Biology subjects

Mackie, K.

Publications and source records attributed to Mackie, K..

At least 19 recordsLinked to original sources

bioRxiv2026

Morphine causes distinct changes in the lipidome throughout the brain and body after acute or chronic administration: implications for novel endogenous lipid signaling systems involved in opioid reward and withdrawal

A growing body of evidence demonstrates that signaling pathways of endogenous lipids (endolipids) modulate the reinforcing properties of opioids including reward and withdrawal. Many of these studies are focused on the endocannabinoid (eCB) system, and its primary eCB ligands, Anandamide (AEA) and 2-arachidonoylglycerol (2-AG). The central hypothesis is that modulation of the eCB system through eCB receptors and enzymes may improve therapeutic outcomes for opioid use disorder (OUD). However, outcomes in preclinical and clinical studies using the low efficacy, CB1/CB2 orthosteric agonist, THC, found limited to no effectiveness, suggesting that targeting this aspect of CB1/CB2 is not a useful therapeutic tool for OUD. Previous studies finding that genetic deletion or pharmacological inhibition of endolipid-regulating enzymes (including eCBs) can alter behavioral sensitivity to opioids provide insight into an alternative approach. If opioid use dysregulates a wide range of endolipid biosynthesis and metabolism, then a clearer understanding of these changes, especially in signaling ligands, will provide a novel avenue to both understand the underlying physiological changes with opioid use as well as providing novel targets for therapeutic interventions. In this study, we tested the hypothesis that if morphine dysregulates multiple endolipid signaling systems in the brain and body, and this dysregulation evolves over time, then these differential effects will be measurable by changes in endolipid levels. Using an Acute (30 minutes post injection 20mg/kg) and a Chronic paradigm (5 days, twice daily, 20mg to 100mg/kg escalating dose) we measured 100 targeted endolipids in 8 brain regions, plasma, liver, and feces in male mice. In the Acute condition, we found that the most screened endolipids were changed in the striatum (42%), while the fewest were changed in the thalamus (19%) and 38% in the plasma. In the Chronic condition, 79% of plasma endolipids were changed. The highest level of change in the CNS was in the cortex (39%). Levels of AEA and 2-AG were largely unchanged; however, levels of the N-acyl GABAs, N-acyl valines, N-acyl taurines, and specific bile acids (e.g. DCA, TCA) showed the most dynamic changes by treatment group. These results provide information on novel endolipid signaling pathways that may contribute to the unwanted side effects of opioids, such as dependence and withdrawal, and provide novel avenues for the development of therapeutic strategies.

neuroscience↗

bioRxiv2026

Engineering human myelin microphysiological systems for testing patient treatment response in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system characterized by neuroinflammation, demyelination, and neurodegeneration, associated with a complex interplay between the innate and adaptive immune systems. Currently, no cure is available for MS, and personalized disease-modifying treatment remains largely limited, partially due to the lack of preclinical human models that can faithfully recapitulate disease pathology and evaluate treatment responses at the individual-patient level. Here, we report a human myelin microphysiological system (myelin MPS) platform that recaptures disease phenotype and treatment response for testing patient treatment response. By culturing neural organoids on 3D-printed devices containing directional microfibers, followed by coculture with oligodendrocyte progenitor cells, 96 myelin MPS models can be generated within a conventional well plate. Using this myelin MPS platform, autologous T cells and monocytes from MS patients induced substantially greater demyelination than those from healthy donors, accompanied by expansion of proinflammatory T-cell subsets and increased myelin uptake by monocytes/macrophages after coculture with these healthy myelinating neural tissues. Integration of imaging and flow-cytometric features distinguished healthy-donor, untreated-MS, responder, and nonresponder profiles following treatment with prednisone, glatiramer acetate, interferon {beta}-1a, or dimethyl fumarate. Thus, the myelin MPS platform provides a scalable, human pathophysiology-relevant platform for functional phenotyping and individualized treatment-response evaluation in MS.

bioengineering↗

bioRxiv2026

Brain organoid computing for robotic decision-making

Biomimicry has inspired the evolution of robotics toward greater autonomy, adaptability, and symbiosis with humans and dynamic environments. However, current robotic systems still face major challenges in recapitulating the high-efficiency decision-making capabilities of the human brain under complex and dynamic conditions. Here, we present Brainobot, a biohybrid robotic system that establishes a brain organoid controller as a high-level robotic decision-making layer for closed-loop embodiment. By leveraging brain organoid reservoir computing, Brainobot interacts with dynamic environments by receiving and processing sensory inputs and generating motor actions. As a proof-of-concept demonstration, Brainobot is implemented in a humanoid robotic system to perform real-world tasks, including object grasping and laser chasing. Interestingly, Brainobot exhibits unique features, including cross-task adaptivity, high computing efficiency, and low energy consumption. Thus, our approach may provide insights for advancing robotic embodiment and understanding biological decision-making.

bioengineering↗

bioRxiv2026

Transdermal diagnosis and therapy using an integrated acoustofluidic patch

Transdermal biosensing and drug delivery provide convenient, pain-free, and user-friendly solutions for personalized therapy. However, challenges remain in detecting and treating acute diseases, primarily due to current limitations in effective detection of transdermal biomarkers and administration of therapeutics to an individual within a short time window in a real-world environment. Here, we integrate a compact acoustofluidic patch for transdermal sampling, sensing, and delivery in a rapid and automated manner. By leveraging acoustic streaming and 3D-printed microfluidic designs, acoustofluidic sampler and injector modules are assembled for penetration of the skin stratum corneum, precise sampling of skin interstitial fluids, and controlled percutaneous release of therapeutics, respectively. By incorporating an electrochemical sensing module, the integrated patch can be further developed to achieve in situ and rapid detection of transdermal biomarkers and automated transdermal delivery of therapeutics via closed-loop control. As a proof-of-concept application, we demonstrate our approach can detect and reverse life-threatening acute allergic reactions in a mouse model of anaphylaxis by rapid sampling and sensing transdermal histamine followed by automated transdermal delivery of epinephrine. The innovative acoustofluidic patch may enable a new kind of transdermal devices for personalized therapy of various acute diseases.

bioengineering↗

bioRxiv2026

State-dependent cannabidiol interactions with fentanyl-bound mouse μ-opioid receptor conformations: a three-state molecular dynamics study

We published recently that one of the main constituents of cannabis products, cannabidiol (CBD), is an efficacious negative allosteric modulator (NAM) of the mu opioid receptor (MOR1) (Bosquez-Berger et al., 2023). Here, we investigated how the presence of cannabidiol (CBD) is associated with fentanyl (FEN) binding across MOR1 conformations. We performed molecular dynamics simulations of systems containing FEN alone or FEN+CBD in three mouse MOR1 conformational backgrounds: active-like 5C1M, inactive-like 4DKL, and a modeled Morph50 intermediate between the 5C1M and 4DKL conformations. Three independently seeded 200 ns trajectories were analyzed per model and condition (18 trajectories total), with the trajectory treated as the independent unit. Across the matched 0-200 ns window, consensus CBD contacts and CBD-associated changes in FEN contacts were strongly state dependent. Corrected intracellular TM3 to TM6 analyses separated the expected active-like, intermediate, and inactive-like backgrounds but did not identify a CBD-associated shift that was consistent across both geometric definitions and all three replicates. Equal-weight replicate-composite density maps preserved both the shared ligand distributions and this between-trajectory variability. These descriptive results support receptor-state-dependent CBD, FEN, MOR1 interactions while emphasizing the limited inferential power of three trajectories per condition.

pharmacology and toxicology↗

bioRxiv2026

Cannabidiol attenuates chemotherapy-induced peripheral neuropathic pain through a mechanism that requires the enzyme N-acylphosphatidylethanolamine-specific phospholipase D (NAPE-PLD)

Cannabidiol (CBD) is a non-psychoactive component of cannabis that has been studied as a potential therapy for chronic pain. CBD attenuates behavioral hypersensitivities in models of neuropathic pain, and promotes production of bioactive lipids (e.g., anandamide), altering lipid signaling. However, a lack of understanding of the mechanisms underlying the therapeutic effects of CBD has hindered development and application of CBD to mechanism-based therapies for pain in people. We asked whether the analgesics effects of CBD were dependent upon the enzyme NAPE-PLD. We used a mouse model of chemotherapy-induced peripheral neuropathy (CIPN) to evaluate the acute and chronic antinociceptive effects of CBD and investigate its mechanisms. Pharmacological specificity was tested with antagonists targeting CB1, CB2, PPAR{gamma}, and PPAR receptors. Mechanisms were further examined using NAPE-PLD and GPR55 knockout mice. We also assessed repeated CBD dosing during both the development and maintenance of paclitaxel-induced CIPN in wild-type, GPR55 KO, and NAPE-PLD KO mice. CBD suppressed paclitaxel-induced behavioral hypersensitivities; these effects were attenuated by a PPAR and PPAR{gamma} antagonists, but not CB1 or CB2 antagonists. CBD reduced both the development and maintenance of neuropathic nociception in a model CIPN in wild-type mice, but these effects were absent in NAPE-PLD KO mice. By contrast, anti-allodynic efficacy of CBD was fully preserved in GPR55 KO mice. Pharmacological blockade of the PPAR receptor and genetic deletion of NAPE-PLD abolished the antinociceptive effects of CBD in a model of CIPN, suggesting a pivotal role for NAPE-PLD and PPAR receptors in CBD-mediated analgesia in chemotherapy-induced neuropathic pain.

neuroscience↗

bioRxiv2026

Integrated lipidomic and transcriptomic analyses reveal novel endogenous lipid signaling system regulation in skin and plasma during psoriasiform inflammation

Psoriasis is a chronic inflammatory skin disease characterized by keratinocyte hyperproliferation and immune dysregulation. Emerging clinical and experimental evidence suggests that endogenous lipid (endolipid) signaling systems, including the endocannabinoid system (ECS), represent a promising therapeutic target to treat psoriasis; however, comprehensive characterization of small-molecule endolipids and related proteins in psoriatic skin and their relationship to systemic changes remains limited. Here, we used the imiquimod (IMQ)-induced mouse model of psoriasis to perform combined lipidomic and transcriptional profiling of endolipid signaling in both skin and plasma. Targeted lipidomics revealed a striking divergence between tissues: most endolipids increased in inflamed skin but decreased in plasma, including the canonical ECS lipids anandamide and 2-arachidonoylglycerol. In contrast, selected lipid species, including taurine-conjugated metabolites (both N-acyl taurines and bile acids), were elevated in both tissues, indicating pathway-specific regulation. Targeted transcriptional analysis of whole skin showed reduced expression of key endolipid biosynthetic enzymes (Napepld, Dagla, Daglb) and the cannabinoid receptor Cnr1, while Cnr2 and ECS-related metabolic enzymes remained unchanged. Additional alterations were observed in transcripts involved in related endolipid signaling (Trpv1, Trpv4, Ppara, Pparg, Gpr55), bile acid metabolism (Fxr, Bsep, Fabp4, Fabp5, Cyp27a1, Cyp8b1), and inflammatory pathways (Cox-2). To resolve this apparent discrepancy between lipid levels and gene expression, we performed compartment-specific analyses of epidermal and dermal layers. These revealed a predominantly suppressive epidermal response across multiple ECS-related proteins, contrasted by a more variable dermal profile with selective preservation or upregulation, particularly of Cnr2. Together, these findings demonstrate that psoriasiform inflammation is associated with compartment-specific remodeling of endolipid signaling across skin and systemic compartments, underscoring the functional heterogeneity of epidermal and dermal layers. This dataset provides novel insights into the dysregulation of endolipid signaling systems in psoriasis and provides a foundation for the development of spatially informed, lipid-based therapeutic strategies.

molecular biology↗

bioRxiv2026

Perinatal cannabidiol exposure reshapes astrocyte morphology and tripartite synapse organization in a sex-dependent manner

Cannabidiol (CBD) has recently gained significant public acceptance as a safe therapeutic, contributing to increased use during pregnancy. However, little is known about how maternal CBD exposure impacts fetal brain development. Here, we established a preclinical CBD perinatal exposure (CBD-PCE) model to examine the impacts of CBD on astrocyte morphology in the medial prefrontal cortex (mPFC), a brain region critical for working memory and affective behaviors. Astrocytes play critical roles in maintaining ionic/metabolic homeostasis, neurotransmission, and neurovascular coupling in the CNS. They exhibit highly ramified processes with endfeet surrounding synapses, forming tripartite synapses. We quantitatively assessed the impact of CBD-PCE on astrocyte morphology and the composition of tripartite synapses in mPFC using high-resolution three-dimensional (3D) imaging. Our morphometric analyses revealed that CBD-PCE reduced astrocyte density and increased the number of major branches and whole-cell volume in the mPFC of male, but not female, progenies. Using high-magnification 3D analysis, we found that mPFC astrocytes after CBD-PCE exhibited increased neuropil infiltration volume and reduced surface-to-volume ratios in males but not in females. Moreover, the levels of aquaporin-4 (AQP4) and Kir4.1 inwardly rectifying potassium channel, two key components in regulating ionic homeostasis, are elevated on the membranes of male CBD-PCE astrocytes. We also analyzed mPFC tripartite synapses and observed significant increases in thalamocortical tripartite synapse density in both sexes, whereas intracortical excitatory synapses were reduced only in females. Collectively, these findings demonstrate that CBD-PCE induces sex-specific changes in astrocyte morphology and in the composition of tripartite synapses in the mPFC of the progenys brains.

neuroscience↗

bioRxiv2025

Mice lacking the endocannabinoid-synthesizing enzyme NAPE-PLD exhibit sex-dependent dysregulations in responsiveness to oxycodone and a natural reward

The endogenous opioid and endogenous cannabinoid (endocannabinoid) systems are highly interconnected in the context of drug reward. Bioactive lipids known as N-acylethanolamines (NAEs), and, specifically, anandamide (AEA), influence several unwanted side effects of opioids, including dependence and tolerance. AEA undergoes degradation by the enzyme fatty-acid amide hydrolase (FAAH), whereas the biosynthesis of AEA in vivo is catalyzed by the enzyme N-acyl phosphatidylethanolamine phospholipase-D (NAPE-PLD). AEA and FAAH are implicated in opioid reward, but the impact of genetic deletion of NAPE-PLD on responsiveness to opioids remains unknown. Here we explored the role of NAPE-PLD in behavioral sensitivity to the opioid analgesic oxycodone. We evaluated NAPE-PLD knockout (KO) and wild type (WT) mice of both sexes in preclinical assays that assess either opioid-induced psychomotor responses or voluntary oral consumption of oxycodone. In our studies, genetic deletion of NAPE-PLD produced a shift in sexually dimorphic responses to oxycodone. Psychomotor response to oxycodone was reduced in female NAPE-PLD KO mice but not in males. Female NAPE-PLD KO mice consumed more oral oxycodone that female WT mice, while no genotypic differences in consumption were observed in males. Oxycodone consumption also increased the number of striatal {Delta}FosB positive cells in female WT mice, but not in male WT mice or NAPE-PLD KO mice of either sex. Additionally, NAPE-PLD KO mice of both sexes consumed more sucrose than WT mice. Together, these findings suggest that NAPE-PLD may regulate responses to opioids in a sexually dimorphic manner as the impact of genetic deletion of NAPE-PLD was greater in females than males.

neuroscience↗

bioRxiv2025

Acetaminophen inhibits diacylglycerol lipase synthesis of 2-arachidonoyl glycerol: implications for nociception

SUMMARYThough acetaminophen is a ubiquitous analgesic, its mechanism of action remains unknown. Thus, even though acetaminophen causes ∼500 deaths each year in the US it has not been possible to design safer alternatives. Because endocannabinoids may have a role in acetaminophen action, we examined interactions between the two. We now report that acetaminophen inhibits the activity of diacylglycerol lipase α (DAGLα), but not DAGLβ, decreasing production of the endocannabinoid 2-arachidonoyl glycerol. This gave rise to the counterintuitive hypothesis that decreasing endocannabinoid production by DAGLαinhibitionmay be antinociceptive in certain settings. Supporting this hypothesis, we find that DAGL inhibition by RHC80267 is antinociceptive in wildtype but not CB1 knockout mice in the hotplate test. We propose 1) that activation of DAGLα may exacerbate some forms of nociception and 2) a novel mechanism for the antinociceptive actions of acetaminophen whereby acetaminophen inhibits a DAGLα/CB1-based circuit that plays a permissive role in at least one form of nociception.

neuroscience↗

bioRxiv2024

CB1 and CB2 receptors differentially modulate the cognitive impact of maternal immune activation and perinatal cannabinoid exposure

Maternal immune activation (MIA) commonly arises in response to an infection during pregnancy. MIA elevates cytokine levels, triggering an inflammatory cascade, which may be detrimental to the developing nervous system. Similarly, cannabis use and exposure of the fetus to cannabinoids during pregnancy (PCE) may elicit neuroinflammation and lead to detrimental behavioral outcomes. This is particularly concerning as there has been a notable rise in cannabis use during pregnancy. This study endeavors to examine the interaction between MIA and PCE and elucidate the role of CB1 and CB2 receptors in MIA and PCE outcomes. To this end, we compared the impact of MIA, PCE and MIA+PCE in wildtype, CB1, and CB2 cannabinoid receptor knockout mice of both sexes. PCE was modeled by daily 3 mg/kg THC administration from gestational day 5 (GD5) to postnatal day 10. MIA was modeled by intravenous Poly (I:C) injection at GD16.5. Subsequently, we assessed emotional and cognitive behaviors of adult offspring. Adult male offspring of dams exposed to PCE or MIA were impaired in novel object recognition and the delayed alternation working memory tasks. Interestingly, these behavioral impairments were absent when MIA and PCE were combined. Cannabinoid receptor knockout studies found that CB1 receptors mediated behavioral deficits after PCE. In contrast CB2 receptors were necessary for full expression of MIA-induced behavioral impairments. Although females showed more modest behavioral changes after MIA or PCE, CB1 receptors were required for the PCE deficit and CB2 receptors were required for the MIA deficit also in females. Notably, lack of CB2 receptors in males prevented the "protection" following combined MIA + PCE, while CB1 knockout mice remained protected. Taken together, these results suggest a complex interplay between PCE, MIA and CB1 and CB2 cannabinoid receptors. HighlightsO_LIBoth PCE and MIA impair cognitive behaviors. C_LIO_LICombined PCE and MIA did not affect the cognitive behaviors examined. C_LIO_LICB1 receptors are required for deficits after prenatal cannabis exposure. C_LIO_LICB2 receptors are required for deficits after maternal immune activation. C_LIO_LICB2 receptors are necessary for protection from deficits by combined PCE and MIA. C_LI

pharmacology and toxicology↗

bioRxiv2024

Genetic deletion of NAPE-PLD induces context-dependent dysregulation of anxiety-like behaviors, stress responsiveness, and HPA-axis functionality in mice

The endocannabinoid (eCB) system regulates stress responsiveness and hypothalamic-pituitary-adrenal (HPA) axis activity. The enzyme N-acyl phosphatidylethanolamine phospholipase-D (NAPE-PLD) is primarily responsible for the synthesis of the endocannabinoid signaling molecule anandamide (AEA) and other structurally related lipid signaling molecules known as N-acylethanolamines (NAEs). However, little is known about how activity of this enzyme affects behavior. As AEA plays a regulatory role in stress adaptation, we hypothesized that reducing synthesis of AEA and other NAEs would dysregulate stress reactivity. To test this hypothesis, we evaluated wild type (WT) and NAPE-PLD knockout (KO) mice in behavioral assays that assess stress responsiveness and anxiety-like behavior. NAPE-PLD KO mice exhibited anxiety-like behaviors in the open field test and the light-dark box test after a period of single housing. NAPE-PLD KO mice exhibited a heightened freezing response to the testing environment that was further enhanced by exposure to 2,3,5-trimethyl-3-thiazoline (TMT) predator odor. NAPE-PLD KO mice exhibited an exaggerated freezing response at baseline but blunted response to TMT when compared to WT mice. NAPE-PLD KO mice also exhibited a context-dependent dysregulation of HPA axis in response to TMT in the paraventricular hypothalamic nucleus at a neuronal level, as measured by c-Fos immunohistochemstry. Male, but not female, NAPE-PLD knockout mice showed higher levels of circulating corticosterone relative to same-sex wildtype mice in response to TMT exposure, suggesting a sexually-dimorphic dysregulation of the HPA axis at the hormonal level. Together, these findings suggest the enzymatic activity of NAPE-PLD regulates emotional resilience and recovery from both acute and sustained stress. Significance StatementThe endocannabinoid anandamide (AEA) regulates stress responsiveness and activity of the hypothalamic-pituitary-adrenal (HPA) axis. Currently, little is known about how an enzyme (i.e. N-acylphosphatidylethanolamine phospholipase-D (NAPE-PLD)) involved in the synthesis of AEA affects behavior. We hypothesized that genetic deletion of NAPE-PLD would dysregulate responsiveness to stress at a behavioral and neuronal level. Our studies provide insight into potential vulnerabilities to stress and anxiety that may result from dysregulation of the enzyme NAPE-PLD in people.

neuroscience↗

bioRxiv2024

Vascular network-inspired diffusible scaffolds for engineering functional neural organoids

Organoids, three-dimensional in vitro organ-like tissue cultures derived from stem cells, show promising potential for developmental biology, drug discovery, and regenerative medicine. However, the function and phenotype of current organoids, especially neural organoids, are still limited by insufficient diffusion of oxygen, nutrients, metabolites, signaling molecules, and drugs. Herein, we present Vascular network-Inspired Diffusible (VID) scaffolds to fully recapture the benefits of physiological diffusion physics for generating functional organoids and phenotyping their drug response. In a proof-of-concept application, the VID scaffolds, 3D-printed meshed tubular channel networks, support the successful generation of engineered human midbrain organoids almost without necrosis and hypoxia in commonly used well-plates. Compared to conventional organoids, these engineered organoids develop with more physiologically relevant features and functions including midbrain-specific identity, oxygen metabolism, neuronal maturation, and network activity. Moreover, these engineered organoids also better recapitulate pharmacological responses, such as neural activity changes to fentanyl exposure, compared to conventional organoids with significant diffusion limits. Combining these unique scaffolds and engineered organoids may provide insights for organoid development and therapeutic innovation.

bioengineering↗

bioRxiv2024

Deletion of endocannabinoid synthesizing enzyme DAGLα from cerebellar Purkinje cells decreases social preference and elevates anxiety

The endocannabinoid (eCB) signaling system is robustly expressed in the cerebellum starting from the embryonic developmental stages to adulthood. There it plays a key role in regulating cerebellar synaptic plasticity and excitability, suggesting that impaired eCB signaling will lead to deficits in cerebellar adjustments of ongoing behaviors and cerebellar learning. Indeed, human mutations in DAGL are associated with neurodevelopmental disorders. In this study, we show that selective deletion of the eCB synthesizing enzyme diacylglycerol lipase alpha (Dagl) from mouse cerebellar Purkinje cells (PCs) alters motor and social behaviors, disrupts short-term synaptic plasticity in both excitatory and inhibitory synapses, and reduces Purkinje cell activity during social exploration. Our results provide the first evidence for cerebellar-specific eCB regulation of social behaviors and implicate eCB regulation of synaptic plasticity and PC activity as the neural substrates contributing to these deficits. O_FIG O_LINKSMALLFIG WIDTH=173 HEIGHT=200 SRC="FIGDIR/small/607068v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@1a0a1d8org.highwire.dtl.DTLVardef@e17f34org.highwire.dtl.DTLVardef@665a75org.highwire.dtl.DTLVardef@1bcc7f1_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstract.C_FLOATNO Cerebellar anatomy, morphology of Purkinje cells, localization, density, and spontaneous activity of excitatory and inhibitory synapses are normal in cerebellar-Purkinje-cell-specific Dagl KOs. However, endocannabinoid-dependent short-term synaptic plasticity (DSE and DSI) and activity of Purkinje cells in lobe VI during social exploration are dramatically reduced, and the KO mice exhibit alterations in sensorimotor coordination, deceased social preference, and increased anxiety. C_FIG

neuroscience↗

bioRxiv2024

CB1 Cannabinoid Receptor Agonists Induce Acute Respiratory Depression in Awake Mice

Recreational use of synthetic cannabinoid agonists (i.e., "Spice" compounds) that target the Cannabinoid Type 1 receptor (CB1) can cause respiratory depression in humans. However, {Delta}9-tetrahydrocannabinol (THC), the major psychoactive phytocannabinoid in cannabis, is not traditionally thought to interact with CNS control of respiration, based largely upon sparse labeling of CB1 receptors in the medulla and few reports of clinically significant respiratory depression following cannabis overdose. The respiratory effects of CB1 agonists have rarely been studied in vivo, suggesting that additional inquiry is required to reconcile the conflict between conventional wisdom and human data. Here we used whole body plethysmography to examine the respiratory effects of the synthetic high efficacy CB1 agonist CP55,940, and the low efficacy CB1 agonist {Delta}9-tetrahydrocannabinol in male and female mice. CP55,940 and THC, administered systemically, both robustly suppressed minute ventilation. Both cannabinoids also produced sizable reductions in tidal volume, decreasing both peak inspiratory and expiratory flow - measures of respiratory effort. Similarly, both drugs reduced respiratory frequency, decreasing both inspiratory and expiratory time while markedly increasing expiratory pause, and to a lesser extent, inspiratory pause. Respiratory suppressive effects occurred at lower doses in females than in males, and at many of the same doses shown to produce cardinal behavioral signs of CB1 activation. We next used RNAscope in situ hybridization to localize CB1 mRNA to glutamatergic neurons in the medullary pre-Botzinger Complex, a critical nucleus in controlling respiration. Our results show that, contrary to previous conventional wisdom, CB1 mRNA is expressed in glutamatergic neurons in a brain region essential for breathing and CB1 agonists can cause significant respiratory depression.

neuroscience↗

bioRxiv2024

Cannabinoid CB2 receptors in primary sensory neurons are implicated in CB2 agonist-mediated suppression of paclitaxel-induced neuropathic nociception and sexually-dimorphic sparing of morphine tolerance

Cannabinoid CB2 agonists show therapeutic efficacy without the unwanted side effects commonly associated with direct activation of CB1 receptors. The G protein-biased CB2 receptor agonist LY2828360 attenuates the maintenance of chemotherapy-induced neuropathic nociception in male mice and blocks the development of morphine tolerance in this model. However, the specific cell types involved in this phenomenon have never been investigated and whether this therapeutic profile is observed in female mice remains poorly understood. We used conditional deletion of CB2 receptors from specific cell populations to determine the population(s) mediating the anti-allodynic and morphine-sparing effects of CB2 agonists. Anti-allodynic effects of structurally distinct CB2 agonists (LY2828360 and AM1710) were present in paclitaxel-treated CB2f/f mice of either sex. The anti-allodynic effect of the CB2 agonists were absent in conditional knockout (KO) mice lacking CB2 receptors in peripheral sensory neurons (AdvillinCRE/+; CB2f/f) but preserved in mice lacking CB2 receptors in CX3CR1 expressing microglia/macrophages (CX3CR1CRE/+; CB2f/f). The morphine-sparing effect of LY28282360 occurred in a sexually-dimorphic manner, being present in male mice but absent in female mice of any genotype. In mice with established paclitaxel-induced neuropathy, prior LY2828360 treatment (3 mg/kg per day i.p. x 12 days) blocked the subsequent development of morphine tolerance in male CB2f/f mice but was absent in male (or female) AdvillinCRE/+; CB2f/f mice. LY2828360-induced sparing of morphine tolerance was preserved in male CX3CR1CRE/+; CB2f/f mice, but this effect was not observed in female CX3CR1CRE/+; CB2f/f mice. Similarly, co-administration of morphine with a low dose of LY2828360 (0.1 mg/kg per day i.p. x 6 days) reversed tolerance to the anti-allodynic efficacy of morphine in paclitaxel-treated male CB2f/f mice, but this effect was absent in female CB2f/f mice and AdvillinCRE/+; CB2f/f mice of either sex. Additionally, LY2828360 (3 mg/kg per day i.p. x 8 days) delayed, but did not prevent, the development of paclitaxel-induced mechanical and cold allodynia in either CB2f/f or CX3CR1CRE/+; CB2f/f mice of either sex. Our studies reveal that CB2 receptors in primary sensory neurons are required for the anti-allodynic effects of CB2 agonists in a mouse model of paclitaxel-induced neuropathic nociception. We also find that CB2 agonists acting on primary sensory neurons produce a sexually-dimorphic sparing of morphine tolerance in males, but not female, paclitaxel-treated mice.

neuroscience↗

bioRxiv2023

NAPE-PLD in the ventral tegmental area regulates reward events, feeding and energy homeostasis

The N-acyl phosphatidylethanolamine-specific phospholipase D (NAPE-PLD) catalyzes the production of N-acylethanolamines (NAEs), a family of endogenous bioactive lipids, which are involved in various biological processes ranging from neuronal functions to energy homeostasis and feeding behaviors. Reward-dependent behaviors depend on the dopamine (DA) transmission between the ventral tegmental area (VTA) and the nucleus accumbens (NAc) which conveys reward-values and scales reinforced behaviors. However, whether and how NAPE-PLD may contribute to the regulation of feeding and reward-dependent behaviors has not been investigated yet. This biological question is of paramount importance since NAEs are altered in obesity and metabolic disorders. Here, we show that transcriptomic meta-analysis highlights a potential role for NAPE-PLD within the VTA[->]NAc circuit. Using brain-specific invalidation approaches, we report that the integrity of NAPE-PLD is required for the proper homeostasis of NAEs within the midbrain VTA and it affects food-reward behaviors. Moreover, region-specific knock-down of NAPE-PLD in the VTA resulted in enhanced food-reward seeking and reinforced behaviors which were associated with increased in vivo DA release dynamics in response to both food and non-food-related rewards together with heightened tropism towards food consumption. Furthermore, midbrain knock-down of NAPE-PLD, which led to increased energy expenditure and adapted nutrients partitioning, elicited a relative protection against high-fat diet-mediated body fat gain and obesity-associated metabolic features. In conclusion, these findings unravel a new key role of VTA NAPE-PLD in shaping DA-dependent events, feeding behaviors and energy homeostasis, thus providing new insights on the regulation of body metabolism. Highlights- NAPE-PLD and NAEs are enriched in the VTA and regulate food-reinforced behaviors and reward processes. - NAPE-PLD scales in vivo VTA[->]NAc dopamine dynamics. - NAPE-PLD in the VTA contributes to whole-body energy balance and metabolic efficiency. - Downregulation of VTA NAPE-PLD ameliorates obesity-associated metabolic features.

neuroscience↗

bioRxiv2023

Brain Organoid Computing for Artificial Intelligence

Brain-inspired hardware emulates the structure and working principles of a biological brain and may address the hardware bottleneck for fast-growing artificial intelligence (AI). Current brain-inspired silicon chips are promising but still limit their power to fully mimic brain function for AI computing. Here, we develop Brainoware, living AI hardware that harnesses the computation power of 3D biological neural networks in a brain organoid. Brain-like 3D in vitro cultures compute by receiving and sending information via a multielectrode array. Applying spatiotemporal electrical stimulation, this approach not only exhibits nonlinear dynamics and fading memory properties but also learns from training data. Further experiments demonstrate real-world applications in solving non-linear equations. This approach may provide new insights into AI hardware.

bioengineering↗