Design and synthesis of novel anti-multidrug-resistant staphylococcus aureus derivatives of glycyrrhetinic acid by blocking arginine biosynthesis, metabolic and H2S biogenesis.

With the soaring number of multidrug-resistant bacteria, it is imperative to develop novel efficient antibacterial agents and discovery new antibacterial pathways. Herein, we designed and synthesized a series of structurally novel glycyrrhetinic acid (GA) derivatives against multidrug-resistant Staphylococcus aureus (MRSA). The in vitro antibacterial activity of these compounds was evaluated using the microbroth dilution method, agar plate coating experiments and real-time growth curves, respectively. Most of the target derivatives showed moderate antibacterial activity against Staphylococcus aureus (S. aureus) and MRSA (MIC = 3.125-25 µM), but inactivity against Escherichia coli (E. Coli) and Pseudomonas aeruginosa (P. aeruginosa) (MIC > 200 µM). Among them, compound 11 had the strongest antibacterial activity against MRSA, with an MIC value of 3.125 µM, which was 32 times and 64 times than the first-line antibiotics penicillin and norfloxacin, respectively. Additionally, transcriptomic (RNA-seq) and quantitative polymerase chain reaction (qPCR) analysis revealed that the antibacterial mechanism of compound 11 was through blocking the arginine biosynthesis and metabolic and the H2S biogenesis. Importantly, compound 11 was confirmed to have good biocompatibility through the in vitro hemolysis tests, cytotoxicity assays and the in vivo quail chicken chorioallantoic membrane (qCAM) experiments. Current study provided new potential antibacterial candidates from glycyrrhetinic acid derivatives for clinical treatment of MRSA infections.

Immune-mediated membranous nephropathy: Long term fluconazole usage caused podocyte autophagy.

The primary consequences of membranous nephropathy (MN) are the development of nephrotic syndrome including hypogammaglobulinemia, the increased infectious risk, the loss of protein-bound vitamin D, and, above all, an elevated thromboembolic incidence of up to 50% in severe proteinuria patients. Membrane nephropathy may be either idiopathic or primary, not recognized (70%-80%) or secondary (20%-30%) to pathological sicknesses such as hepatitis B, systemic lupus erythematosus, malignancies, and side-effects of medicines. The immunological responses in MN involve multiple components: immunoglobulin G (IgG), long-escaped antigens, and the membrane attachment complex, formed by the supplement to form C5b-9. In general, IgG4 is the most significant IgG subclass deposited in idiopathic membranous nephropathic disease but fluctuating IgG1 levels also are linked with immunological deposits. In contrast, IgG1, IgG2, and IgG3 deposition are greater than IgG4 deposition in secondary nephropathy. Fluconazole is a synthetic antifungal triazole that is often used. It is well tolerated in general and has never been identified as a cause of nephropathies. We report on the development of MN caused by fluconazole therapy that could potentiate podocyte autophagy.

Effects of occlusion on mandibular morphology and architecture in rats.

BACKGROUND: A rodent occlusal hypofunction model has been widely established in jawbone-related studies. However, the effects of occlusal stimuli, with total elimination of molar contacts, and its rehabilitation on mandibular remodeling remain unclear. MATERIALS AND METHODS: Forty-eight 5-wk-old Sprague-Dawley male rats were used. Twenty-four experimental rats underwent occlusal hypofunction by insertion of a bite-raising appliance. Twenty-four rats received no treatment (control group). Two weeks later, half the experimental rats (occlusal hypofunction group) were killed; the appliance was removed from the remaining experimental rats (recovery group) for two additional weeks before killing. Control animals were killed biweekly. Body weight and masseter muscle weight were measured, and the mandibles were subjected to micro-computed tomography to evaluate the mandibular morphology and cortical bone characteristics. The expressions of osteoblast- and osteoclast-related genes were evaluated with quantitative polymerase chain reaction. RESULTS: No significant body weight differences were observed between the experimental and control rats. However, lighter masseter muscle, shorter mandibular incisor crown, mandibular body and ramus, and higher mandibular alveolar process and first molar fossae were observed in the occlusal hypofunction group. Moreover, the cortical bone characteristics associated with the expression of osteoblast- and osteoclast-related genes were remarkably different in the central and posterior mandible in the occlusal hypofunction group. At the 2-wk recovery time point after occlusal stimuli, the altered parameters in the masseter and mandible returned to normal levels. CONCLUSIONS: Mandibular remodeling via bone turnover is region specific for altered occlusal stimuli. Normal occlusion is an important determinant of the mandibular morphology and architecture.

Potential dental pulp revascularization and odonto-/osteogenic capacity of a novel transplant combined with dental pulp stem cells and platelet-rich fibrin.

Our aim is to investigate the cytobiological effects of autologous platelet-rich fibrin (PRF) on dental pulp stem cells (DPSCs) and to explore the ectopic and orthotopic possibilities of dental pulp revascularization and pulp-dentin complex regeneration along the root canal cavities of the tooth by using a novel tissue-engineered transplant composed of cell-sheet fragments of DPSCs and PRF granules. Canine DPSCs were isolated and characterized by assaying their colony-forming ability and by determining their cell surface markers and osteogenic/adipogenic differentiation potential. The biological effects of autologous PRF on DPSCs, including cell proliferation, alkaline phosphatase (ALP) activity and odonto-/osteogenic gene expression, were then investigated and quantified. A novel transplant consisting of cell-sheet fragments of DPSCs and PRF granules was adopted to regenerate pulp-dentin-like tissues in the root canal, both subcutaneously in nude mice and in the roots of canines. PRF promoted the proliferation of DPSCs in a dose- and time-dependent manner and induced the differentiation of DPSCs to odonto-/osteoblastic fates by increasing the expression of the Alp, Dspp, Dmp1 and Bsp genes. Transplantation of the DPSC/PRF construct led both to a favorable regeneration of homogeneous and compact pulp-like tissues with abundantly distributed blood capillaries and to the deposition of regenerated dentin along the intracanal walls at 8 weeks post-operation. Thus, the application of DPSC/PRF tissue constructs might serve as a potential therapy in regenerative endodontics for pulp revitalization or revascularization.

Locus coeruleus activation contributes to masseter muscle overactivity induced by chronic restraint stress in mice.

It is commonly accepted that exposure to stress may cause overactivity in the orofacial muscles, leading to consistent muscle pain, which is the main symptom of temporomandibular disorders. The central neural mechanism underlying this process, however, remains unclear. The locus coeruleus is considered to play an important role in stress-related behavioral changes. Therefore, the present study was designed to examine the role of locus coeruleus neurons in masseter overactivity induced by stress. C57BL/6 mice were subjected to chronic restraint stress for 14 days to establish an animal model. The behavioral changes and the electromyography of the masseter muscle in mice were measured. The expression of Fos in locus coeruleus was observed by immunofluorescence staining to assess neuronal activation. A chemogenetic test was used to inhibit locus coeruleus neuronal activity, and the behavioral changes and electromyography of the masseter muscle were observed again. The results exhibited that chronic restraint stress could induce anxiety-like behavior, overactivity of the masseter muscle, and significant activation of locus coeruleus neurons in mice. Furthermore, inhibition of noradrenergic neuron activity within the locus coeruleus could alleviate stress-induced anxiety behavior and masseter muscle overactivity. Activation of noradrenergic neurons in locus coeruleus induced by stress may be one of the central regulatory mechanisms for stress-induced anxiety-like behaviors and overactivity of masseter muscles.

Poly[[di-aqua-(µ4-benzene-1,2,4,5-tetra-carboxyl-ato)tetrakis-(1H-imidazole-κN (3))dicopper(II)] N,N-di-methyl-formamide monosolvate].

The asymmetric unit of the polymeric title compound, {[Cu2(C10H2O8)(C3H4N2)4(H2O)2]·C3H7NO} n , contains two independent Cu(II) ions, each coordinated by one water mol-ecule, two imidazole N atoms and two carboxyl-ate O atoms from benzene-1,2,4,5-tetra-carboxyl-ate anions in a distorted square-pyramidal geometry. The benzene-1,2,4,5-tetra-carboxyl-ate anion bridges four Cu(II) ions, forming a polymeric sheet parallel to (010). In the crystal, extensive N-H⋯O and O-H⋯O hydrogen bonds link the polymeric sheets and di-methyl-formamide solvent mol-ecules into a three-dimensional supra-molecular structure.

[Application of the Oxford classification of IgA nephropathy to predict renal outcome].

OBJECTIVE: To validate the value of the Oxford classification of IgA nephropathy in predicting the renal outcome in Chinese population. METHODS: Retrospective study was done in patients with IgA nephropathy. All slides were re-assessed according to the Oxford classification of IgA nephropathy. The primary end point is doubling serum creatinine, or a 50% reduction in estimated glomerular filtration rate (eGFR), or end-stage renal disease. Pathologic predictors for the progression to the end point were determined by univariate and multivariate Cox regression. RESULTS: Totally 533 patients were enrolled in the study. During the follow-up (median: 39 months; range: 12-263 months), 5.07% of the patients reached the end point. While tubular atrophy and interstitial fibrosis and arterial/ arteriolar lesion were associated with the endpoint in univariate analysis, only the T score was predictive of the renal outcome in multivariate Cox regression. Combination of the patho- logic lesions had no impact on renal outcome. CONCLUSION: According to the Oxford classification of IgA nephropathy, the degree of tubulointerstitial fibrosis is the only feature independently predictive of renal outcome.

[Degradation of Ciprofloxacin by CuNiFe LDHs/BiO2-x Heterojunction-activated Peroxymonosulfate Under Visible Light Irradiation].

Herein, a CuNiFe LDHs/BiO2-x composite photocatalyst was successfully synthesized using a hydrothermal method and applied to activate peroxymonosulfate to degrade ciprofloxacin under visible light irradiation. Owing to the synergistic effect of photocatalysis and PMS activation, a high removal efficiency of CIP up to 88.3% was achieved. The prepared photocatalysts were characterized using XRD, FT-IR, SEM, XPS, UV-Vis DRS, and other methods. The optimal loading amount of CuNiFe LDHs was determined, and the effects of PMS dosage, initial pH value, and inorganic anions (Cl-, CO32-, and NO3-) on the degradation were investigated. Electron paramagnetic resonance and free radical trapping experiments demonstrated that·OH and h+ were the main active species for degrading CIP, and the possible degradation mechanism of the system was proposed.

Research progress on acupuncture treatment in central nervous system diseases based on NLRP3 inflammasome in animal models.

Central nervous system (CNS) disorders exhibit complex neurophysiological and pathological mechanisms, which seriously affect the quality of life in patients. Acupuncture, widely accepted as complementary and alternative medicine, has been proven to exert significant therapeutic effects on CNS diseases. As a part of the innate immune system, NLRP3 inflammasome contributes to the pathogenesis of CNS diseases via regulating neuroinflammation. To further explore the mechanisms of acupuncture regulating NLRP3 inflammasome in CNS diseases, our study focused on the effects of acupuncture on neuroinflammation and the NLRP3 inflammasome in vascular dementia, Alzheimer's disease, stroke, depression, and spinal cord injury. This study confirmed that the activation of NLRP3 inflammasome promotes the development of CNS diseases, and inhibiting the activation of NLRP3 inflammasome is a potential key target for the treatment of CNS diseases. In addition, it is concluded that acupuncture alleviates neuroinflammation by inhibiting the activation of the NLRP3 inflammasome pathway, thereby improving the progression of CNS diseases, which provides a theoretical basis for acupuncture to attenuate neuroinflammation and improve CNS diseases.

Region-specific sympatho-adrenergic regulation of specialized vasculature in bone homeostasis and regeneration.

Type H vessels couple angiogenesis with osteogenesis, while sympathetic cues regulate vascular and skeletal function. The crosstalk between sympathetic nerves and type H vessels in bone remains unclear. Here, we first identify close spatial connections between sympathetic nerves and type H vessels in bone, particularly in metaphysis. Sympathoexcitation, mimicked by isoproterenol (ISO) injection, reduces type H vessels and bone mass. Conversely, beta-2-adrenergic receptor (ADRB2) deficiency maintains type H vessels and bone mass in the physiological condition. In vitro experiments reveal indirect sympathetic modulation of angiogenesis via paracrine effects of mesenchymal stem cells (MSCs), which alter the transcription of multiple angiogenic genes in endothelial cells (ECs). Furthermore, Notch signaling in ECs underlies sympathoexcitation-regulated type H vessel formation, impacting osteogenesis and bone mass. Finally, propranolol (PRO) inhibits beta-adrenergic activity and protects type H vessels and bone mass against estrogen deficiency. These findings unravel the specialized neurovascular coupling in bone homeostasis and regeneration.

Psychological stress delays periodontitis healing in rats: the involvement of basic fibroblast growth factor.

OBJECTIVE: To evaluate the effects of psychological stress on periodontitis healing in rats and the contribution of basic fibroblast growth factor (bFGF) expression to the healing process. METHODS: Ninety-six rats were randomly distributed into control group, periodontitis group, and periodontitis plus stress group. Then, the rats were sacrificed at baseline and week(s) 1, 2, and 4. The periodontitis healing condition was assessed, and the expression of interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), and bFGF were tested by immunohistochemistry. RESULTS: The stressed rats showed reduced body weight gain, behavioral changes, and increased serum corticosterone and ACTH levels (P < 0.05). The surface of inflammatory infiltrate, alveolar bone loss, attachment loss, and expression of IL-1ß and TNF-α in the stress group were higher than those in the periodontitis group at weeks 2 and 4 (P < 0.05). Rats with experimental periodontitis showed decreased bFGF expression (P < 0.05), and the recovery of bFGF expression in the stress group was slower than that in the periodontitis group (P < 0.05). Negative correlations between inflammatory cytokines and bFGF were detected. CONCLUSION: Psychological stress could delay periodontitis healing in rats, which may be partly mediated by downregulation of the expression of bFGF in the periodontal ligament.

Activation of the Mesencephalic Trigeminal Nucleus Contributes to Masseter Hyperactivity Induced by Chronic Restraint Stress.

Psychological stress is commonly accepted to be closely associated with masticatory muscle disorder, which is the main symptom of temporomandibular disorder (TMD). Previous studies have confirmed that exposure to stress may cause masticatory muscle hyperactivity. However, the central mechanism underlying this process remains unclear. The mesencephalic trigeminal nucleus (Vme), which resides in the brainstem, is the primary afferent center for masticatory proprioception and plays a key role in oral-motor movements by projecting to the trigeminal motor nucleus (Vmo). Therefore, the present study was designed to examine the role of Vme neurons in masseter overactivity induced by chronic stress. We found that subjecting mice to restraint stress (6 h/day) for 14 days caused significant anxiety-like behavior, obvious masseter overactivity, and markedly enhanced electrophysiological excitability of Vme neurons. By using anterograde tract tracing combined with immunofluorescence staining methods, we observed vesicular glutamate transporter 1 (VGLUT1)-positive glutamatergic projections from the Vme to the Vmo. Moreover, chronic restraint stress (CRS) elevated the expression of VGLUT1 and choline acetyltransferase (ChAT) in Vmo. Furthermore, administration of VGLUT1-targeted short hairpin RNA (shRNA) into the bilateral Vme significantly suppressed the enhanced overexcitability of Vme neurons, downregulated the overexpression of VGLUT1 and ChAT in the Vmo, and attenuated the elevated overactivity of the masseter caused by CRS. Taken together, we showed that CRS can excite neurons in the Vme, enhancing glutamatergic excitatory projections from the Vme to the Vmo and resulting in masseter muscle overactivity. These findings provide us with a novel central mechanism underlying the correlation between psychological factors and TMD.

Rituximab for the management of idiopathic membranous nephropathy: a meta-analysis.

PURPOSE: The aim of this study was to evaluate the efficacy of rituximab therapy in the management of idiopathic membranous nephropathy (IMN). METHODS: After literature search, data from eligible studies were used to perform random-effects meta-analyses to estimate remission rates and changes in proteinuria at the latest follow-up after rituximab therapy. The outcomes were used for metaregression to identify the factors affecting the efficacy of rituximab. RESULTS: Twenty-one studies were included in the analysis (602 patients; age 50 years [95% CI 46.8, 53.3]; 30% females [95% CI 23, 31]). Follow-up duration was 20.3 months [95% CI 17.1, 23.5]. Remission rate (67% [95% CI 61, 73]) was higher in studies with below average baseline proteinuria (76% [95% CI 61, 88]) than in studies with above average baseline proteinuria (61% [95% CI 54, 68]). The complete and partial remission rates were 26% [95% CI 20, 33] and 37% [95% CI 31, 43], respectively. Rituximab therapy significantly reduced proteinuria (mean difference between final and baseline values: - 4.90 g/day [95% CI - 6.18, - 3.63]; p < 0.00001; % reduction: 62% [95% CI 57, 68]). The reduction in proteinuria was inversely associated with baseline serum albumin levels (p = 0.021) and the estimated glomerular filtration rate (p < 0.00001) and was positively associated with baseline proteinuria (p < 0.00001). The remission rate or decrease in proteinuria was not significantly related to the anti-PLA2R antibody status or previous immunosuppressant therapy. CONCLUSION: Rituximab therapy in IMN patients can provide approximately 67% remission rate. The reduction in proteinuria was greater in patients who had higher baseline proteinuria.

A study of altered calcium sensing system caused primary membranous nephropathy to end-stage renal failure.

PMN (primary membranous nephropathy) is the most prevalent source of idiopathic nephrotic syndrome, which further progressed to ESRD (end-stage renal disease) in non-diabetic adults worldwide. Autoantibodies circulating against podocyte membrane proteins PLA2R1 and THSD7A are present in approximately 75-80% of incidents. Furthermore, a research presented an unusual case of IgG4-RD correlated with elevated serum levels of calcium concluded that renal irregularities have been preceded and triggered by hypercalcemia. In-addition, previous research also indicates an elevated amount of calcium in the blood of PMN patients. However, we also found conflicting evidence from previous studies showing that autoantibodies that suppress the calcium-sensing receptor (CaSR) induce a high level of calcium in some cases of IgG4RD. Notably, the calcium ion plays a critical function not only as intracellular signaling molecule but binds extracellular receptor activity to intracellular events. Moreover, the raise in intracellular calcium levels during PMN is known as a crucial event involved in the activation of numerous nucleases, proteases and implicitly facilitates the release of prostaglandins, cytokines and superoxide radicals capable of causing cell damage and death. Thus, the precise mechanism of the PMN disease to renal failure is not fully clear and the disease incidence differs among patients. Therefore, we are hypothesizing the role of disrupted calcium signaling in PMN that progress to ESRD.

[Effects of glutamine on platelet-derived growth factor and its receptor following septic brain damage in rats].

OBJECTIVE: This study investigated the expression of platelet-derived growth factor-B (PDGF-B) and its receptor-ß (PDGFR-ß) in rat cerebral cortex following sepsis and explored the possible underlying mechanism of neuro-protective effect of glutamine (Gln). METHODS: One hundred and twenty 10-day-old Wistar rats were randomly divided into three groups: a control group that received an intraperitoneal injection of normal saline (1 mL/kg), a sepsis group that received an intraperitoneal injection of lipopolysaccharide (LPS, 5 mg/kg), and a Gln treatment group that was administered with Gln (1.346 g/kg) 1 hr before LPS injection. The rats were subdivided into 5 groups sacrificed at 2, 6, 12, 24 and 72 hrs after LPS or normal saline injection (n=8). The distribution and expression of PDGF-B and PDGFR-ß in the cerebral cortex were ascertained by immunohistochemistry and Western blot. RESULTS: The immunohistochemistry results showed that the PDGF-B and PDGFR-ß expression in the cerebral cortex increased significantly in the Gln treatment group 72 hrs after LPS injection compared with that in the control and the sepsis groups. The Western blot results showed that the PDGF-B expression in the brain tissue in the sepsis and the Gln treatment groups were significantly lower than that in the control group 2, 6, and 12 hrs after LPS injection, while the Gln treatment group had increased PDGF-B expression compared with the sepsis group 12 and 72 hrs after LPS injection. Compared with the control group, the PDGFR-ß expression in the brain tissue in the sepsis group increased 2 and 6 hrs after LPS injection but decreased significantly 72 hrs after LPS injection. There were no significant differences in the PDGFR-ß expression between the Gln treatment and the control groups at all different time points. CONCLUSIONS: Gln can increase the PDGF-B and PDGFR-ß expression in the brain tissue of rats with sepsis. The increased PDGF-B and PDGFR-ß expression might contribute to neuro-protective effects of Gln.

Synthesis and antitumor activity of amino acid ester derivatives containing 5-fluorouracil.

A series of amino acid ester derivatives containing 5-fluorouracil were synthesized using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC*HCl) and N-hydroxybenzotriazole (HOBt) as a coupling agent. The structures of the products were assigned by NMR, MS, IR etc. The in vitro antitumor activity tests against leukaemia HL-60 and liver cancer BEL-7402 indicated that (R)-ethyl 2-(2-(5-fluoro-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamido)-3-(4-hydroxyphenyl) propanoate showed more inhibitory effect against BEL-7402 than 5-FU.

A six-connected alpha-polonium net based on tetranuclear Cd(II) nodes.

The cadmium(II) coordination polymer poly[[(pyrazino[2,3-f][1,10]phenanthroline-kappa(2)N(8),N(9))cadmium(II)]-mu(3)-naphthalene-1,4-dicarboxylato-kappa(5)O(1):O(1),O(1'):O(4),O(4')], [Cd(C(12)H(6)O(4))(C(14)H(8)N(4))](n), contains two Cd(II) cations, two pyrazino[2,3-f][1,10]phenanthroline (L) ligands and two naphthalene-1,4-dicarboxylate (1,4-ndc) anions in the asymmetric unit. Both Cd(II) ions are in a distorted CdO(5)N(2) monocapped octahedral coordination geometry. Both unique 1,4-ndc ligands are bonded to three Cd(II) ions. In these modes, tetranuclear clusters are formed in which four Cd(II) ions are bridged by the carboxylate groups of the 1,4-ndc ligands to form discrete rods. The tetranuclear cadmium carboxylate clusters act as rod-shaped secondary building units (SBUs) within the structure. The SBUs are connected together by the aromatic backbone of the dicarboxylate ligands, connecting the clusters into a three-dimensional alpha-polonium net. The title compound represents the first alpha-polonium net constructed from rod-like clusters in coordination polymers. The result indicates that an appropriate combination of dicarboxylate and aromatic chelating ligands is critical to the formation of high-dimensional structures based on metal clusters in these systems.

Decreased expression of matrix metalloproteinase-1 in the maternal umbilical serum, trophoblasts and decidua leads to preeclampsia.

The aim of the present study was to explore the levels of matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the maternal umbilical serum, placenta and decidua of patients with preeclampsia compared with those in normotensive pregnant females. A total of 73 pregnant females were recruited as the test subjects, including 43 inpatients with hypertensive disorders in pregnancy and 30 normal pregnant females as the control. The 43 inpatients with hypertensive disorders in pregnancy included 18 patients with gestational hypertension, nine with mild preeclampsia and 16 with severe preeclampsia. MMP-1 and TIMP-1 ELISA kits were used to determine the MMP-1 and TIMP-1 levels in the umbilical serum of the parturient following delivery. MMP-1 and TIMP-1 expressed in the placenta and decidua of the parturient following delivery were evaluated using immunohistochemistry. MMP-1 and TIMP-1 were mainly located in cytotrophoblasts and syncytiotrophoblasts in the placenta and decidua. The levels of MMP-1 in the umbilical serum of the normal, gestational hypertension, mild preeclampsia and severe preeclampsia groups were 294.33±11.53, 247.78±20.32, 177.67±12.63 and 124.68±15.41 pg/ml, respectively, and there were significant differences between each two groups (P<0.05). The positive expression rate of MMP-1 in the placenta and decidua of patients with hypertensive disorders in pregnancy was lower than that of the controls (P<0.01 and P<0.01, respectively). However, no significant difference was identified between each two groups with regard to the levels of TIMP-1 in the umbilical cord and the positive rates in the placenta and decidua (P>0.05). Reduced MMP-1 levels in the umbilical serum, placenta and decidua were observed in women who developed preeclampsia.

Activation of satellite glial cells in the trigeminal ganglion contributes to masseter mechanical allodynia induced by restraint stress in rats.

It is commonly accepted that psychological stress contributes to the development of chronic orofacial pain. However, the neural mechanism underlying this process has remained unclear. The present study was performed to determine the involvement of satellite glia cells (SGCs) in the trigeminal ganglion (TG) in stress-induced increases in masseter muscle allodynia in rats. Using a chronic restraint stress model, we found that exposure to a 14-day stress but not a 3-day stress (6 h/day) caused decreased body weight gain, behavioral changes and marked masseter allodynia in rats. SGCs were dramatically activated, and substance P (SP) expression was significantly increased in the TG. A further analysis was undertaken to investigate the contribution of SGCs; the expression of interleukin-1ß (IL-1ß) in SGCs and interleukin-1 receptor I (IL-1RI) in neurons was significantly increased after chronic restraint stress, whereas injection of L-α-aminoadipate (a SGC inhibitor, LAA) into the TG dramatically inhibited the overexpression of these proteins. In addition, LAA or interleukin-1 receptor antagonist (IL-1ra) administration into the TG could significantly attenuate the mechanical masseter allodynia and overexpression of SP in the TG induced by restraint stress. These results suggest that SGC activation in the TG may play a role in masseter allodynia induced by restraint stress. The over-release of IL-1ß and excessive IL1-RI expressions have close relationship with the stress induced masseter allodynia.

Involvement of trigeminal astrocyte activation in masseter hyperalgesia under stress.

It is commonly accepted that psychological stress contributes to the development of temporomandibular joint disorders, in which chronic orofacial pain is the main symptom. However, the central mechanism underlying the development of these disorders has remained unclear. The current study was performed to determine the involvement of the glia in the trigeminal spinal subnucleus caudalis in stress-induced increases in masseter muscle hyperalgesia in rats. After being subjected to chronic restraint stress, the animals showed decreased body weight gain, behavioral changes and marked masseter allodynia. We also found that astrocytes, but not microglia, in the trigeminal subnucleus caudalis (Vc) were dramatically activated. A further analysis was undertaken to investigate the contribution of the glia; we intrathecally injected l-α-aminoadipate (astrocyte-specific inhibitor) and/or minocycline (microglia-specific inhibitor) into the stressed rats. Our results showed that l-α-aminoadipate (LAA), but not minocycline, could significantly attenuate the mechanical masseter allodynia and behavioral changes induced by restraint stress. In addition, the expression of interleukin-1ß (IL-1ß) and phosphorylated N-methyl-d-aspartic acid receptor 1 (p-NR1) in the Vc was significantly increased after chronic restraint stress, whereas LAA dramatically inhibited the overexpression of IL-1ß and p-NR1. Taken together, these results suggest that activated astrocytes in the Vc may be one of the most important factors in the pathophysiology of masseter hyperalgesia induced by restraint stress and the following overexpression of IL-1ß and excessive NMDAR phosphorylation may ultimately contribute to masseter hyperalgesia. Thus, inhibiting spinal astrocytic activation may represent a novel therapeutic strategy for the treatment of orofacial pain induced by stress.