FibroScan-aspartate transaminase: A superior non-invasive model for diagnosing high-risk metabolic dysfunction-associated steatohepatitis.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) with hepatic histological NAFLD activity score ≥ 4 and fibrosis stage F ≥ 2 is regarded as "at risk" non-alcoholic steatohepatitis (NASH). Based on an international consensus, NAFLD and NASH were renamed as metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH), respectively; hence, we introduced the term "high-risk MASH". Diagnostic values of seven non-invasive models, including FibroScan-aspartate transaminase (FAST), fibrosis-4 (FIB-4), aspartate transaminase to platelet ratio index (APRI), etc. for high-risk MASH have rarely been studied and compared in MASLD. AIM: To assess the clinical value of seven non-invasive models as alternatives to liver biopsy for diagnosing high-risk MASH. METHODS: A retrospective analysis was conducted on 309 patients diagnosed with NAFLD via liver biopsy at Beijing Ditan Hospital, between January 2012 and December 2020. After screening for MASLD and the exclusion criteria, 279 patients were included and categorized into high-risk and non-high-risk MASH groups. Utilizing threshold values of each model, sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPV), were calculated. Receiver operating characteristic curves were constructed to evaluate their diagnostic efficacy based on the area under the curve (AUROC). RESULTS: MASLD diagnostic criteria were met by 99.4% patients with NAFLD. The MASLD population was analyzed in two cohorts: Overall population (279 patients) and the subgroup (117 patients) who underwent liver transient elastography (FibroScan). In the overall population, FIB-4 showed better diagnostic efficacy and higher PPV, with sensitivity, specificity, PPV, NPV, and AUROC of 26.9%, 95.2%, 73.5%, 72.2%, and 0.75. APRI, Forns index, and aspartate transaminase to alanine transaminase ratio (ARR) showed moderate diagnostic efficacy, whereas S index and gamma-glutamyl transpeptidase to platelet ratio (GPR) were relatively weaker. In the subgroup, FAST had the highest diagnostic efficacy, its sensitivity, specificity, PPV, NPV, and AUROC were 44.2%, 92.3%, 82.1%, 67.4%, and 0.82. The FIB-4 AUROC was 0.76. S index and GPR exhibited almost no diagnostic value for high-risk MASH. CONCLUSION: FAST and FIB-4 could replace liver biopsy as more effectively diagnostic methods for high-risk MASH compared to APRI, Forns index, ARR, S index, and GPR; FAST is superior to FIB-4.

E3 ubiquitin ligase neural precursor cell-expressed developmentally downregulated gene 4 motivates FOXA1 ubiquitination and restrains proliferation of diffuse large B-cell lymphoma cells via the Wnt/ß-Catenin pathway.

Neural precursor cell-expressed developmentally downregulated gene 4 (NEDD4) is an E3 ubiquitin ligase that recognizes substrates via protein-protein interactions and takes part in tumor development. This study aims to clarify NEDD4's functions in diffuse large B-cell lymphoma (DLBCL) and its downstream mechanisms. Collection of 53 DLBCL tissues and adjacent normal lymphoid tissues, and detection of NEDD4 and Forkhead box protein A1 (FOXA1) in the tissues were conducted. The selection of DLBCL cells was for FARAGE, and test of cells' advancement was after transfection. Analysis of NEDD4 and FOXA1's link, and test of Wnt/ß-catenin pathway were implemented. In vivo tumor xenograft experiments were put into effect. Detection of the pathological conditions of tumor tissues and the positive Ki67 in the family was implemented. It came out NEDD4 was reduced in DLBCL tissues and cell lines, and FOXA1 was elevated; Enhancing NEDD4 or repressing FOXA1 refrained DLBCL cells' advancement; NEDD4 could combine with FOXA1 and trigger its ubiquitination and degradation; NEDD4 inactivates the Wnt/ß-catenin pathway by motivating FOXA1 ubiquitination; NEDD4 enhancement refrained DLBCL growth in vivo. In conclusion, the E3 ubiquitin ligase NEDD4 accelerates FOXA1 ubiquitination but refrains DLBCL cell proliferation via the Wnt/ß-Catenin pathway.

Oral oxycodone self-administration leads to features of opioid misuse in male and female mice.

Use of prescription opioids, particularly oxycodone, is an initiating factor driving the current opioid epidemic. There are several challenges with modelling oxycodone abuse. First, prescription opioids including oxycodone are orally self-administered and have different pharmacokinetics and dynamics than morphine or fentanyl, which have been more commonly used in rodent research. This oral route of administration determines the pharmacokinetic profile, which then influences the establishment of drug-reinforcement associations in animals. Moreover, the pattern of intake and the environment in which addictive drugs are self-administered are critical determinants of the levels of drug intake, of behavioural sensitization and of propensity to relapse behaviour. These are all important considerations when modelling prescription opioid use, which is characterized by continuous drug access in familiar environments. Thus, to model features of prescription opioid use and the transition to abuse, we designed an oral, homecage-based oxycodone self-administration paradigm. Mice voluntarily self-administer oxycodone in this paradigm without any taste modification such as sweeteners, and the majority exhibit preference for oxycodone, escalation of intake, physical signs of dependence and reinstatement of seeking after withdrawal. In addition, a subset of animals demonstrate drug taking that is resistant to aversive consequences. This model is therefore translationally relevant and useful for studying the neurobiological substrates of prescription opioid abuse.

Synthesis of polychloromethylated and halogenated spiro[5,5]trienones via dearomative spirocyclization of biaryl ynones.

We disclosed a selective polychloromethylation and halogenation reaction of alkynes via a radical addition/spirocyclization cascade sequence, in which polyhaloalkanes were used as the precursor for polyhalomethyl and halogen radicals. Using this strategy, a series of valuable halogen-, CHCl2- or CCl3-containing spiro[5,5]trienones were synthesized in good yields with good functional group tolerance in one pot under simple and mild conditions. It is noted that an unprecedented halogenation instead of dibromomethylation was achieved when CH2Br2 was used in this work.

Topographic organization underlies intrinsic and morphological heterogeneity of central amygdala neurons expressing corticotropin-releasing hormone.

The central nucleus of the amygdala (CeA) network consists of a heterogeneous population of inhibitory GABAergic neurons distributed across distinct subregions. While the specific roles for molecularly defined CeA neurons have been extensively studied, our understanding of functional heterogeneity within classes of molecularly distinct CeA neurons remains incomplete. In addition, manipulation of genetically defined CeA neurons has produced inconsistent behavioral results potentially due to broad targeting across CeA subregions. Therefore, elucidating heterogeneity within molecularly defined neurons in subdivisions of the CeA is pivotal for gaining a complete understanding of how CeA circuits function. Here, we used a multifaceted approach involving transgenic reporter mice, brain slice electrophysiology, and neuronal morphology to dissect the heterogeneity of corticotropin-releasing hormone (CRH) neurons in topographically distinct subregions of the CeA. Our results revealed that intrinsic and morphological properties of CRH-expressing (CRH+) neurons in the lateral (CeL) and medial (CeM) subdivisions of the CeA were significantly different. We found that CeL-CRH+ neurons are relatively homogeneous in morphology and firing profile. Conversely, CeM-CRH+ neurons displayed heterogeneous electrophysiological and morphological phenotypes. Overall, these results show phenotypic differences between CRH+ neurons in CeL and CeM.

[Clinical Study of Haploid Allogeneic Hematopoietic Stem Cell Transplantation Combined with Post-transplant Cyclophosphamide in Severe Aplastic Anemia Patients].

OBJECTIVE: To evaluate the clinical effect of haploid allogeneic hematopoietic stem cell transplantation(haplo-HSCT) in the treatment of severe aplastic anemia (SAA), and to explore the efficacy different between post-transplant cyclophosphamide (PT/Cy) and standard-dose ATG. METHODS: The clinical data of 38 patients with SAA in our hospital from January 2012 to December 2019 were collected and retrospectively analyzed. The efficacy was evaluated. The patients with haplo-HSCT were divided into low-dose ATG combined with PT/Cy group and standard-dose ATG group, and the blood cell hematopoietic reconstruction time, GVHD incidence, mortality and survival time of the patients in the two groups was compared. RESULTS: Among the 32 patients, hematopoietic reconstitution were detected in 9375%(30/32) recipients. The median time of neutrophil and platelet engraftment was 15(10-22) days and 13(7-30) days, respectively. The incidence of GVHD was 21.89%, the incidence of infection was 93.75%, and the 2-year overall survival rate was 84.38%. The hematopoietic reconstitution time, incidence of GVHD, mortality rate and survival time were no statistical differences between the patients in the two groups(all P>0.05). CONCLUSION: Haplo-HSCT is an effective method for the treatment of SAA，low-dose ATG combined with PT/Cy can lighten the economic burden on patients, it would be a feasible treatment plan for SAA with light side effect.

A photoswitchable GPCR-based opsin for presynaptic inhibition.

Optical manipulations of genetically defined cell types have generated significant insights into the dynamics of neural circuits. While optogenetic activation has been relatively straightforward, rapid and reversible synaptic inhibition has proven more elusive. Here, we leveraged the natural ability of inhibitory presynaptic GPCRs to suppress synaptic transmission and characterize parapinopsin (PPO) as a GPCR-based opsin for terminal inhibition. PPO is a photoswitchable opsin that couples to Gi/o signaling cascades and is rapidly activated by pulsed blue light, switched off with amber light, and effective for repeated, prolonged, and reversible inhibition. PPO rapidly and reversibly inhibits glutamate, GABA, and dopamine release at presynaptic terminals. Furthermore, PPO alters reward behaviors in a time-locked and reversible manner in vivo. These results demonstrate that PPO fills a significant gap in the neuroscience toolkit for rapid and reversible synaptic inhibition and has broad utility for spatiotemporal control of inhibitory GPCR signaling cascades.

[Network Meta-analysis of Chinese patent medicine in treatment of unstable angina pectoris].

Network Meta-analysis was used to compare the efficacy and safety of Chinese patent medicines in the treatment of unstable angina pectoris. PubMed, Cochrane Library, CNKI, Wanfang, VIP and other databases were retrieved by computers from the establishment of the databases to June 2020. Randomized controlled trials(RCTs) of Chinese patent medicines for the treatment of unstable angina pectoris were collected. Two investigators independently screened out the literatures, and extracted data according to the inclusion and exclusion criteria. The quality of the included RCTs was evaluated according to the bias risk assessment tool recommended by the Cochrane System Reviewer Manual, and the Stata 13.0 software was used for data analysis and mapping. Through screening, 28 eligible studies were finally included, with the sample size of 2 885 cases, involving 8 Chinese patent medicines. The results of the network Meta-analysis showed that in terms of total effective rate for angina symptom improvement, the order was as follows: Shenshao Capsules > Naoxintong Capsules > Ginkgo Ketone Ester Dripping Pills > Compound Danshen Dripping Pills > Ginkgo Leaf Tablets > Shexiang Baoxin Pills > Tongxinluo Capsules > Yindan Xinnaotong Soft Capsules; in terms of total effective rate for ECG curative effect, the order was as follows: Ginkgo Ketone Ester Dripping Pills>Compound Danshen Dripping Pills > Tongxinluo Capsules > Shenshao Capsules > Shexiang Baoxin Pills > Yindan Xinnaotong Soft Capsules; in terms of hypersensitivity-C-reactive protein curative effect, the order was as follows: Tongxinluo Capsules > Shenshao Capsules > Ginkgo Leaf Tablets>Compound Danshen Dropping Pills> Shexiang Baoxin Pills > Naoxintong Capsules > Yindan Xinnaotong Soft Capsules > Ginkgo Ketone Ester Dropping Pills. Chinese patent medicine combined with conventional therapy can improve the clinical efficacy of unstable angina pectoris. Due to the differences in the quantity and quality of the included studies, the order results of Chinese patent medicines need to be further verified.

The role of umbilical artery velocities in the clinical assessment of twin-twin transfusion syndrome at stage.

OBJECTIVE: To analyze the discordances of the umbilical artery velocities between pregnancies with twin-twin transfusion syndrome (TTTS) at stage I and those with normal monochorionic-diamniotic (MCDA) twins, and investigate the value of their discordances in predicting TTTS at stage I. METHODS: We recruited 58 twin pregnancies with TTTS at stage I and 60 normal MCDA twin pregnancies in a tertiary referral center retrospectively. The umbilical artery velocities and their discordances were compared between the normal and TTTS twins. RESULTS: The discordances of umbilical artery mean diastolic velocity (UA-MDV), umbilical artery time-averaged maximum velocity (UA-TAmax), umbilical artery peak systolic velocity (UA-PSV), and umbilical artery end-diastolic velocity (UA-EDV) were higher in the TTTS group than in the normal group. In TTTS co-twins, the UA-MDV, UA-TAmax, UA-PSV, and UA-EDV in recipients were higher than those in donors. The discordances of UA-TAmax and UA-PSV were found to be independent predicting factors for TTTS at stage I. CONCLUSION: Co-twin umbilical artery velocity discordances were significantly associated with stage I TTTS. The results suggest that UA-TAmax and UA-PSV might be new parameters for predicting TTTS at stage I.

The complete chloroplast genome of Cryptomeria japonica var. sinensis (Cupressaceae).

The complete chloroplast genome of Cryptomeria japonica var. sinensis Miquel was assembled and analyzed. The chloroplast genome of C. japonica var. sinensis Miquel did not have a typical quadripartite structure with the inverted repeats (IR) absent, and the size of C. japonica var. sinensis is 131,412 bp. The overall GC content was 35.4%. The genome encoded a set of 119 genes, containing 83 protein-coding genes, 32 tRNA genes, and 4 rRNA genes. Phylogenomic analysis indicated that C. japonica var. sinensis is sister to C. japonica (Thunb. ex L. f.) D. Don.

Spared nerve injury differentially alters parabrachial monosynaptic excitatory inputs to molecularly specific neurons in distinct subregions of the central amygdala.

Dissecting the organization of circuit pathways involved in pain affect is pivotal for understanding behavior associated with noxious sensory inputs. The central nucleus of the amygdala (CeA) comprises distinct populations of inhibitory GABAergic neurons expressing a wide range of molecular markers. CeA circuits are associated with aversive learning and nociceptive responses. The CeA receives nociceptive signals directly from the parabrachial nucleus (PBn), contributing to the affective and emotional aspects of pain. Although the CeA has emerged as an important node in pain processing, key questions remain regarding the specific targeting of PBn inputs to different CeA subregions and cell types. We used a multifaceted approach involving transgenic reporter mice, viral vector-mediated optogenetics, and brain slice electrophysiology to delineate cell-type-specific functional organization of the PBn-CeA pathway. Whole-cell patch clamp recordings of molecularly defined CeA neurons while optogenetically driving long-range inputs originating from PBn revealed the direct monosynaptic excitatory inputs from PBn neurons to 3 major subdivisions of the CeA: laterocapsular (CeC), lateral (CeL), and medial (CeM). Direct monosynaptic excitatory inputs from PBn targeted both somatostatin-expressing (SOM+) and corticotropin-releasing hormone expressing (CRH+) neurons in the CeA. We find that monosynaptic PBn input is preferentially organized to molecularly specific neurons in distinct subdivisions of the CeA. The spared nerve injury model of neuropathic pain differentially altered PBn monosynaptic excitatory input to CeA neurons based on molecular identity and topographical location within the CeA. These results provide insight into the functional organization of affective pain pathways and how they are altered by chronic pain.

Predictors of sustained functional cure in hepatitis B envelope antigen-negative patients achieving hepatitis B surface antigen seroclearance with interferon-alpha-based therapy.

Hepatitis B surface antigen (HBsAg) loss is considered a functional cure in chronic hepatitis B (CHB). However, the durability of HBsAg loss after stopping treatment remains unknown. This study aimed to assess the sustained functional cure achieved by interferon therapy in hepatitis B envelope antigen (HBeAg)-negative CHB patients. In this prospective study, 176 HBeAg-negative CHB patients with functional cure were enrolled for 12 weeks of cessation treatment, and treatment information and baseline data were collected. Hepatitis B virus (HBV) biomarkers and clinical biochemical indicators were evaluated every 3 months; liver imaging examinations were performed every 3-6 months during the 48-week follow-up. The sustained functional cure was evaluated. After the 48-week follow-up, the sustained functional cure rate was 86.63%. The cumulative rates of HBsAg reversion and HBV DNA reversion were 12.79% and 2.33%, respectively. Consolidation treatment ≥ 12 weeks after HBsAg loss achieved a significantly higher rate of sustained functional cure and significantly lower rate of HBsAg reversion than consolidation treatment < 12 weeks (76.19% vs 90.00%, P = 0.022 and 23.81% vs 9.23%, P = 0.014, respectively). Patients with hepatitis B surface antibody (HBsAb) had higher rate of sustained functional cure than patients achieving HBsAg loss but without HBsAb (89.86% vs 73.53%, P = 0.012). Consolidation treatment ≥ 12 weeks (odds ratio [OR] 16.478; 95% confidence interval [CI], 2.135-127.151; P = 0.007) and high HBsAb levels (OR 8.312; 95% CI, 1.824-37.881; P = 0.006) were independent predictors of sustained functional cure. Results suggested that 12 weeks of consolidation therapy after HBsAg clearance and elevated HBsAb levels help to improve functional cure.

Successful second allogeneic stem-cell transplantation from the same sibling donor for a patient with recurrent hepatosplenic gamma-delta (γ/δ) T-cell lymphoma: A case report.

RATIONALE: Hepatosplenic T-cell lymphoma (HSTCL) is a rare but aggressive type of peripheral T-cell lymphoma (PTCL). There is an urgent need for effective treatment due to the poor prognosis of HSTCL. Here, for the 1st time we describe the rare successful case of HSTCL who relapsed after a previous allogeneic stem-cell transplantation (allo-SCT), achieved remission with the second allo-SCT from the same donor. PATIENT CONCERNS: A 24-year-old male, presented with a 2-week history of fever, drenching night sweats and nonquantified weight loss. DIAGNOSES: Laboratory studies, flow cytometry of immunophenotyped, and physical examination results strongly suggested hepatosplenic γ/δ T-cell lymphoma, stage IVB. INTERVENTIONS: We proceeded to an allo-SCT with a human leukocyte antigen (HLA) identical sibling donor. The bone marrow examination and fluorescent in situ hybridization were observed for complete donor chimerism of bone marrow cells on day 34. On day 157 after the initial allo-SCT, the bone marrow examination revealed the relapse of the sinusoidal infiltration with lymphoma cells. Considering the disease persistence, we conducted the second allo-SCT from the same HLA-identical sibling donor immediately. OUTCOMES: Bone marrow examination indicated hematologic recovery without residual lymphoma cells. LESSONS: Our encouraging outcome suggests that the latter allo-SCT needs to be considered early for patients with disease recurrence, and it also demonstrates that graft-vs-lymphoma conferred by allo-SCT may play an essential role on HSTCL treatment. Furthermore, detecting related genes at diagnosis may have prognostic implications and guidance value for personal chemotherapy program.

The central amygdala to periaqueductal gray pathway comprises intrinsically distinct neurons differentially affected in a model of inflammatory pain.

KEY POINTS: The central nucleus of the amygdala (CeA) encompasses the main output pathways of the amygdala, a temporal lobe structure essential in affective and cognitive dimensions of pain. A major population of neurons in the CeA send projections to the periaqueductal gray (PAG), a key midbrain structure that mediates coping strategies in response to threat or stress. CeA-PAG neurons are topographically organized based on their targeted subregion within the PAG. PAG-projecting neurons in the central medial (CeM) and central lateral (CeL) regions of CeA are intrinsically distinct. CeL-PAG neurons are a homogeneous population of intrinsically distinct neurons while CeM-PAG neurons are intrinsically heterogeneous. Membrane properties of distinct CeM-PAG subtypes are altered in the complete Freund's adjuvant model of inflammatory pain. ABSTRACT: A major population of neurons in the central nucleus of amygdala (CeA) send projections to the periaqueductal gray (PAG), a key midbrain structure that mediates coping strategies in response to threat or stress. While the CeA-PAG pathway has proved to be a component of descending anti-nociceptive circuitry, the functional organization of CeA-PAG neurons remains unclear. We identified CeA-PAG neurons in C57BL/6 mice of both sexes using intracranial injection of a fluorescent retrograde tracer into the PAG. In acute brain slices, we investigated the topographical and intrinsic characteristics of retrogradely labelled CeA-PAG neurons using epifluorescence and whole-cell electrophysiology. We also measured changes to CeA-PAG neurons in the complete Freund's adjuvant (CFA) model of inflammatory pain. Neurons in the central lateral (CeL) and central medial (CeM) amygdala project primarily to different regions of the PAG. CeL-PAG neurons consist of a relatively homogeneous population of intrinsically distinct neurons while CeM-PAG neurons are intrinsically heterogeneous. Membrane properties of distinct CeM-PAG subtypes are altered 1 day after induction of the CFA inflammatory pain model. Collectively, our results provide insight into pain-induced changes to a specific population of CeA neurons that probably play a key role in the integration of noxious input with endogenous analgesia and behavioural coping response.

[Effects of defoliation on the allocation of non-structural carbohydrates in roots of Fraxinus mandshurica seedlings.] / åŽ»å¶å¯¹æ°´æ›²æŸ³è‹—æœ¨æ ¹ç³»éžç»“æž„æ€§ç¢³æ°´åŒ–åˆç‰©åˆ†é çš„å½±å“.

Global climate changes would lead to outbreaks of leaf-feeding insects. Leaf loss could reduce photosynthate production, with consequences on non-structural carbohydrates (NSC) storage and allocation in trees. In this study, the responses of NSC and its compartment concentrations in tap-, coarse- and the first to fifth order fine roots of 2-year-old seedlings of Fraxinus mandshurica to defoliation (40% loss of leaf area) were measured from June to October. The results showed that NSC and its compartment concentrations in roots exhibited distinct seasonal dynamics in both control and defoliation treatments. Following defoliation, NSC concentration decreased in tap- and coarse roots by 3.8% and 30.7%, respectively, while increased in the first five order roots by 1.2%-23.5%, to which starch contributed majorly for each root compartment. Soluble sugar concentration was enhanced by defoliation in tap- and coarse roots by 7.1% and 62.3%, respectively, but decreased in the first to fifth order roots by 2.7%-42.8%. Defoliation had different influences on starch and soluble sugar, with positive effects on the ratio of soluble sugar to starch concentrations in tap- and coarse roots but negative effects on the first to fifth order roots. Overall, defoliation decreased photosynthate production in leaves, leading to the remobilization of starch in tap- and coarse roots and the transportation as soluble sugar to fine roots, as well as the following storage in these roots, which would facilitate the resistance of fine roots to the low temperature in winter.

Neuropeptide Y-mediated sex- and afferent-specific neurotransmissions contribute to sexual dimorphism of baroreflex afferent function.

BACKGROUND: Molecular and cellular mechanisms of neuropeptide-Y (NPY)-mediated gender-difference in blood pressure (BP) regulation are largely unknown. METHODS: Baroreceptor sensitivity (BRS) was evaluated by measuring the response of BP to phenylephrine/nitroprusside. Serum NPY concentration was determined using ELISA. The mRNA and protein expression of NPY receptors were assessed in tissue and single-cell by RT-PCR, immunoblot, and immunohistochemistry. NPY was injected into the nodose while arterial pressure was monitored. Electrophysiological recordings were performed on nodose neurons from rats by patch-clamp technique. RESULTS: The BRS was higher in female than male and ovariectomized rats, while serum NPY concentration was similar among groups. The sex-difference was detected in Y1R, not Y2R protein expression, however, both were upregulated upon ovariectomy and canceled by estrogen replacement. Immunostaining confirmed Y1R and Y2R expression in myelinated and unmyelinated afferents. Single-cell PCR demonstrated that Y1R expression/distribution was identical between A- and C-types, whereas, expressed level of Y2R was ~15 and ~7 folds higher in Ah- and C-types than A-types despite similar distribution. Activation of Y1R in nodose elevated BP, while activation of Y2R did the opposite. Activation of Y1R did not alter action potential duration (APD) of A-types, but activation of Y2R- and Y1R/Y2R in Ah- and C-types frequency-dependently prolonged APD. N-type ICa was reduced in A-, Ah- and C-types when either Y1R, Y2R, or both were activated. The sex-difference in Y1R expression was also observed in NTS. CONCLUSIONS: Sex- and afferent-specific expression of Neuropeptide-Y receptors in baroreflex afferent pathway may contribute to sexual-dimorphic neurocontrol of BP regulation.

Sphingosine 1-phosphate enhances the excitability of rat sensory neurons through activation of sphingosine 1-phosphate receptors 1 and/or 3.

BACKGROUND: Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that acts through a family of five G-protein-coupled receptors (S1PR1-5) and plays a key role in regulating the inflammatory response. Our previous studies demonstrated that rat sensory neurons express the mRNAs for all five S1PRs and that S1P increases neuronal excitability primarily, but not exclusively, through S1PR1. This raises the question as to which other S1PRs mediate the enhanced excitability. METHODS: Isolated sensory neurons were treated with either short-interfering RNAs (siRNAs) or a variety of pharmacological agents targeted to S1PR1/R2/R3 to determine the role(s) of these receptors in regulating neuronal excitability. The excitability of isolated sensory neurons was assessed by using whole-cell patch-clamp recording to measure the capacity of these cells to fire action potentials (APs). RESULTS: After siRNA treatment, exposure to S1P failed to augment the excitability. Pooled siRNA targeted to S1PR1 and R3 also blocked the enhanced excitability produced by S1P. Consistent with the siRNA results, pretreatment with W146 and CAY10444, selective antagonists for S1PR1 and S1PR3, respectively, prevented the S1P-induced increase in neuronal excitability. Similarly, S1P failed to augment excitability after pretreatment with either VPC 23019, which is a S1PR1 and R3 antagonist, or VPC 44116, the phosphonate analog of VPC 23019. Acute exposure (10 to 15 min) to either of the well-established functional antagonists, FTY720 or CYM-5442, produced a significant increase in the excitability. Moreover, after a 1-h pretreatment with FTY720 (an agonist for S1PR1/R3/R4/R5), neither SEW2871 (S1PR1 selective agonist) nor S1P augmented the excitability. However, after pretreatment with CYM-5442 (selective for S1PR1), SEW2871 was ineffective, but S1P increased the excitability of some, but not all, sensory neurons. CONCLUSIONS: These results demonstrate that the enhanced excitability produced by S1P is mediated by activation of S1PR1 and/or S1PR3.