“Runner’s high” refers to a momentary sense of pleasure that suddenly appears during running or other exercise activities, characterized by anti-anxiety, pain relief, and other symptoms. The neurobiological mechanism of “runner’s high” is unclear. This review summarizes human and animal models for studying “runner’s high”, analyzes the neurotransmitters and neural circuits involved in runner’s high, and elucidates the evidence and shortcomings of researches related to “runner’s high”. This review also provides prospects for future research. Research has found that exercise lasting more than 30 min and with an intensity exceeding 70% of the maximum heart rate can reach a “runner’s high”. Human experiments on “runner’s high” mostly use treadmill exercise intervention, and evaluate it through questionnaire surveys, measurement of plasma AEA, miRNA and other indicators. Animal experiments often use voluntary wheel running intervention, and evaluate it through behavioral experiments such as conditional place preference, light dark box experiments (anxiety), hot plate experiments (pain sensitivity), and measurement of plasma AEA and other indicators. Dopamine, endogenous opioid peptides, endogenous cannabinoids, brain-derived neurotrophic factor, and other substances increase after exercise, which may be related to the “runner’s high”. However, attention should be paid to the functional differences of these substances in the central and peripheral regions, as well as in different brain regions. Moreover, current studies have not identified the targets of the neurotransmitters or neural factors mentioned above, and further in-depth researches are needed. The mesolimbic dopamine system, prefrontal cortex-nucleus accumbens projection, ventral hippocampus-nucleus accumbens projection, red nucleus-ventral tegmental area projection, cerebellar-ventral tegmental area projection, and brain-gut axis may be involved in the regulation of runner’s high, but there is a lack of direct evidence to prove their involvement. There are still many issues that need to be addressed in the research on the neurobiological mechanisms of “runner’s high”. (1) Most studies on “runner’s high” involve one-time exercise, and the characteristics of changes in “runner’s high” during long-term exercise still need to be explored. (2) The using of scales to evaluate subjects lead to the lacking of objective indicators. However, some potential biomarkers (such as endocannabinoids) have inconsistent characteristics of changes after one-time and long-term exercise. (3) The neurotransmitters involved in the formation of the “runner’s high” all increase in the peripheral and/or central nervous system after exercise. Attention should be paid to whether peripheral substances can enter the blood-brain barrier and the binding effects of neurotransmitters to different receptors are completely different in different brain regions. (4) Most of the current evidence show that some brain regions are activated after exercise. Is there a functional circuit mediating “runner’s high” between these brain regions? (5) Although training at a specific exercise intensity can lead to “runner’s high”, most runners have not experienced “runner’s high”. Can more scientific training methods or technological means be used to make it easier for people to experience the “runner’s high” and thus be more willing to engage in exercise? (6) The “runner’s high” and “addiction” behaviors are extremely similar, and there are evidences that exercise can reverse addictive behaviors. However, why is there still a considerable number of people in the sports population and even athletes who smoke or use addictive drugs instead of pursuing the “pleasure” brought by exercise? Solving the problems above is of great significance for enhancing the desire of exercise, improving the clinical application of neurological and psychiatric diseases through exercise, and enhancing the overall physical fitness of the population.

ObjectiveBased on the phosphoinositide 3-kinase （PI3K）/protein kinase B （Akt） signaling pathway， the effects of Huanglian Zhimutang on glucose and lipid metabolism disorders and hepatic insulin resistance （IR） with type 2 diabetes mellitus （T2DM） were investigated. MethodsGoto-Kakizaki （GK） rats were fed a high-fat diet to induce a T2DM rat model and then randomly divided into four groups： normal control group， model control group， metformin group （0.10 g·kg^-1）， and Huanglian Zhimutang group （3.60 g·kg^-1）， with eight rats in each group. Drug intervention was administered continuously for 8 weeks. Serum and liver tissues were collected from each group. Fasting insulin （FINS） levels were measured using enzyme-linked immunosorbent assay （ELISA）， and the homeostasis model assessment of insulin resistance （HOMA-IR） index was calculated. Total cholesterol （TC）， triglyceride （TG）， low-density lipoprotein cholesterol （LDL-C）， and high-density lipoprotein cholesterol （HDL-C） levels were measured using an automatic biochemical analyzer. Liver tissue pathology was observed via hematoxylin-eosin （HE） staining. Serum interleukin-6 （IL-6） and tumor necrosis factor-α （TNF-α） levels were detected using ELISA. Network pharmacology and transcriptomics sequencing were combined to analyze differentially expressed genes （DEGs） in liver tissue from the normal control group， model control group， and Huanglian Zhimutang group. Kyoto Encyclopedia of Genes and Genomes （KEGG） pathway enrichment analysis was performed to identify pathways affected by Huanglian Zhimutang intervention in T2DM. Real-time quantitative polymerase chain reaction （Real-time PCR） was used to assess the mRNA expression of insulin receptor substrate-1 （IRS-1）， PI3K， Akt， and peroxisome proliferator-activated receptor gamma （PPARγ） in liver tissue， while Western blot was used to evaluate corresponding protein expression levels. ResultsAfter 8 weeks of Huanglian Zhimutang intervention， typical symptoms of T2DM rats such as polydipsia， polyphagia， and polyuria were significantly alleviated， along with reductions in fasting blood glucose levels and insulin resistance（P<0.01）. Histopathological results revealed that Huanglian Zhimutang effectively improved hepatic steatosis and inflammatory edema and reduced lipid vacuole formation. Biochemical tests demonstrated that Huanglian Zhimutang significantly reduced serum levels of TC， TG， and LDL-C（P<0.01）. ELISA results showed that Huanglian Zhimutang effectively decreased serum concentrations of IL-6 and TNF-α（P<0.05，P<0.01）. Combined network pharmacology predictions with KEGG pathway analysis of transcriptomics showed that DEGs between the Huanglian Zhimutang and model control groups were significantly enriched in the PI3K/Akt signaling pathway. Real-time PCR and Western blot results confirmed that Huanglian Zhimutang upregulated the expression of PI3K/Akt signaling pathway-related mRNAs and proteins in liver tissue（P<0.05，P<0.01）， thereby reducing inflammation， alleviating hepatic lipid accumulation， and enhancing insulin sensitivity. ConclusionHuanglian Zhimutang effectively ameliorates glucose and lipid metabolism disorders in T2DM rats. Its mechanism may be related to the regulation of the PI3K/Akt pathway， which reduces inflammation and hepatic lipid deposition and relieves hepatic insulin resistance.

ObjectiveBased on the phosphoinositide 3-kinase （PI3K）/protein kinase B （Akt） signaling pathway， the effects of Huanglian Zhimutang on glucose and lipid metabolism disorders and hepatic insulin resistance （IR） with type 2 diabetes mellitus （T2DM） were investigated. MethodsGoto-Kakizaki （GK） rats were fed a high-fat diet to induce a T2DM rat model and then randomly divided into four groups： normal control group， model control group， metformin group （0.10 g·kg^-1）， and Huanglian Zhimutang group （3.60 g·kg^-1）， with eight rats in each group. Drug intervention was administered continuously for 8 weeks. Serum and liver tissues were collected from each group. Fasting insulin （FINS） levels were measured using enzyme-linked immunosorbent assay （ELISA）， and the homeostasis model assessment of insulin resistance （HOMA-IR） index was calculated. Total cholesterol （TC）， triglyceride （TG）， low-density lipoprotein cholesterol （LDL-C）， and high-density lipoprotein cholesterol （HDL-C） levels were measured using an automatic biochemical analyzer. Liver tissue pathology was observed via hematoxylin-eosin （HE） staining. Serum interleukin-6 （IL-6） and tumor necrosis factor-α （TNF-α） levels were detected using ELISA. Network pharmacology and transcriptomics sequencing were combined to analyze differentially expressed genes （DEGs） in liver tissue from the normal control group， model control group， and Huanglian Zhimutang group. Kyoto Encyclopedia of Genes and Genomes （KEGG） pathway enrichment analysis was performed to identify pathways affected by Huanglian Zhimutang intervention in T2DM. Real-time quantitative polymerase chain reaction （Real-time PCR） was used to assess the mRNA expression of insulin receptor substrate-1 （IRS-1）， PI3K， Akt， and peroxisome proliferator-activated receptor gamma （PPARγ） in liver tissue， while Western blot was used to evaluate corresponding protein expression levels. ResultsAfter 8 weeks of Huanglian Zhimutang intervention， typical symptoms of T2DM rats such as polydipsia， polyphagia， and polyuria were significantly alleviated， along with reductions in fasting blood glucose levels and insulin resistance（P<0.01）. Histopathological results revealed that Huanglian Zhimutang effectively improved hepatic steatosis and inflammatory edema and reduced lipid vacuole formation. Biochemical tests demonstrated that Huanglian Zhimutang significantly reduced serum levels of TC， TG， and LDL-C（P<0.01）. ELISA results showed that Huanglian Zhimutang effectively decreased serum concentrations of IL-6 and TNF-α（P<0.05，P<0.01）. Combined network pharmacology predictions with KEGG pathway analysis of transcriptomics showed that DEGs between the Huanglian Zhimutang and model control groups were significantly enriched in the PI3K/Akt signaling pathway. Real-time PCR and Western blot results confirmed that Huanglian Zhimutang upregulated the expression of PI3K/Akt signaling pathway-related mRNAs and proteins in liver tissue（P<0.05，P<0.01）， thereby reducing inflammation， alleviating hepatic lipid accumulation， and enhancing insulin sensitivity. ConclusionHuanglian Zhimutang effectively ameliorates glucose and lipid metabolism disorders in T2DM rats. Its mechanism may be related to the regulation of the PI3K/Akt pathway， which reduces inflammation and hepatic lipid deposition and relieves hepatic insulin resistance.

The present study aimed to explore whether hydrogen sulfide (H₂S) improved hypoxic pulmonary hypertension (HPH) in rats by inhibiting aerobic glycolysis-pyroptosis. Male Sprague-Dawley (SD) rats were randomly divided into normal group, normal+NaHS group, hypoxia group, and hypoxia+NaHS group, with 6 rats in each group. The control group rats were placed in a normoxic (21% O₂) environment and received daily intraperitoneal injections of an equal volume of normal saline. The normal+NaHS group rats were placed in a normoxic environment and intraperitoneally injected with 14 μmol/kg NaHS daily. The hypoxia group rats were placed in a hypoxia chamber, and the oxygen controller inside the chamber maintained the oxygen concentration at 9% to 10% by controlling the N₂ flow rate. An equal volume of normal saline was injected intraperitoneally every day. The hypoxia+NaHS group rats were also placed in an hypoxia chamber and intraperitoneally injected with 14 μmol/kg NaHS daily. After the completion of the four-week modeling, the mean pulmonary artery pressure (mPAP) of each group was measured using right heart catheterization technique, and the right ventricular hypertrophy index (RVHI) was weighed and calculated. HE staining was used to observe pathological changes in lung tissue, Masson staining was used to observe fibrosis of lung tissue, and Western blot was used to detect protein expression levels of hexokinase 2 (HK2), pyruvate dehydrogenase (PDH), pyruvate kinase isozyme type M2 (PKM2), nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), GSDMD-N-terminal domain (GSDMD-N), Caspase-1, interleukin-1β (IL-1β) and IL-18 in lung tissue. ELISA was used to detect contents of IL-1β and IL-18 in lung tissue. The results showed that, compared with the normal control group, there were no significant changes in all indexes in the normal+NaHS group, while the hypoxia group exhibited significantly increased mPAP and RVHI, thickened pulmonary vascular wall, narrowed lumen, increased collagen fibers, up-regulated expression levels of aerobic glycolysis-related proteins (HK2 and PKM2), up-regulated expression levels of pyroptosis-related proteins (NLRP3, GSDMD-N, Caspase-1, IL-1β, and IL-18), and increased contents of IL-1β and IL-18. These changes of the above indexes in the hypoxia group were significantly reversed by NaHS. These results suggest that H₂S can improve rat HPH by inhibiting aerobic glycolysis-pyroptosis.
Animals ; Rats, Sprague-Dawley ; Male ; Hypertension, Pulmonary/metabolism* ; Glycolysis/drug effects* ; Hydrogen Sulfide/therapeutic use* ; Hypoxia/complications* ; Rats ; Pyroptosis/drug effects*

Selenoproteins, as the active form of selenium, play an important role in various physiological and pathological processes, such as anti-oxidation, anti-tumor, immune response, metabolic regulation, reproduction and aging. Although the expression level of selenoproteins in adipose tissue is significantly influenced by dietary selenium intake, it is closely related to the homeostasis of adipose tissue. In this review, we summarized the role of selenoproteins in the physiological function of adipose tissue and the pathogenesis of obesity in recent years, in order to provide a rationale for developing potential therapeutic agents for the treatment of obesity and related metabolic diseases.
Selenoproteins/metabolism* ; Adipose Tissue/physiology* ; Obesity/metabolism* ; Humans ; Animals ; Selenium

Osteoporosis(OP) is a senile bone disease characterized by an imbalance between bone remodeling and bone formation. Targeting pathogenesis of kidney deficiency, spleen deficiency, and blood stasis, Bushen Jianpi Huoxue Decoction has a significant effect on the treatment of OP by tonifying kidney, invigorating spleen, and activating blood circulation. MicroRNA(miRNA) and the anti-apoptotic protein B-cell lymphoma-2-like protein 1(BCL2L1) are closely related to bone cell metabolism. Therefore, in this study, the binding of miR-140-5p to BCL2L1 was detected by dual luciferase assay and polymerase chain reaction(PCR). After silencing or overexpressing miR-140-5p, the apoptosis, autophagy, and osteogenic function of human fetal osteoblast cell line 1.19(HFOB1.19) were observed by flow cytometry and Western blot. Bushen Jianpi Huoxue Decoction-containing serum was prepared by intragastric administration of Bushen Jianpi Huoxue Decoction in rats. Different concentrations of Bushen Jianpi Huoxue Decoction-containing serum were used to treat HFOB1.19 with or without miR-140-5p mimic. The expression of osteogenic proteins in each group was observed, and the role of miR-140-5p/BCL2L1 in apoptosis and autophagy of HFOB1.19 was studied, along with the effect of Bushen Jianpi Huoxue Decoction on these processes. As indicated by the dual luciferase assay, miR-140-5p bound to BCL2L1. Flow cytometry and Western blot showed that miR-140-5p promoted apoptosis and inhibited autophagy in HFOB1.19. After intervention with high, medium, and low doses of Bushen Jianpi Huoxue Decoction-medicated serum, compared with the miR-140-5p NC group, the expression of osteocalcin(OCN), osteopontin(OPN), Runt-related transcription factor 2(RUNX2), and transforming growth factor beta 1(TGF-β1) decreased in the miR-140-5p mimic group, while the expression of bone morphogenetic protein 2(BMP2) showed no significant difference under high-dose intervention. Therefore, miR-140-5p/BCL2L1 can promote apoptosis and inhibit autophagy in HFOB1.19. Bushen Jianpi Huoxue Decoction can affect the osteogenic effect of miR-140-5p through BMP2.
MicroRNAs/metabolism* ; Autophagy/drug effects* ; Apoptosis/drug effects* ; Humans ; Drugs, Chinese Herbal/administration & dosage* ; Animals ; Cell Line ; bcl-X Protein/metabolism* ; Osteoblasts/metabolism* ; Rats ; Osteoporosis/physiopathology* ; Male ; Rats, Sprague-Dawley ; Osteogenesis/drug effects*

This paper aims to study the effect of Ziziphi Spinosae Semen extracts on chronic unpredictable mild stress(CUMS)-induced depression-like and insomnia behavior models of mice. The CUMS-induced depression-like and insomnia behavior model of mice was established by CUMS treatment for three weeks. The mice were randomly divided into control group, model group, positive drug diazepam group(2 mg·kg~(-1)), as well as low-dose group(1.95 g·kg~(-1)), medium-dose group(3.9 g·kg~(-1)), and high-dose group(7.8 g·kg~(-1)) of Ziziphi Spinosae Semen extracts, with 18 mice in each group. On the 15th day of modeling, the drug was administered intragastrically once a day for one week. Then, the pentobarbital sodium cooperative righting experiment, open field experiment, and elevated plus maze experiment were carried out, respectively. The contents of neurotransmitters 5-hydroxytryptamine(5-HT) and 5-hydroxyindoleacetic acid(5-HIAA) in serum and thalamus of mice, as well as the levels of corticotropin releasing hormone(CRH), adrenocorticotropic hormone(ACTH), and corticosterone(CORT) in serum, were determined by enzyme-linked immunosorbent assay(ELISA). The neuron damage in the hippocampus of mice was observed by hematoxylin-eosin(HE) staining and Nissl staining. Western blot was used to detect the expressions of tryptophan hydroxylase 2(TPH2), serotonin transporter(SERT), monoamine oxidase A(MAOA), five prime repressors under dual repression binding protein 1(Freud1), synaptic plasticity-related proteins [cellular gene FOS(C-FOS), postsynaptic density protein 95(PSD95), synapsin 1(SYN1), and activity-regulated cytoskeleton-associated gene(ARC)], blood-brain barrier(BBB) permeability-related proteins [zonula occludens 1(ZO-1), occludin, and claudin 1], inflammatory factors [NOD-, LRR-and pyrin domain-containing protein 3(NLRP3), apoptosis-associated speck-like protein(ASC), gasdermin D(GSDMD), caspase-3, and caspase-8], and antioxidant factors [nuclear factor erythroid 2-related factor 2(NRF2) and heme oxygenase 1(HO1)] in thalamic tissue of mice. The results indicated that compared with that in the model group, the sleep latency was significantly shortened, and the sleep duration was significantly prolonged in each dose group of Ziziphi Spinosae Semen extracts. The number of visits to the central area of the open field and the distance and time of visits were significantly increased in each dose group of Ziziphi Spinosae Semen extracts. In addition, the proportion of distance and time of entering the open arm area of the elevated plus maze was significantly increased in each dose group of Ziziphi Spinosae Semen extracts. The contents of 5-HT and 5-HIAA in serum and thalamus of mice increased to varying degrees in each dose group of Ziziphi Spinosae Semen extracts; the contents of CRH, ACTH, and CORT in serum of mice were significantly decreased. The protein expression of TPH2 was significantly increased. The protein expression of MAOA, SERT, and Freud1 was significantly decreased. Ziziphi Spinosae Semen extracts could also significantly reduce the protein expression of C-FOS but significantly increase the protein expression of PSD95, ARC, and SYN1. They could reduce the pathological damage of the hippocampus in mice and significantly increase the protein expression of ZO-1, occluding, and claudin 1. The protein expression of NLRP3, GSDMD, ASC, caspase-3, and caspase-8 in the thalamic tissue of mice was significantly decreased, and the protein expression of HO1 and NRF2 was significantly increased. In conclusion, Ziziphi Spinosae Semen extracts could effectively improve sleep disorders and depression-like behaviors in CUMS-induced model mice, which may be related to regulating the 5-HT anabolism process and hypothalamic-pituitary-adrenal(HPA) axis-related hormone levels, reducing pathological damage in the hippocampus, improving synaptic plasticity, repairing BBB integrity, and alleviating inflammatory response and oxidative stress damage.
Animals ; Ziziphus/chemistry* ; Mice ; Male ; Depression/psychology* ; Drugs, Chinese Herbal/administration & dosage* ; Sleep Initiation and Maintenance Disorders/psychology* ; Stress, Psychological/complications* ; Behavior, Animal/drug effects* ; Humans ; Disease Models, Animal

This study explores the role and underlying molecular mechanisms of fucoidan sulfate(FPS) in regulating heme oxygenase-1(Hmox1)-mediated ferroptosis to ameliorate myocardial injury in diabetic cardiomyopathy(DCM) through in vivo and in vitro experiments and network pharmacology analysis. In vivo, a DCM rat model was established using a combination of "high-fat diet feeding + two low-dose streptozotocin(STZ) intraperitoneal injections". The rats were randomly divided into four groups: normal, model, FPS, and dapagliflozin(Dapa) groups. In vitro, a cellular model was created by inducing rat cardiomyocytes(H9c2 cells) with high glucose(HG), using zinc protoporphyrin(ZnPP), an Hmox1 inhibitor, as the positive control. An automatic biochemical analyzer was used to measure blood glucose(BG), serum aspartate aminotransferase(AST), serum lactate dehydrogenase(LDH), and serum creatine kinase-MB(CK-MB) levels. Echocardiography was used to assess rat cardiac function, including ejection fraction(EF) and fractional shortening(FS). Pathological staining was performed to observe myocardial morphology and fibrotic characteristics. DCFH-DA fluorescence probe was used to detect reactive oxygen species(ROS) levels in myocardial tissue. Specific assay kits were used to measure serum brain natriuretic peptide(BNP), myocardial Fe~(2+), and malondialdehyde(MDA) levels. Western blot(WB) was used to detect the expression levels of myosin heavy chain 7B(MYH7B), natriuretic peptide A(NPPA), collagens type Ⅰ(Col-Ⅰ), α-smooth muscle actin(α-SMA), ferritin heavy chain 1(FTH1), solute carrier family 7 member 11(SLC7A11), glutathione peroxidase 4(GPX4), 4-hydroxy-2-nonenal(4-HNE), and Hmox1. Immunohistochemistry(IHC) was used to examine Hmox1 protein expression patterns. FerroOrange and Highly Sensitive DCFH-DA fluorescence probes were used to detect intracellular Fe~(2+) and ROS levels. Transmission electron microscopy was used to observe changes in mitochondrial morphology. In network pharmacology, FPS targets were identified through the PubChem database and PharmMapper platform. DCM-related targets were integrated from OMIM, GeneCards, and DisGeNET databases, while ferroptosis-related targets were obtained from the FerrDb database. A protein-protein interaction(PPI) network was constructed for the intersection of these targets using STRING 11.0, and core targets were screened with Cytoscape 3.9.0. Molecular docking analysis was conducted using AutoDock and PyMOL 2.5. In vivo results showed that FPS significantly reduced AST, LDH, CK-MB, and BNP levels in DCM model rats, improved cardiac function, decreased the expression of myocardial injury proteins(MYH7B, NPPA, Col-Ⅰ, and α-SMA), alleviated myocardial hypertrophy and fibrosis, and reduced Fe~(2+), ROS, and MDA levels in myocardial tissue. Furthermore, FPS regulated the expression of ferroptosis-related markers(Hmox1, FTH1, SLC7A11, GPX4, and 4-HNE) to varying degrees. Network pharmacology results revealed 313 potential targets for FPS, 1 125 targets for DCM, and 14 common targets among FPS, DCM, and FerrDb. Hmox1 was identified as a key target, with FPS showing high docking activity with Hmox1. In vitro results demonstrated that FPS restored the expression levels of ferroptosis-related proteins, reduced intracellular Fe~(2+) and ROS levels, and alleviated mitochondrial structural damage in cardiomyocytes. In conclusion, FPS improves myocardial injury in DCM, with its underlying mechanism potentially involving the regulation of Hmox1 to inhibit ferroptosis. This study provides pharmacological evidence supporting the therapeutic potential of FPS for DCM-induced myocardial injury.
Animals ; Ferroptosis/drug effects* ; Rats ; Diabetic Cardiomyopathies/physiopathology* ; Male ; Rats, Sprague-Dawley ; Polysaccharides/pharmacology* ; Heme Oxygenase-1/genetics* ; Myocytes, Cardiac/metabolism* ; Myocardium/pathology* ; Humans ; Cell Line ; Heme Oxygenase (Decyclizing)

Sepsis is a systemic inflammatory response caused by severe infection or trauma, and is one of the common causes of acute lung injury(ALI) and acute respiratory distress syndrome(ARDS). Sepsis-acute lung injury(SALI) is a critical clinical condition with high morbidity and mortality. Its pathogenesis is complex and not yet fully understood, and there is currently a lack of targeted and effective treatment options. Pyroptosis, a novel form of programmed cell death, plays a key role in the pathological process of SALI by activating inflammasomes and releasing inflammatory factors, making it a potential therapeutic target. In recent years, the role of traditional Chinese medicine(TCM) in regulating signaling pathways related to pyroptosis through multi-components and multi-targets has attracted increasing attention. TCM may intervene in pyroptosis by inhibiting the activation of NLRP3 inflammasomes and regulating the expression of Caspase family proteins, thus alleviating inflammatory damage in lung tissues. This paper systematically reviews the molecular regulatory network of pyroptosis in SALI and explores the potential mechanisms and research progress on TCM intervention in cellular pyroptosis. The aim is to provide new ideas and theoretical support for basic research and clinical treatment strategies of TCM in SALI.
Pyroptosis/drug effects* ; Humans ; Sepsis/genetics* ; Acute Lung Injury/physiopathology* ; Animals ; Drugs, Chinese Herbal/therapeutic use* ; Medicine, Chinese Traditional ; Inflammasomes/metabolism* ; NLR Family, Pyrin Domain-Containing 3 Protein/genetics*

PURPOSE: To investigate the pathological changes of the synovium in mice with post-traumatic osteoarthritis (PTOA) treated with 4-octyl itaconate (4-OI) and evaluate the therapeutic effects of 4-OI. METHODS: In the phenotypic validation experiment, the mice were randomly divided into 3 groups: wild-type (WT) group, sham group, and destabilization of the medial meniscus (DMM) group. Through MRI, micro-CT, and histological analysis, it was determined that the DMM surgery induced a mouse PTOA model with significant signs of synovitis. At 12 weeks post-DMM surgery, synovial tissues from the DMM group and WT group mice were collected for ribonucleic acid sequencing analysis. In the 4-OI treatment experiment, mice were randomly divided into the sham group, DMM group, DMM + 4-OI (50 mg/kg) group, and DMM + 4-OI (100 mg/kg) group. Von Frey tests and open field tests were conducted at intervals during the 12 weeks following the DMM surgery. After 12 weeks of surgery, the efficacy of 4-OI treatment on PTOA in mice was evaluated using MRI, micro-CT, histological analysis, and quantitative real-time polymerase chain reaction. Finally, we utilized network pharmacology analysis to predict the mechanism of 4-OI in treating PTOA synovitis and conducted preliminary validation. Statistical analysis was performed using one-way ANOVA and the Kruskal-Wallis test. Difference was considered statistically significant at p < 0.05. RESULTS: The DMM surgery effectively induced a PTOA mouse model, which displayed significant symptoms of synovitis. These symptoms included a notable increase in both the number of calcified tissues and osteophytes (p < 0.001), an enlargement of the calcified meniscus and synovial tissue volume (p < 0.001), and thickening of the synovial lining layer attributable to M1 macrophage accumulation (p = 0.035). Additionally, we observed elevated histological scores for synovitis (p < 0.001). Treatment with 4-OI inhibited the thickening of M1 macrophages in the synovial lining layer of PTOA mice (p < 0.001) and reduced fibrosis in the synovial stroma (p = 0.004). Furthermore, it reduced the histological scores of knee synovitis in PTOA mice (p = 0.006) and improved the inflammatory microenvironment associated with synovitis. Consequently, this treatment alleviated pain in PTOA mice (p < 0.001) and reduced spontaneous activity (p = 0.003). Bioinformatics and network pharmacology analyses indicated that 4-OI may exert its therapeutic effects by inhibiting the differentiation of synovial Th17 cells. Specifically, compared to the lipopolysaccharide stimulation group, 4-OI reduced the levels of positive regulatory factors of Th17 cell differentiation (IL-1: p < 0.001, IL-6: p < 0.001), key effector molecules (IL-17A: p < 0.001, IL-17F: p = 0.004), and downstream effector molecules in the IL-17 signaling pathway (CCL2: p < 0.001, MMP13: p < 0.001). CONCLUSION 4-OI is effective in inhibiting synovitis in PTOA, thereby alleviating the associated painful symptoms.
Animals ; Synovitis/etiology* ; Mice ; Osteoarthritis/etiology* ; Disease Models, Animal ; Male ; Succinates/pharmacology* ; Mice, Inbred C57BL ; X-Ray Microtomography