Biology subjects

Barkai, O.

Publications and source records attributed to Barkai, O..

9 recordsLinked to original sources

bioRxiv2026

Colitis-induced visceral pain recruits central neurotensin neurons that modulate colonic sensitivity

Inflammatory bowel disease produces debilitating visceral pain that remains a major clinical challenge. Notably, many patients experience persistent pain even after the inflammation resolves, indicating a sustained sensitization of central neural circuits that drives enduring pain. The brainstem parabrachial nucleus integrates interoceptive signals from the gastrointestinal tract to elicit both pain perception and affective responses. Using activity-dependent mapping and an RNAscope assay, we identified a neurotensin (NT)-expressing neuronal population in the lateral PBN (PBNL) that is selectively activated during dextran sulfate sodium-induced colitis. In vivo neural activity recordings demonstrate that PBNL NT neurons encode colon-derived nociceptive signals in an intensity-dependent manner. Silencing these neurons attenuates colonic reflexes evoked by luminal distension and normalizes aberrant gastrointestinal transit and nociceptive licking behavior in colitic mice. Pharmacological blockade of NT signaling alleviates colitis-associated hypersensitivity. These findings identify a central neural population that encodes visceral inflammation and regulates peripheral organ function, and pinpoints neurotensin as a promising therapeutic target to treat colitis-induced visceral pain.

neuroscience↗

bioRxiv2025

Machine learning behavioral analysis reveals cervical instability as an early biomarker of Amyotrophic Lateral Sclerosis

Early detection of neuromuscular disorders is a major clinical challenge, with most diagnoses only occurring after considerable motor neuron degeneration has already taken place. The central problem for early diagnosis of neuromuscular diseases is the subtlety of early symptoms and where to look for them. Without defined behavioral markers, the earliest stages of disease go undetected, delaying intervention and limiting neuroprotective therapeutic evaluation. Here, we present a machine learning (ML) based framework that identifies subtle postural alterations in freely behaving animals. Using longitudinal pose data from SOD1G93A mice, a widely used Amyotrophic Lateral Sclerosis (ALS) mouse model, we focused on postural states in idle periods, behavioral states usually overlooked in disease monitoring. Our analyses revealed consistent deviations in posture and a feature analysis pinpointed cervical instability during adolescence as a key distinguishing feature. We validated these findings through two independent behavioral assays engaging cervical musculature: rearing and wet-dog shakes, both of which showed significant impairments in male SOD1G93A mice as early as 3 weeks of age, many weeks earlier than conventional muscle function assays. This approach establishes an unbiased, non-invasive, scalable strategy for detecting early-stage neuromuscular dysfunction, and provides a foundation both for clinical behavioral biomarker development in ALS and related disorders and will enable evaluation of early neuroprotective interventions.

neuroscience↗

bioRxiv2025

Injured SSTR2+ nociceptor axons in neuromas drive chronic spontaneous neuropathic pain

Spontaneous pain is a common but poorly understood consequence of peripheral nerve injury1-3, including injuries that lead to the formation of neuromas4,5. We developed a chronic neuroma model for measuring spontaneous pain-related behaviours in mice, which revealed that limb flicks - emerging predominantly 2 months post-injury - reflect spontaneous paroxysmal pain. Ectopic activity of injured dorsal root ganglia (DRG) sensory neurons whose axonal endings terminate within the neuroma drives this spontaneous pain. In vivo imaging showed that a subset of small-diameter DRG sensory neurons are the source of spontaneous neural signals emanating from the neuroma, and these spontaneously active neurons are distinct from the intact larger diameter sensory neurons that mediate stimulus-evoked mechanical allodynia from spared nerves. Cell-type-specific gain- and loss-of-function studies identified a genetically- and functionally-defined subtype of small-diameter C-fibre nociceptors whose injured axons in neuromas drive spontaneous limb flicks/neuropathic pain. These findings establish the neurobiological basis of spontaneous pain enabling targeted pain management strategies and define a cellular and mechanistic separation between spontaneous and evoked neuropathic pain.

neuroscience↗

bioRxiv2025

Efferent signaling along nociceptive peripheral terminals in vivo is enhanced during inflammation

Primary nociceptors are essentially characterized as afferent neurons carrying noxious sensory information from the periphery to the CNS. However, the information flow on primary nociceptors is bidirectional. Nociceptor peripheral terminals release a variety of mediators to the target organ in the vicinity of the injured area. These mediators promote sensitization of adjacent sensory neurons, vasodilation, and edema and affect innate and adaptive immunity, leading to hyperalgesia and inflammation that often expands beyond the injured areas. Many theories associate these phenomena with the antidromic action potential propagation along nociceptor terminals; however, the antidromic efferent signaling at the single nociceptor terminals has never been demonstrated. Here, using in vivo calcium imaging from the individual nociceptive terminals innervating the mouse cornea together with a computational approach, we demonstrated that short-lasting activation of a single terminal in vivo was sufficient to activate the remote, non-activated terminal, which branches from the same nociceptor fiber. This increase was dependent on the activation of voltage-gated sodium and calcium channels. Moreover, we showed that the efferent signaling along nociceptive terminals increases under inflammatory conditions, culminating in enhanced calcium signaling in the remote non-activated terminals. This inflammation-induced increase in intra-terminal calcium could trigger the enhanced release of inflammatory mediators, spilling over wider areas and affecting terminals from adjacent unstimulated receptive fields, leading to the expansion of hyperalgesia and inflammation.

neuroscience↗

bioRxiv2025

Lipid nanoparticle delivery of siRNA to dorsal root ganglion neurons to treat pain

Sensory neurons within the dorsal root ganglion (DRG) are the primary trigger of pain, relaying activity about noxious stimuli from the periphery to the central nervous system; however, targeting DRG neurons for pain management has remained a clinical challenge. Here, we demonstrate the use of lipid nanoparticles (LNPs) for effective intrathecal delivery of small interfering RNA (siRNA) to DRG neurons, achieving potent silencing of the transient receptor potential vanilloid 1 (TRPV1) ion channel that is predominantly expressed in nociceptor sensory neurons. This leads to a reversible interruption of heat-, capsaicin-, and inflammation-induced nociceptive conduction, as observed by behavioral outputs. Our work provides a proof-of-concept for intrathecal siRNA therapy as a novel and selective analgesic modality.

neuroscience↗

bioRxiv2024

ARBEL: A Machine Learning Tool with Light-Based Image Analysis for Automatic Classification of 3D Pain Behaviors

A detailed analysis of pain-related behaviors in rodents is essential for exploring both the mechanisms of pain and evaluating analgesic efficacy. With the advancement of pose-estimation tools, automatic single-camera video animal behavior pipelines are growing and integrating rapidly into quantitative behavioral research. However, current existing algorithms do not consider an animals body-part contact intensity with- and distance from- the surface, a critical nuance for measuring certain pain-related responses like paw withdrawals ( flinching) with high accuracy and interpretability. Quantifying these bouts demands a high degree of attention to body part movement and currently relies on laborious and subjective human visual assessment. Here, we introduce a supervised machine learning algorithm, ARBEL: Automated Recognition of Behavior Enhanced with Light, that utilizes a combination of pose estimation together with a novel light-based analysis of body part pressure and distance from the surface, to automatically score pain-related behaviors in freely moving mice in three dimensions. We show the utility and accuracy of this algorithm for capturing a range of pain-related behavioral bouts using a bottom-up animal behavior platform, and its application for robust drug-screening. It allows for rapid objective pain behavior scoring over extended periods with high precision. This open-source algorithm is adaptable for detecting diverse behaviors across species and experimental platforms.

neuroscience↗

bioRxiv2021

Encoding of inflammatory hyperalgesia in mice spinal cord

Inflammation modifies the input-output properties of peripheral nociceptive neurons, thus leading to hyperalgesia, a condition in which the perception of noxious heat stimuli is altered such that the same stimulus produces enhanced pain. The increased nociceptive output enters the superficial dorsal spinal cord (SDH), which comprises the first CNS network integrating the noxious information. Here we used in vivo calcium imaging and a computational approach to investigate how the SDH network in mice encodes the injury-mediated abnormal input from peripheral nociceptive neurons. We show that the application of noxious heat stimuli to the hind paw in naive mice before induction of injury affects the activity of 70% of recorded neurons by either increasing or suppressing it. Application of the same noxious heat stimuli to hyperalgesic skin following injury leads to activation of previously non-responded cells and de-suppression of the "suppressed" neurons. We further demonstrate that reduction in synaptic inhibition mimics the response to the noxious stimuli in hyperalgesic conditions. Using a computational model of the SDH network, we predict that the "disinhibitory" effect of hyperalgesic stimuli results from the inflammation-mediated increased afferent input to the SDH network and a decrease in SDH inhibition. Both of these processes synergistically contribute to the injury-mediated increase in SDH output towards higher brain centers.

neuroscience↗

bioRxiv2021

RNA-controlled nucleocytoplasmic shuttling of mRNA decay factors regulates mRNA synthesis and initiates a novel mRNA decay pathway

mRNA level is controlled by factors that mediate both mRNA synthesis and decay, including the exonuclease Xrn1 - a major mRNA synthesis and decay factor. Here we show that nucleocytoplasmic shuttling of Xrn1 and of some of its associated mRNA decay factors plays a key role in determining both mRNA synthesis and decay. Shuttling is regulated by RNA-controlled binding of the karyopherin Kap120 to two nuclear localization sequences (NLSs) in Xrn1. The decaying RNA binds and masks NLS1, establishing a link between mRNA decay and Xrn1 shuttling. Mutations in the two NLSs, which prevent Xrn1 import, compromise transcription and, unexpectedly, also the cytoplasmic decay of [~]50% of the cellular mRNAs - comparably to Xrn1 deletion. These findings uncover a cytoplasmic mRNA decay pathway that begins in the nucleus. Interestingly, Xrn1 shuttling is required for proper adaptation to environmental changes, in particular to ever changing environmental fluctuations.

molecular biology↗

bioRxiv2020

The input-output relation of primary nociceptive neurons is determined by the morphology of the peripheral nociceptive terminals

The output from the peripheral terminals of primary nociceptive neurons, which detect and encode the information regarding noxious stimuli, is crucial in determining pain sensation. The nociceptive terminal endings are morphologically complex structures assembled from multiple branches of different geometry, which converge in a variety of forms to create the terminal tree. The output of a single terminal is defined by the properties of the transducer channels producing the generation potentials and voltage-gated channels, translating the generation potentials into action potential firing. However, in the majority of cases, noxious stimuli activate multiple terminals; thus, the output of the nociceptive neuron is defined by the integration and computation of the inputs of the individual terminals. Here we used a computational model of nociceptive terminal tree to study how the architecture of the terminal tree affects input-output relation of the primary nociceptive neurons. We show that the input-output properties of the nociceptive neurons depend on the length, the axial resistance, and location of individual terminals. Moreover, we show that activation of multiple terminals by capsaicin-like current allows summation of the responses from individual terminals, thus leading to increased nociceptive output. Stimulation of terminals in simulated models of inflammatory or nociceptive hyperexcitability led to a change in the temporal pattern of action potential firing, emphasizing the role of temporal code in conveying key information about changes in nociceptive output in pathological conditions, leading to pain hypersensitivity. Significance statementNoxious stimuli are detected by terminal endings of the primary nociceptive neurons, which are organized into morphologically complex terminal trees. The information from multiple terminals is integrated along the terminal tree, computing the neuronal output, which propagates towards the CNS, thus shaping the pain sensation. Here we revealed that the structure of the nociceptive terminal tree determines the output of the nociceptive neurons. We show that the integration of noxious information depends on the morphology of the terminal trees and how this integration and, consequently, the neuronal output change under pathological conditions. Our findings help to predict how nociceptive neurons encode noxious stimuli and how this encoding changes in pathological conditions, leading to pain.

neuroscience↗