Biology subjects

Bibi, N.

Publications and source records attributed to Bibi, N..

5 recordsLinked to original sources

bioRxiv2025

Lemborexant Reduces Infarct Volume and Improves Long-Term Functional Recovery in a Murine Model of Ischemic Stroke

IntroductionRecovery following ischemic stroke is highly variable and often incomplete, underscoring the urgent need to develop novel targeted poststroke treatments. While the mechanisms underlying poststroke recovery remain incompletely understood, sleep fragmentation, a common consequence of stroke, has been linked to worse patient outcomes. Lemborexant is a dual orexin receptor antagonist that promotes sleep by suppressing wakefulness and enhancing sleep continuity. We hypothesized that lemborexant would reduce poststroke sleep disturbances and promote recovery in a rodent model of stroke. MethodsWe examined the effects of lemborexant (10 mg/kg and 30 mg/kg) and zolpidem (30 mg/kg) on sleep macrostructure, fragmentation, and EEG spectra in both healthy mice and in stroke model mice, which underwent photothrombotic ischemia of the forelimb somatosensory cortex. We also evaluated whether 12 days of drug administration altered infarct volume and functional recovery following the experimental induction of stroke in model mice. ResultsLemborexant treatment (30 mg/kg) increased the percentage of NREM sleep, while preserving sleep continuity, in both healthy and stroke model mice. In contrast, zolpidem increased NREM sleep after stroke, but also increased sleep fragmentation in both groups. Lemborexant treatment at 10 mg/kg and 30 mg/kg significantly reduced infarct volume eight weeks after the induction of stroke. In addition, lemborexant-treated mice showed greater use of the impaired limb four weeks after stroke. InterpretationThese preclinical findings suggest that lemborexant stabilizes sleep and promotes structural and functional recovery following the experimental induction of stroke in model mice, supporting its potential as a novel therapeutic intervention following ischemic stroke. Summary for Social Media if PublishedO_LIIf you and/or a co-author has a X handle that you would like to be tagged, please enter it here. (format: @AUTHORSHANDLE). @EricLandsness C_LIO_LIWhat is the current knowledge on the topic? Sleep plays a critical role in structural and functional recovery after stroke, but most pharmacologic sleep aids, such as benzodiazepines and zolpidem, can fragment sleep and impair neuroplasticity. Dual orexin receptor antagonists like lemborexant may offer a newer, mechanistically distinct approach with potential neuroprotective benefits. C_LIO_LIWhat question did this study address? This study investigated whether the dual orexin receptor antagonist lemborexant could improve sleep quality, reduce ischemic injury, and enhance functional recovery following stroke in adult mice, compared with the sleep-promoting agent zolpidem. C_LIO_LIWhat does this study add to our knowledge? Lemborexant increased NREM sleep without causing fragmentation, reduced infarct volume, and improved motor recovery when administered. These findings suggest that modulating sleep architecture through orexin antagonism during the subacute phase after stroke can promote neural repair and functional recovery. C_LIO_LIHow might this potentially impact on the practice of neurology? Since lemborexant is already FDA-approved for insomnia, these results could be rapidly translated into a therapeutic opportunity to improve stroke recovery through targeted sleep modulation. This approach may shift poststroke care toward integrating neurorestorative, sleep-based interventions during the subacute phase. C_LI

neuroscience↗

bioRxiv2025

Dendrite-targeting inhibitory interneurons form biased circuits with deep and superficial pyramidal cells in hippocampal CA1

In CA1 hippocampus, pyramidal cells (PCs) can be classified as deep or superficial based on their radial position within the stratum pyramidale. Deep and superficial PCs form biased circuits with perisomatic-targeting PV+ basket cells, but it is unknown if such cell-type-specific circuit motifs extend to dendrite-targeting interneurons. Using male and female mice, we investigated synaptic connectivity and physiology in brain slices from four transgenic lines thought to capture distinct subsets of interneurons: SST-IRES-Cre, Nkx2.1-Cre, Chrna2-Cre, and Htr3a-GFP. First, we found that oriens-lacunosum moleculare (OLM) cells captured by the Chrna2-Cre line are a subset of Htr3a-GFP+ cells in the hippocampus. This novel finding is consistent with previous work showing Nkx2.1-Cre OLM cells are distinct from both Chrna2-Cre and Htr3a-GFP+ cells. Indeed, in paired whole-cell recordings, Nkx2.1-Cre+ interneurons in the stratum oriens, but not Chrna2-Cre+ or Htr3a-GFP+ cells, received more excitatory synaptic connections from superficial PCs relative to deep PCs. Next, we used optogenetic-assisted circuit mapping to investigate inhibition along the proximal and distal dendrites of PCs. We found that superficial PCs received stronger inhibition along their proximal dendrites than deep PCs from SST+ interneurons. Furthermore, this circuit motif was dependent on layer but not PC projection class. Finally, Chrna2-Cre OLM cells provided stronger inhibition to the distal dendrites of deep PCs relative to superficial PCs. Our data reveal that superficial and deep PCs engage in cell-type-specific circuits with dendrite-targeting interneurons. Furthermore, they support that Nkx2.1-Cre OLM cells and Chrna2-Cre/Htr3a-GFP OLM cells are distinct subtypes that form unique circuits in CA1.

neuroscience↗

bioRxiv2024

Arid1b haploinsufficiency in cortical inhibitory interneurons causes cell-type-dependent changes in cellular and synaptic development

Autism spectrum disorder (ASD) presents with diverse cognitive and behavioral abnormalities beginning during early development. Although the neural circuit mechanisms remain unclear, recent work suggests pathology in cortical inhibitory interneurons (INs) plays a crucial role. However, we lack fundamental information regarding changes in the physiology of synapses to and from INs in ASD. Here, we used transgenic mice to conditionally knockout one copy of the high confidence ASD risk gene Arid1b from the progenitors of parvalbumin-expressing fast-spiking (PV-FS) INs and somatostatin-expressing non-fast-spiking (SST-NFS) INs. In brain slices, we performed paired whole-cell recordings between INs and excitatory projection neurons (PNs) to investigate changes in synaptic physiology. In neonates, we found reduced synaptic input to INs but not PNs, with a concomitant reduction in the frequency of spontaneous network events, which are driven by INs in immature circuits. In mature mice, we found a reduction in the number of PV-FS INs in cortical layers 2/3 and 5. However, changes in PV-FS IN synaptic physiology were cortical layer and PN cell-type dependent. In layer 5, synapses from PV-FS INs to subcortical-projecting PNs were weakened. In contrast, in layer 2/3, synapses to and from PV-FS INs and corticocortical-projecting PNs were strengthened, leading to enhanced feedforward inhibition of input from layer 4. Finally, we found a novel synaptic deficit among SST-NFS INs, in which excitatory synapses from layer 2/3 PNs failed to facilitate. Our data highlight that changes in unitary synaptic dynamics among INs in ASD depend on neuronal cell-type.

neuroscience↗

bioRxiv2024

Arid1b haploinsufficiency in pyramidal neurons causes cellular and circuit changes in neocortex but is not sufficient to produce behavioral or seizure phenotypes

Arid1b is a high confidence risk gene for autism spectrum disorder that encodes a subunit of a chromatin remodeling complex expressed in neuronal progenitors. Haploinsufficiency causes a broad range of social, behavioral, and intellectual disability phenotypes, including Coffin-Siris syndrome. Recent work using transgenic mouse models suggests pathology is due to deficits in proliferation, survival, and synaptic development of cortical neurons. However, there is conflicting evidence regarding the relative roles of excitatory projection neurons and inhibitory interneurons in generating abnormal cognitive and behavioral phenotypes. Here, we conditionally knocked out either one or both copies of Arid1b from excitatory projection neuron progenitors and systematically investigated the effects on intrinsic membrane properties, synaptic physiology, social behavior, and seizure susceptibility. We found that disrupting Arid1b expression in excitatory neurons alters their membrane properties, including hyperpolarizing action potential threshold; however, these changes depend on neuronal subtype. Using paired whole-cell recordings, we found increased synaptic connectivity rate between projection neurons. Furthermore, we found reduced strength of excitatory synapses to parvalbumin (PV)-expression inhibitory interneurons. These data suggest an increase in the ratio of excitation to inhibition. However, the strength of inhibitory synapses from PV interneurons to excitatory neurons was enhanced, which may rebalance this ratio. Indeed, Arid1b haploinsufficiency in projection neurons was insufficient to cause social deficits and seizure phenotypes observed in a preclinical germline haploinsufficient mouse model. Our data suggest that while excitatory projection neurons likely contribute to autistic phenotypes, pathology in these cells is not the primary cause.

neuroscience↗

bioRxiv2024

Satb2 regulates pyramidal cell differentiation and the development of feedforward inhibitory circuits in CA1 hippocampus

Pyramidal cells (PCs) in CA1 hippocampus can be classified by their radial position as deep or superficial and organize into subtype-specific circuits necessary for differential information processing. Specifically, superficial PCs receive fewer inhibitory synapses from parvalbumin (PV)-expressing interneurons than deep PCs, resulting in weaker feedforward inhibition of input from CA3 Schaffer collaterals. Using mice, we investigated mechanisms underlying PC differentiation and the development of this inhibitory circuit motif. We found that expression of the transcriptional regulator SATB2 is biased towards superficial PCs during early postnatal development and necessary to suppress PV+ interneuron synapse formation. In the absence of SATB2, the number of PV+ interneuron synaptic puncta surrounding superficial PCs increases during development to match deep PCs. This results in equivalent inhibitory current strength observed in paired whole-cell recordings, and equivalent feedforward inhibition of Schaffer collateral input. Thus, SATB2 is necessary for superficial PC differentiation and biased feedforward inhibition in CA1.

neuroscience↗