Group α-BGT Research Articles

Nicotine plays a protective role in rats with induced viral pneumonia with polyinosinic-polycytidylic acid through α7nAChR

ObjectiveTo study the effect of nicotine in rat model of pneumonia induced by polyinosinic-polycytidylic acid [Poly (I:C)] and explore the underlying mechanism. MethodsTwenty-four healthy adult male Sprague-Dawley (SD) rats (200–250 g) were randomly divided into normal saline control group (NS group); Poly (I:C) group; nicotine group (NIC group); and α7 nicotinic acetylcholine receptor (α7nAChR) antagonist group (α-BGT group) (n = 6 each). Rats in the Poly (I: C), NIC, and α-BGT groups were administered 1.5 mg/mL 100 μL Poly (I:C) intranasally to establish pneumonia model. In α-BGT group, 1 μg/kg α-bungarotoxin (α-BGT) was intraperitoneally injected 45 min before intranasal Poly (I:C), and 400 μg/kg nicotine was intraperitoneally injected 15 min after α-BGT injection. The NIC group received an equal volume of NS in place of α-BGT while the other treatments were same. The Poly (I:C) group received equal volume of NS in place of nicotine while the other treatments were same as in NIC group. In the NS group, only NS was administered at all three time points. PaCO2, PaO2, and PaO2/FiO2 levels were determined 24 h after administration of Poly (I:C). After euthanization, rat lung tissues were extracted for pathological examination, and wet weight/dry weight (W/D ratio) was determined. Expression of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-1β, and interferon (IFN)-γ in lung tissue was determined by ELISA. q-PCR was used to detect nuclear factor kappa-B P65 (NF-κBP65). ResultsCompared with NS group, Poly (I:C) and α-BGT groups showed significantly increased W/D ratio, PaCO2, TNF-α, IL-6, IL-1β, and IFN-γ content, NF-κB P65 expression, and reduced PaO2 and PaO2/FiO2 (p < 0.05), along with obvious signs of pathological injury. Nicotine pre-treatment reduced W/D ratio, PaCO2, proinflammatory cytokines, NF-κBP65 expression, and increased PaO2 and PaO2/FiO2 levels. The above effects were negated in α-BGT group. ConclusionPre-administration of nicotine improved Poly (I:C)-induced pneumonia by activating the cholinergic anti-inflammatory pathway.

Electroacupuncture Pretreatment Ameliorates Anesthesia and Surgery-Induced Cognitive Dysfunction via Activation of an α7-nAChR Signal in Aged Rats.

ObjectivePostoperative cognitive dysfunction (POCD) after anesthesia and surgery (AS) is a common complication in the elderly population. A cholinergic-dependent signal, the alpha7-nicotinic acetylcholine receptor (α7-nAChR), has been suggested to regulate cognitive processes in a variety of neurologic diseases. In the current study, we determined whether electroacupuncture (EA) pretreatment ameliorates AS-induced POCD in aged rats, as well as the underlying mechanism.MethodsMale Sprague-Dawley rats (20 months old) were randomly assigned to the following 5 groups (n=12): vehicle; POCD (tibial fracture surgery); EA plus POCD; EA plus POCD and alpha-bungarotoxin (α-BGT); and POCD plus α-BGT groups. Alpha-bungarotoxin (1 μg/kg), a selective antagonist of α7-nAChR, was administrated via intraperitoneal injection before EA. Thirty days post-AS, the Morris water maze and a novel objective recognition test were used to evaluate cognitive function. Neuronal amount, apoptosis, microglial activation, percentage of high mobility group box 1 (HMGB1)- and nuclear factor-κB (NF-κB)-positive microglia, and levels of HMGB-1 downstream factors, including NF-κB, interleukin-6 (IL-6), and IL-1β, were detected by Nissl staining, immunofluorescence, and Western blot assays.ResultsEA pretreatment significantly increased crossing platform times and elevated the time with a novel object, restored the quantity of neurons, decreased TUNEL-positive neurons, alleviated activation of microglia, downregulated expression of HMGB1 and NF-κB in the microglia, and reduced levels of phosphor-NF-κB, IL-6, and IL-1β 35 days after AS, while α-BGT partially reversed these changes.ConclusionEA pretreatment improved AS-induced POCD in aged rats, and the underlying mechanism may be associated with inhibition of HMGB1–NF-κB via an α7-nAChR signal in the microglia.

Relationship between α7nAChR signaling pathway and regulatory T cells during vagus nerve stimulation-induced reduction of endotoxin-caused acute lung injury in mice

Objective To evaluate the relationship between α7 nicotinic acetylcholine receptor (α7nAChR) signaling pathway and regulatory T cells (Tregs) during vagus nerve stimulation-induced reduction of endotoxin-caused acute lung injury (ALI) in mice. Methods Clean-grade healthy male C57BL/6 mice, aged 6-8 weeks, weighing 22-25 g, were divided into 5 groups (n=10 each) using a random number table method: control group (group C), group ALI, vagus nerve stimulation group (group VNS), α-BGT group (group α-BGT) and vagus nerve stimulation plus α-BGT group (group VNS + α-BGT). After successful establishment of the model, the vagus nerve was stimulated for 30 s with a stimulus intensity of 0.5 mA, frequency of 20 Hz, an interval of 5 min, 60 min in total.Sterile normal saline 100 μl was injected into the trachea, and the vagus nerve was only exposed but not stimulated in group C. In group ALI, the ALI model was established, and the vagus nerve was isolated but not stimulated.In group α-BGT, α-BGT 1 μg/kg was intraperitoneally injected, the ALI model was established 1 h later, and the vagus nerve was isolated but not stimulated.In group VNS+ α-BGT, α-BGT 1 μg/kg was intraperitoneally injected, the ALI model was established 1 h later, and the vagus nerve was stimulated at 1 h after the end of establishment.Animals were sacrificed at 72 h after establishing the model, and lungs were removed for determination of lung water content, percentage of Tregs (using flow cytometry), myeloperoxidase (MPO) activity (by colorimetric assay), expression of α7nAChR (by Western blot) and contents of interleukin-10 (IL-10), transforming growth factor-β (TGF-β) and IL-1β (by enzyme-linked immunosorbent assay). Results Compared with group C, the lung water content, MPO activity and IL-1β content were significantly increased in the other four groups, the expression of α7nAChR was significantly down-regulated in ALI, α-BGT and VNS+ α-BGT groups, the percentage of Tregs was significantly increased in group VNS, the IL-10 content was significantly decreased in ALI and α-BGT groups and increased in VNS and VNS+ α-BGT groups, and TGF-β contents were significantly decreased in ALI, α-BGT and VNS+ α-BGT groups and increased in group VNS (P<0.05). Compared with group ALI, the lung water content, MPO activity and IL-1β content were significantly decreased, the expression of α7nAChR was up-regulated, and the percentage of Tregs and contents of IL-10 and TGF-β were increased in group VNS, and the TGF-β content in group α-BGT and contents of IL-10 and TGF-β in group VNS+ α-BGT were significantly increased (P<0.05). Compared with group VNS, the lung water content, MPO activity and IL-1β content were significantly increased, the expression of α7nAChR was down-regulated, and the percentage of Tregs and contents of IL-10 and TGF-β were decreased in α-BGT and VNS+ α-BGT groups (P<0.05). The contents of IL-10 and TGF-β were significantly higher in group VNS+ α-BGT than in group α-BGT (P<0.05). Conclusion Vagus nerve stimulation can activate α7nAChR signaling pathway and raise the percentage of Tregs, thus reducing ALI in mice. Key words: Vagus nerve; Respiratory distress syndrome, adult; T-Lymphocytes, regulatory; Receptors, nicotinic

Role of cholinergic anti-inflammatory pathway in dexmedetomidine pretreatment-induced reduction of acute lung injury in a rat model of intestinal ischemia-reperfusion

Objective To evaluate the role of cholinergic anti-inflammatory pathway in dexmedetomidine pretreatment-induced reduction of acute lung injury in a rat model of intestinal ischemia-reperfusion (I/R). Methods Twenty-four healthy male Sprague-Dawley rats, aged 2-3 months, weighing 200-250 g, were divided into 4 groups (n=6) using a random number table method: sham operation group (S group), intestinal I/R group (II/R group ), dexmetomidine group (DEX group) and α7 nicotinic acetylcholine receptor antagonist α-bungarotoxin (α-BGT) group (α-BGT group). Intestinal I/R was produced by occlusion of the superior mesenteric artery (SMA) for 60 min followed by 120 min of reperfusion in anesthetized rats.Dexmetomidine 5 μg·kg-1·h-1 was injected via the tail vein at 1 h before operation in DEX group and α-BGT group.α-BGT 1 μg/kg was intraperitoneally injected at 15 min before dexmetomidine injection in α-BGT group.Rats were sacrificed at 120 min of reperfusion, and lung tissues were obtained for microscopic examination of pathological changes (with a light microscope) and for determination of wet/dry weight ratio (W/D ratio), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) contents (using enzyme-linked immunosorbent assay), malondialdehyde (MDA) content (using thiobarbital acid method) and superoxide dismutase (SOD) activity (by xanthine oxidase method). Results Compared with group S, the W/D ratio and contents of MDA, TNF-α and IL-6 were significantly increased, and the SOD activity was decreased in II/R and α-BGT groups, and TNF-α and IL-6 contents were significantly increased in group DEX (P<0.05). Compared with group II/R, the W/D ratio and contents of MDA, TNF-α and IL-6 were significantly decreased, SOD activity was increased (P<0.05), and the pathological changes were significantly attenuated in group DEX.Compared with group DEX, the W/D ratio and contents of MDA, TNF-α and IL-6 were significantly increased, SOD activity was decreased (P<0.05), and the pathological changes were accentuated in group α-BGT. Conclusion Activation of cholinergic anti-inflammatory pathway is involved in the mechanism by which dexmedetomidine pretreatment reduces acute lung injury in a rat model of intestinal I/R. Key words: Acetylcholine; Dexmetomidine; Reperfusion injury; Intestines; Hespiratory distress syndrome, adult

Effect of dexmedetomidine on intestinal injury in rats with endotoxemia

Objective To evaluate the effect of dexmedimidine on intestinal injury in rats with endotoxemia. Methods Twenty-four healthy adult male Sprague-Dawley rats, aged 2-3 months, weighing 200-250 g, were divided into 4 groups (n = 6 each) using a random number table method: control group (group C), endotoxemia group (group E), dexmedimidine group (group D) and dexmedimidine plus α7 subunit-containing nicotinic acetylcholine receptor antagonist group (D+ α-BGT group). The endotoxemia model was established by injecting lipopolysaccharide (LPS) 10 mg/kg via the femoral vein.Dexmedetomidine 40 μg/kg was injected and 15 min later LPS was intravenously injected in group D. Dexmedetomidine 40 μg/kg was intraperitoneally injected after intraperitoneal injection of α-bungarotoxin 1 μg/kg, and 15 min later LPS was intravenously injected in group D+ α-BGT.Blood samples were collected from the abdominal aorta at 6 h after LPS injection for determination of the plasma interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) concentrations (by enzyme-linked immunosorbent assay). Rats were sacrificed after blood sampling, and intestinal tissues were obtained for examination of the pathological changes and for determination of the myeloperoxidase (MPO) activity (by chemical colorimetry) and expression of NF-κB p65 in nucleoprotein (by Western blot). Results Compared with group C, the plasma IL-6 and TNF-α concentrations and MPO activity in intestinal tissues were significantly increased, and the expression of NF-κB p65 in nucleoprotein was up-regulated in the other 3 groups (P<0.05). Compared with group E, the plasma IL-6 and TNF-α concentrations and MPO activity in intestinal tissues were significantly decreased, the expression of NF-κB p65 in nucleoprotein was down-regulated (P<0.05), and the pathological changes of intestinal tissues were significantly attenuated in group D. Compared with group D, the plasma IL-6 and TNF-α concentrations and MPO activity in intestinal tissues were significantly increased, the expression of NF-κB p65 in nucleoprotein was up-regulated (P<0.05), and the pathological changes of intestinal tissues were accentuated in group D+ α-BGT. Conclusion Dexmedetomidine can reduce the intestinal injury in rats with endotoxemia, and the mechanism may be related to activating cholinergic anti-inflammatory pathway and further inhibiting inflammatory responses. Key words: Dexmetomidine; Endotoxemia; Intestines; Cholinergic anti-inflammatory pathway

Astragaloside IV Prevents Obesity-Associated Hypertension by Improving Pro-Inflammatory Reaction and Leptin Resistance.

Low-grade pro-inflammatory state and leptin resistance are important underlying mechanisms that contribute to obesity-associated hypertension. We tested the hypothesis that Astragaloside IV (As IV), known to counteract obesity and hypertension, could prevent obesity-associated hypertension by inhibiting pro-inflammatory reaction and leptin resistance. High-fat diet (HFD) induced obese rats were randomly assigned to three groups: the HFD control group (HF con group), As IV group, and the As IV + α-bungaratoxin (α-BGT) group (As IV+α-BGT group). As IV (20 mg·Kg−1·d−1) was administrated to rats for 6 weeks via daily oral gavage. Body weight and blood pressure were continuously measured, and NE levels in the plasma and renal cortex was evaluated to reflect the sympathetic activity. The expressions of leptin receptor (LepRb) mRNA, phosphorylated signal transducer and activator of transcription-3 (p-STAT3), phosphorylated phosphatidylinositol 3-kinase (p-PI3K), suppressor of cytokine signaling 3 (SOCS3) mRNA, and protein-tyrosine phosphatase 1B (PTP1B) mRNA, pro-opiomelanocortin (POMC) mRNA and neuropeptide Y (NPY) mRNA were measured by Western blot or qRT-PCR to evaluate the hypothalamic leptin sensitivity. Additionally, we measured the protein or mRNA levels of α7nAChR, inhibitor of nuclear factor κB kinase subunit β/ nuclear factor κB (IKKβ/NF-KB) and pro-inflammatory cytokines (IL-1β and TNF-α) in hypothalamus and adipose tissue to reflect the anti-inflammatory effects of As IV through upregulating expression of α7nAChR. We found that As IV prevented body weight gain and adipose accumulation, and also improved metabolic disorders in HFD rats. Furthermore, As IV decreased BP and HR, as well as NE levels in blood and renal tissue. In the hypothalamus, As IV alleviated leptin resistance as evidenced by the increased p-STAT3, LepRb mRNA and POMC mRNA, and decreased p-PI3K, SOCS3 mRNA, and PTP1B mRNA. The effects of As IV on leptin sensitivity were related in part to the up-regulated α7nAchR and suppressed IKKβ/NF-KB signaling and pro-inflammatory cytokines in the hypothalamus and adipose tissue, since co-administration of α7nAChR selective antagonist α-BGT could weaken the improved effect of As IV on central leptin resistance. Our study suggested that As IV could efficiently prevent obesity-associated hypertension through inhibiting inflammatory reaction and improving leptin resistance; furthermore, these effects of As IV was partly related to the increased α7nAchR expression.

Dexmedetomidine attenuates pyohemia-associated delirium in mice through the cholinergic anti-inflammatory pathway

Objective To study if the protective effect of dexmedetomidine on the pyohemia-associated delirium is through the cholinergic anti-inflammatory pathway. Methods Sixty male adult C57 mice were randomly divided into five groups (n=12 each): saline group (group C), dexmedetomidine (DEX) alone group (group DEX), endotoxemia (LPS) group (group LPS), dexmedetomidine protection group (group LPS+ DEX) and alpha-bungarotoxin (α-BGT) group (group α-BGT). Each group were assigned to two subunits (n=6 each), mice in subunit one were sacrificed after examining the open field test, mice in subunit two were sacrificed after testing the novel object recognition. The level of inflammatory factors were measured by enzyme-linked immune sorbent assay (ELISA). The ultrastructure changes of the hippocampus in mice were observed by transmission electron microscopy. Results Compared with group C, there are no significant differences in group DEX. Dexmedetomidine significantly attenuated the delirious syndrome after LPS induced endotoxemia, however, the effect of dexmedetomidine disappeared in group α-BGT, and the syndrome of cognitive dysfunction in LPS group were more severe than that in group α-BGT. (1) The open field test show that there are no significant differences each group with that before model establishment; after the models were established 24 h, compared with group C, group LPS show that the abilities of cognition to new environment、learning and memory were decreasing, the tension is increasing. preemptive administration of dexmedetomidine significantly attenuated the delirious syndrome after LPS induced endotoxemia; however, preemptive administration of dexmedetomidine failed to control the delirious syndrome in group α-BGT. (2) The novel object recognition testshow that compared to group C, the ability of exploring the novel object is decreasing; preemptive administration of dexmedetomidine significantly improve the exploration ability, however, preemptive administration of dexmedetomidine failed to control the delirious syndrome in group α-BGT. (3) The results of ELISA show that: Compared with group C, the concentrations of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β in serum and Hippocampus were all increased in LPS groups[Serum (ng/L) TNF-α: 794.80±93.99 vs. 23.60±3.03, IL-1β: 148.49±24.80 vs. 64.55±5.13, Hippocampus (pg/mg·prot) TNF-α: 176.14±11.25 vs. 6.71±0.49, IL-1β: 50.61±5.86 vs. 16.73±1.15, P=0.000], compared with group LPS, the concentrations were all significantly decreased in group LPS+ DEX[Serum (ng/L) TNF-α: 184.44±26.58 vs. 794.80±93.99, IL-1β: 77.43±10.75 vs. 148.49±24.80, Hippocampus (pg/mg·prot) TNF-α: 64.83±13.09 vs. 176.14±11.25, IL-1β: 17.97±2.26 vs. 50.61±5.86, P=0.000]. However, α-BGT can reverse the protective effect[Serum (ng/L): TNF-α: 812.31±86.25 vs. 184.44±26.58, IL-1β: 156.42±17.94 vs. 77.43±10.75, Hippocampus (pg/mg·prot) TNF-α: 181.94±8.69 vs. 64.83±13.09, IL-1β: 52.10±5.59 vs. 17.97±2.26, P=0.000]. TEM shown that the histopathological damage of hippocampus tissue in group LPS and α-BGT were heavier, which in group LPS+ DEX was reversed partially. Conclusion Central alpha-2 agonist dexmedetomidine attenuates sepsis-associated delirium syndrome likely through activating cholinergic anti-inflammatory pathway and inhibiting the inflammatory responses in serum and brain. Key words: Delirium; Dexmedetomidine; Endotoxemia; Cholinergic anti-inflammatory pathway; Inflammatory response

Effect of electro-acupuncture at Zusanli acupoint on blood coagulation during intestinal ischemia-reperfusion in rats

Objective To evaluate the effect of electro-acupuncture (EA) at Zusanli (ST36) acupoint on blood coagulation during intestinal ischemia-reperfusion (I/R) in rats. Methods Forty healthy male Sprague-Dawley rats, aged 6-8 months, weighing 250-300 g, were divided into 5 groups (n=8 each) using a random number table: sham operation group (group S), intestinal I/R group (group I/R), EA at Zusanli acupoint group (group EA), EA at non-acupoint group (group NE) and α7 nicotinic acetylcholine receptor antagonist α-bungarotoxin (α-BGT) group (group α-BGT). Intestinal I/R was induced by clamping the superior mesenteric artery for 45 min followed by 120 min of reperfusion.Bilateral Zusanli acupoints were stimulated with an electric stimulator (frequency 3 Hz, voltage 2-4 V, wave length 2 ms) for 30 min starting from the time point immediately after beginning of ischemia in group EA, while EA was performed at the points 5 mm lateral to the bilateral Zusanli instead in group NE.In group α-BGT, α-BGT 1 μg/kg was intraperitoneally injected at 45 min before ischemia, and the other treatments were similar to those previously described in group EA.Blood samples were collected from the abdominal aorta at 120 min of reperfusion for determination of the concentrations of tumor necrosis factor alpha (TNFα), tissue factor (TF), antithrombin (AT), tissue plasminogen activator (tPA), fiber plasminogen activator inhibitor-1 (PAI-1) and D-dimer in plasma (by enzyme-linked immunosorbent assay) and platelet count (PLT). The animals were sacrificed after blood sampling, the distal ileum specimens were removed for examination of the pathological changes with a light microscope, and the damage to the intestinal mucous membrane was assessed and scored according to Chiu. Results Compared with group S, the concentrations of plasma TNFα, TF, tPA, PAI-1 and D-dimer were significantly increased, and the plasma AT concentration and PLT were decreased in I/R, NE and α-BGT groups, the concentrations of plasma TNFα and TF were significantly increased, and the plasma AT concentration was decreased in group EA, and Chiu′s scores were significantly increased in I/R, EA, NE and α-BGT groups (P 0.05). Compared with group EA, the concentrations of plasma TNFα, TF, tPA, PAI-1 and D-dimer were significantly increased, the plasma AT concentration and PLT were decreased, and Chiu′s scores were increased in group NE (P<0.05). Conclusion EA at Zusanli acupoint can improve blood coagulation during intestinal I/R in rats, and the mechanism is related to activating the cholinergic anti-inflammatory pathway. Key words: Electroacupuncture; POINT ST36 (ZUSANLI); Reperfusion injury; Intestines; Blood coagulation

Role of Cholinergic Anti-Inflammatory Pathway in Treatment of Intestinal Ischemia-Reperfusion Injury by Electroacupuncture at Zusanli.

Electroacupuncture (EA) at Zusanli is a widely used method for the treatment of intestinal ischemic disease. The current study attempts to investigate the possible mechanism from the point of cholinergic anti-inflammatory pathway (CAP) in rats. Thirty rats were divided into five groups: control group, I/R group, EA group (I/R + EA), PNU group (I/R + α7 nAChR agonist), and α-BGT group (I/R + EA + α7 nAChR antagonist). EA and medicine injection were performed immediately after ischemia. After 2 h of reperfusion, blood and intestine samples were collected and intestinal histopathological score, mRNA expression of mucosal α7 nAChR and NF-κBp65, and serum cytokine levels (IL-6, TNF-α) were examined. Compared with the I/R group, the EA group and PNU group could significantly attenuate the mucosal damage, promote α7 nAChR mRNA expression, and reduce levels of NF-κBp65, IL-6, and TNF-α. Compared with the EA group, α7 nAChR mRNA was decreased, while concentrations of NF-κBp65, IL-6, and TNF-α increased in the α-BGT group. EA at Zusanli could inhibit NF-κBp65 and proinflammatory cytokines production after intestinal I/R injury; its mechanism may be related to the cholinergic anti-inflammatory pathway.

Role of α7nAChR in reduction of endotoxin-induced acute lung injury by limb ischemic preconditioning in mice

Objective To evaluate the role of α7 nicotinic acetylcholine receptor (α7nAChR) in reduction of endotoxin-induced acute lung injury (ALI) by limb ischemic preconditioning in mice. Methods Eighty healthy male C57BL/6 mice, aged 8-10 weeks, weighing 22-26 g, were randomly divided into 5 groups (n=16 each) using a random number table: control group (group C), ALI group, limb ischemic preconditioning group (group P), α-bungarotoxin (α-BGT) group, and limb ischemic preconditioning + α-BGT group (group P+ α-BGT). Normal saline 100 μl was intratracheally instilled in group C. In group ALI, lipopolysaccharide 5 mg/kg was intratracheally instilled (in normal saline) to establish the model of endotoxin-induced ALI.In group P, the mice were subjected to 6 cycles of 5-min ischemia of the right hindlimb followed by 5-min reperfusion, and then the model of ALI was established.In group α-BGT, α-BGT 1 μg/kg was injected intraperitoneally before establishment of the model.In group P+ α-BGT, limb ischemic preconditioning was performed, α-BGT 1 μg/kg was then injected intraperitoneally, and the model of ALI was established.At 24 h after LPS instillation, 6 mice were selected from each group and sacrificed, and lungs were removed for microscopic examination and for determination of wet and dry lung weight, myeloperoxidase (MPO) activities, contents of interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α) and IL-6, and expression of α7nAChR and high mobility group box-1 (HMGB1) in lung tissues.The lung water content was calculated.The survival of the left 10 mice in each group was observed at 7 days after establishment of the model, and the survival rate was calculated. Results Compared with group C, the lung water content, MPO activities, contents of IL-1β, TNF-α and IL-6, and HMGB1 expression were significantly increased, α7nAChR expression was significantly down-regulated, and the 7-day survival rate was significantly decreased in group ALI (P<0.05). Compared with group ALI, the lung water content, MPO activities, contents of IL-1β, TNF-α and IL-6, and HMGB1 expression were significantly decreased, α7nAChR expression was significantly up-regulated, and the 7-day survival rate was significantly increased in group P (P<0.05). Compared with group P, the lung water content, MPO activities, contents of IL-1β, TNF-α and IL-6, and HMGB1 expression were significantly increased, α7nAChR expression was significantly down-regulated, and the 7-day survival rate was significantly decreased in group P+ α-BGT (P<0.05). Conclusion The mechanism by which limb ischemic preconditioning inhibits inflammatory responses and reduces endotoxin-induced ALI is related to activation of α7nAChR in mice. Key words: Receptors, nicotinic; Ischemic preconditioning; Respiratory distress syndrome, adult; Inflammation

Effect of dexmedetomidine on scalds-induced acute lung injury in rats

Objective To evaluate the effect of dexmedetomidine on acute lung injury induced by scalds in rats. Methods Seventy-five male Sprague-Dawley rats, weighing 200-220 g, were randomly divided into 5 groups(n=15 each)using a random number table: control group(group C), scald group(group S), dexmedetomidine group(group D), α-bungarotoxin(α-BGT)group, and dexmedetomidine+ α-BGT group(group D+ α-BGT). About 30% of the total body surface was shaved and then exposed to 98 ℃ water for 12 s in S, D, α-BGT and D+ α-BGT groups.The back of rats was exposed to 37 ℃ water for 12 s in group C. Rats were resuscitated with lactated Ringer's solution injected intraperitoneally according to Parkland formula within 24 h after establishment of the model.In D, α-BGT, and D+ α-BGT groups, dexmedetomidine 40 μg/kg, α7 nicotinic acetylcholine receptor antagonist α-BGT 1 μg/kg, and α-BGT 1 μg/kg plus dexmedetomidine 40 μg/kg were injected intraperitoneally, respectively, at 15 min before establishment of the model.At 24 h after establishment of the model, the rats were sacrificed, and lungs were removed for examination of the pathological changes and for determination of myeloperoxidase(MPO)activity, interleukin-1beta(IL-1β), tumor necrosis factor-alpha(TNF-α), and IL-6 contents(by enzyme-linked immunosorbent assay), and nucleoprotein factor kappa B(NF-κB)(by Western blot). The lung water content [(wet weight-dry weight)÷wet weight×100%] was calculated. Results Compared with group C, the lung water content, MPO activities, and contents of IL-1β, TNF-α and IL-6 were significantly increased, and the expression of NF-κB was up-regulated in S, α-BGT and D groups(P 0.05), and the pathological changes were significantly attenuated in group α-BGT.Compared with group D, the lung water content, MPO activities, and contents of IL-1β, TNF-α and IL-6 were significantly increased, the expression of NF-κB was up-regulated(P<0.05), and the pathological changes were aggravated in group D+ α-BGT. Conclusion Dexmedetomidine can mitigate scalds-induced acute lung injury in rats. Key words: Dexmedetomidine; Burns; Respiratory distress syndrome, adult

Effect of dexmedetomidine on high-mobility group box 1 protein in rats with sepsis

To explore the effect of dexmedetomidine (DEX) on high-mobility group box 1 protein (HMGB1) in the serum and spleen in rats with sepsis and the underlying mechanisms. A total of 100 male Wistar rats were randomly divided into five groups: a control group, a sepsis group, a DEX group, an α-bungarotoxin- tetramethylrhodamine (α-BGT) plus DEX group and an α-BGT group (n=20 in each group). In the control group, same volume of normal saline (NS) was administrated, while lipopolysaccharide (LPS) was injected to the vein to develop a classic sepsis model. At the 48th h after LPS injection, the rats were sacrificed, and the blood and spleen were collected. The content of tumor necrosis factor-α (TNF-α) and HMGB1 in blood serum were detected by enzyme-linked immuno sorbent assay (ELISA), and the HMGB1 in the spleen was examined by Western blot. Among the 5 groups, there were statistical significance in the mortality, the serum level of TNF-α and HMGB1, and the content of secreting type of HMGB1 in spleen (all P<0.05), and the serum level of HMGB1 was positively correlated with the content of secreting type of HMGB1 (r=0.863, P<0.05). DEX exert late anti-inflammatory effects in the serum and spleen in rats with sepsis, which is related to the activation of the cholinergic anti-inflammatory pathway.

Dexmedetomidine controls systemic cytokine levels through the cholinergic anti-inflammatory pathway.

Previous studies have shown that dexmedetomidine exerted anti-inflammatory effect on several animal models with inflammation, but the mechanism is not clear. This study intends to elucidate the anti-inflammatory mechanism of dexmedetomidine through the cholinergic anti-inflammatory pathway. To investigate this therapeutic potential of dexmedetomidine, a murine model of endotoxemia was established induced by lipopolysaccharide (LPS). Animals were assigned to one of four protocols. Protocol one: animals were randomly assigned to control group, dexmedetomidine group, and sterile saline group (n=20 each), and these animals were used for survival analysis. The survival rate was assessed up to 120 h after endotoxin injection. Protocol two: animals were randomly assigned to one of four groups (n=16 each): group 1 (group Saline), treated with sterile saline 15 min prior to endotoxin treatment (10 mg kg(-1) over 2 min); group 2 (group Dex), treated with dexmedetomidine 15 min prior to endotoxin treatment; group 3 (group αBGT+Dex), treated with alpha-7 nicotinic acetylcholine receptors (α7nAChR) antagonist alpha-bungarotoxin (αBGT, 1 μg/kg) 15 min prior to dexmedetomidine treatment; group 4 (group saline+Dex), treated with equivalent sterile saline 15 min prior to dexmedetomidine treatment. Protocol three: animals were randomly assigned to one of two groups (n=16 each): vagotomy group (group VNX+Dex), right cervical vagus nerve was exposed and transected; sham-operated group (group SHAM+Dex), the cervical vagus nerve was visualized, but was neither isolated from the surrounding tissues nor transected. Protocol four: animals were treated with dexmedetomidine (40 μg/kg) and sterile saline to observe the discharge activity of cervical vagus nerves by using BL-420F data acquisition and analysis system (n=16 each). In the survival analysis groups, the survival rate of dexmedetomidine group was significantly higher than that of the endotoxemia group (65 versus 25 %, P<0.01). Preemptive administration of dexmedetomidine significantly attenuated the cytokine response after lipopolysaccharide (LPS) induced endotoxemia (TNF-alpha, IL-1beta, IL-6, P<0.01, respectively). However, preemptive administration of dexmedetomidine failed to suppress cytokine response in α-bungarotoxin group and vagotomy group (TNF-alpha, IL-1beta, IL-6, P>0.05, respectively). Furthermore, preemptive administration of dexmedetomidine significantly increased the discharge frequency of cervical vagus nerves in comparison with sterile saline treatment (P<0.01).Our results demonstrate that the preemptive administration of dexmedetomidine increases the activity of cervical vagus nerve and have the ability to successfully improve survival in experimental endotoxemia by inhibiting the inflammatory cytokines release. However, administration of dexmedetomidine to vagotomy or α7 nAChR antagonist pretreatment mice failed to suppress TNF levels, indicating that the vagus nerve and α7nAChR-mediated cholinergic anti-inflammatory pathway is required for the anti-inflammatory effect of dexmedetomidine. These findings show that central alpha-2 agonist dexmedetomidine suppresses systemic inflammation through vagal- and α7nAChR-dependent mechanism.