Shaojie Yue

Protective effect of ginsenoside Rg1 on glutamate-induced lung injury

AbstractAim:To examine the possible protective effect of ginsenoside Rg1, an active component of ginseng, on lung injury caused by glutamate in vivo.Methods:The lungs of mice receiving glutamate (0.5 g/kg) and/or ginsenoside Rg1 (0.03 g/kg) via intraperitoneal administration were collected. The indexes of lung wet weight/ body weight ratios (LW/BW), lung wet/dry weight ratios (W/D), heart rate (HR), and breathing rate (BR) were determined. The activity of nitric oxide synthase (NOS), xanthine oxidase (XOD), superoxide dismutase (SOD), catalase (CAT), the content of NO, and malondialdehyde in the lung homogenate were measured.Results:Treatment with glutamate for 2 h increased LW/BW, W/D, HR, and BR. These changes were nearly abolished by pretreatment with ginsenoside Rg1 for 30 min before glutamate injection. An analysis of the lung homogenate demonstrated the protective effect as evidenced by the inhibition of NOS (12%) and XOD (50%) inactivity, the enhanced activity of SOD (20%) and CAT (25%).Conclusion:Ginsenoside Rg1 has a potential protective role in lung diseases associated with glutamate toxicity.

Glutamate Mediates Hyperoxia-Induced Newborn Rat Lung Injury through N-Methyl-D-Aspartate Receptors

Our laboratory found that the N-methyl-D-aspartate receptor (NMDAR) antagonist, MK-801, was able to decrease hyperoxia-induced lung damage. To further search for direct evidence of glutamate and its NMDARs participating in hyperoxia-induced lung injury, the amount of glutamate in the bronchoalveolar lavage fluid and the expression of NMDAR 2D in lung tissue were tracked in newborn rats that were exposed to 95% oxygen for 1, 3, and 7 days. The protective effect of MK-801 was then observed at different hyperoxia exposure times. As demonstrated by RT-PCR, NMDAR 2D expression was much higher in hyperoxia exposure on the third and the seventh days than in the air control group. The levels of glutamate in the bronchoalveolar lavage fluid on the first and third days of hyperoxia exposure were significantly higher than in the air control group. MK-801 alleviated lung injury and inflammatory reaction induced by 95% O(2) for 3 and 7 days. These results indicate that large amounts of endogenous glutamate from the lungs were released, and its NMDAR were expressed strongly under conditions of high oxygen concentration. We conclude that the endogenous glutamate mediated newborn rat lung damage induced by hyperoxia through NMDARs.

Antiflammin-1 attenuates bleomycin-induced pulmonary fibrosis in mice.

BackgroundAntiflammin-1 (AF-1), a derivative of uteroglobin (UG), is a synthetic nonapeptide with diverse biological functions. In the present study, we investigated whether AF-1 has a protective effect against bleomycin-induced pulmonary fibrosis.MethodsC57BL/6 mice were injected with bleomycin intratracheally to create an animal model of bleomycin-induced pulmonary fibrosis. On Day 7 and Day 28, we examined the anti-inflammatory effect and antifibrotic effect, respectively, of AF-1 on the bleomycin-treated mice. The effects of AF-1 on the transforming growth factor-beta 1 (TGF-β1)-induced proliferation of murine lung fibroblasts (NIH3T3) were examined by a bromodeoxycytidine (BrdU) incorporation assay and cell cycle analysis.ResultsSevere lung inflammation and fibrosis were observed in the bleomycin-treated mice on Day 7 and Day 28, respectively. Administration of AF-1 significantly reduced the number of neutrophils in the bronchoalveolar lavage fluid (BALF) and the levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in the lung homogenates on Day 7. Histological examination revealed that AF-1 markedly reduced the number of infiltrating cells on Day 7 and attenuated the collagen deposition and destruction of lung architecture on Day 28. The hydroxyproline (HYP) content was significantly decreased in the AF-1-treated mice. In vitro, AF-1 inhibited the TGF-β1-induced proliferation of NIH3T3 cells, which was mediated by the UG receptor.ConclusionsAF-1 has anti-inflammatory and antifibrotic actions in bleomycin-induced lung injury. We propose that the antifibrotic effect of AF-1 might be related to its suppression of fibroblast growth in bleomycin-treated lungs and that AF-1 has potential as a new therapeutic tool for pulmonary fibrosis.

Superior effect of hypertonic saline over mannitol to attenuate cerebral edema in a rabbit bacterial meningitis model.

Objective: Adjunctive therapies that reduce the cerebral edema in bacterial meningitis include osmotic agents. There is a lack of information comparing mannitol vs. hypertonic saline as an osmotic agent for adjunctive therapy of bacterial meningitis. We attempted to elucidate the impact of hypertonic saline in cerebral edema in the setting of bacterial meningitis as well as to explore potential mechanisms of action. Design: Randomized controlled in vivo study. Setting: University research laboratory. Subjects: Rabbits. Interventions: A rabbit model of bacterial meningitis was used comparing 3% hypertonic saline with 20% mannitol as adjunctive therapy. Measurements and Main Results: Adjunctive 3% hypertonic saline treatment persistently elevated mean arterial pressure as compared with the model or ampicillin group (p < .01). Although both 20% mannitol and 3% hypertonic saline efficiently elevated serum osmolality for almost 5 hrs (p < .01), 20% mannitol lowered intracranial pressure for only a short time (<2 hrs) and did not elevate cerebral perfusion pressure. Three percent hypertonic saline treatment efficiently lowered intracranial pressure and elevated cerebral perfusion pressure for almost 5 hrs (p < .01). Furthermore, 3% hypertonic saline treatment efficiently elevated serum Na+ concentration for >5 hrs (p < .01). Three percent hypertonic saline treatment was superior to 20% mannitol in lowering leukocyte number and protein content in cerebrospinal fluid (p < .01). Three percent hypertonic saline treatment reduced water content and Evans blue incorporation in the brain (p < .01). Three percent hypertonic saline treatment inhibited aquaporin 4 expression (p < .01) and attenuated pathologic brain damage more efficiently compared with adjuvant 20% mannitol treatment (p < .01). Conclusions: Adjunctive 3% hypertonic saline treatment significantly elevated mean arterial pressure, reduced intracranial pressure, greatly improved cerebral perfusion pressure, inhibited brain aquaporin 4 expression, reduced cerebral edema, and attenuated brain damage with a superior effect over 20% mannitol in a rabbit bacterial meningitis model.

An excessive increase in glutamate contributes to glucose-toxicity in β-cells via activation of pancreatic NMDA receptors in rodent diabetes

In the nervous system, excessive activation of NMDA receptors causes neuronal injury. Although activation of NMDARs has been proposed to contribute to the progress of diabetes, little is known about the effect of excessive long-term activation of NMDARs on β-cells, especially under the challenge of hyperglycemia. Here we thoroughly investigated whether endogenous glutamate aggravated β-cell dysfunction under chronic exposure to high-glucose via activation of NMDARs. The glutamate level was increased in plasma of diabetic mice or patients and in the supernatant of β-cell lines after treatment with high-glucose for 72u2009h. Decomposing the released glutamate improved GSIS of β-cells under chronic high-glucose exposure. Long-term treatment of β-cells with NMDA inhibited cell viability and decreased GSIS. These effects were eliminated by GluN1 knockout. The NMDAR antagonist MK-801 or GluN1 knockout prevented high-glucose-induced dysfunction in β-cells. MK-801 also decreased the expression of pro-inflammatory cytokines, and inhibited I-κB degradation, ROS generation and NLRP3 inflammasome expression in β-cells exposed to high-glucose. Furthermore, another NMDAR antagonist, Memantine, improved β-cells function in diabetic mice. Taken together, these findings indicate that an increase of glutamate may contribute to the development of diabetes through excessive activation of NMDARs in β-cells, accelerating β-cells dysfunction and apoptosis induced by hyperglycemia.

Mechanism of neuroprotective effect induced by QingKaiLing as an adjuvant drug in rabbits with E. coli bacterial meningitis

OBJECTIVEnTo explore the neuroprotective effects and underlying mechanism of QingKaiLing (QKL) as an adjuvant treatment for bacterial meningitis.nnnMETHODnE. coli bacterial meningitis rabbits were treated with antibiotics (ampicillin) alone or in combination with QKL. The number of leukocytes and the concentration of protein in the cerebrospinal fluid (CSF) of rabbits were determined at 0, 16, and 26 hours after treatment. Brain water, sodium, potassium, and calcium contents were determined at the 26-hour time point. The level of matrix metalloproteinase-9 in the brain was also determined by Western blot.nnnRESULTnThe average number of leukocytes and the concentration of protein in CSF of the QKL adjuvant treatment group were reduced compared with the ampicillin alone group. Brain water, sodium, and calcium contents were reduced in the QKL adjuvant treatment group. The level of MMP-9 in brain tissue was also reduced in the QKL adjuvant treatment group.nnnCONCLUSIONnQKL adjuvant treatment alleviates the aggravated inflammatory reaction and partially protects brain tissue from antibiotic-induced injury. The mechanism of this neuroprotective effect of QKL may be due to decreased levels of Ca2+ and MMP-9 in the brain.

Inhibition of Pulmonary Surfactants Synthesis during N-Methyl-d-Aspartate-Induced Lung Injury

N-methyl-D-aspartate (NMDA) receptors are ionotropic glutamate receptors widely distributed in the central nervous system, and have been extensively investigated for their roles in embryonic development, synaptic plasticity and neuroexcitoxicity. Their functions in the peripheral nervous system and non-neural tissues have caught much attention recently. Over-activation of NMDA receptors induces excitotoxic lung injury. But the endogenous cell types in the lungs that express NMDA receptors remains elusive and the molecular mechanism underlies NMDA-induced lung injury has not been fully characterized. In this work, we reported that functional NMDA receptors were expressed in alveolar type II cells in the lungs. Over-activation of these receptors led to down-regulation of pulmonary surfactants synthesis. We further demonstrated that decreased cellular choline-phosphate cytidylyltransferase alpha expression induced by NMDA treatment accounted for the decreased pulmonary surfactants synthesis. Our results provided important clues for treatment of glutamate lung injury by modulating pulmonary surfactants system.

N-Methyl-D-aspartate Receptor Excessive Activation Inhibited Fetal Rat Lung Development In Vivo and In Vitro

Background. Intrauterine hypoxia is a common cause of fetal growth and lung development restriction. Although N-methyl-D-aspartate receptors (NMDARs) are distributed in the postnatal lung and play a role in lung injury, little is known about NMDARs expression and role in fetal lung development. Methods. Real-time PCR and western blotting analysis were performed to detect NMDARs between embryonic days (E) 15.5 and E21.5 in fetal rat lungs. NMDAR antagonist MK-801s influence on intrauterine hypoxia-induced retardation of fetal lung development was tested in vivo, and NMDAs direct effect on fetal lung development was observed using fetal lung organ culture in vitro. Results. All seven NMDARs are expressed in fetal rat lungs. Intrauterine hypoxia upregulated NMDARs expression in fetal lungs and decreased fetal body weight, lung weight, lung-weight-to-body-weight ratio, and radial alveolar count, whereas MK-801 alleviated this damage in vivo. In vitro experiments showed that NMDA decreased saccular circumference and area per unit and downregulated thyroid transcription factor-1 and surfactant protein-C mRNA expression. Conclusions. The excessive activation of NMDARs contributed to hypoxia-induced fetal lung development retardation and appropriate blockade of NMDAR might be a novel therapeutic strategy for minimizing the negative outcomes of prenatal hypoxia on lung development.

Nitric oxide-induced activation of NF-κB-mediated NMDA-induced CTP:phosphocholine cytidylyltransferase alpha expression inhibition in A549 cells

Pulmonary surfactant is a lipoprotein complex on the alveolar surface. It reduces the surface tension at the air–water interface and stabilizes the alveoli during expiration. Surfactant deficiency or dysfunction is associated with occurrence and development of many pulmonary diseases. Family members of CTP:phosphocholine cytidylyltransferase are rate-limiting enzymes for surfactant phospholipid synthesis. We had reported recently that the expression of CTP:phosphocholine cytidylyltransferase alpha (CCT-α) was inhibited during N-methyl-d-aspartic acid (NMDA)-induced lung injury. But the molecular mechanism underlining remains elusive. In this work, we reported that NMDA induced nitric oxide synthase (NOS) activation and nuclear factor–kB (NF–κB) subunit p65 nuclear translocation in A549 cells, which were responsible for decreased (CCT-α) expression. Furthermore, NOS activation and elevated NO production are upstream regulators for p65 nuclear translocation and (CCT-α) expression inhibition. Our results provided important clues for further elucidating the mechanisms underlying glutamate-induced lung injury.

Role of c-fos gene in vasoactive intestinal peptide promoted synthesis of pulmonary surfactant phospholipids

We previously reported that vasoactive intestinal peptide (VIP) promoted synthesis of phosphatidylcholine (PC) in alveolar type II (ATII) cells. But the intracellular mechanism for this effect was unknown. In this work, we investigated the intracellular signal transduction pathway for VIP promoted synthesis of PC, the major lipid component of pulmonary surfactant (PS), by using an antagonist of VIP receptors, inhibitor of protein kinase C (PKC) and antisense oligonucleotides (AS-ODN) for c-fos oncogene. Our results showed that: 1 in circle [D-P-Cl-Phe(6)-Leu(17)]-VIP (10(-6) mol/l), an antagonist of VIP receptors, could decrease the quantity of [(3)H] choline incorporation, microsomal choline-phosphate cytidylyltransferase (CCT) mRNA expression and CCT activity induced by VIP (10(-8) mol/l) in cultured lung explants to the control levels; 2 in circle VIP (10(-8) mol/l) upregulated c-Fos protein expression in ATII cells. AS-ODN for c-fos oncogene (9x10(-6) mol/l) could block the elevation of [(3)H] choline incorporation, microsomal CCT mRNA expression and CCT activity induced by VIP in cultured lung explants and in ATII cells; 3 in circle H7 (10(-5) mol/l), a PKC inhibitor could also reduce VIP induced [(3)H] choline incorporation, microsomal CCT mRNA expression and CCT activity in cultured lung explants and in ATII cells. These results demonstrated that VIP receptors, PKC and c-Fos protein played important roles in the signaling pathway through which VIP promoted the synthesis of PC.