ObjectiveTo observe the effect and therapeutic effect of Kaixuan Jiedu core prescription （KXJD） on skin homing of Th17 cells in the mouse model of imiquimod （IMQ） combined with restraint stress-induced psoriasis-like skin damage， and to explore its potential mechanism from the perspective of neuro-immune axis. MethodsThirty male C57BL/6J mice were randomly allocated into five groups （n=6）： Control， model （IMQ）， restraint stress model （IMQ+RS）， KXJD， and methotrexate （MTX）. The mouse model of psoriasis-like skin damage was established by 5% IMQ combined with restraint stress. At the same time of modeling， each treatment group was treated with corresponding doses of drugs， and the control， IMQ， and IMQ+RS groups were treated with the same amount of normal saline by gavage once a day for 5 days. Hematoxylin-eosin （HE） staining was used to observe the pathological changes in the skin tissue and Baker scoring was performed. Serum levels of interleukin-1β （IL-1β） and angiopoietin-2 （Ang-2） were measured by enzyme-linked immunosorbent assay （ELISA）. The levels of matrix metalloproteinase-9 （MMP-9）， tissue inhibitor of metalloproteinase-1 （TIMP-1）， C-C motif chemokine ligand 20 （CCL20）， and C-C motif chemokine receptor 6 （CCR6） in the skin tissue were determined. Immunohistochemistry （IHC） was employed to determine the protein expression of cutaneous lymphocyte-associated antigen （CLA）， integrin α_E （CD103）， cytokeratin 10 （CK10）， and nuclear factor-kappa B （NF-κB） in the skin. Immunofluorescence double staining （DIF） was adopted to detect the expression and co-localization of vascular endothelial cadherin （VE-cadherin） and platelet-endothelial cell adhesion molecule （CD31）， CCR6， CD103， substance P （SP）， calcitonin gene-related peptide （CGRP）， and protein gene product 9.5 （PGP9.5） in the skin tissue. Real-time PCR was employed to quantify the mRNA levels of IL-10， IL-17A， and IL-23. ResultsCompared with the control group， the IMQ group and IMQ+RS group showed significant inflammatory cell infiltration， abnormal proliferation of epidermal cells， keratinization and other pathological changes in the skin tissue， and a significant increase in Baker score， elevated levels of IL-1β and Ang-2 in the serum and MMP-9， CCL20 and CCR6 in the skin lesions， upregulated expression of CLA， CD103， CK10， NF-κB， IL-17A mRNA， and IL-23 mRNA in the skin lesions， and downregulated expression of TIMP-1 and IL-10 mRNA. In addition， the fluorescence intensities of VE-cadherin and CD31 co-localization， CCR6 and CD103 co-localization， SP and PGP9.5 co-localization， and CGRP and PGP9.5 co-localization were increased （P<0.05）. Compared with the IMQ group， the above indicators in the IMQ+RS group were further aggravated. Compared with the IMQ group， the above indicators in the IMQ+RS group were further aggravated. Compared with the IMQ+RS group， KXJD and MTX significantly alleviated the pathological damage of skin lesions， significantly decreased the Baker score， lowered the levels of IL-1β and Ang-2 in the serum and MMP-9， CCL20 and CCR6 in skin lesions， downregulated the expression of CLA， CD103， CK10， NF-κB， IL-17A mRNA and IL-23 mRNA in skin lesions， and upregulated the expression of TIMP-1 and IL-10 mRNA. Furthermore， KXJD and MTX reduced the fluorescence intensities of VE-cadherin and CD31 co-localization， CCR6 and CD103 co-localization， CGRP and PGP9.5 co-localization， and SP and PGP9.5 co-localization （P<0.05）. ConclusionKXJD can significantly ameliorate the psoriasis-like skin damage induced by IMQ combined with restraint stress in mice by regulating the neural-immune axis and inhibiting the skin homing of Th17 cells.

ObjectiveTo establish the mouse models of psoriasis-like lesions induced by continuous cold exposure or intermittent cold exposure combined with imiquimod （IMQ）， and to evaluate the interventional effects of Kaixuan Jiedu core prescription （KXJD） on the two models. MethodsMale C57BL/6J mice were selected and classified into two experimental batches. The first batch of 36 mice was randomized into a room temperature group， a continuous cold exposure （10 ℃/24 h） group， and an intermittent cold exposure （10 ℃/6 h） group. Each group was further divided into a normal subgroup and a model subgroup （topical application of IMQ to induce skin lesions）， with 6 mice in each subgroup， for modeling and evaluation. The second batch of 54 mice， with 6 in each group， were subjected to the same temperature grouping with an additional KXJD （30.42 g·kg^-1， continuous gavage for 5 days） group. Comprehensive evaluation of model characteristics and KXJD efficacy was conducted through Psoriasis Area and Severity Index （PASI） scoring， skin temperature measurement by infrared thermography， histopathological observation by hematoxylin-eosin （HE） staining， detection of vascular endothelial growth factor （VEGF） and platelet endothelial cell adhesion molecule 1 （CD31） by immunohistochemistry， detection of Claudin-1 and Occludin by immunofluorescence assay， determination of serum levels of tumor necrosis factor-α （TNF-α） and interleukin （IL）-10 by enzyme-linked immunosorbent assay （ELISA）， and quantification of mRNA levels of IL-17A， IL-23， IL-6， and chemokine ligand 20 （CCL20） in skin lesions by quantitative Real-time polymerase chain reaction （Real-time PCR）. ResultsModel mice in all temperature groups exhibited typical psoriasis-like skin lesions. Compared with the normal groups， the model groups showed increased PASI scores， decreased skin temperatures （P<0.05）， obvious epidermal thickening， parakeratosis， and dermal inflammatory cell infiltration， as well as elevated mRNA levels of IL-17A， IL-23， IL-6， and CCL20 （P<0.05）. Cold exposure further aggravated psoriasis. The total PASI score of the intermittent cold exposure model group was higher than that of the room temperature model group （P<0.05）. The serum IL-10 did not show a compensatory elevation， and the blood vessels presented a characteristic of elevated CD31 expression （P<0.05） without a synchronous increase in VEGF. The continuous cold exposure model group exhibited more significant dermal capillary tortuosity and dilation， with the highest mRNA levels of IL-17A， IL-23， IL-6， and CCL20 among all groups. Compared with the respective model groups， KXJD intervention alleviated skin lesions， reduced epidermal thickness and inflammatory cell infiltration， and increased skin temperature， with the temperature increase being particularly significant in the intermittent cold exposure+KXJD group （P<0.05）. Furthermore， KXJD down-regulated the expression of VEGF and CD31， restored the expression of Claudin-1 and Occludin， decreased the mRNA levels of IL-17A and IL-23 （P<0.05）， and reduced the serum TNF-α level. ConclusionThis study successfully established compound psoriasis-like mouse models induced by cold exposure combined with IMQ. It confirms that cold aggravates the severity of psoriasis by exacerbating the closure of Xuanfu （sweat pores）， microcirculation disorders， and immune imbalance. Moreover， different cold exposure patterns have distinct mechanism differences. Continuous cold exposure focuses on enhancing the inflammatory response via the IL-23/IL-17 axis and angiogenesis， simulating chronic aggravation under a long-term cold environment. Intermittent cold exposure tends to impair immune regulation and induce microvascular endothelial stress， corresponding to acute exacerbations caused by sudden temperature drops. KXJD can effectively alleviate psoriasis-like skin lesions under cold conditions by unblocking Xuanfu， regulating vasomotor function， and correcting abnormal immune-inflammatory responses.

ObjectiveTo investigate the ameliorative effects of Kaixuan Jiedu core prescription （KXJD） on skin lesions in psoriasis-like mouse models under cold environment exposure， and to analyze its influences on transient receptor potential （TRP） channels and related neuroimmune regulatory factors. MethodsThirty-six C57BL/6J mice were randomized into 6 groups， with 6 mice in each group. Two feeding conditions were set： Normal temperature and cold ［simulating a cold environment at （10±0.5） ℃， for 6 h daily］. Mice were induced to develop psoriasis-like lesions by applying imiquimod externally. The model mice were allocated into model groups and KXJD （30.42 g·kg^-1， continuous gavage for 5 days） groups. Normal mice were used as the control group. Specifically， mice were allocated into normal temperature， normal temperature model， normal temperature+KXJD， cold exposure control， cold exposure model， and cold exposure+KXJD groups. The pathological changes in skin lesions were observed by hematoxylin-eosin （HE） staining. The expression of cluster of differentiation （CD） 3⁺ T lymphocytes， CD11c⁺ dendritic cells （DCs）， phosphorylated extracellular signal-regulated kinase （p-ERK）， and substance P （SP） were detected by immunofluorescence assay. The protein level of transient receptor potential cation channel subfamily M member 8 （TRPM8） in the skin tissue was determined by Western blot. The expression of TRPM8， transient receptor potential cation channel subfamily V member 1 （TRPV1）， transient receptor potential cation channel subfamily A member 1 （TRPA1）， and transient receptor potential cation channel subfamily V member 2 （TRPV2） at the protein and mRNA levels was determined by immunohistochemistry and Real-time PCR， respectively. The levels of calcitonin gene-related peptide （CGRP） and neuropeptide Y （NPY） in the serum were analyzed by enzyme-linked immunosorbent assay （ELISA）. The enrichment analysis of differentially expressed genes （DEGs） and TRP pathway network construction were conducted based on the GEO database. The co-expression of TRPM8 and CGRP in the skin lesions was verified by immunofluorescence double labeling. ResultsBoth the normal temperature and cold exposure model groups showed typical psoriasis-like skin lesions. Compared with the normal temperature and cold exposure control groups， the model groups had excessive epidermal keratinization， thickened spinous layer， and inflammatory infiltration in the dermis， with increased pathological scores （P<0.05）， increased infiltration of CD3⁺ and CD11c⁺ cells and expression of p-ERK and SP， upregulated mRNA levels of TRPM8， TRPA1， and TRPV2， downregulated mRNA level of TRPV1 （P<0.05）， and reduced content of CGRP and increased content of NPY in the serum. Compared with the normal temperature and cold exposure model groups， KXJD reduced the pathological manifestations and pathological scores of psoriasis-like skin lesions （P<0.05）， and inhibited the infiltration of CD3⁺ and CD11c⁺ cells and the expression of p-ERK and SP. Gene enrichment analysis suggested that the DEGs of psoriasis were significantly enriched in the interleukin （IL）-17 signaling pathway and TRP channel inflammatory regulation. Compared with the normal temperature and cold exposure model groups， KXJD reversed the abnormal mRNA levels of genes related to the TRP channel subfamilies （P<0.05）， increased the CGRP level， and decreased the NPY level. Immunofluorescence double labeling further confirmed that compared with the model groups， KXJD down-regulated the co-expression of TRPM8 and CGRP in the skin lesions. ConclusionKXJD may ameliorate psoriasis-like skin lesions by downregulating the overexpressed cold-sensitive receptor TRPM8 in skin lesions and correcting the disorder of neuropeptide （such as SP and CGRP） release mediated by it， thereby inhibiting the IL-23/helper T cell 17 （Th17） core inflammatory pathway， suppressing the infiltration of inflammatory cells and the activation of the ERK signaling pathway， and regulating the Xuanfu （sweat pore）-TRPM8-neuroimmune response axis.

ObjectiveTo investigate the ameliorative effects and mechanisms of Kaixuan Jiedu core prescription （KXJD） on neuroimmunological inflammation in imiquimod （IMQ）-induced psoriasis-like mice. MethodsA total of 24 C57BL/6J mice were randomly divided into four groups （n=6）： Normal， model， KXJD， and tropomyosin receptor kinase A （TrkA） inhibitor GW441756 groups. The mice in the model， KXJD， and GW441756 groups were topically treated with 5% IMQ cream （62.5 mg·d^-1） on the back to induce psoriasis-like inflammation. The KXJD group received KXJD by gavage （30.42 g·kg^-1）， the GW441756 group received intraperitoneal injection of GW441756 （10 mg·kg^-1）， and the normal and model groups received an equal volume of normal saline by gavage， with continuous intervention for 5 days. The severity of skin lesions was evaluated using the psoriasis area and severity index （PASI）. Hematoxylin-eosin （HE） staining was used to measure epidermal thickness and observe pathological changes in the lesioned skin. Immunohistochemistry was employed to detect the expression of proliferating cell nuclear antigen （Ki67） and interleukin-17A （IL-17A） in the lesioned skin. Enzyme-linked immunosorbent assay （ELISA） was used to quantify the levels of interleukin-23 （IL-23） and calcitonin gene-related peptide （CGRP） in the lesioned tissues. Western blot was used to detect the expression of TrkA and phosphorylated TrkA （p-TrkA）. Immunofluorescence assay was performed to detect the expression of TrkA receptor， protein gene product 9.5 （PGP9.5）， cluster of differentiation 11c （CD11c）， and CGRP in the lesions. Flow cytometry was used to detect the activation of splenic dendritic cells （DCs）. ResultsCompared with the normal group， the model group exhibited typical psoriasis-like inflammation， characterized by erythema， infiltration and scaling， with histopathological findings of epidermal hyperkeratosis and acanthosis. The model group showed significantly increased expression of Ki67， IL-17A， IL-23 and p-TrkA （P<0.05， P<0.01）， increased fluorescence intensity of CD11c， and significantly decreased CGRP expression （P<0.05）. The splenic DC activation was significantly enhanced， as indicated by the increased mean fluorescence intensity （MFI） of CD86 （P<0.05）. Compared with the model group， both the KXJD and GW441756 groups showed amelioration of the psoriasis-like skin inflammation， with significantly down-regulated expression of IL-17A， IL-23 and p-TrkA （P<0.05， P<0.01）， significantly up-regulated expression of CGRP （P<0.01）， reduced CD11c⁺ DC infiltration， and restored splenic DC activation balance （down-regulated CD86 MFI and up-regulated CD80 and CD40 MFI）. Furthermore， the inhibitory effect of KXJD on Ki67 was significantly superior to that of the GW441756 group （P<0.01）. ConclusionKXJD may alleviate IMQ-induced psoriasis-like inflammation in mice by targeting and inhibiting TrkA receptor phosphorylation， regulating CGRP expression in the lesions， and ameliorating aberrant activation of dendritic cells， while also significantly inhibiting keratinocyte proliferation.

ObjectiveTo investigate the effects and molecular mechanisms of Kaixuan Jiedu core prescription （KXJD） on neuroinflammation and immuno-inflammation in the mouse model of imiquimod （IMQ）-induced psoriasis-like skin lesions by regulating the nerve growth factor （NGF）-tropomyosin receptor kinase A （TrkA）/transient receptor potential vanilloid 1 （TRPV1）-protease-activated receptor-2 （PAR-2） signaling pathway. MethodsA psoriasis-like skin lesion model was established in male C57BL/6J mice with IMQ. A total of 24 mice were randomized into four groups （n=6 per group）： Blank control， model， methotrexate （MTX， 1 mg·kg^-1）， and KXJD （30.42 g·kg^-1）. Immunohistochemistry was employed to detect the expression of cluster of differentiation 3 （CD3）， EGF-like module-containing mucin-like hormone receptor-like 1 （F4/80）， lymphocyte antigen 6 complex locus G （Ly-6G）， substance P （SP）， calcitonin gene-related peptide （CGRP）， NGF， phosphorylated TrkA （p-TrkA）， phosphorylated TRPV1 （p-TRPV1）， and PAR-2 in skin lesions. Serum levels of interleukin-17A （IL-17A） and interleukin-23 （IL-23） were measured by enzyme-linked immunosorbent assay （ELISA）. Immunofluorescence assay and Western blot were employed to determine the expression of phosphorylated p38 mitogen-activated protein kinase （p-p38 MAPK） and phosphorylated nuclear factor-κB p65 （p-NF-κB p65）. Reverse transcription quantitative polymerase chain reaction （Real-time PCR） was used to measure the mRNA levels of interleukin-1β （IL-1β）， tumor necrosis factor （TNF）， interleukin-6 （IL-6）， and C-X-C motif chemokine ligand 1 （CXCL1） in skin lesions. Correlation analysis was performed. ResultsCompared with the blank control group， the model group showed increased positive areas of CD3⁺， F4/80⁺， and Ly-6G⁺ in skin lesions （P<0.05）， elevated serum levels of IL-17A and IL-23 （P<0.05）， increased positive areas of SP and CGRP in skin lesions （P<0.05）， increased positive areas of NGF， p-TrkA， p-TRPV1， and PAR-2 （P<0.05）， elevated ratios of p-p38 MAPK/p38 MAPK and p-NF-κB p65/NF-κB p65 （P<0.05）， and upregulated mRNA levels of IL-1β， TNF， IL-6， and CXCL1 （P<0.05）. Compared with those in the model group， all the above indicators were reversed in the KXJD group （P<0.05）. MTX only downregulated the expression of p-TRPV1 and PAR-2 （P<0.05）， with no significant effects on the expression of NGF， p-TrkA， or CGRP. ConclusionKXJD inhibits the NGF-TrkA/TRPV1-PAR-2 signaling pathway to reduce neuropeptide release and simultaneously downregulates the p38 MAPK/NF-κB signaling pathway and the expression of downstream pro-inflammatory factors to ameliorate psoriasis-like neuroinflammation and immuno-inflammation. The therapeutic effect of KXJD on psoriasis-like inflammation is closely associated with the inhibition of the NGF-TrkA/TRPV1-PAR-2 signaling pathway. This study provides experimental evidence for the modern interpretation of the Xuanfu theory.

Objective To examine the changing prevalence and antimicrobial resistance profiles of Burkholderia cepacia in 52 hospitals across China from 2015 to 2021.Methods A total of 9 261 strains of B.cepacia were collected from 52 hospitals between January 1,2015 and December 31,2021.Antimicrobial susceptibility of the strains was tested using Kirby-Bauer method or automated antimicrobial susceptibility testing systems according to a unified protocol.The results were interpreted according to the breakpoints released in the Clinical & Laboratory Standards Institute(CLSI)guidelines(2023 edition).Results A total of 9 261 strains of B.cepacia were isolated from all age groups,especially elderly patients.The proportion was 11.1％(1 032 strains)in children,significantly lower than the proportion in adults.About half(46.5％,4 310/9 261)of the strains were isolated from patients at least 60 years old and 42.3％(3 919/9 261)of the strains were isolated from young adults.Most isolates(71.1％)were isolated from sputum and respiratory secretions,followed by urine(10.7％)and blood samples(8.1％).B.cepacia isolates were highly susceptible to the five antimicrobial agents recommended in the CLSI M100 document(33rd edition,2023).B.cepacia isolates showed relatively higher resistance rates to meropenem and levofloxacin.However,the resistance rates to ceftazidime,trimethoprim-sulfamethoxazole,and minocycline remained below 8.1％.The percentage of B.cepacia strains resistant to levofloxacin was the highest compared to other antibiotics in any of the three age groups(from 12.4％in the patients＜18 years old to 20.6％in the patients aged 60 years or older).Conclusions B.cepacia is one of the clinically important non-fermenting gram-negative bacteria.Accurate and timely reporting of antimicrobial susceptibility test results and ongoing antimicrobial resistance surveillance are helpful for rational prescription of antimicrobial agents and proper prevention and control of nosocomial infections.

Body weight abnormalities, including overweight, obesity, and underweight, have become a dual public health challenge in Chinese adults: overweight and obesity lead to a variety of chronic complications, while underweight increases the risks of malnutrition, sarcopenia, and organ dysfunction. To systematically address these issues, multidisciplinary experts in endocrinology, sports science, nutrition, and psychiatry from various regions have held multiple weight management seminars. Based on the latest epidemiological data and clinical evidence, they expanded the guideline to include assessment and intervention strategies for underweight, in addition to the core content of obesity management. This guideline outlines the etiological mechanisms, evaluation methods, and multidimensional management strategies for overweight and obesity, covering key areas such as diagnosis and assessment, medical nutrition therapy, exercise prescription, pharmacological intervention, and psychological support. It is intended to provide a scientific and standardized approach to weight management across the adult population, aiming to curb the rising prevalence of obesity, mitigate complications associated with abnormal body weight, and improve nutritional status and overall quality of life.

Objective To summarize the changing prevalence of carbapenem resistance in Enterobacterales based on the data of CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021 for improving antimicrobial treatment in clinical practice.Methods Antimicrobial susceptibility testing was performed using a commercial automated susceptibility testing system according to the unified CHINET protocol.The results were interpreted according to the breakpoints of the Clinical & Laboratory Standards Institute(CLSI)M100 31st ed in 2021.Results Over the seven-year period(2015-2021),the overall prevalence of carbapenem-resistant Enterobacterales(CRE)was 9.43％(62 342/661 235).The prevalence of CRE strains in Klebsiella pneumoniae,Citrobacter freundii,and Enterobacter cloacae was 22.38％,9.73％,and 8.47％,respectively.The prevalence of CRE strains in Escherichia coli was 1.99％.A few CRE strains were also identified in Salmonella and Shigella.The CRE strains were mainly isolated from respiratory specimens(44.23±2.80)％,followed by blood(20.88±3.40)％and urine(18.40±3.45)％.Intensive care units(ICUs)were the major source of the CRE strains(27.43±5.20)％.CRE strains were resistant to all the β-lactam antibiotics tested and most non-β-lactam antimicrobial agents.The CRE strains were relatively susceptible to tigecycline and polymyxins with low resistance rates.Conclusions The prevalence of CRE strains was increasing from 2015 to 2021.CRE strains were highly resistant to most of the antibacterial drugs used in clinical practice.Clinicians should prescribe antimicrobial agents rationally.Hospitals should strengthen antibiotic stewardship in key clinical settings such as ICUs,and take effective infection control measures to curb CRE outbreak and epidemic in hospitals.

Objective To characterize the changing species distribution and antibiotic resistance profiles of respiratory isolates in hospitals participating in the CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021.Methods Commercial automated antimicrobial susceptibility testing systems and disk diffusion method were used to test the susceptibility of respiratory bacterial isolates to antimicrobial agents following the standardized technical protocol established by the CHINET program.Results A total of 589 746 respiratory isolates were collected from 2015 to 2021.Overall,82.6％of the isolates were Gram-negative bacteria and 17.4％were Gram-positive bacteria.The bacterial isolates from outpatients and inpatients accounted for(6.0±0.9)％and(94.0±0.1)％,respectively.The top microorganisms were Klebsiella spp.,Acinetobacter spp.,Pseudomonas aeruginosa,Staphylococcus aureus,Haemophilus spp.,Stenotrophomonas maltophilia,Escherichia coli,and Streptococcus pneumoniae.Each microorganism was isolated from significantly more males than from females(P＜0.05).The overall prevalence of methicillin-resistant S.aureus(MRSA)was 39.9％.The prevalence of penicillin-resistant S.pneumoniae was 1.4％.The prevalence of extended-spectrum β-lactamase(ESBL)-producing E.coli and K.pneumoniae was 67.8％and 41.3％,respectively.The overall prevalence of carbapenem-resistant E.coli,K.pneumoniae,Enterobacter cloacae,Pseudomonas aeruginosa,and Acinetobacter baumannii was 3.7％,20.8％,9.4％,29.8％,and 73.3％,respectively.The prevalence of β-lactamase was 96.1％in Moraxella catarrhalis and 60.0％in Haemophilus influenzae.The H.influenzae isolates from children(＜18 years)showed significantly higher resistance rates to β-lactam antibiotics than the isolates from adults(P＜0.05).Conclusions Gram-negative bacteria are still predominant in respiratory isolates associated with serious antibiotic resistance.Antimicrobial resistance surveillance should be strengthened in clinical practice to support accurate etiological diagnosis and appropriate antimicrobial therapy based on antimicrobial susceptibility testing results.

Objective"Lie flat"has recently become a buzz word describing a specific psychological state in some individuals.However,its psychological meaning and mechanisms remain unclear.Lack of motivation under certain conditions may be one of the key psychological characteristics of this condition.Methods Sixteen male SD rats were randomly assigned to two food-restriction levels(90%and 80%of baseline weight,respectively),and subjected to a sucrose-pellet self-administration task.The establishment of the model is divided into three stages.The rats were trained to self-administer sucrose pellets in a high-reward learning stage and in a low-reward learning stage.We then assessed"lie flat"behavior in a preference-test stage,in which rats could choose between high-reward-and low-reward-paired nose-pokes in a discrete choice procedure.Results Combining self-feeding training with Western blot,the results showed that:(1)rats showed significantly decreased nose-poke behavior for low-reward,i.e."lie flat"behavior,but not for high-reward,when≥90%of the maximal reward was obtained in the high-reward task and the effort(X)in the low-reward task increased to the breaking point.(2)Dopamine D1R expression in the NAc was significantly higher in the"lie flat"group compared with the"not lie flat"rats,while D2R expression was similar in both groups.Conclusions Rats can show"lie flat"behavior,and up-regulation of D1R expression in the NAc may be a key part of the molecular basis responsible for this motivation deficiency in"lie flat"behavior.These results extend our understanding of"lie flat"behavior,and provide a new paradigm for the study of its mechanism.