Biology subjects

Murphy-Royal, C.

Publications and source records attributed to Murphy-Royal, C..

9 recordsLinked to original sources

bioRxiv2026

Sex-dependent and region-specific morphological adaptations in astrocytes following early-life stress

Astrocytes are structurally heterogeneous, with cell morphology providing a valuable readout of experi-ence-dependent plasticity. Despite this, single-cell reconstruction including complete cellular territories remains challenging to compare across brain regions and experimental groups. We used unilateral retro-orbital delivery of PHP.eB-GfaABC1D-eGFP as a practical method for sparse astrocyte labeling and ap-plied it to evaluate regional, sex, and early-life-stress comparisons in the mouse amygdala. Systemic vi-rus delivery to broadly target astrocytes across the brain produced eGFP-positive cells throughout cortex, hippocampus, hypothalamus, and amygdala with spatially isolated cells suitable for intensity projection, three-dimensional surface reconstruction, filament tracing, and Sholl analysis. In naive females, we report relatively homogenous morphological features between lateral amygdala and basal amygdala. In naive males, basal amygdala astrocytes had greater volume and a lower surface-area-to-volume ratio, while surface area, soma diameter, territory, and arborization measures did not differ significantly. Interestingly, early-life stress produced sex-specific morphological responses in the basal amygdala. Females showed increased perimeter, area, and Feret diameter without significant changes in three-dimensional volume or resolved filament measures. Males instead showed reduced surface area and volume, with no significant changes in projected territorial dimensions, soma diameter or resolved filament measures. S100{beta}-positive cell density was unchanged in the displayed regional and stress comparisons. These findings es-tablish systemic sparse eGFP labeling as an efficient route to single-cell astrocyte morphometry and re-veal a sex-dependent and region-specific dissociation between territorial expansion and three-dimensional volumetric contraction after early-life stress.

neuroscience↗

bioRxiv2026

Lipid droplet lipolysis in POMC neurons regulates energy homeostasis in a sex-specific manner

The hypothalamus is a central regulator of glucose and energy homeostasis, with arcuate nucleus (ARC) neurons orchestrating these processes. Agouti-related peptide (AgRP) and pro-opiomelanocortin (POMC) neurons integrate metabolic cues to control feeding behavior and systemic metabolism. Among these cues, fatty acids (FA) have emerged as key modulators of ARC neuronal activity. While neuronal sensing of circulating FA has begun to be defined, the contribution of FA derived from endogenous lipid stores to ARC neuron function and energy homeostasis remains largely unexplored. We recently identified lipid droplets (LD) as regulated FA reservoirs that control FA availability and metabolism in orexigenic AgRP neurons, thereby modulating their activity and regulating feeding. This prompted us to investigate whether LD-derived FA similarly regulate POMC neuron function. To this end, we targeted adipose triglyceride lipase (ATGL), which catalyzes the first committed step of LD lipolysis, in POMC neurons. We show that LD are present in POMC neurons under basal conditions both in vitro and in vivo, and that pharmacological or genetic inhibition of ATGL increases LD abundance. ATGL deficiency enhances spontaneous firing of POMC neurons and leads to reduced body weight, fat and lean mass in males, but not females. Consistent with enhanced glucose metabolism, ATGL loss lowers glycemia and insulinemia and increases carbohydrate utilization in chow-fed males. In contrast, ATGL deficiency does not alter metabolic adaptations to cold exposure, fasting or diet-induced obesity in either sex. Collectively, these findings establish ATGL-dependent LD lipolysis in POMC neurons as a previously unrecognized, sex-dependent regulator of energy homeostasis.

neuroscience↗

bioRxiv2026

Astrocytic Encoding of Threat in the Basolateral Amygdala

AO_SCPLOWBSTRACTC_SCPLOWThe basolateral amygdala (BLA) has long been implicated in threat detection and the generation of anxiety states. While previous experiments have demonstrated the important role of BLA principal neurons in driving anxiety-related behaviors, population-level recordings suggest that principal neurons encode broad exploratory states rather than anxiety per se. This discrepancy questions whether anxiety is indeed represented within the BLA, or if the BLA reflects a broader representation of behavioral states. Here, using simultaneous in vivo calcium recordings in both astrocytes and principal neurons in the BLA we find that in contrast to neurons, astrocytic activity provides a stable and scalable representation of threat-induced anxiety across an array of behavioral tasks. We find that the magnitude of astrocyte response to threatening stimuli is modulated by the individual anxiety levels of animals, and that exploration of anxiogenic environment can be decoded across multiple tasks using astrocyte activity alone. Our results shed light on a specialized encoding property of BLA astrocytes and establish these cells as key computational elements of threat processing in anxiety circuits.

neuroscience↗

bioRxiv2024

Microglial engulfing of glutamatergic inputs and diminished excitability of D1 medium spiny neurons of the nucleus accumbens by peripheral inflammatory insult

Neuroimmune responses to systemic inflammation can generate anxiodepressive behaviors and psychomotor slowing. The nucleus accumbens (NAc) is a neural hub encoding mood and motivation that contributes to the locomotor and mood dampening effects of neuroinflammation. Dopamine receptor 1 mediums spiny neurons (D1-MSNs) of the NAc regulate locomotor activity, motivated behavior and emotional states and are modulated by microglial reactivity. Here, we evaluated sickness- and anxiety-like behaviors along with D1-MSN activity and microglial responses in the NAc to systemic lipopolysaccharide (LPS) administration. LPS stimulated anxiety-like behavior, blunted locomotion and reduced cFos expression in D1-MSNs of the NAc core and shell of male mice. These effects associated with reduced excitatory inputs (EPSCs) onto D1-MSNs as measured by whole cell patch-clamp. To determine if microglia contribute to changes in MSN activity, Ca2+ imaging of primary cultures containing NAc neurons with or without primary NAc microglia was performed. The presence of microglia decreased the activity of LPS-treated MSNs in response to dopamine and glutamate application and LPS stimulated microglial phagocytosis of MSN processes in co-cultures. Immunohistochemical analyses revealed that in vivo LPS treatment enhanced morphological indices of microglia reactivity and engulfment of vesicular glutamate transporter 1 (VGLUT1) inputs in the NAc. Our results suggest that LPS reduces locomotion and stimulates anxiety via increasing microglia engulfment of excitatory inputs onto D1-MSNs, and highlight changes in NAc microglia phagocytic activity in the behavioral consequences of neuroinflammation.

neuroscience↗

bioRxiv2024

Neuronal lipid droplets play a conserved and sex-biased role in maintaining whole-body energy homeostasis

ABSTRACTLipids are essential for neuron development and physiology. Yet, the central hubs that coordinate lipid supply and demand in neurons remain unclear. Here, we combine invertebrate and vertebrate models to establish the presence and functional significance of neuronal lipid droplets (LD) in vivo. We find that LD are normally present in neurons in a non-uniform distribution across the brain, and demonstrate triglyceride metabolism enzymes and lipid droplet-associated proteins control neuronal LD formation through both canonical and recently-discovered pathways. Appropriate LD regulation in neurons has conserved and male-biased effects on whole-body energy homeostasis across flies and mice, specifically neurons that couple environmental cues with energy homeostasis. Mechanistically, LD-derived lipids support neuron function by providing phospholipids to sustain mitochondrial and endoplasmic reticulum homeostasis. Together, our work identifies a conserved role for LD as the organelle that coordinates lipid management in neurons, with implications for our understanding of mechanisms that preserve neuronal lipid homeostasis and function in health and disease. HIGHLIGHTSO_LILipid droplets (LD) normally form in neurons across species Neuronal LD are regulated by a conserved gene network C_LIO_LINeuronal LD regulation plays a conserved and sex-biased role in maintaining energy homeostasis C_LIO_LILD regulation supports ER and mitochondrial function in hunger-activated neurons C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/613929v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@1936e92org.highwire.dtl.DTLVardef@40478aorg.highwire.dtl.DTLVardef@18d5faorg.highwire.dtl.DTLVardef@882ee9_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

Astrocyte glucocorticoid receptors mediate sex-specific changes in activity following stress

Interactions between orexin neurons and astrocytes in the lateral hypothalamus influence activity levels including circadian and motivated behaviour. These behaviors are disrupted by stress in rodents and form a hallmark of stress-related neuropsychiatric disorders. Here we set out to understand how stress influences activity and the underlying cellular mechanisms. We report that the long-term effects of stress on activity levels correlate with spontaneous firing of orexin neurons with hyperactivity in males and hypoactivity presented by female mice. These neuronal changes were accompanied by extensive astrocyte remodelling. Causal manipulations identified lateral hypothalamic astrocytes as key regulators of activity patterns. In the context of stress, genetic deletion of glucocorticoid receptors in lateral hypothalamic astrocytes rescued the effects of stress on orexin neuron firing, restoring activity to control levels in both males and females. Overall, these data suggest that astrocytic regulation of orexin neuron firing enables the maintenance of activity levels, and their dysfunction drives stress-induced activity dysregulation. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=185 HEIGHT=200 SRC="FIGDIR/small/613499v1_ufig1.gif" ALT="Figure 1"> View larger version (71K): org.highwire.dtl.DTLVardef@1e4b3b9org.highwire.dtl.DTLVardef@1d35774org.highwire.dtl.DTLVardef@12a168org.highwire.dtl.DTLVardef@122d9dc_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

Astrocyte glucocorticoid signaling mediates cognitive impairment induced by early-life stress

Early-life stress can have lifelong consequences, enhancing stress susceptibility and resulting in behavioural and cognitive deficits. While the effects of early-life stress on neuronal function have been well-described, we still know very little about the contribution of non-neuronal brain cells. Investigating the complex interactions between distinct brain cell types is critical to fully understand how cellular changes manifest as behavioural deficits following early-life stress. Here, using male and female mice we report that early-life stress induces anxiety-like behaviour and fear generalisation in an amygdala-dependent learning and memory task. These behavioural changes were associated with impaired synaptic plasticity, increased neural excitability, and astrocyte hypofunction. Genetic perturbation of amygdala astrocyte function by either reducing astrocyte calcium activity or reducing astrocyte network function was sufficient to replicate cellular, synaptic, and fear memory generalisation associated with early-life stress. Our data reveal a role of astrocytes in tuning emotionally salient memory and provide mechanistic links between early-life stress, astrocyte hypofunction, and behavioural deficits. Summary Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=157 SRC="FIGDIR/small/519598v4_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1d9a228org.highwire.dtl.DTLVardef@124ff67org.highwire.dtl.DTLVardef@1fbe186org.highwire.dtl.DTLVardef@19362fb_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2021

A genetically encoded fluorescent biosensor for extracellular L-lactate

To enable investigations of the emerging roles of cell-to-cell shuttling of L-lactate, we have developed an intensiometric green fluorescent genetically encoded biosensor for extracellular L-lactate. We demonstrate that this biosensor, designated eLACCO1.1, enables minimally invasive cellular resolution imaging of extracellular L-lactate in cultured mammalian cells and brain tissue.

molecular biology↗

bioRxiv2020

Obesity-induced astrocyte dysregulation of heterosynaptic plasticity within the orbitofrontal cortex

SO_SCPLOWUMMARYC_SCPLOWOverconsumption of highly palatable, energy dense food is considered a key driver of the obesity pandemic. The orbitofrontal cortex (OFC) is critical for reward valuation of gustatory signals, yet how the OFC adapts to obesogenic diets is poorly understood. Here we show that extended access to a cafeteria diet impairs astrocyte glutamate clearance, which leads to a heterosynaptic depression of GABA transmission onto pyramidal neurons of the OFC. This decrease in GABA tone is due to an increase in extrasynaptic glutamate, which acts via metabotropic glutamate receptors to liberate endocannabinoids. This impaired the induction of endocannabinoid-mediated long-term plasticity. In obese rats, this cascade of synaptic impairments was rescued by restoring astrocyte glutamate transport with the nutritional supplement, N-acetylcysteine. Together, our findings indicate that obesity targets astrocytes to disrupt the delicate balance between excitatory and inhibitory transmission in the OFC. HO_SCPLOWIGHLIGHTSC_SCPLOWO_LIDiet-induced obesity induces hypertrophy of astrocytes and impairs their ability to transport glutamate. C_LIO_LIFailure of astrocytes to clear extrasynaptic glutamate drives endocannabinoid-mediated inhibitory long-term depression of principal output neurons in the OFC. C_LIO_LIAstrocytic glutamate transporter function is restored with NAC, which rescues the synaptic deficits. C_LI

neuroscience↗