for understanding memory impairment in epilepsy.
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Hodges SL, Reynolds CD, Smith GD, Jefferson TS, Gao N, Morrison JB, White J, Nolan SO, Lugo JN. Neuronal subset-specific deletion of Pten results in aberrant Wnt signaling and memory impairments. Brain Res 2018; 1699:100-106. [PMID: 30086265 DOI: 10.1016/j.brainres.2018.08.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/02/2018] [Accepted: 08/03/2018] [Indexed: 11/16/2022]
Abstract
The canonical Wnt and PI3K/Akt/mTOR pathways both play critical roles in brain development early in life. There is extensive evidence of how each pathway is involved in neuronal and synaptic maturation, however, how these molecular networks interact requires further investigation. The present study examines the effect of neuronal subset-specific deletion of phosphatase and tensin homolog (Pten) in mice on Wnt signaling protein levels and associated cognitive impairments. PTEN functions as a negative regulator of the PI3K/Akt/mTOR pathway, and mutations in Pten can result in cognitive and behavioral impairments. We found that deletion of Pten resulted in elevated Dvl2, Wnt5a/b, and Naked2, along with decreased GSK3β hippocampal synaptosome protein expression compared to wild type mice. Aberrations in the canonical Wnt pathway were associated with learning and memory deficits in Pten knockout mice, specifically in novel object recognition and the Lashley maze. This study demonstrates that deletion of Pten not only significantly impacts PI3K/Akt/mTOR signaling, but affects proper functioning of the Wnt signaling pathway. Overall, these findings will help elucidate how the PI3K/Akt/mTOR pathway intersects with Wnt signaling to result in cognitive impairments, specifically in memory.
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Hodges SL, Lugo JN. Wnt/β-catenin signaling as a potential target for novel epilepsy therapies. Epilepsy Res 2018; 146:9-16. [PMID: 30053675 DOI: 10.1016/j.eplepsyres.2018.07.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 06/28/2018] [Accepted: 07/11/2018] [Indexed: 01/01/2023]
Abstract
Epilepsy is one of the most common neurological disorders, and yet many afflicted individuals are resistant to all available therapeutic treatments. Existing pharmaceutical treatments function primarily to reduce hyperexcitability and prevent seizures, but fail to influence the underlying pathophysiology of the disorder. Recently, research efforts have focused on identifying alternative mechanistic targets for anti-epileptogenic therapies that can prevent the development of chronic epilepsy. The Wnt/β-catenin pathway, one possible target, has been demonstrated to be disrupted in both acute and chronic phases of epilepsy. Wnt/β-catenin signaling can regulate many seizure-induced changes in the brain, including neurogenesis and neuronal death, as well as can influence seizure susceptibility and potentially the development of chronic epilepsy. Several genome-wide studies and in vivo knockout animal models have provided evidence for an association between disrupted Wnt/β-catenin signaling and epilepsy. Furthermore, approved pharmaceutical drugs and other small molecule compounds that target components of the β-catenin destruction complex or antagonize endogenous inhibitors of the pathway have shown to be protective following seizures. However, additional studies are needed to determine the optimal time period in which modulation of the pathway may be most beneficial. Overall, disrupted molecular networks such as Wnt/β-catenin signaling, could be a promising anti-epileptogenic target for future epilepsy therapies.
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