NAAA-regulated lipid signaling in monocytes controls the induction of hyperalgesic priming in mice.

Circulating monocytes participate in pain chronification but the molecular events that cause their deployment are unclear. Using a mouse model of hyperalgesic priming (HP), we show that monocytes enable progression to pain chronicity through a mechanism that requires transient activation of the hydrolase, N-acylethanolamine acid amidase (NAAA), and the consequent suppression of NAAA-regulated lipid signaling at peroxisome proliferator-activated receptor-α (PPAR-α). Inhibiting NAAA in the 72 hours following administration of a priming stimulus prevented HP. This effect was phenocopied by NAAA deletion and depended on PPAR-α recruitment. Mice lacking NAAA in CD11b+ cells - monocytes, macrophages, and neutrophils - were resistant to HP induction. Conversely, mice overexpressing NAAA or lacking PPAR-α in the same cells were constitutively primed. Depletion of monocytes, but not resident macrophages, generated mice that were refractory to HP. The results identify NAAA-regulated signaling in monocytes as a control node in the induction of HP and, potentially, the transition to pain chronicity.

Frequent low-impact exposure to THC during adolescence causes persistent sexually dimorphic alterations in the response to viral infection in mice.

Adolescent exposure to Δ9-tetrahydrocannabinol (THC) has enduring effects on energy metabolism and immune function. Prior work showed that daily administration of a low-impact dose of THC (5 mg/kg, intraperitoneal) during adolescence alters transcription in adult microglia and disrupts their response to bacterial endotoxin or social stress. To explore the lasting impact of adolescent THC exposure on the brain's reaction to viral infection, we administered THC (5 mg/kg, intraperitoneal) in male and female mice once daily on postnatal day (PND) 30-43. When the mice reached adulthood (PND 70), we challenged them with the viral mimic, polyinosinic acid:polycytidylic acid [Poly(I:C)], and assessed sickness behavior (motor activity, body temperature) and whole brain gene transcription. Poly(I:C) caused an elevation in body temperature which was lessened by prior THC exposure in female but not male mice. Adolescent THC exposure did not affect the locomotor response to Poly(I:C) in either sex. Transcriptomic analyses showed that Poly(I:C) produced a substantial upregulation of immune-related genes in the brain, which was decreased by THC in females. Additionally, the viral mimic caused a male-selective downregulation in transcription of genes involved in neurodevelopment and synaptic transmission, which was abrogated by adolescent THC treatment. The results indicate that Poly(I:C) produces complex transcriptional alterations in the mouse brain, which are sexually dimorphic and differentially affected by early-life THC exposure. In particular, adolescent THC dampens the brain's antiviral response to Poly(I:C) in female mice and prevents the transcriptional downregulation of neuron-related genes caused by the viral mimic in male mice.

Metabolic complications of obesity in children and adolescents.

The global prevalence of childhood and adolescent obesity, exacerbated by the COVID-19 pandemic, is affecting not only school-aged children but also preschoolers. Early-onset obesity, along with a higher risk of metabolic complications, may contribute to a lower age of onset of cardiovascular disease (CVD). As metabolic diseases such as diabetes, dyslipidemia, and non-alcoholic fatty liver disease (NAFLD) observed in adulthood are increasingly recognized in the pediatric population, there is an emphasis on moving disease susceptibility assessment from adulthood to childhood for early detection. Unlike adults, there is a lack of consensus in the definition of metabolic diseases in children. In response to this, various indicators such as pediatric simple metabolic syndrome score (PsiMS), continuous metabolic syndrome score (cMetS), single point insulin sensitivity estimator (SPISE), and fatty liver index (FLI) have been proposed in several studies. These indicators may help explain and early detect metabolic complications associated with pediatric obesity, although more validity studies are needed. Meanwhile, obesity assessment is shifting its perspective from visual obesity to metabolic health and body composition considerations to fill the gap in health impact assessment. Sarcopenic obesity, defined as muscle-to-fat ratio (MFR), has been proposed in pediatric populations and has also been found to be associated with metabolic health in children and adolescents. The National health screening program for children in Korea has expanded but still faces limitations in laboratory testing. These tests facilitate timely intervention by identifying high-risk groups for metabolic complications. Early detection and intervention through comprehensive health screening are critical to mitigate long-term complications of childhood obesity.

Microtubule-destabilizing agents enhance STING-mediated innate immune response via biased mechanism in human monocyte cells.

The stimulator of the interferon gene (STING) signaling pathway acts as a primary defense system against DNA pathogens. Because of the crucial role of STING in type I interferon (IFN) response and innate immunity, extensive research has been conducted to elucidate the roles of various effector molecules involved in STING-mediated signal transduction. However, despite the substantial contribution of microtubules to the immune system, the association between the STING signaling pathway and microtubules remains unclear. In this study, we revealed that the modulation of STING via microtubule-destabilizing agents (MDAs) specifically induced type I IFN responses rather than inflammatory responses in human monocytes. Co-treatment of MDAs with STING agonists induced the elevation of phospho-TANK-binding kinase 1 (TBK1), amplifying the innate immune response. However, during the deficiency of TBK1, the non-canonical signaling pathway through nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) contributed to MDA-induced STING activation in type I IFN response which suggested the versatile regulation of MDA in STING-mediated immunity.

Discovery of novel amidobenzimidazole derivatives as orally available small molecule modulators of stimulator of interferon genes for cancer immunotherapy.

Stimulator of interferon genes (STING) agonists show promise as immunomodulatory agents for cancer therapy. In this study, we report the discovery of a novel orally available STING agonist, SAP-04, that exhibits potent immunomodulatory effects for cancer therapy. By optimizing the amidobenzimidazole core with various pyridine-based heterocyclic substituents, we identified a monomeric variant that displayed more efficient STING agonistic activity than the corresponding dimer. SAP-04 efficiently induced cytokine secretion related to innate immunity by directly binding of the compound to the STING protein, followed by sequential signal transduction for the STING signaling pathway and type I interferon (IFN) responses. Further pharmacological validation in vitro and in vivo demonstrated the potential utility of SAP-04 as an immunomodulatory agent for cancer therapy in vivo. The in vivo anticancer effect was observed in a 4T1 breast tumor syngeneic mouse model through oral administration of the compound. Our findings suggest a possible strategy for developing synthetically accessible monomeric variants as orally available STING agonists.

Evaluation on the Nutrition Quotient Scores of Elderly People Living Alone in Korea.

As the Korean society is aging rapidly, the issues on physical, social, economic, and mental disabilities of single-person households aged 65 years or older has also increased. This study aimed to investigate the nutrition-related dietary conditions of elderly people living alone and determine their dietary behavior by calculating the nutrition quotient for elderly (NQ-E). One hundred and three elderly people living alone who were basic living recipients were recruited from six senior welfare centers in Seoul, and the data were collected using a questionnaire from 19 July 2016 to 17 August 2016, with a 1:1 in-depth interview using the modified version of the NQ-E questionnaire. The data were analyzed using SPSS 27.0 for Mac (IBM Corp., Armonk, NY, USA); a p value of <0.05 was considered significant. The nutrition-related dietary conditions of the elderly living alone were limited, and many of them received support from the government, which helped improve their diet. The nutrition quotient score of the elderly living alone was 50.14, which was lower than the NQ-E mean score (57.6) of the Korean elderly and the NQ-E (62 points), which is the top 25% of the national survey subjects according to the criteria value presented by the Korean Nutrition Society. Elderly people living alone often have poor dietary habits and nutritional status. The NQ-E presented in this study can be used to evaluate the dietary conditions of the elderly and is expected to be used as an indicator for developing community programs for health promotion and evaluating their effectiveness.

Stretchable Gold Nanomembrane Electrode with Ionic Hydrogel Skin-Adhesive Properties.

Skin has a dynamic surface and offers essential information through biological signals originating from internal organs, blood vessels, and muscles. Soft and stretchable bioelectronics can be used in wearable machines for long-term stability and to continuously obtain distinct bio-signals in conjunction with repeated expansion and contraction with physical activities. While monitoring bio-signals, the electrode and skin must be firmly attached for high signal quality. Furthermore, the signal-to-noise ratio (SNR) should be high enough, and accordingly, the ionic conductivity of an adhesive hydrogel needs to be improved. Here, we used a chitosan-alginate-chitosan (CAC) triple hydrogel layer as an interface between the electrodes and the skin to enhance ionic conductivity and skin adhesiveness and to minimize the mechanical mismatch. For development, thermoplastic elastomer Styrene-Ethylene-Butylene-Styrene (SEBS) dissolved in toluene was used as a substrate, and gold nanomembranes were thermally evaporated on SEBS. Subsequently, CAC triple layers were drop-casted onto the gold surface one by one and dried successively. Lastly, to demonstrate the performance of our electrodes, a human electrocardiogram signal was monitored. The electrodes coupled with our CAC triple hydrogel layer showed high SNR with clear PQRST peaks.

Development of a novel histone deacetylase inhibitor unveils the role of HDAC11 in alleviating depression by inhibition of microglial activation.

Histone deacetylases (HDACs) are key epigenetic regulators and classified into four subtypes. Despite the various roles of each HDAC isoform, the lack of selective HDAC inhibitors has limited the elucidation of their roles in biological systems. HDAC11, the sole class-IV HDAC, is highly expressed in the brain, however, the role of HDAC11 in microglia is not fully understood. Based on the modification of MC1568, we developed a novel HDAC inhibitor, 5. Interestingly, 5 suppresses lipopolysaccharide-induced microglial activation by the initiation of autophagy and subsequent inhibition of nitric oxide production. Furthermore, we demonstrated that 5 significantly alleviates depression-like behavior by inhibiting microglial activation in mouse brain. Our discovery reveals that specific pharmacological regulation of HDAC11 induces autophagy and reactive nitrogen species balance in microglia for the first time, which makes HDAC11 a new therapeutic target for depressive disorder.

Effectiveness of creating digital twins with different digital dentition models and cone-beam computed tomography.

Distortion of dentition may occur in cone-beam computed tomography (CBCT) scans due to artifacts, and further imaging is frequently required to produce digital twins. The use of a plaster model is common; however, it has certain drawbacks. This study aimed to assess the feasibility of different digital dentition models over that of plaster casts. Plaster models, alginate impressions, intraoral scan (IOS) images, and CBCT images of 20 patients were obtained. The desktop model scanner was used to scan the alginate impression twice, five minutes and two hours after impression-making. Using an IOS, the full arch was scanned in segments using CS 3600 and simultaneously with i700 wireless. The digital twins obtained from the alginate impression and IOS were superimposed with those obtained from the plaster cast. The differences and distances at each reference point were measured. Scans of alginate impressions after two hours showed the greatest discrepancies, but these were all less than the CBCT voxel size of 0.39 mm. Alginate impression scans and IOS are suitable supplements to CBCT compared to the plaster model. Accuracy can be improved by scanning the alginate impression within five minutes or by intraoral scanning of the entire arch with segmentation.

Adolescent exposure to low-dose THC disrupts energy balance and adipose organ homeostasis in adulthood.

One of cannabis' most iconic effects is the stimulation of hedonic high-calorie eating-the "munchies"-yet habitual cannabis users are, on average, leaner than non-users. We asked whether this phenotype might result from lasting changes in energy balance established during adolescence, when use of the drug often begins. We found that daily low-dose administration of cannabis' intoxicating constituent, Δ9-tetrahydrocannabinol (THC), to adolescent male mice causes an adult metabolic phenotype characterized by reduced fat mass, increased lean mass and utilization of fat as fuel, partial resistance to diet-induced obesity and dyslipidemia, enhanced thermogenesis, and impaired cold- and ß-adrenergic receptor-stimulated lipolysis. Further analyses revealed that this phenotype is associated with molecular anomalies in the adipose organ, including ectopic overexpression of muscle-associated proteins and heightened anabolic processing. Thus, adolescent exposure to THC may promote an enduring "pseudo-lean" state that superficially resembles healthy leanness but might in fact be rooted in adipose organ dysfunction.

Signalling by senescent melanocytes hyperactivates hair growth.

Niche signals maintain stem cells in a prolonged quiescence or transiently activate them for proper regeneration1. Altering balanced niche signalling can lead to regenerative disorders. Melanocytic skin nevi in human often display excessive hair growth, suggesting hair stem cell hyperactivity. Here, using genetic mouse models of nevi2,3, we show that dermal clusters of senescent melanocytes drive epithelial hair stem cells to exit quiescence and change their transcriptome and composition, potently enhancing hair renewal. Nevus melanocytes activate a distinct secretome, enriched for signalling factors. Osteopontin, the leading nevus signalling factor, is both necessary and sufficient to induce hair growth. Injection of osteopontin or its genetic overexpression is sufficient to induce robust hair growth in mice, whereas germline and conditional deletions of either osteopontin or CD44, its cognate receptor on epithelial hair cells, rescue enhanced hair growth induced by dermal nevus melanocytes. Osteopontin is overexpressed in human hairy nevi, and it stimulates new growth of human hair follicles. Although broad accumulation of senescent cells, such as upon ageing or genotoxic stress, is detrimental for the regenerative capacity of tissue4, we show that signalling by senescent cell clusters can potently enhance the activity of adjacent intact stem cells and stimulate tissue renewal. This finding identifies senescent cells and their secretome as an attractive therapeutic target in regenerative disorders.

Identification of (-)-Epigallocateshin gallate derivatives promoting innate immune activation via 2',3'-cyclic GMP-AMP-stimulator of interferon genes pathway.

(-)-Epigallocatehin-3-gallate (EGCG) is a catechin derived from green tea, which has been widely studied for its anti-oxidant and anti-tumor properties. Although EGCG plays important roles in various biological processes, the its effect on the immune system is not fully understood. In this study, we investigated the potential of EGCG as an activator of the stimulator of interferon genes (STING) pathway in the immune system. The cyclic GMP-AMP synthase (cGAS)-2-3-cyclic GMP-AMP (cGAMP)-STING pathway is crucial in the innate immune response to microbial infections, autoimmunity, and anticancer immunity. We confirmed that EGCG enhanced the immune response of cGAMP and identified E2 from 13 synthetic derivatives of EGCG. E2 specifically activated the interferon (IFN) signaling pathway specifically through STING- and cGAMP-dependent mechanisms. These results demonstrate the potential of EGCG and its derivatives as new STING activators that can stimulate the type I interferon response by boosting cGAMP-mediated STING activity.

Adolescent exposure to low-dose Δ9-tetrahydrocannabinol depletes the ovarian reserve in female mice.

Cannabis use by adolescents is widespread, but its effects on the ovaries remain largely unknown. Δ9-tetrahydrocannabinol (THC) exerts its pharmacological effects by activating, and in some conditions hijacking, cannabinoid receptors (CBRs). We hypothesized that adolescent exposure to THC affects ovarian function in adulthood. Peripubertal female C57BL/6N mice were given THC (5 mg/kg) or its vehicle, once daily by intraperitoneal injection. Some mice received THC from postnatal day (PND) 30-33 and their ovaries were harvested PND34; other mice received THC from PND30-43, and their ovaries were harvested PND70. Adolescent treatment with THC depleted ovarian primordial follicle numbers by 50% at PND70, 4 weeks after the last dose. The treatment produced primordial follicle activation, which persisted until PND70. THC administration also caused DNA damage in primary follicles and increased PUMA protein expression in oocytes of primordial and primary follicles. Both CB1R and CB2R were expressed in oocytes and theca cells of ovarian follicles. Enzymes involved in the formation (N-acylphosphatidylethanolamine phospholipase D) or deactivation (fatty acid amide hydrolase) of the endocannabinoid anandamide were expressed in granulosa cells of ovarian follicles and interstitial cells. Levels of mRNA for CBR1 were significantly increased in ovaries after adolescent THC exposure, and upregulation persisted for at least 4 weeks. Our results support that adolescent exposure to THC may cause aberrant activation of the ovarian endocannabinoid system in female mice, resulting in substantial loss of ovarian reserve in adulthood. Relevance of these findings to women who frequently used cannabis during adolescence warrants investigation.

Estimation of nutrient sources and fate in groundwater near a large weir-regulated river using multiple isotopes and microbial signatures.

The excessive input of nutrients into groundwater can accelerate eutrophication in associated surface water systems. This study combined hydrogeochemistry, multi isotope tracers, and microbiological data to estimate nutrient sources and the effects of groundwater-surface water interactions on the spatiotemporal variation of nutrients in groundwater connected to a large weir-regulated river in South Korea. δ11B and δ15N-NO3- values, in combination with a Bayesian mixing model, revealed that manure and sewage contributed 40 % and 25 % respectively to groundwater nitrate, and 42 % and 27 % to nitrate in surface water during the wet season. In the dry season, the source apportionment was similar for groundwater while the sewage contribution increased to 52 % of nitrate in river water. River water displayed a high correlation between NO3- concentration and cyanobacteria (Microcystis and Prochlorococcus) in the wet season. The mixing model using multiple isotopes indicated that manure-derived nutrients delivered with increased contributions of groundwater to the river during the wet season governed the occurrence of cyanobacterial blooms in the river. We postulate that the integrated approach using multi-isotopic and microbiological data is highly effective for evaluating nutrient sources and for delineating hydrological interactions between groundwater and surface water, as well as for investigating surface water quality including eutrophication in riverine and other surface water systems.

An Oscillatory Path to Vaccination: The Roles of Normative and Epistemic Factors in Explaining Vaccination Hesitancy in COVID-19.

This study examined the roles of normative and epistemic factors in influencing individuals' reluctance to be vaccinated during the COVID-19 pandemic. Individuals' ethical orientations (IEO; teleology vs. deontology) were introduced as normative characteristics, while COVID-19 vaccine conspiracy beliefs and vaccine knowledge were addressed as issue-specific epistemic factors. We conducted two online surveys to investigate each of these three factors' influences on the level of Americans' reluctance to receive COVID-19 vaccines. Combinations of these factors that predict COVID-19 vaccination hesitancy levels were also explored to provide integrated perspectives in the specific vaccination context. Our findings demonstrated the positive association between IEO and reluctance to receive COVID-19 vaccines. Significant interactions between 1) COVID-19 vaccine conspiracy beliefs and IEO and 2) conspiracy beliefs and vaccine knowledge were also identified. Implications, limitations, and suggestions for future study were addressed.

The effects of standardized ileal digestible His to Lys ratio on growth performance, intestinal health, and mobilization of histidine-containing proteins in pigs at 7 to 11 kg body weight.

The objectives were to evaluate the effects of standardized ileal digestible (SID) His:Lys ratio above the current NRC requirement on growth performance, intestinal health, and mobilization of His-containing proteins, including hemoglobin, carnosine, and trypsinogen, in nursery pigs from 7 to 11 kg body weight (BW). Forty pigs (26 d of age; initial BW of 7.1 ±â€…0.5 kg) were allotted to 5 dietary treatments based on a randomized complete block design with sex and initial BW as blocks. Dietary treatments were supplemented with varying SID His to Lys ratios of 26%, 32%, 38%, 43%, and 49% and fed to pigs for 14 d (SID Lys = 1.22%). Feed intake and BW were recorded at d 0, 7, and 14 to measure growth performance. Blood samples were collected on d 12. Pigs were euthanized on d 14 to collect pancreas, longissimus dorsi muscles, mid-jejunum, and jejunal mucosa. Data were analyzed using the Proc Mixed of SAS. Growth performance was not affected, whereas varying SID His to Lys ratio affected hemoglobin (P < 0.05, max: 12 g/dL at 36%), immunoglobulin A (IgA, P < 0.05, min: 1.25 µg/mg at 35%) in jejunal mucosa, villus height (P = 0.065, max: 536 µm at 40%) in jejunum, trypsinogen (P = 0.083, max: 242 pg/mg at 41%) in pancreas, and carnosine (P = 0.051, max: 4.7 ng/mg at 38%) in muscles. Varying SID His to Lys ratios linearly increased (P < 0.05, from 1.95 to 2.80 nmol/mg) protein carbonyl in muscles and decreased (P < 0.05, from 29.1% to 26.9%) enterocyte proliferation. In conclusion, SID His to Lys ratio between 35% and 41% in diets fed to nursery pigs at 7 to 11 kg enhanced intestinal health and maximized concentrations of His-containing proteins, indicating that His-containing proteins are effective response criteria when determining His requirement.

Histidine is an essential amino acid for protein synthesis, but it also plays a vital role in the metabolic system of pigs. An accurate assessment of His requirement provides pivotal information for efficient growth and health of pigs. Growth performance and plasma His concentration have been used to assess His requirement, but they may not be the effective parameters due to the contribution of His from mobilization of His-containing proteins, such as hemoglobin, carnosine, and pancreatic enzymes. Hemoglobin is a transport protein and the main component in red blood cells, enabling oxygen transport throughout the body. Most carnosine is stored in muscles at 3 to 4 g/kg wet weight and has antioxidative effects to prevent cells from oxidative damages. In addition, His has a critical role in serine peptidases as a part of the catalytic triad. In this study, growth performance did not respond to His deficiency due to the compensation of His from His-containing proteins and potentially due to a short experimental period. Standardized ileal digestible His to Lys ratio between 35% and 41% maximized concentrations of His-containing proteins and enhanced intestinal health in pigs at 7 to 11 kg body weight. This study indicated that hemoglobin, carnosine, and trypsinogen are effective response criteria when determining His requirement.

Nano-Theranostic Modality for Visualization of the Placenta and Photo-Hyperthermia for Potential Management of Ectopic Pregnancy.

Ectopic pregnancy (EP) is the leading cause of maternity-related death in the first trimester of pregnancy. Approximately 98% of ectopic implantations occur in the fallopian tube, and expedient management is crucial for preventing hemorrhage and maternal death in the event of tubal rupture. Current ultrasound strategies misdiagnose EP in up to 40% of cases, and the failure rate of methotrexate treatment for confirmed EP exceeds 10%. Here the first theranostic strategy for potential management of EP is reported using a near-infrared naphthalocyanine dye encapsulated within polymeric nanoparticles. These nanoparticles preferentially accumulate in the developing murine placenta within 24 h following systemic administration, and enable visualization of implantation sites at various gestational stages via fluorescence and photoacoustic imaging. These nanoparticles do not traverse the placental barrier to the fetus or impact fetal development. However, excitation of nanoparticles localized in specific placentas with focused NIR light generates heat (>43 °C) sufficient for disruption of placental function, resulting in the demise of targeted fetuses with no effect on adjacent fetuses. This novel approach would enable diagnostic confirmation of EP when current imaging strategies are unsuccessful, and elimination of EP could subsequently be achieved using the same nano-agent to generate localized hyperthermia resulting in targeted placental impairment.

Poly(aspartic acid)-Based Polymeric Nanoparticle for Local and Systemic mRNA Delivery.

Recently, therapeutics based on mRNA (mRNA) have attracted significant interest for vaccines, cancer immunotherapy, and gene editing. However, the lack of biocompatible vehicles capable of delivering mRNA to the target tissue and efficiently expressing the encoded proteins impedes the development of mRNA-based therapies for a variety of diseases. Herein, we report mRNA-loaded polymeric nanoparticles based on diethylenetriamine-substituted poly(aspartic acid) that induce protein expression in the lungs and muscles following intravenous and intramuscular injections, respectively. Animal studies revealed that the amount of polyethylene glycol (PEG) on the nanoparticle surface affects the translation of the delivered mRNA into the encoded protein in the target tissue. After systemic administration, only mRNA-loaded nanoparticles modified with PEG at a molar ratio of 1:1 (PEG/polymer) induce protein expression in the lungs. In contrast, protein expression was detected only following intramuscular injection of mRNA-loaded nanoparticles with a PEG/polymer ratio of 10:1. These findings suggest that the PEG density on the surface of poly(aspartic acid)-based nanoparticles should be optimized for different delivery routes depending on the purpose of the mRNA treatment.

Diet-Induced Obesity Disrupts Histamine-Dependent Oleoylethanolamide Signaling in the Mouse Liver.

INTRODUCTION: Previous work suggests the existence of a paracrine signaling mechanism in which histamine released from visceral mast cells into the portal circulation contributes to fasting-induced ketogenesis by stimulating biosynthesis of the endogenous high-affinity PPAR-α agonist oleoylethanolamide (OEA). METHODS: Male C57Bl/6J mice were rendered obese by exposure to a high-fat diet (HFD; 60% fat). We measured histamine, OEA, and other fatty-acid ethanolamides by liquid-chromatography/mass spectrometry, gene transcription by RT-PCR, protein expression by ELISA, neutral lipid accumulation in the liver using Red Oil O and BODIPY staining, and collagen levels using picrosirius red staining. RESULTS: Long-term exposure to HFD suppressed both fasting-induced histamine release into portal blood and histamine-dependent OEA production in the liver. Additionally, subchronic OEA administration reduced lipid accumulation, inflammatory responses, and fibrosis in the liver of HFD-exposed mice. DISCUSSION: The results suggest that disruption of histamine-dependent OEA signaling in the liver might contribute to pathology in obesity-associated liver steatosis.

Frequent Low-Dose Δ9-Tetrahydrocannabinol in Adolescence Disrupts Microglia Homeostasis and Disables Responses to Microbial Infection and Social Stress in Young Adulthood.

BACKGROUND: During adolescence, microglia are actively involved in neocortical maturation while concomitantly undergoing profound phenotypic changes. Because the teenage years are also a time of experimentation with cannabis, we evaluated whether adolescent exposure to the drug's psychotropic constituent, Δ9-tetrahydrocannabinol (THC), might persistently alter microglia function. METHODS: We administered THC (5 mg/kg, intraperitoneal) once daily to male and female mice from postnatal day (PND) 30 to PND44 and examined the transcriptome of purified microglia in adult animals (PND70 and PND120) under baseline conditions or following either of two interventions known to recruit microglia: lipopolysaccharide injection and repeated social defeat. We used high-dimensional mass cytometry by time-of-flight to map brain immune cell populations after lipopolysaccharide challenge. RESULTS: Adolescent THC exposure produced in mice of both sexes a state of microglial dyshomeostasis that persisted until young adulthood (PND70) but receded with further aging (PND120). Key features of this state included broad alterations in genes involved in microglia homeostasis and innate immunity along with marked impairments in the responses to lipopolysaccharide- and repeated social defeat-induced psychosocial stress. The endocannabinoid system was also dysfunctional. The effects of THC were prevented by coadministration of either a global CB1 receptor inverse agonist or a peripheral CB1 neutral antagonist and were not replicated when THC was administered in young adulthood (PND70-84). CONCLUSIONS: Daily low-intensity CB1 receptor activation by THC during adolescence may disable critical functions served by microglia until young adulthood with potentially wide-ranging consequences for brain and mental health.