Biology subjects

Xu, X.-H.

Publications and source records attributed to Xu, X.-H..

9 recordsLinked to original sources

bioRxiv2024

Intra-hypothalamic circuit orchestrates β-endorphin release following coital ejaculation in male mice

Survey-based evidence suggests that men experience a distinct post-ejaculation affective state1,2, marked by intense pleasure sometimes compared to the euphoric rush from intravenous injection of opioid drugs such as heroin3. However, the intrinsic neural circuit mechanisms underlying the ejaculation-triggered affective state remain unclear. Here, we discovered that Calbindin1-expressing (Calb1+) neurons in the preoptic area (POA) of the hypothalamus, an evolutionarily conserved regulatory region for male mating behavior4, are specifically activated during ejaculation in male mice. Inhibiting POA Calb1+ neurons prolongs mating and delays ejaculation. Importantly, POA Calb1+ neurons transmit the ejaculation signal and activate proopiomelanocortin-expressing (Pomc+) neurons in the arcuate nucleus of the hypothalamus, which show robust and sustained activity lasting for tens of seconds, specifically upon ejaculation. This activity is accompanied by elevated levels of {beta}-endorphins5, opioid peptides secreted by Pomc+ neurons, post-ejaculation in male mice. Optogenetic activation of Pomc+ neurons increases {beta}-endorphins levels and conditioned placed preference, similar to ejaculation. Conversely, intracerebroventricular (i.c.v.) infusion of drugs blocking Pomc neuropeptides signaling eliminates ejaculation-conditioned place preference. Collectively, these results elucidate an intra-hypothalamic circuit from POA Calb1+ neurons to arcuate Pomc+ neurons that coordinate {beta}-endorphin release with ejaculation, shedding light on the neurobiological basis of the post-ejaculation affective state.

neuroscience↗

bioRxiv2023

Projectome-defined subtypes and modular intra-hypothalamic subnetworks of peptidergic neurons

The hypothalamus plays a vital role in coordinating essential neuroendocrine, autonomic, and somatomotor responses for survival and reproduction. While previous studies have explored population-level projections of hypothalamic neurons, the specific innervation patterns of individual hypothalamic axons remain unclear. To understand the organization of hypothalamic axon projections, we conducted a comprehensive reconstruction of single-cell projectomes from 7,180 mouse hypothalamic neurons expressing specific neuropeptides. Our analysis identified 31 distinct subtypes based on projectome-defined characteristics, with many exhibiting long-range axon collateral projections to multiple brain regions. Notably, these subtypes selectively targeted specific subdomains within downstream areas, either unilaterally or bilaterally. Furthermore, we observed that individual peptidergic neuronal types encompassed multiple projectome-defined subtypes, explaining their diverse functional roles. Additionally, by examining intra-hypothalamic axon projections, we uncovered six modular subnetworks characterized by enriched intramodular connections and distinct preferences for downstream targets. This modular organization of the intra-hypothalamic network likely contributes to the coordinated organization of hypothalamic outputs. In summary, our comprehensive projectome analysis reveals the organizational principles governing hypothalamic axon projections, providing a framework for understanding the neural circuit mechanisms underlying the diverse and coordinated functions of the hypothalamus.

neuroscience↗

bioRxiv2022

Inhibition inputs from hippocampal CA1 to retrosplenial agranular cortex gate social behavior

Retrosplenial cortex has been implicated in processing sensory information and spatial learning, with abnormal neural activity observed in association with psychedelics and in mouse and non-human primate models of autism spectrum disorders (ASD). The direct role of the retrosplenial cortex in regulating social behaviors remains unclear. This work reveals that the neural activity of retrosplenial agranular cortex (RSA), a subregion of retrosplenial cortex, is initially activated, then quickly suppressed upon social contact. The up-down phase of RSA neurons is crucial for normal social behaviors. PV-positive GABAergic neurons in the hippocampal CA1 region were found to send inhibitory projections to RSA. Blocking these CA1-RSA inhibitory inputs significantly impaired social behavior. Notably, enhancing the CA1-RSA inhibitory input could rescue social behavior defects in an ASD mouse model. This work suggests a neural mechanism for salience processing of social behavior and identifies a potential target for ASD intervention using neural modulation approaches.

neuroscience↗

bioRxiv2022

A hippocampal-hypothalamic circuit essential for anxiety-related behavioral avoidance

Anxiety over perceived threats triggers avoidance behavior, but the underlying neural circuit mechanism remains poorly understood. Taking hints from the deep connection between anxiety and predator defense, we examined the role of the anterior hypothalamic nucleus (AHN), a critical node in the predator defense network, in anxiety-related behaviors. By recording Ca2+ transients in behaving mice, we found that activity of AHN GABAergic (AHNVgat+) neurons showed individually stable increases when animals approached unfamiliar objects in an open field (OF) or explored the open arm of an elevated plus-maze (EPM). Moreover, AHNVgat+ neuron activity foreshadowed behavioral retreats and correlated with object and open-arm avoidance. Crucially, exploration-triggered optogenetic inhibition of AHNVgat+ neurons dramatically reduced avoidance behaviors. Furthermore, retrograde viral tracing identified the ventral subiculum (vSub) of the hippocampal formation as a significant input to AHNVgat+ neurons in driving avoidance behaviors. Thus, the activity of the hippocampal-hypothalamic pathway promotes idiosyncratic anxiety-related behavioral avoidance.

neuroscience↗

bioRxiv2021

Selfee: Self-supervised Features Extraction of animal behaviors

Fast and accurately characterizing animal behaviors is crucial for neuroscience research. Deep learning models are efficiently used in laboratories for behavior analysis. However, it has not been achieved to use a fully unsupervised method to extract comprehensive and discriminative features directly from raw behavior video frames for annotation and analysis purposes. Here, we report a self-supervised feature extraction (Selfee) convolutional neural network with multiple downstream applications to process video frames of animal behavior in an end-to-end way. Visualization and classification of the extracted features (Meta-representations) validate that Selfee processes animal behaviors in a comparable way of human understanding. We demonstrate that Meta-representations can be efficiently used to detect anomalous behaviors that are indiscernible to human observation and hint in-depth analysis. Furthermore, time-series analyses of Meta-representations reveal the temporal dynamics of animal behaviors. In conclusion, we present a self-supervised learning approach to extract comprehensive and discriminative features directly from raw video recordings of animal behaviors and demonstrate its potential usage for various downstream applications.

neuroscience↗

bioRxiv2021

Direct and Indirect Pathway Neurons in Ventrolateral Striatum Differentially Regulate Licking Movement and Nigral Responses

Drinking behavior in rodents is characterized by stereotyped, rhythmic licking movement, which is regulated by the basal ganglia. It is unclear how direct and indirect pathways control the lick bout and individual spout contact. We find that inactivating D1 and D2 receptors-expressing medium spiny neurons (MSNs) in the ventrolateral striatum (VLS) oppositely alters the number of licks in a bout. D1- and D2-MSNs exhibit different patterns of lick sequence-related activity and different phases of oscillation time-locked to the lick cycle. On timescale of a lick cycle, transient inactivation of D1-MSNs during tongue protrusion reduces spout contact probability, whereas transiently inactivating D2-MSNs has no effect. On timescale of a lick bout, inactivation of D1-MSNs (D2-MSNs) causes rate increase (decrease) in a subset of basal ganglia output neurons that decrease firing during licking. Our results reveal the distinct roles of D1- and D2-MSNs in regulating licking at both coarse and fine timescales.

neuroscience↗

bioRxiv2021

An intein-split transactivator for intersectional neural imaging and optogenetic manipulation

The complexity of brain circuitry is manifested by numerous cell types based on genetic marker, location and neural connectivity. Cell-type specific recording and manipulation is essential to disentangle causal neural mechanisms in physiology and behavior; however, many current approaches are largely limited by number of intersectional features, incompatibility of common effectors and insufficient gene expression. To tackle these limitations, we devise an intein-based intersectional synthesis of transactivator (IBIST) to selectively control gene expression of common effectors in specific cell types defined by a combination of multiple features. We validate the specificity and sufficiency of IBIST to control common effectors including fluorophores, optogenetic opsins and Ca2+ indicators in various intersectional conditions in vivo. Using IBIST-based Ca2+ imaging, we show that the IBIST can intersect up to five features, and that hippocampal cells tune differently to distinct emotional valences depending on the pattern of projection targets. Collectively, the IBIST multiplexes the capability to intersect cell-type features and is compatible with common effectors to effectively control gene expression, monitor and manipulate neural activities.

neuroscience↗

bioRxiv2020

Parabrachial neuron types categorically encode thermoregulation variables during heat defense

Heat defense is crucial for survival and fitness, and its dysregulation may result in deaths due to poor management. Transmission of thermosensory signals into hypothalamic thermoregulation centers represent a key layer of regulation in heat defense. However, the mechanism by which these signals are transmitted into the hypothalamus remains poorly understood. Here, we reveal that glutamatergic prodynorphin and cholecystokinin neuron populations in the lateral parabrachial (LPB) are progressively recruited to defend elevated body temperature. These two nonoverlapping neuron types form circuitries with downstream preoptic hypothalamic neurons to inhibit BAT thermogenesis and activate tail vasodilation, respectively. Both circuitries are selectively activated by warm temperatures and are required for fever limiting. The prodynorphin circuitry is further required for regulation of energy expenditure and weight homeostasis. Thus, these findings establish that the genetic and functional specificity of heat defense neurons occurs as early as in the LPB and uncover categorical neuron types for encoding two heat defense variables, which may provide targets for treating thermoregulation disorders.

neuroscience↗

bioRxiv2019

Sex differences in electrophysiological properties of mouse mPOA neurons revealed by in vitro whole-cell recordings

The medial preoptic area (mPOA) of the hypothalamus is sexually dimorphic and controls sexually dimorphic display of male mating and parental care. Yet, despite extensive characterization of sex differences in the mPOA, we know surprisingly little about whether or how male and female mPOA neurons differ electrophysiologically, which relate more directly to neuronal firing and behavioral pattern generation. In this study, we performed whole-cell patch clamp recordings of the mPOA in acute brain slices cut from virgin adult mice, and compared in total 29 electrophysiological parameters between male and female mPOA neurons. We find that resting membrane potential (Vm), input resistance (Rm), time constant ({tau}m), threshold (Vth) and minimum current (rheobase) required to generate an action potential differ significantly between male and female in a cell-type dependent manner. Nonetheless, there is little evidence for profuse sex differences in neuronal excitability, except for a higher probability of rebound neurons in males. Depletion of male gonadal hormones in adulthood partially de-masculinizes sexually dimorphic electrophysiological parameters, suggesting that some of these sex differences may establish during development. Furthermore, as a demonstration of the behavioral relevance of these sex differences, we show that pharmacologic blockage of currents mediated by T-type Ca2+ channel, which underlie rebound and tends to be larger in male mPOA neurons, result in behavioral deficits in male mating. In summary, we have identified key sex differences in electrophysiological properties of mPOA neurons that likely contribute to sexually dimorphic display of behaviors.\n\nSignificance StatementSex represents an important biological variable that impact an individuals behaviors, physiology and disease susceptibility. Indeed, sex differences in the nervous system manifest across many different levels and scales. Yet, throughout previous multifaceted investigations on sex differences in the brain, electrophysiological characterizations, which could potentially bridge cellular and molecular sex differences with sexually dimorphic brain functions and behaviors, remains scant. Here, focusing on an evolutionarily conserved sexually dimorphic nucleus, we investigated sex differences in electrophysiological properties of mPOA neurons and its modulation by gonadal hormones in adult males via in vitro whole-cell patch clamp. As a result, we identified novel sex differences in electrophysiological properties that likely contribute to sexually dimorphic display of behaviors and physiological functions.

neuroscience↗