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Aim To explore the effeet of chemogenetic designer reeeptors exclusively activated by designer drugs( DREADD) mediated inhibition of glutamatergic neurons in paraventricular nucleus of hypothalamus (PVN ) on myocardial ischemia-reperfusion injury in mice.Methods Mice were catheterized in PVN by stereotaxic technique, followed by recover}' for three days in individual cages.The mice were then received the inhibitory virus rAAV CaMK E cx-hM4d (Gi)-EG- FP-WPRE-hGHpA or the control vims rAAV CaMK H a - E GF P- W PRE - h GH pA in the PVN nucleus.Three weeks after virus infection, myocardial ischemia-reperfusion injury ( IR) was performed by ligating the left anterior descending coronary artery for 1 h and then releasing it for 2 h.Clozapine N-oxide (CNO) 2 mg •kg 1 was injected intraperitoneally 1 h before IR, to induce inhibition of glutamatergic neurons in PVN by specifically binding to the hM4D receptor ( Gi).TTC staining was used to measure the infarct size, and ELISA was used to measure the serum cTnl concentration.During experiments, the ECG was recorded by PowerLab system.Western blot was used to detect the pro-survival kinase ERK and cleaved caspase-3 proteins in heart tissues, and the expressions of EGFP, CaMKII and c-fos in PVN were examined under fluorescence microscope.Results The glutamatergic neurons in PV N were specifically infected by AAV vectors.When compared with sham group, the ratio of IS/AAR, serum cTnl, c-fos in PVN, and cleaved caspase-3 protein all increased in IR group , but the pERK level decreased.However, hM4D ( Gi) DREADD mediated inhibition of PVN glutamatergic neurons significantly reduced IS/AAR, cTnl concentration and c-fos expression in PVN, as well as the decrease of cleaved caspase-3 and the increase of pERK in heart tissues.Conclusion Chemogenetic DREADD mediated inhibition of glutamatergic neurons in paraventricular nu- cleus of hypothalamus ( PVN) reduces myocardial is- chemia-reperfusion injury in mice.
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Aim To investigate the effects of lysophosphatidic acid on ischemia / reperfusion injury(IRI)and TRPV1 expression in isolated mouse heart.Methods The IRI model of isolated mouse heart was established by Langendorff device.The hearts in sham group were continuously perfused for 100 min.The hearts in IR group were stabilized for 10 min followed by no perfusion for 30 min and reperfusion for 60 min.Exogenous LPA was added in the K-H solution during IR in IR+LPA group while HA130, an LPA synthesis inhibitor, was intraperitoneally injected before IR in IR+HA130 group.The infarct volume was measured by TTC staining, the determination of LPA and LDH levels in coronary effluent and LPA concentration in serum was measured by ELISA method.Finally, the expression levels of pTRPV1/TRPV1 and Bcl-2/Bax in myocardial tissues were determined by Western blot.Results Compared with sham group, IR caused evident myocardial infarction and increased the levels of LDH and LPA in coronary effluent.The increase of LPA was linearly correlated with myocardial infarction volume.In addition, the protein levels of pTRPV1 and TRPV1 in myocardium increased, while the ratio of Bcl-2/Bax decreased.The myocardial injury in IR+LPA group was aggravated.In contrast, myocardial IRI was reversed in IR+HA130 group.Conclusions Myocardial ischemia-reperfusion induces the release of LPA, which aggravates myocardial post-ischemic injury, while the inhibition of LPA release exerts cardioprotective effects.The underlying mechanisms might be related to the regulation on cardiac TRPV1 expression and apoptotic signals.
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Aim To investigate the effects of morphine preconditioning (MPC) on transient receptor potential vanilloid 1 (TRPV1) channel current in rat dorsal root ganglia (DRG) neurons and the phosphorylation (p) of TRPV1 and extracellular regulated protein kinases (ERK) in PC12 cells that sensitized by nerve growth factor (NGF). Methods DRG neurons isolated from T2-T8 segments of 10 days old SD rat or pheochromo-cytoma (PC12) cells were seeded into 24-well plates or 6-well plates, respectively, and randomly divided into 5 groups:control group (group C), NGF sensiti-zation group (group NGF), and morphine precondi-tioning groups (group MPC 0.3, group MPC 1.0 and group MPC 3.0). DRG neurons were identified by im-munofluorescent method with neuronal specific enolase (NSE). Cells were treated by morphine, NGF and capsaicin to simulate the effects of MPC on DRG neu-rons in T2-T8 segments during myocardial ischemia reperfusion injury (IRI). Afterwards, the inward cur-rent of DRG neurons induced by capsaicin in all groups were detected by whole cell recording; the expression and phosphorylation of TRPV 1 and ERK in PC12 cells were detected by Western blot. Results DRG neu-rons survived and grew nicely,and the staining of neu-ronal specific markers,NSE,was positive. In compar-ison with group C, the inward current of group NGF was enhanced (P <0.05), while MPC inhibited the enhancement (P <0.05). The relative expression of TRPV1,p-TRPV1 and p-ERK in group NGF was up-regulated when compared with group C (P <0.05).Moreover, the up-regulation was also suppressed by MPC (P <0.05). Conclusions MPC inhibits TR-PV1 channel current sensitized by NGF in neurocytes, and the mechanism might be associated with the down-regulation of TRPV1 p-TRPV1 and p-ERK expression.
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Aim To observe the role of ERK signaling protein in morphine preconditioning reducing global ischemia-reperfusion injury in isolated rat hearts.Methods Adult male Sprague-Dawley rats were distributed into six groups (n =10 for each) using a random number table:control group (CON),ischemia-reperfusion group (I/R),ischemia preconditioning group (IPC),morphine preconditioning group at the concentration of 1 μmol · L-1 (MPC),ERK inhibitor PD98059 + MPC (MPD),and group of ERK inhibitor-PD98059 (PD).The isolated rat hearts were treated on a Langendorff perfusion apparatus system.The coronary effluent was collected at 15 min of equilibration (baseline),5 and 10 min of reperfusion for detection of the activity of LDH.Meanwhile,a water-filled balloon was inserted into the left ventricular for continuous LVDP measurement.The IS and AAR and IS/AAR ratios were observed by TTC.Western blot was used to examine the level of phosphorylated ERK in myocardium.Results As compared with the I/R group,MPC significantly decreased IS and IS/AAR ratio as well as LDH activities at 5 min and 10 min of reperfusion,but improved the LVDP at the end of reperfusion.Moreover,the phosphorylation level of ERK in myocardium was up-regulated by MPC.However,ERK inhibitor PD98059 could block the protective effects of MPC,as indicated by the increased IS and IS/AAR ratio,elevated LDH activity at the reperfusion of 5 and 10 min,and the suppressed LVDP at the end of reperfusion.Furthermore,the MPC-induced phosphorylation of ERK was also reversed by PD98059.Conclusion Morphine preconditioning may confer cardio-protection against the global ischemia-reperfusion injury in rat hearts through enhancing the phosphorylation of ERK.
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This study aims to synthesize new phospholipids, 1,3-dipalmaminophospholipid(Pad-PC-Pad), and prepare shear-stress sensitive liposomes(SSSL). 1H NMR and MS indicated that Pad-PC-Pad were fully synthesized successfully. SSSL were prepared by filming-rehydration method with Pad-PC-Pad, which loaded calcein with aggregation-caused quenching(ACQ)characteristics to evaluate shear-stress sensitivity of liposomes and release behavior of liposomes in vitro. The results showed that the particle size of liposomes was 106.91 ± 1.24 nm and liposomes had lenticular morphology under transmission electron microscope. The release of calcein was increased with ultrasonic power, which suggests that the liposomes is shear-stress sensitive. Moreover, the liposomes exhibited a releasing effect for obstructed region under high shear-stress in a model system. Therefore, we synthesized quick functional phospholipid Pad-PC-Pad and the liposomes made from Pad-PC-Pad was shear-stress sensitive, which may be used for treatment of thrombosis.
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This study aims to prepare lipid bilayer-coated calcium phosphate core-shell nanoparticles (LCAPNs), which can dissolve in an acidic environment to improve the tumor cell toxicity of antitumor drug. Paclitaxel (PTX) loaded lipid coated calcium phosphate nanoparticles (PTX-LCAPNs) were prepared by thin-film dispersion method. The morphology, particle size and in vitro release behavior were characterized. Meanwhile, the intracellular uptake, intracellular dissolution, cell toxicity of PTX-LCAPNs and intracellular accumulation of PTX were evaluated in human HCC cell line (Huh-7). The results suggested that the mean diameter of the spherical LCAPNs was 124.73±6.41 nm. The PTX-LCAPNs demonstrated little drug leakage in simulated normal physiological conditions, while a rapid release was observed in simulated intracellular condition in vitro. Moreover, the PTX-LCAPNs achieved 1.7 fold improvement in the intracellular PTX concentration leading to 5-fold reduction in half maximal inhibitory concentration (IC50) values of PTX compared with calcium phosphate nanoparticles loaded with PTX (PTX-CAPNs), demonstrating a stronger cancer cell lethality.
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Polymyxin E shows effective treatment of the infection induced by resistant gramnegative bacteria, but its nephrotoxicity severely limits the clinical application of this drug. In this work, methoxypolyethylene glycols 2000 (mPEG2K)-polymyxin E (PME) was synthesized via chemical grafting reaction and had been characterized. The antimicrobial activity and cytotoxicity of mPEG2K-PME in vitro were investigated on Escherichia coli and HK-2 cells, separately. Intra-abdominal infection model was further established in order to study the therapeutic effect and the toxic effect on kidney of mice. The results showed that mPEG2K-PME exhibited significant inhibitory effect on Escherichia coli and had a lower toxicity on HK-2 cells in vitro. At the same time, mPEG2K-PME had a good efficacy in the treatment of Escherichia coli infected mice in vivo. Moreover, nephrotoxicity caused by mPEG2K-PME was significantly reduced compared to free PME. mPEG2K-PME is promising in development of new preparations with high efficiency and low toxicity.