Oxytocin signaling is necessary for synaptic maturation of adult-born neurons.

Neural circuit plasticity and sensory response dynamics depend on forming new synaptic connections. Despite recent advances toward understanding the consequences of circuit plasticity, the mechanisms driving circuit plasticity are unknown. Adult-born neurons within the olfactory bulb have proven to be a powerful model for studying circuit plasticity, providing a broad and accessible avenue into neuron development, migration, and circuit integration. We and others have shown that efficient adult-born neuron circuit integration hinges on presynaptic activity in the form of diverse signaling peptides. Here, we demonstrate a novel oxytocin-dependent mechanism of adult-born neuron synaptic maturation and circuit integration. We reveal spatial and temporal enrichment of oxytocin receptor expression within adult-born neurons in the murine olfactory bulb, with oxytocin receptor expression peaking during activity-dependent integration. Using viral labeling, confocal microscopy, and cell type-specific RNA-seq, we demonstrate that oxytocin receptor signaling promotes synaptic maturation of newly integrating adult-born neurons by regulating their morphological development and expression of mature synaptic AMPARs and other structural proteins.

Age and number of lesions predict chalazion recurrence.

PURPOSE: Periocular lesions in pediatric patients usually require general anesthesia for surgical intervention. The US Food and Drug Administration (FDA) warns against multiple exposures to anesthesia in children younger than 3 years due to the increased risk of learning disabilities in this population. This study aimed to evaluate risk factors associated with chalazion recurrence after surgery. METHODS: A retrospective chart review over a five-year period identified 649 patients at our institution undergoing surgical intervention for chalazion. The primary outcomes examined were as follows: (1) return to the operating room for additional surgical intervention and (2) recurrence of chalazion during convalescence from surgery and follow-up. RESULTS: Fewer than one-third of patients suffered a recurrence after surgery. Multivariate logistic regression found younger age (p = 0.01), female sex (p = 0.01), and a greater number of chalazia drained (p < 0.001) were significantly correlated with recurrence of chalazia after surgery. CONCLUSIONS: Patients presenting at a younger age and with a greater number of chalazion were statistically more likely to have a recurrence of chalazion after surgery. Given recurrence is more likely in younger children, reconciling this with the risk-benefit ratio with regard to FDA guidelines on anesthesia in children under three years is a critical consideration for ophthalmologists.

Predictors of postoperative performance status after surgical management of infratemporal fossa malignancies.

Infratemporal fossa (ITF) tumors are difficult to access surgically due to anatomical constraints. Moreover, aggressive ITF carcinomas and sarcomas necessitate aggressive treatment strategies that, along with tumor-related symptoms, contribute to decreases in patient performance status. To assess factors that predict postoperative performance in patients undergoing surgery for ITF tumors. We reviewed medical records for all patients surgically treated for an ITF malignancy between January 1, 1999, and December 31, 2017, at our institution. We collected patient demographics, preoperative performance, tumor stage, tumor characteristics, treatment modalities, pathological data, and postoperative performance data. The 5-year survival rate was 62.2%. Higher preoperative Karnofsky Performance Status (KPS) score (n = 64; p < 0.001), short length of stay (p = 0.002), prior surgery at site (n = 61; p = 0.0164), and diagnosis of sarcoma (n = 62; p = 0.0398) were predictors of higher postoperative KPS scores. Percutaneous endoscopic gastrostomy (PEG) (n = 9; p = 0.0327), and tracheostomy tube placement (n = 20; p = 0.0436) were predictors of lower postoperative KPS scores, whereas age at presentation (p = 0.72), intracranial tumor spread (p = 0.8197), and perineural invasion (n = 40; p = 0.2195) were not. Male patients and patients with carcinomas showed the greatest decreases in KPS scores between pretreatment and posttreatment. Higher preoperative KPS score and short length of stay were the best predictors of higher postoperative KPS scores. This work provides treatment teams and patients with better information on outcomes for shared decision-making.

A CRISPR toolbox for generating intersectional genetic mouse models for functional, molecular, and anatomical circuit mapping.

BACKGROUND: The functional understanding of genetic interaction networks and cellular mechanisms governing health and disease requires the dissection, and multifaceted study, of discrete cell subtypes in developing and adult animal models. Recombinase-driven expression of transgenic effector alleles represents a significant and powerful approach to delineate cell populations for functional, molecular, and anatomical studies. In addition to single recombinase systems, the expression of two recombinases in distinct, but partially overlapping, populations allows for more defined target expression. Although the application of this method is becoming increasingly popular, its experimental implementation has been broadly restricted to manipulations of a limited set of common alleles that are often commercially produced at great expense, with costs and technical challenges associated with production of intersectional mouse lines hindering customized approaches to many researchers. Here, we present a simplified CRISPR toolkit for rapid, inexpensive, and facile intersectional allele production. RESULTS: Briefly, we produced 7 intersectional mouse lines using a dual recombinase system, one mouse line with a single recombinase system, and three embryonic stem (ES) cell lines that are designed to study the way functional, molecular, and anatomical features relate to each other in building circuits that underlie physiology and behavior. As a proof-of-principle, we applied three of these lines to different neuronal populations for anatomical mapping and functional in vivo investigation of respiratory control. We also generated a mouse line with a single recombinase-responsive allele that controls the expression of the calcium sensor Twitch-2B. This mouse line was applied globally to study the effects of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) on calcium release in the ovarian follicle. CONCLUSIONS: The lines presented here are representative examples of outcomes possible with the successful application of our genetic toolkit for the facile development of diverse, modifiable animal models. This toolkit will allow labs to create single or dual recombinase effector lines easily for any cell population or subpopulation of interest when paired with the appropriate Cre and FLP recombinase mouse lines or viral vectors. We have made our tools and derivative intersectional mouse and ES cell lines openly available for non-commercial use through publicly curated repositories for plasmid DNA, ES cells, and transgenic mouse lines.

Evolution of a genetic incompatibility in the genus Xiphophorus.

Genetic incompatibilities are commonly observed between hybridizing species. Although this type of isolating mechanism has received considerable attention, we have few examples describing how genetic incompatibilities evolve. We investigated the evolution of two loci involved in a classic example of a Bateson-Dobzhansky-Muller (BDM) incompatibility in Xiphophorus, a genus of freshwater fishes from northern Central America. Hybrids develop a lethal melanoma due to the interaction of two loci, an oncogene and its repressor. We cloned and sequenced the putative repressor locus in 25 Xiphophorus species and an outgroup species, and determined the status of the oncogene in those species from the literature. Using phylogenetic analyses, we find evidence that a repeat region in the proximal promoter of the repressor is coevolving with the oncogene. The data support a hypothesis that departs from the standard BDM model: it appears the alleles that cause the incompatibilities have coevolved simultaneously within lineages, rather than in allopatric or temporal isolation.

Monoclonal antibodies in neuro-ophthalmology.

Neuro-ophthalmologic diseases include a broad range of disorders affecting the afferent and efferent visual pathways. Recently, monoclonal antibody (mAb) therapies have emerged as a promising targeted approach in the management of several of these complex conditions. Here, we describe the mechanism-specific applications and advancements in neuro-ophthalmologic mAb therapies. The application of mAbs in neuro-ophthalmologic diseases highlights our increasing understanding of disease-specific mechanisms in autoimmune conditions such as neuromyelitis optica, thyroid eye disease, and myasthenia gravis. Due to the specificity of mAb therapies, applications in neuro-ophthalmologic diseases have yielded exceptional clinical outcomes, including both reduced rate of relapse and progression to disability, visual function preservation, and quality of life improvement. These advancements have not only expanded the range of treatable neuro-ophthalmologic diseases but also reduced adverse events and increased the response rate to treatment. Further research into neuro-ophthalmologic disease mechanisms will provide accurate and specific targeting of important disease mediators through applications of future mAbs. As our understanding of these diseases and the relevant therapeutic targets evolve, we will continue to build on our understanding of how mAbs interfere with disease pathogenesis, and how these changes improve clinical outcomes and quality of life for patients.

Lymphocytic Panhypophysitis Mimicking Glaucoma: Case Report.

Lymphocytic hypophysitis (LH) is a primary inflammatory disorder of the pituitary gland and infundibulum that commonly manifests in both mass effect and endocrinologic symptoms. Although the exact pathophysiology remains unclear, it has been increasingly linked to an autoimmune process. Complications arise by two separate mechanisms. Inflammation in the sella can lead to headaches and visual field defects. Pituitary inflammation and, chronically, fibrosis interfere with the gland's hormone-secreting capacity, often resulting in various endocrinopathies such as polyuria, polydipsia, amenorrhea, and others. While final histologic classification requires pathologic evaluation, diagnosis can often be made clinically with appropriate imaging. Treatment often consists of conservative management but can also include glucocorticoids or surgical resection. We present a case of biopsy-proven LH involving the entire pituitary, dubbed lymphocytic panhypophysitis (LPH) that was misdiagnosed for years as glaucoma due to the lack of endocrinopathy as well as delay in magnetic resonance imaging. After imaging revealed the sellar mass, the patient responded symptomatically to surgical resection and glucocorticoid treatment. LPH may present without endocrinologic symptoms and therefore mimic alternate diagnoses such as glaucoma. Clinicians should be suspicious of a diagnosis of glaucoma in the setting of a temporal field defect and lack of response to traditional therapy. A personal or family history of autoimmune disease in such patients should prompt further imaging and investigation. Therefore, endocrinopathy is supportive but not present in every case of LPH.

Co-transmitting neurons in the lateral septal nucleus exhibit features of neurotransmitter switching.

The lateral septal nucleus (LSN) is a highly interconnected region of the central brain whose activity regulates widespread circuitry. As such, the mechanisms that govern neuronal activity within the LSN have far-reaching implications on numerous brain-wide nuclei, circuits, and behaviors. We found that GABAergic neurons within the LSN express markers that mediate the release of acetylcholine (ACh). Moreover, we show that these vGATLSN neurons release both GABA and ACh onto local glutamatergic LSN neurons. Using both short-term and long-term neuronal labeling techniques we observed expression of the cholinergic neuron marker Choline Acetyltransferase (ChAT) in vGATLSN neurons. These findings provide evidence of cholinergic neurotransmission from vGATLSN neurons, and provide an impetus to examine dynamic co-neurotransmission changes as a potential mechanism that contributes to neuronal and circuit-wide plasticity within the LSN.

Advancements in the Quest to Map, Monitor, and Manipulate Neural Circuitry.

Neural circuits and the cells that comprise them represent the functional units of the brain. Circuits relay and process sensory information, maintain homeostasis, drive behaviors, and facilitate cognitive functions such as learning and memory. Creating a functionally-precise map of the mammalian brain requires anatomically tracing neural circuits, monitoring their activity patterns, and manipulating their activity to infer function. Advancements in cell-type-specific genetic tools allow interrogation of neural circuits with increased precision. This review provides a broad overview of recombination-based and activity-driven genetic targeting approaches, contemporary viral tracing strategies, electrophysiological recording methods, newly developed calcium, and voltage indicators, and neurotransmitter/neuropeptide biosensors currently being used to investigate circuit architecture and function. Finally, it discusses methods for acute or chronic manipulation of neural activity, including genetically-targeted cellular ablation, optogenetics, chemogenetics, and over-expression of ion channels. With this ever-evolving genetic toolbox, scientists are continuing to probe neural circuits with increasing resolution, elucidating the structure and function of the incredibly complex mammalian brain.

Activation of basal forebrain-to-lateral habenula circuitry drives reflexive aversion and suppresses feeding behavior.

Environmental cues and internal states such as mood, reward, or aversion directly influence feeding behaviors beyond homeostatic necessity. The hypothalamus has been extensively investigated for its role in homeostatic feeding. However, many of the neural circuits that drive more complex, non-homeostatic feeding that integrate valence and sensory cues (such as taste and smell) remain unknown. Here, we describe a basal forebrain (BF)-to-lateral habenula (LHb) circuit that directly modulates non-homeostatic feeding behavior. Using viral-mediated circuit mapping, we identified a population of glutamatergic neurons within the BF that project to the LHb, which responds to diverse sensory cues, including aversive and food-related odors. Optogenetic activation of BF-to-LHb circuitry drives robust, reflexive-like aversion. Furthermore, activation of this circuitry suppresses the drive to eat in a fasted state. Together, these data reveal a role of basal forebrain glutamatergic neurons in modulating LHb-associated aversion and feeding behaviors by sensing environmental cues.

Distinct immune signature predicts progression of vestibular schwannoma and unveils a possible viral etiology.

BACKGROUND: The management of sub-totally resected sporadic vestibular schwannoma (VS) may include observation, re-resection or irradiation. Identifying the optimal choice can be difficult due to the disease's variable progression rate. We aimed to define an immune signature and associated transcriptomic fingerprint characteristic of rapidly-progressing VS to elucidate the underpinnings of rapidly progressing VS and identify a prognostic model for determining rate of progression. METHODS: We used multiplex immunofluorescence to characterize the immune microenvironment in 17 patients with sporadic VS treated with subtotal surgical resection alone. Transcriptomic analysis revealed differentially-expressed genes and dysregulated pathways when comparing rapidly-progressing VS to slowly or non-progressing VS. RESULTS: Rapidly progressing VS was distinctly enriched in CD4+, CD8+, CD20+, and CD68+ immune cells. RNA data indicated the upregulation of anti-viral innate immune response and T-cell senescence. K - Top Scoring Pair analysis identified 6 pairs of immunosenescence-related genes (CD38-KDR, CD22-STAT5A, APCS-CXCR6, MADCAM1-MPL, IL6-NFATC3, and CXCL2-TLR6) that had high sensitivity (100%) and specificity (78%) for identifying rapid VS progression. CONCLUSION: Rapid progression of residual vestibular schwannoma following subtotal surgical resection has an underlying immune etiology that may be virally originating; and despite an abundant adaptive immune response, T-cell immunosenescence may be associated with rapid progression of VS. These findings provide a rationale for clinical trials evaluating immunotherapy in patients with rapidly progressing VS.

Mini-review: Trophic interactions between cancer cells and primary afferent neurons.

Cancer neurobiology is an emerging discipline that inevitably unfurls new perspectives in oncology. The role that nerves play in cancer progression resonates with the long-reported dependency of tumors on neuro-molecular mechanisms that remain insufficiently elucidated. Whereas interactions between neurotrophic growth factors and receptors have been heavily studied in the nervous system, their expression in cancers and their impact on tumor cell growth and metastasis through their corresponding signaling pathways has been undervalued. Accumulating evidence suggests that trophic factors released by nerves strongly influence tumor development and that this neural contribution appears to not only play a stimulatory role but also function as an essential part of the tumor's microenvironment. This bidirectional communication between proliferating cells and tumor-infiltrating nerves drives axonogenesis and tumor growth and migration. Acquiring a better understanding of the trophic interactions between primary afferent neurons and invading tumors will guide clinically actionable strategies to prevent tumor-associated axonogenesis, disrupting the chemical crosstalk between neurons and tumors and ultimately decreasing tumor growth and spread.

A systematic-review of olfactory deficits in neurodevelopmental disorders: From mouse to human.

Olfactory impairment is a common clinical motif across neurodevelopmental disorders, suggesting olfactory circuits are particularly vulnerable to disease processes and can provide insight into underlying disease mechanisms. The mouse olfactory bulb is an ideal model system to study mechanisms of neurodevelopmental disease due to its anatomical accessibility, behavioral relevance, ease of measuring circuit input and output, and the feature of adult neurogenesis. Despite the clinical relevance and experimental benefits, olfactory testing across animal models of neurodevelopmental disease has been inconsistent and non-standardized. Here we performed a systematic literature review of olfactory function testing in mouse models of neurodevelopmental disorders, and identified intriguing inconsistencies that include evidence for both increased and decreased acuity in odor detection in various mouse models of Autism Spectrum Disorder (ASD). Based on our identified gaps in the literature, we recommend direct comparison of different mouse models of ASD using standardized tests for odor detection and discrimination. This review provides a framework to guide future olfactory function testing in mouse models of neurodevelopmental diseases.

Imaging and Quantification of Intact Neuronal Dendrites via CLARITY Tissue Clearing.

Brain activity, the electrochemical signals passed between neurons, is determined by the connectivity patterns of neuronal networks, and from the morphology of processes and substructures within these neurons. As such, much of what is known about brain function has arisen alongside developments in imaging technologies that allow further insight into how neurons are organized and connected in the brain. Improvements in tissue clearing have allowed for high-resolution imaging of thick brain slices, facilitating morphological reconstruction and analyses of neuronal substructures, such as dendritic arbors and spines. In tandem, advances in image processing software provide methods of quickly analyzing large imaging datasets. This work presents a relatively rapid method of processing, visualizing, and analyzing thick slices of labeled neural tissue at high-resolution using CLARITY tissue clearing, confocal microscopy, and image analysis. This protocol will facilitate efforts toward understanding the connectivity patterns and neuronal morphologies that characterize healthy brains, and the changes in these characteristics that arise in diseased brain states.

Head and neck cancer exosomes drive microRNA-mediated reprogramming of local neurons.

Solid tumors are complex collections of cells surrounded by benign tissues that influence and are influenced by the tumor. These surrounding cells include vasculature, immune cells, neurons, and other cell types, and are collectively known as the tumor microenvironment. Tumors manipulate their microenvironment for the benefit of the tumor. Autonomic neurons innervate and drive malignant growth in a variety of solid tumors. However, the mechanisms underlying neuron-tumor relationships are not well understood. Recently, Amit et al. described that trophic relationships between oral cavity squamous cell carcinomas (OCSCCs) and nearby autonomic neurons arise through direct signaling between tumors and local neurons. An inducible tumor model in which 4NQO was introduced into the drinking water of Trp53 knockout mice was used to model OCSCC-microenvironment interactions. Using this model, this group discovered that loss of p53 expression in OCSCC tumors resulted in increased nerve density within these tumors. This neuritogenesis was controlled by tumor-derived microRNA-laden extracellular vesicles (EVs). Specifically, EV-delivered miR-34a inhibited neuritogenesis, whereas EV-delivered miR-21 and miR-324 increased neuritogenesis. The neurons innervating p53-deficient OCSCC tumors were predominantly adrenergic and arose through the transdifferentiation of trigeminal sensory nerve fibers to adrenergic nerve fibers. This transdifferentiation corresponded with increased expression of neuron-reprogramming transcription factors, including POU5F1, KLF4, and ASCL1, which were overexpressed in the p53-deficient samples, and are proposed targets of miR-34a-mediated regulation. Human OCSCC samples enriched in adrenergic neuron markers are associated strongly with poor outcomes, thus demonstrating the relevance of these findings to cancer patients.

Oxytocin and Sensory Network Plasticity.

An essential characteristic of nervous systems is their capacity to reshape functional connectivity in response to physiological and environmental cues. Endogenous signals, including neuropeptides, governs nervous system plasticity. Particularly, oxytocin has been recognized for its role in mediating activity-dependent circuit changes. These oxytocin-dependent changes occur at the synaptic level and consequently shape the cellular composition of circuits. Here we discuss recent advances that illustrate how oxytocin functions to reshape neural circuitry in response to environmental changes. Excitingly, recent findings pave the way for promising therapeutic applications of oxytocin to treat neurodevelopmental and neuropsychiatric diseases.

Interrupting Neuron-Tumor Interactions to Overcome Treatment Resistance.

Neurons in the tumor microenvironment release neurotransmitters, neuroligins, chemokines, soluble growth factors, and membrane-bound growth factors that solid tumors leverage to drive their own survival and spread. Tumors express nerve-specific growth factors and microRNAs that support local neurons and guide neuronal growth into tumors. The development of feed-forward relationships between tumors and neurons allows tumors to use the perineural space as a sanctuary from therapy. Tumor denervation slows tumor growth in animal models, demonstrating the innervation dependence of growing tumors. Further in vitro and in vivo experiments have identified many of the secreted signaling molecules (e.g., acetylcholine, nerve growth factor) that are passed between neurons and cancer cells, as well as the major signaling pathways (e.g., MAPK/EGFR) involved in these trophic interactions. The molecules involved in these signaling pathways serve as potential biomarkers of disease. Additionally, new treatment strategies focus on using small molecules, receptor agonists, nerve-specific toxins, and surgical interventions to target tumors, neurons, and immune cells of the tumor microenvironment, thereby severing the interactions between tumors and surrounding neurons. This article discusses the mechanisms underlying the trophic relationships formed between neurons and tumors and explores the emerging therapies stemming from this work.

Improving long term patient outcomes from deep brain stimulation for treatment-refractory obsessive-compulsive disorder.

Introduction: Deep brain stimulation (DBS) has emerged as an effective treatment for patients with severe treatment-refractory obsessive-compulsive disorder (OCD). Over the past two decades, several clinical trials with multiple years of follow-up have shown that DBS offers long-term symptom relief for individuals with severe OCD, though a portion of patients do not achieve an adequate response.Areas covered: This review sought to summarize the literature on the efficacy and long-term effectiveness of DBS for OCD, and to identify strategies that have the potential to improve treatment outcomes.Expert opinion: Although this literature is just emerging, a small number of DBS enhancement strategies have shown promising initial results. More posterior targets along the striatal axis and at the bed nucleus of the stria terminalis appear to offer greater symptom relief than more anterior targets. Research is also beginning to demonstrate the feasibility of maximizing treatment outcomes with target selection based on neural activation patterns during symptom provocation and clinical presentation. Finally, integrating DBS with post-surgery exposure and response prevention therapy appears to be another promising approach. Definitive conclusions about these strategies are limited by a low number of studies with small sample sizes that will require multi-site replication.

Surgical management of carcinomas of the infratemporal fossa and skull base: patterns of failure and predictors of long-term outcomes.

OBJECTIVE: Infratemporal fossa (ITF) tumors are unique in histological characteristics and difficult to treat. Predictors of patient outcomes in this context are not known. The objective of this study was to identify independent predictors of outcome and to characterize patterns of failure in patients with ITF carcinoma. METHODS: All patients who had been surgically treated for anterolateral skull base malignancy between 1999 and 2017 at the authors' institution were retrospectively reviewed. Patient demographics, preoperative performance status, tumor stage, tumor characteristics, treatment modalities, and pathological data were collected. Primary outcomes were disease-specific survival (DSS) and local progression-free survival (LPFS) rates. Overall survival (OS) and patterns of progression were secondary outcomes. RESULTS: Forty ITF malignancies with skull base involvement were classified as carcinoma. Negative margins were achieved in 23 patients (58%). Median DSS and LPFS were 32 and 12 months, respectively. Five-year DSS and OS rates were 55% and 36%, respectively. The 5-year LPFS rate was 69%. The 5-year overall PFS rate was 53%. Disease recurrence was noted in 28% of patients. Age, preoperative performance status, and margin status were statistically significant prognostic factors for DSS. Lower preoperative performance status and positive surgical margins increased the probability of local recurrence. CONCLUSIONS: The ability to achieve negative margins was significantly associated with improved tumor control rates and DSS. Cranial base surgical approaches must be considered in multimodal treatment regimens for anterolateral skull base carcinomas.