Excitatory Projections of Wide Field Collicular Neurons to the Nucleus of the Optic Tract in the Rat.

The superficial layers of the mammalian superior colliculus (SC) contain neurons that are generally responsive to visual stimuli but can differ considerably in morphology and response properties. To elucidate the structure and function of these neurons, we combined extracellular recording and juxtacellular labeling, detailed anatomical reconstruction, and ultrastructural analysis of the synaptic contacts of labeled neurons, using transmission electron microscopy. Our labeled neurons project to different brainstem nuclei. Of particular importance are neurons that fit the morphological criteria of the wide field (WF) neurons and whose dendrites are horizontally oriented. They display a rather characteristic axonal projection pattern to the nucleus of optic tract (NOT); thus, we call them superior collicular WF projecting to the NOT (SCWFNOT) neurons. We corroborated the morphological characterization of this neuronal type as a distinct neuronal class with the help of unsupervised hierarchical cluster analysis. Our ultrastructural data demonstrate that SCWFNOT neurons establish excitatory connections with their targets in the NOT. Although, in rodents, the literature about the WF neurons has focused on their extensive projection to the lateral posterior nucleus of the thalamus, as a conduit for information to reach the visual association areas of the cortex, our data suggest that this subclass of WF neurons may participate in the optokinetic nystagmus.

Comprehensive mapping of histamine H1 receptor mRNA in the mouse brain.

Histamine H1 receptor (H1R) in the central nervous system plays an important role in various functions, including learning and memory, aggression, feeding behaviors, and wakefulness, as evidenced by studies utilizing H1R knockout mice and pharmacological interventions. Although previous studies have reported the widespread distribution of H1R in the brains of rats, guinea pigs, monkeys, and humans, the detailed distribution in the mouse brain remains unclear. This study provides a comprehensive description of the distribution of H1R mRNA in the mouse brain using two recently developed techniques: RNAscope and in situ hybridization chain reaction, both of which offer enhanced sensitivity and resolution compared to traditional methodologies such as radioisotope labeling, which were used in previous studies. The H1R mRNA expression was observed throughout the entire brain, including key regions implicated in sleep-wake regulatory functions, such as the pedunculopontine tegmental nucleus and dorsal raphe. Additionally, strong H1R mRNA signals were identified in the paraventricular hypothalamus and ventromedial hypothalamus, which may explain the potential mechanisms underlying histamine-mediated feeding regulation. Notably, we identified strong H1R mRNA expression in previously unreported cerebral regions, such as the dorsal endopiriform nucleus, bed nucleus of the accessory olfactory tract, and postsubiculum. These findings significantly contribute to our understanding of the multifaceted roles of H1R in diverse brain functions.

Multi-organ single-cell RNA sequencing in mice reveals early hyperglycemia responses that converge on fibroblast dysregulation.

Diabetes causes a range of complications that can affect multiple organs. Hyperglycemia is an important driver of diabetes-associated complications, mediated by biological processes such as dysfunction of endothelial cells, fibrosis, and alterations in leukocyte number and function. Here, we dissected the transcriptional response of key cell types to hyperglycemia across multiple tissues using single-cell RNA sequencing (scRNA-seq) and identified conserved, as well as organ-specific, changes associated with diabetes complications. By studying an early time point of diabetes, we focus on biological processes involved in the initiation of the disease, before the later organ-specific manifestations had supervened. We used a mouse model of type 1 diabetes and performed scRNA-seq on cells isolated from the heart, kidney, liver, and spleen of streptozotocin-treated and control male mice after 8 weeks and assessed differences in cell abundance, gene expression, pathway activation, and cell signaling across organs and within organs. In response to hyperglycemia, endothelial cells, macrophages, and monocytes displayed organ-specific transcriptional responses, whereas fibroblasts showed similar responses across organs, exhibiting altered metabolic gene expression and increased myeloid-like fibroblasts. Furthermore, we found evidence of endothelial dysfunction in the kidney, and of endothelial-to-mesenchymal transition in streptozotocin-treated mouse organs. In summary, our study represents the first single-cell and multi-organ analysis of early dysfunction in type 1 diabetes-associated hyperglycemia, and our large-scale dataset (comprising 67 611 cells) will serve as a starting point, reference atlas, and resource for further investigating the events leading to early diabetic disease.

Palatal segment contributions to midfacial growth in three inbred mouse strains.

Following facial prominence fusion, anterior-posterior (A-P) elongation of the palate is a critical aspect of palatogenesis and integrated midfacial elongation. Reciprocal epithelial-mesenchymal interactions drive secondary palate elongation and periodic signaling center formation within the rugae growth zone (RGZ). However, the relationship between RGZ dynamics and the morphogenetic behavior of underlying palatal bone mesenchymal precursors has remained enigmatic. Our results indicate that cellular activity at the RGZ simultaneously drives rugae formation and elongation of the maxillary bone primordium within the anterior secondary palate, which more than doubles in length prior to palatal shelf fusion. The first formed palatal ruga, found just posterior to the RGZ, represents a consistent morphological boundary between anterior and posterior secondary palate bone precursors, being found at the future maxillary-palatine suture. These results suggest a model where changes in RGZ-driven A-P growth of the anterior secondary palate may produce interspecies and intraspecies differences in facial prognathism and differences in the proportional contribution of palatal segment-associated bones to total palate length. An ontogenetic comparison of three inbred mouse strains indicated that while RGZ-driven growth of the anterior secondary palate is critical for early midfacial outgrowth, subtle strain-specific bony contributions to adult palate length are not present until after this initial palatal growth period. This multifaceted illustration of normal midfacial growth dynamics confirms a one-to-one relationship between palatal segments and upper jaw bones during the earliest stages of palatal growth, which may serve as the basis for evolutionary change in upper jaw morphology. Additionally, identified mouse strain-specific differences in palatal segment elongation provide a useful foundation for understanding the impact of background genetic effects on facial morphogenesis.

Intranasal insulin helps overcome brain insulin deficiency and improves survival and post-stroke cognitive impairment in male mice.

Obesity increases the risk for stroke and is associated with worse post-stroke outcomes; however, the mechanisms are poorly understood. Diet-induced obesity leads to insulin resistance and subsequently, brain insulin deficiency. The purpose of this study was to investigate the potential impact of brain insulin deficiency on post-stroke outcomes. To accomplish this, brain insulin levels were assessed in male C57BL/6J (B6) mice placed on either a standard diet or 54% kcal high-fat diet, a known model of insulin resistance. Mice were subjected to either a sham surgery (control) or 30-min middle cerebral artery occlusion to induce an ischemic stroke and administered either intranasal saline (0.9%) or intranasal insulin (1.75 U) twice daily for 5 days beginning on day 1 post-stroke. High-fat diet-induced brain insulin deficiency was associated with increased mortality, neurological and cognitive deficits. On the other hand, increasing brain insulin levels via intranasal insulin improved survival, neurological and cognitive function in high-fat diet mice. Our data suggests that brain insulin deficiency correlates with worse post-stroke outcomes in a diet-induced mouse model of insulin resistance and increasing brain insulin levels may be a therapeutic target to improve stroke recovery.

Astrocytic deletion of protein kinase R-like ER kinase (PERK) does not affect learning and memory in aged mice but worsens outcome from experimental stroke.

Aging is associated with cognitive decline and is the main risk factor for a myriad of conditions including neurodegeneration and stroke. Concomitant with aging is the progressive accumulation of misfolded proteins and loss of proteostasis. Accumulation of misfolded proteins in the endoplasmic reticulum (ER) leads to ER stress and activation of the unfolded protein response (UPR). The UPR is mediated, in part, by the eukaryotic initiation factor 2α (eIF2α) kinase protein kinase R-like ER kinase (PERK). Phosphorylation of eIF2α reduces protein translation as an adaptive mechanism but this also opposes synaptic plasticity. PERK, and other eIF2α kinases, have been widely studied in neurons where they modulate both cognitive function and response to injury. The impact of astrocytic PERK signaling in cognitive processes was previously unknown. To examine this, we deleted PERK from astrocytes (AstroPERKKO ) and examined the impact on cognitive functions in middle-aged and old mice of both sexes. Additionally, we tested the outcome following experimental stroke using the transient middle cerebral artery occlusion (MCAO) model. Tests of short-term and long-term learning and memory as well as of cognitive flexibility in middle-aged and old mice revealed that astrocytic PERK does not regulate these processes. Following MCAO, AstroPERKKO had increased morbidity and mortality. Collectively, our data demonstrate that astrocytic PERK has limited impact on cognitive function and has a more prominent role in the response to neural injury.

Persistent hypersomnia following repetitive mild experimental traumatic brain injury: Roles of chronic stress and sex differences.

Traumatic brain injury (TBI) is often more complicated than a single head injury. An extreme example of this point may be military service members who experience a spectrum of exposures over a prolonged period under stressful conditions. Understanding the effects of complex exposures can inform evaluation and care to prevent persistent symptoms. We designed a longitudinal series of non-invasive procedures in adult mice to evaluate the effects of prolonged mild stress and head injury exposures. We assessed anxiety, depression, and sleep-wake dysfunction as symptoms that impact long-term outcomes after mild TBI. Unpredictable chronic mild stress (UCMS) was generated from a varied sequence of environmental stressors distributed within each of 21 days. Subsequently, mice received a mild blast combined with closed-head mild TBI on 5 days at 24-h intervals. In males and females, UCMS induced anxiety without depressive behavior. A major finding was reproducible sleep-wake dysfunction through 6- to 12-month time points in male mice that received UCMS with repetitive blast plus TBI events, or surprisingly after just UCMS alone. Specifically, male mice exhibited hypersomnia with increased sleep during the active/dark phase and fragmentation of longer wake bouts. Sleep-wake dysfunction was not found with TBI events alone, and hypersomnia was not found in females under any conditions. These results identify prolonged stress and sex differences as important considerations for sleep-wake dysfunction. Furthermore, this reproducible hypersomnia with impaired wakefulness is similar to the excessive daytime sleepiness reported in patients, including patients with TBI, which warrants further clinical screening, care, and treatment development.

High-resolution mapping of sensory fibers at the healthy and post-myocardial infarct whole transgenic hearts.

The sensory nervous system is critical to maintain cardiac function. As opposed to efferent innervation, less is known about cardiac afferents. For this, we mapped the VGLUT2-expressing cardiac afferent fibers of spinal and vagal origin by using the VGLUT2::tdTomato double transgenic mouse as an approach to visualize the whole hearts both at the dorsal and ventral sides. For comparison, we colabeled mixed-sex transgenic hearts with either TUJ1 protein for global cardiac innervation or tyrosine hydroxylase for the sympathetic network at the healthy state or following ischemic injury. Interestingly, the nerve density for global and VGLUT2-expressing afferents was found significantly higher on the dorsal side compared to the ventral side. From the global nerve innervation detected by TUJ1 immunoreactivity, VGLUT2 afferent innervation was detected to be 15-25% of the total network. The detailed characterization of both the atria and the ventricles revealed a remarkable diversity of spinal afferent nerve ending morphologies of flower sprays, intramuscular endings, and end-net branches that innervate distinct anatomical parts of the heart. Using this integrative approach in a chronic myocardial infarct model, we showed a significant increase in hyperinnervation in the form of axonal sprouts for cardiac afferents at the infarct border zone, as well as denervation at distal sites of the ischemic area. The functional and physiological consequences of the abnormal sensory innervation remodeling post-ischemic injury should be further evaluated in future studies regarding their potential contribution to cardiac dysfunction.

Peptidyl arginine deiminase 4 deficiency protects against subretinal fibrosis by inhibiting Müller glial hypercitrullination.

Retinal scarring with vision loss continues to be an enigma in individuals with advanced age-related macular degeneration (AMD). Müller glial cells are believed to initiate and perpetuate scarring in retinal degeneration as these glial cells participate in reactive gliosis and undergo hypertrophy. We previously showed in the murine laser-induced model of choroidal neovascularization that models wet-AMD that glial fibrillary acidic protein (GFAP) expression, an early marker of reactive gliosis, increases along with its posttranslational modification citrullination. This was related to increased co-expression of the citrullination enzyme peptidyl arginine deiminase-4 (PAD4), which also colocalizes to GFAP filaments. However, whether such hypercitrullination in Müller glial drives fibrotic pathology has remained understudied. Here, using male and female C57Bl6 mice subjected to laser injury, we investigated in a temporal study how citrullination impacts GFAP and PAD4 dynamics. We found that high molecular weight citrullinated species that accumulate in Müller glia corresponded with dynamic changes in GFAP and PAD4 showing their temporal redistribution from polymeric cytoskeletal to soluble protein fractions using immunostaining and western blot analysis. In conditional glial-specific PAD4 knockout (PAD4cKO) mice subjected to laser injury, there was a stark reduction of citrullination and of polymerized GFAP filaments. These injured PAD4cKO retinas showed improved lesion healing, as well as reduced fibronectin deposition in the subretinal space at 30 days. Taken together, these findings reveal that pathologically overexpressed PAD4 in reactive Müller glia governs GFAP filament dynamics and alters their stability, suggesting chronic PAD4-driven hypercitrullination may be a target for retinal fibrosis.

Processing of information from the parafascicular nucleus of the thalamus through the basal ganglia.

Accumulating evidence implicates the parafascicular nucleus of the thalamus (Pf) in basal ganglia (BG)-related functions and pathologies. Despite Pf connectivity with all BG components, most attention is focused on the thalamostriatal system and an integrated view of thalamic information processing in this network is still lacking. Here, we addressed this question by recording the responses elicited by Pf activation in single neurons of the substantia nigra pars reticulata (SNr), the main BG output structure in rodents, in anesthetized mice. We performed optogenetic activation of Pf neurons innervating the striatum, the subthalamic nucleus (STN), or the SNr using virally mediated transcellular delivery of Cre from injection in either target in Rosa26-LoxP-stop-ChR2-EYFP mice to drive channelrhodopsin expression. Photoactivation of Pf neurons connecting the striatum evoked an inhibition often followed by an excitation, likely resulting from the activation of the trans-striatal direct and indirect pathways, respectively. Photoactivation of Pf neurons connecting the SNr or the STN triggered one or two early excitations, suggesting partial functional overlap of trans-subthalamic and direct thalamonigral projections. Excitations were followed in about half of the cases by an inhibition that might reflect recruitment of intranigral inhibitory loops. Finally, global Pf stimulation, electrical or optogenetic, elicited similar complex responses comprising up to four components: one or two short-latency excitations, an inhibition, and a late excitation. These data provide evidence for functional connections between the Pf and different BG components and for convergence of the information processed through these pathways in single SNr neurons, stressing their importance in regulating BG outflow.

Interleukin-18 mediated inflammatory brain injury after intracerebral hemorrhage in male mice.

Interleukin-18 (IL-18), a pro-inflammatory cytokine, is thought to be associated with inflammation in many neurological diseases such as ischemic stroke and poststroke depression, but the role of IL-18 in inflammatory injury after intracerebral hemorrhage (ICH) remains unclear. In this study, we established the ICH model in male mice and found that IL-18 expression including protein and mRNA levels was significantly increased in brain tissues after ICH. Meanwhile, exogenous IL-18 exacerbated cerebral hematoma and neurological deficits following ICH. In the IL-18 knockout group, the size of hematoma and neurological functions after ICH was decreased compared with the wild-type group, suggesting the critical role of IL-18 on the modulation of brain injury after ICH. Importantly, exogenous IL-18 increased microglial activation in brain tissues after ICH. Furthermore, IL-18 knockout resulted in the reduction of activated microglia after ICH. These results indicated that IL-18 may regulate the inflammatory response after ICH through the activation of microglia. Thus, IL-18 is expected to be a promising therapeutic target for secondary brain injury after ICH.

Microglia form satellites with different neuronal subtypes in the adult murine central nervous system.

Microglia are the innate immune cells of the central nervous system (CNS). In the adult uncompromised CNS, they have a highly ramified morphology and continuously extend and retract their processes. A subpopulation of microglial cells forms close soma-to-soma contacts with neurons and have been termed satellite microglia, yet the role of such interaction is largely unknown. Here, we analyzed the distribution of satellite microglia in different areas of the CNS of adult male mice applying transgenic- and immunolabeling of neuronal subtypes and microglia followed by three-dimensional imaging analysis. We quantified satellite microglia associated with GABAergic and glutamatergic neurons in the somatosensory cortex, striatum, and thalamus; with dopaminergic and serotonergic neurons in the basal forebrain and raphe nucleus, respectively; and with cerebellar Purkinje cell neurons. Satellite microglia in the retina were assessed qualitatively. Microglia form satellites with all neuronal subtypes studied, whereas a preference for a specific neuron subtype was not found. The occurrence and frequency of satellite microglia is determined by the histo-architectural organization of the brain area and the densities of neuronal somata therein.

Role of melatonin in autism spectrum disorders in a male murine transgenic model: Study in the prefrontal cortex.

Autism spectrum disorders (ASDs) are a group of clinically heterogeneous neurodevelopmental disorders sharing common features related to impaired social and communication abilities in addition to stereotyped behaviors. ASD patients present encephalic morphological, physiological, and biomolecular alterations with low levels of melatonin due to alterations in its pathways. Therefore, even if ASDs have traditionally been framed as behavioral disorders, several lines of evidence are accumulating that ASDs are characterized by certain anatomical and physiological abnormalities, including oxidative stress and inflammation in peripheral biomarkers, but likewise present in human brain tissue also characterized by alterations in synaptic remodeling and neuromodulation. Melatonin has also protective and antioxidant properties, so we can therefore hypothesize that alterations in melatonin's pathways may be one of the causes of the symptomatology of autism. The aim of the present study was to analyze the beneficial effect induced by melatonin administration and its possible mechanism of action in a transgenic mouse model of autism, immediately after weaning. The male mice were daily treated per os with melatonin (10 mg/Kg/day) or vehicle for 8 weeks starting from the sixth week of life. The antioxidant modulation, the GABAergic/glutamatergic impairment, and the synaptic remodeling in the prefrontal cortex have been evaluated. Social and repetitive behaviors were also evaluated. The behavioral results showed no statistical evidences, instead the immunohistochemical results indicated the ability of melatonin to promote the activity of antioxidant system, the GABAergic/glutamatergic equilibrium, and the synaptic remodeling. The results show that melatonin may be a possible adjuvant therapeutic strategy in ASDs.

Endogenous µ-opioid receptor activity in the lateral and capsular subdivisions of the right central nucleus of the amygdala prevents chronic postoperative pain.

Tissue injury induces a long-lasting latent sensitization (LS) of spinal nociceptive signaling that is kept in remission by an opposing µ-opioid receptor (MOR) constitutive activity. To test the hypothesis that supraspinal sites become engaged, we induced hindpaw inflammation, waited 3 weeks for mechanical hypersensitivity to resolve, and then injected the opioid receptor inhibitors naltrexone, CTOP or ß-funaltrexamine subcutaneously, and/or into the cerebral ventricles. Intracerebroventricular injection of each inhibitor reinstated hypersensitivity and produced somatic signs of withdrawal, indicative of LS and endogenous opioid dependence, respectively. In naïve or sham controls, systemic naloxone (3 mg/kg) produced conditioned place aversion, and systemic naltrexone (3 mg/kg) increased Fos expression in the central nucleus of the amygdala (CeA). In LS animals tested 3 weeks after plantar incision, systemic naltrexone reinstated mechanical hypersensitivity and produced an even greater increase in Fos than in sham controls, particularly in the capsular subdivision of the right CeA. One third of Fos+ profiles co-expressed protein kinase C delta (PKCδ), and 35% of PKCδ neurons co-expressed tdTomato+ in Oprm1Cre ::tdTomato transgenic mice. CeA microinjection of naltrexone (1 µg) reinstated mechanical hypersensitivity only in male mice and did not produce signs of somatic withdrawal. Intra-CeA injection of the MOR-selective inhibitor CTAP (300 ng) reinstated hypersensitivity in both male and female mice. We conclude that MORs in the capsular subdivision of the right CeA prevent the transition from acute to chronic postoperative pain.

Intrinsic circadian timekeeping properties of the thalamic lateral geniculate nucleus.

Circadian rhythmicity in mammals is sustained by the central brain clock-the suprachiasmatic nucleus of the hypothalamus (SCN), entrained to the ambient light-dark conditions through a dense retinal input. However, recent discoveries of autonomous clock gene expression cast doubt on the supremacy of the SCN and suggest circadian timekeeping mechanisms devolve to local brain clocks. Here, we use a combination of molecular, electrophysiological, and optogenetic tools to evaluate intrinsic clock properties of the main retinorecipient thalamic center-the lateral geniculate nucleus (LGN) in male rats and mice. We identify the dorsolateral geniculate nucleus as a slave oscillator, which exhibits core clock gene expression exclusively in vivo. Additionally, we provide compelling evidence for intrinsic clock gene expression accompanied by circadian variation in neuronal activity in the intergeniculate leaflet and ventrolateral geniculate nucleus (VLG). Finally, our optogenetic experiments propose the VLG as a light-entrainable oscillator, whose phase may be advanced by retinal input at the beginning of the projected night. Altogether, this study for the first time demonstrates autonomous timekeeping mechanisms shaping circadian physiology of the LGN.

Maternal background alters the penetrance of growth phenotypes and sex-specific placental adaptation of offspring sired by alcohol-exposed males.

Epigenetic mechanisms of paternal inheritance are an emerging area of interest in our efforts to understand fetal alcohol spectrum disorders. In rodent models examining maternal alcohol exposures, different maternal genetic backgrounds protect or sensitize offspring to alcohol-induced teratogenesis. However, whether maternal background can mitigate sperm-inherited alterations in developmental programming and modify the penetrance of growth defects induced by preconception paternal alcohol exposures remains unaddressed. In our previous studies examining pure C57Bl/6J crosses, the offspring of alcohol-exposed sires exhibited fetal growth restriction, enlarged placentas, and decreased placental efficiency. Here, we find that in contrast to our previous studies, the F1 offspring of alcohol-exposed C57Bl/6J sires and CD-1 dams do not exhibit fetal growth restriction, with male fetuses developing smaller placentas and increased placental efficiencies. However, in these hybrid offspring, preconception paternal alcohol exposure induces sex-specific changes in placental morphology. Specifically, the female offspring of alcohol-exposed sires displayed structural changes in the junctional and labyrinth zones, along with increased placental glycogen content. These changes in placental organization are accompanied by female-specific alterations in the expression of imprinted genes Cdkn1c and H19. Although male placentae do not display overt changes in placental histology, using RNA-sequencing, we identified programmed alterations in genes regulating oxidative phosphorylation, mitochondrial function, and Sirtuin signaling. Collectively, our data reveal that preconception paternal alcohol exposure transmits a stressor to developing offspring, that males and females exhibit distinct patterns of placental adaptation, and that maternal genetic background can modulate the effects of paternal alcohol exposure.

Faim knockout leads to gliosis and late-onset neurodegeneration of photoreceptors in the mouse retina.

Fas Apoptotic Inhibitory Molecule protein (FAIM) is a death receptor antagonist and an apoptosis regulator. It encodes two isoforms, namely FAIM-S (short) and FAIM-L (long), both with significant neuronal functions. FAIM-S, which is ubiquitously expressed, is involved in neurite outgrowth. In contrast, FAIM-L is expressed only in neurons and it protects them from cell death. Interestingly, FAIM-L is downregulated in patients and mouse models of Alzheimer's disease before the onset of neurodegeneration, and Faim transcript levels are decreased in mouse models of retinal degeneration. However, few studies have addressed the role of FAIM in the central nervous system, yet alone the retina. The retina is a highly specialized tissue, and its degeneration has proved to precede pathological mechanisms of neurodegenerative diseases. Here we describe that Faim depletion in mice damages the retina persistently and leads to late-onset photoreceptor death in older mice. Immunohistochemical analyses showed that Faim knockout (Faim-/- ) mice present ubiquitinated aggregates throughout the retina from early ages. Moreover, retinal cells released stress signals that can signal to Müller cells, as shown by immunofluorescence and qRT-PCR. Müller cells monitor retinal homeostasis and trigger a gliotic response in Faim-/- mice that becomes pathogenic when sustained. In this regard, we observed pronounced vascular leakage at later ages, which may be caused by persistent inflammation. These results suggest that FAIM is an important player in the maintenance of retinal homeostasis, and they support the premise that FAIM is a plausible early marker for late photoreceptor and neuronal degeneration.

The ependymal cell cytoskeleton in the normal and injured spinal cord of mice.

The cytoskeleton of ependymal cells is fundamental to organize and maintain the normal architecture of the central canal (CC). However, little is known about the plasticity of cytoskeletal components after spinal cord injury. Here, we focus on the structural organization of the cytoskeleton of ependymal cells in the normal and injured spinal cord of mice (both females and males) using immunohistochemical and electron microscopy techniques. We found that in uninjured animals, the actin cytoskeleton (as revealed by phalloidin staining) was arranged following the typical pattern of polarized epithelial cells with conspicuous actin pools located in the apical domain of ependymal cells. Transmission electron microscopy images showed microvilli tufts, long cilia, and characteristic intercellular membrane specializations. After spinal cord injury, F-actin rearrangements paralleled by fine structural modifications of the apical domain of ependymal cells were observed. These changes involved disruptions of the apical actin pools as well as fine structural modifications of the microvilli tufts. When comparing the control and injured spinal cords, we also found modifications in the expression of vimentin and glial fibrillary acidic protein (GFAP). After injury, vimentin expression disappeared from the most apical domains of ependymal cells but the number of GFAP-expressing cells within the CC increased. As in other polarized epithelia, the plastic changes in the cytoskeleton may be critically involved in the reaction of ependymal cells following a traumatic injury of the spinal cord.

Phenotypic differences in the inner ears of CBA/CaJ and C57BL/6J mice carrying missense and single base pair deletion mutations in the Cdh23 gene.

Different mutations in the cadherin 23 (CDH23) gene in different genetic backgrounds have been linked to either syndromic or nonsyndromic forms of deafness in humans. We previously reported a progressive hearing loss (HL) mouse model, the Cdh23erl/erl mouse, which carries a 208T > C mutation causing an amino acid substitution at S70P in C57BL/6J mice. To investigate the differences in Cdh23 mutation-related HL in different genetic backgrounds, we used the CRISPR/Cas9 system to generate homozygous mice in the CBA/CaJ background that have the same base pair missense mutation (208T > C) (Cdh23erl2/erl2 ) as Cdh23erl/erl mice in the C57BL/6J background or a single base pair deletion (235G) (Cdh23V2J2/V2J2 ) in the Cdh23 gene at exon 5. The two mutant mice exhibit hearing impairment across a broad range of frequencies. The progression of HL in Cdh23erl2/erl2 mice is slower than that in Cdh23erl/erl mice. We also found structural abnormalities in the stereocilia of cochlear hair cells in Cdh23erl2/erl2 and Cdh23V2J2/V2J2 mice. Cdh23V2J2/V2J2 mice show signs of vestibular dysfunction in open field behavior and swimming tests. In addition, we observed hair bundle defects in vestibular hair cells in Cdh23V2J2/V2J2 mice. Our results suggest an interaction between the erl locus and the C57BL/6J background that exacerbates HL in Cdh23erl/erl mice. Moreover, our study confirms that the Cdh23 gene is essential for normal hearing and balance. These two novel mutant mouse strains provide excellent models for studying CDH23 mutation-related deafness in humans.

14-3-3ζ is crucial for the conversion of labile short-term object recognition memory into stable long-term memory.

The consolidation of new memories into long-lasting memories is multistage process characterized by distinct temporal dynamics. However, our understanding on the initial stage of transformation of labile memory of recent experience into stable memory remains elusive. Here, with the use of rats and mice overexpressing a memory enhancer called regulator of G protein signaling 14 of 414 amino acids (RGS14414 ) as a tool, we show that the expression of RGS14414 in male rats' perirhinal cortex (PRh), which is a brain area crucial for object recognition memory (ORM), enhanced the ORM to the extent that it caused the conversion of labile short-term ORM (ST-ORM) expected to last for 40 min into stable long-term ORM (LT-ORM) traceable after a delay of 24 hr, and that the temporal window of 40 to 60 min after object exposure not only was key for this conversion but also was the time frame when a surge in 14-3-3ζ protein was observed. A knockdown of 14-3-3ζ gene abrogated both the increase in 14-3-3ζ protein and the formation of LT-ORM. Furthermore, this 14-3-3ζ upregulation increased brain-derived growth factor (BDNF) levels in the time frame of 60 min and 24 hr and 14-3-3ζ knockdown decreased the BDNF levels, and a deletion of BDNF gene produced loss in mice ability to form LT-ORM. Thus, within 60 min of object exposure, 14-3-3ζ facilitated the conversion of labile ORM into stable ORM, whereas beyond the 60 min, it mediated the consolidation of the stable memory into long-lasting ORM by regulating BDNF signaling.