Biology subjects

Maganti, R.

Publications and source records attributed to Maganti, R..

7 recordsLinked to original sources

bioRxiv2026

Sleep dynamics and epileptogenesis following Kainic acid in epilepsy-susceptible (DBA/2J) and epilepsy-resistant (C57BL/6) mice

Susceptibility to epileptogenesis varies in humans and outbred mouse strains. We hypothesized that baseline sleep abnormalities increase susceptibility to epileptogenesis following Kainic acid (KA) and abnormal circadian rhythm or sleep homeostasis (SH) contribute to worse seizures in epilepsy-susceptible DBAs. Following EEG electrode implantation, C57 and DBA mice underwent repeated low-dose KA or saline treatment. Seizures, interictal spikes and sleep were examined over 8-weeks with continuous electroencephalography (EEG). Seizures were manually scored, and interictal spikes and sleep were analyzed using machine learning algorithms. Slow wave activity (SWA) was derived from non-rapid eye movement (NREM) sleep following Fourier transform, and SH was measured by the decay of SWA during sleep and its rise with preceding wakefulness. The impact of post-KA seizures on circadian rhythm was determined using Cosinor analysis. Seizures were longer and more frequent in KA-treated DBAs than C57s. Interictal spike were much greater in saline-treated DBAs than C57s. SWA across the 24-hours was lower in DBAs at baseline. KA treatment decreased REM and increased SWA activity in DBAs but not in C57s. Cosinor analysis revealed circadian rhythm abnormalities in DBAs but not in C57s. Seizures impaired SH in DBAs, with no increase in SWA with preceding wakefulness and a progressive loss of SWA decay during lights-on over the 8-week recording. These findings suggest that baseline sleep abnormalities, poorly adaptable circadian rhythms and impaired SH are associated with increased vulnerability to epileptogenesis. Therapies enhancing circadian rhythm and SH after an insult may be avenues to mitigate epileptogenesis in vulnerable populations. Significance StatementSusceptibility to spontaneous seizures after a central nervous system insult varies in humans as well as mouse models. The reasons behind the differential susceptibility are not entirely known. Here we show in a Kainic acid model, epilepsy susceptible DBA/2J mice have baseline sleep abnormalities and following Kainic acid treatment, these mice develop more frequent and longer seizures than the epilepsy-resistant C57BL/6 mice. We also show that the epilepsy-susceptible DBAs have abnormalities in circadian rhythm as well as sleep homeostasis measures compared to epilepsy-resistant C57s, which may be contributing to progression of epileptogenesis and worse seizures. Therapies targeted at enhancing sleep, circadian rhythms or sleep homeostasis may be avenues to mitigate development of spontaneous seizures after a central nervous system insult.

neuroscience↗

bioRxiv2022

Dual orexin antagonist DORA-22 suppressed posttraumatic seizures and enhances GABAergic inhibition in dentate granule cells

BackgroundTraumatic brain injury (TBI) can result in posttraumatic epilepsy (PTE) and sleep disturbances. We hypothesized that treatment with sleep aids after TBI can ameliorate PTE. MethodsCD-1 mice underwent controlled cortical impact (CCI), sham craniotomy or no craniotomy. Sham and CCI groups underwent a month-long treatment with sleep aids including a dual orexin antagonist (DORA-22) or THIP (gaboxadol). We performed week-long EEG recordings during week-1 of treatment and again at months 1, 2 and 3. Seizure analysis occurred at all-time points and sleep analysis occurred in week-1 and month-1 recordings in all groups. Subsets of animals in sleep aid-treated and untreated CCI, and sham groups were subjected to voltage clamp experiments. ResultsDORA-22 treated group had seizures at week-1 but none at months 1-3. TBI reduced amplitude and frequency of miniature inhibitory synaptic currents (mIPSCs) in dentate granule cells and these changes were rescued by DORA-22 treatment. Sleep analysis showed that DORA-22 increased non-rapid eye movement sleep (NREM) in the first 4hours of lights-off whereas THIP increased REM sleep in the first 4-hours of lights-on in week-1, At month-1 both treatments reduced time in NREM during lights-off. TBI increased NREM delta power (N{Delta}) along with loss of the homeostatic overnight decline of N{Delta} in week-1 regardless of treatment. DORA-22 and THIP treatment restored N{Delta} to levels similar to no craniotomy animals at month-1. ConclusionsDORA-22 treatment suppressed posttraumatic seizures possibly due to enhanced GABAergic inhibition in dentate granule cells. DORA-22 may have therapeutic potential in suppressing PTE. Summary for Social MediaTraumatic brain injury (TBI) can result is posttraumatic epilepsy and sleep disturbances. There are no treatments to prevent these complications. We tested whether treatment with sleep aids after TBI can mitigate seizures and sleep disturbances. We found that a sleep aid DORA-22 but not THIP suppressed post traumatic seizures possibly be enhancing GABAergic inhibition in the hippocampus. Sleep analysis showed that TBI disrupts the sleep homeostatic drive and DORA treatment restored it. Findings may lead to potential disease modifying therapy for posttraumatic epilepsy.

neuroscience↗

bioRxiv2021

Sleep deprivation exacerbates seizures and diminishes GABAergic tonic inhibition

Patients with epilepsy report that sleep deprivation is a common trigger for breakthrough seizures. The basic mechanism of this phenomenon is unknown. In the Kv1.1-/- mouse model of epilepsy, daily sleep deprivation indeed exacerbated seizures though these effects were lost after the 3rd day. Sleep deprivation also accelerated mortality in ~52% of Kv1.1-/- mice, not observed in controls. Voltage-clamp experiments on the day after recovery from sleep deprivation showed reductions in GABAergic tonic inhibition in dentate granule cells both in Kv1.1-/- and wild-type mice. Our results suggest that sleep deprivation is detrimental to seizures and survival, possibly due to reductions in GABAergic tonic inhibition.

neuroscience↗

bioRxiv2020

Sleep-wake Characteristics in a Mouse Model of Severe Traumatic Brain Injury: Relation to Post-Traumatic Epilepsy.

Study objectivesTraumatic brain injury (TBI) results in sequelae that include post-traumatic epilepsy (PTE) and sleep-wake disturbances. Here we sought to determine whether sleep characteristics could predict development of PTE in a model of severe TBI. MethodsFollowing controlled cortical impact (CCI), sham injury (craniotomy only) or no craniotomy (NC), CD-1 mice were implanted with epidural electroencephalography (EEG) and nuchal electromyography (EMG) electrodes. Acute (1st week) and chronic (months 1, 2 and 3 after injury) 1-week long video-EEG/EMG recordings were examined for epileptiform activity. We analyzed sleep-wake patterns manually and extracted high amplitude interictal events from EEG using an automated method. Sleep spindles and EEG delta power were derived from non-rapid eye movement (NREM) sleep epochs. Brain CTs (computerized tomography) were performed to quantify the extent of brain lesions in cohorts of sham and CCI. ResultsPosttraumatic seizures were seen with CCI, whereas interictal epileptiform activity as well as sleep-wake disruptions (shorter wake or NREM bout lengths, shorter duration or lower power for spindles, and increased NREM EEG delta power) were seen in CCI and sham groups. No sleep feature predicted PTE. Follow up brain CTs showed a small lesion in the sham injury group suggesting a milder form of TBI that may account for their interictal activity and sleep changes. ConclusionsIn our model, interictal epileptiform activity and sleep disruptions resulted from CCI and sham and thus, sham injury was not an optimal negative control. Further work is necessary to determine the relationship between sleep-wake disturbances and PTE. Statement of significanceTraumatic brain injury (TBI) results in sequelae such as post-traumatic seizures and sleep-wake disturbances but it is difficult to predict which individuals will develop these symptoms. Our study is novel in that we characterized epileptiform activity and multiple sleep characteristics in a mouse model of severe TBI (Controlled cortical impact-CCI) and explored whether any specific sleep disturbance can predict post-traumatic epilepsy. Specifically, post-traumatic seizures were seen after CCI only whereas epileptiform activity other than seizures as well as sleep-wake disruptions in mice that received a TBI and their sham injury controls. CT imaging showed that the sham injury group also had small brain lesions suggesting that a more optimal control in TBI research is to perform no craniotomy. No single sleep characteristic was predictive of post-traumatic epilepsy although NREM delta power was different in chronic recordings between TBI mice that developed seizures and those that did not. These studies are relevant to further research in TBI models, to develop a sleep biomarker for PTE. The work is also relevant to humans with TBI as monitoring sleep phenotypes may predict risk, but may also help develop therapies to prevent post-traumatic epilepsy.

neuroscience↗

bioRxiv2020

Sleep and Diurnal Rest-Activity Rhythm Disturbances in a Mouse Model of Alzheimer's Disease

Study ObjectivesAccumulating evidence suggests a strong association between sleep, amyloid-beta (A{beta}) deposition, and Alzheimers disease (AD). We sought to determine if: (1) deficits in rest-activity rhythms and sleep are significant phenotypes in J20 AD mice, (2) metabotropic glutamate receptor 5 inhibitors (mGluR5) could rescue deficits in rest-activity rhythms and sleep, and (3) A{beta} levels are responsive to treatment with mGluR5 inhibitors. MethodsDiurnal rest-activity levels were measured by actigraphy and sleep-wake patterns by electroencephalography (EEG), while animals were chronically treated with mGluR5 inhibitors. Behavioral tests were performed, and A{beta} levels measured in brain lysates. ResultsJ20 mice exhibited a 4.5 hour delay in the acrophase of activity levels compared to wild-type littermates, and spent less time in REM sleep during the second half of the light period. J20 mice also exhibited decreased NREM delta power but increased NREM sigma power. The mGluR5 inhibitor CTEP rescued the REM sleep deficit and improved NREM delta and sigma power but did not correct rest-activity rhythms. No statistically significant differences were observed in A{beta} levels, rotarod performance or the passive avoidance task following chronic mGluR5 inhibitor treatment. ConclusionsJ20 mice have disruptions in rest-activity rhythms and reduced homeostatic sleep pressure (reduced NREM delta power). NREM delta power was increased following treatment with an mGluR5 inhibitor. Drug bioavailability was poor. Further work is necessary to determine if mGluR5 is a viable target for treating sleep phenotypes in AD. Statement of SignificanceSleep disruption is evolving as an important risk factor as well as phenotype of neurological diseases including Alzheimers disease. This study is novel in determining alterations in the rest-activity rhythm and sleep-wake pattern of J20 Alzheimers disease mice and wild type littermates. Specifically, there is a delay in acrophase with prolonged hyperactivity during the dark cycle, and reduced sleep pressure that was improved by treatment with mGluR5 inhibitor. Critical remaining knowledge gaps and future directions include testing the effects of Alzheimers disease drugs on rescue of sleep and rest-activity patterns in other Alzheimers disease models. These studies are relevant to human Alzheimers disease as monitoring sleep phenotypes may predict disease risk, and therapies that normalize sleep patterns may slow progression.

neuroscience↗

bioRxiv2019

BRD4 Prevents R-Loop Formation and Transcription-Replication Conflicts by Ensuring Efficient Transcription Elongation

Effective spatio-temporal control of transcription and replication during S-phase is paramount to maintaining genomic integrity and cell survival. Dysregulation of these systems can lead to conflicts between the transcription and replication machinery causing DNA damage and cell death. BRD4, a BET bromodomain protein and known transcriptional regulator, interacts with P-TEFb to ensure efficient transcriptional elongation by stimulating phosphorylation of RNA Polymerase II (RNAPII). Here we report that disruption of BET bromodomain protein function causes RNAPII pausing on the chromatin and DNA damage affecting cells in S-phase. We find that this persistent, RNAPII-dependent pausing leads to accumulation of RNA:DNA hybrids (R-loops), which are known to lead to transcription-replication conflicts (TRCs), DNA damage, and cell death. Furthermore, we show that resolution of R-loops abrogates BET bromodomain inhibitor-induced DNA damage, and that BET bromodomain inhibition induces both R-loops and DNA damage at sites of BRD4 occupancy. Finally, we see that the BRD4 C-terminal domain, which interacts with P-TEFb, is required to prevent R-loop formation and DNA damage caused by BET bromodomain inhibition and that oncogenes which promote transcription and replication exacerbate BET bromodomain inhibitor-induced DNA damage. Together, these findings demonstrate that BET bromodomain inhibitors can damage DNA via induction of R-loops and TRCs in highly replicative cells.

cancer biology↗

bioRxiv2019

A Systems Approach Identifies Enhancer of Zeste Homolog 2 (EZH2) as a Protective Factor in Epilepsy

Complex neurological conditions can give rise to large scale transcriptomic changes that drive disease progression. It is likely that alterations in one or a few transcription factors or cofactors underlie these transcriptomic alterations. Identifying the driving transcription factors/cofactors is a non-trivial problem and a limiting step in the understanding of neurological disorders. Epilepsy has a prevalence of 1% and is the fourth most common neurological disorder. While a number of anti-seizure drugs exist to treat seizures symptomatically, none is curative or preventive. This reflects a lack of understanding of disease progression. We used a novel systems approach to mine transcriptome profiles of rodent and human epileptic brain samples to identify regulators of transcriptional networks in the epileptic brain. We find that Enhancer of Zeste Homolog 2 (EZH2) regulates differentially expressed genes in epilepsy across multiple rodent models of acquired epilepsy. EZH2 undergoes a prolonged upregulation in the epileptic brain. A transient inhibition of EZH2 immediately after seizure induction robustly increases spontaneous seizure burden weeks later. Thus, EZH2 upregulation is a protective response mounted after a seizure. These findings are the first to characterize a role for EZH2 in opposing epileptogenesis and debut a bioinformatic approach to identify nuclear drivers of complex transcriptional changes in disease.\n\nAuthor SummaryEpilepsy is the fourth most common neurological disorder and has been described since the time of Hippocrates. Despite this, no treatments exist to stop epilepsy progression. This is fundamentally due to the complex nature of the disease. Epilepsy is associated with hundreds if not thousands of gene expression changes in the brain that are likely driven by a few key master regulators called transcription factors and cofactors. Finding the aberrantly acting factors is a complex problem that currently lacks a satisfactory solution. We used a novel datamining tool to define key master regulators of gene expression changes across multiple epilepsy models and patient samples. We find that a nuclear enzyme, EZH2, regulates a large number of genes in the rodent and patient epileptic brain and that its function is protective. Thus, inhibiting EZH2 greatly exacerbates seizure burden. This is the first report of a novel datamining tool to define drivers of large-scale gene changes and is also the first report of EZH2 induction as an endogenous protective response in the epilepsy.

neuroscience↗