Xue-Min Song

The protective effect of the cholinergic anti-inflammatory pathway against septic shock in rats.

To investigate the effects of the cholinergic anti-inflammatory pathway on hemodynamics, blood biochemistry, the plasma TNF-&agr; level, and the nuclear factor-&kgr;B (NF-&kgr;B) activation during septic shock, male Sprague-Dawley rats were subjected to cecal ligation and puncture (CLP, a model of polymicrobial sepsis) or sham operation. Forty-eight rats were randomly assigned into six equal groups: sham CLP group; CLP group; VGX group was subjected to bilateral cervical vagotomy after CLP; STM group was subjected to bilateral cervical vagotomy after CLP plus the left vagus nerve trunk electrical stimulation; THA group was administered tetrahydroaminoacridine after CLP and bilateral cervical vagotomy; and &agr;-BGT group was administered &agr;-bungarotoxin before electrical stimulation of the vagus nerve. The right carotid artery was cannulated to monitor MAP. The plasma TNF-&agr; level was measured using enzyme-linked immunosorbent assays. The hepatic NF-&kgr;B activation was determined by Western blotting. Cecal ligation and puncture produced progressive hypotension. Serum aspartate transaminase and alanine transaminase levels significantly increased after CLP challenge. The plasma TNF-&agr; level and the hepatic NF-&kgr;B activation significantly increased after CLP alone or with bilateral cervical vagotomy compared with sham-operated group. Application of constant voltage pulses to the caudal vagus trunk significantly prevented the development of CLP-induced hypotension, alleviated the hepatic damage, and reduced the plasma TNF-&agr; production, but electrical stimulation had no effect on the hepatic NF-&kgr;B activation. Tetrahydroaminoacridine administration after bilateral cervical vagotomy reversed hypotension and attenuated the plasma TNF-&agr; response; in addition, it had no effect on the hepatic NF-&kgr;B activation. &agr;-Bungarotoxin pretreatment significantly reversed the inhibitory effect of vagal electrical stimulation, but it had no effect on the hepatic NF-&kgr;B activation. Our results showed that the cholinergic anti-inflammatory pathway might produce a potential protective effect on polymicrobial sepsis in rats.

Effect of vagus nerve stimulation on thermal injury in rats

OBJECTIVE To investigate the effects of vagus nerve stimulation on haemodynamics, pulmonary histopathology, arterial blood gas and pro-inflammatory responses to thermal injury. INTERVENTIONS Forty-eight male Sprague-Dawley (SD) rats were randomly divided into six equal groups: normal control (NC) group; thermal injury (TEM) group subjected to 40% total body surface area (%TBSA) third-degree thermal injury; vagotomy (VGX) group subjected to bilateral cervical vagotomy after thermal injury; electrical stimulation (STM) group subjected to bilateral cervical vagotomy plus the left vagus nerve trunk electrical stimulation (5 V, 2 ms and 1 Hz) after thermal injury; the antagonist of muscarinic acetylcholine receptor (MRA) group administrated with atropine (0.1 mg kg(-1)) before electrical stimulation and the antagonist of nicotinic acetylcholine receptor (NRA) group administrated with hexamethonium (10 mg kg(-1)) before electrical stimulation. MEASUREMENTS AND MAIN RESULTS The haemodynamics, histopathology of lung tissue, arterial blood gas, lactic acid, tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) levels were measured. Vagus nerve electrical stimulation not only significantly increased the mean arterial pressure (MAP) and heart rate (HR), but also decreased the infiltration of inflammatory cells into interstitial and alveolar spaces after thermal challenge and attenuated TNF-alpha and IL-6 production. Hexamethonium pre-treatment significantly reversed the effects of vagal electrical stimulation, but atropine administration before electrical stimulation had no such effects. CONCLUSIONS Direct electrical stimulation of the vagus nerve might produce therapeutic effect on thermal injury. The effect may be realised by limiting the inflammatory response via nicotinic acetylcholine receptors in rats.

Protective effect of PNU-120596, a selective alpha7 nicotinic acetylcholine receptor-positive allosteric modulator, on myocardial ischemia-reperfusion injury in rats.

Abstract: The cholinergic anti-inflammatory pathway has been found to exert a protective role in myocardial ischemia–reperfusion injury (MIRI). Alpha7 nicotinic acetylcholine receptor (&agr;7nAChR) is a regulator of cholinergic anti-inflammatory pathway; however, little information is available on the effect of &agr;7nAChR on MIRI. In the present study, we hypothesized that 1-(5-chloro-2,4-dimethoxy-phenyl)-3-(5-methyl-isoxanol-3-yl)-urea (PNU-120596), a potent positive allosteric modulator of &agr;7nAChR, could play a protective role on MIRI. Fifty-five rats were randomly assigned into 4 groups: Sham group, ischemia–reperfusion group, PNU-120596 group, &agr;-bungarotoxin group. Compared with ischemia–reperfusion group, PNU-120596 treatment markedly decreased infarct size, ultrastructural damage, serum creatine kinase, and lactate dehydrogenase. Serum proinflammatory cytokine production, myocardium endothelial activation and neutrophil infiltration, myocardium malondialdehyde were also significantly decreased, accompanied by increased myocardium superoxide dismutase production, in the PNU-120596 group compared with the ischemia–reperfusion group. Meanwhile, we observed a significant inhibition of nuclear factor kappa B activation in PNU-120596 group compared with ischemia–reperfusion group. Pretreatment of &agr;7nAChR-selective antagonist, &agr;-bungarotoxin, abolished all the protective effects of PNU-120596 on MIRI. In conclusion, PNU might have a protective effect against MIRI. Its action mechanisms might be involved in the inhibition of inflammatory responses, attenuation of lipid peroxidation, and suppression of nuclear factor kappa B activity.

The effect of electroacupuncture at ST36 on severe thermal injury-induced remote acute lung injury in rats.

OBJECTIVE Acupuncture at ST36 can produce anti-inflammatory effects, which might be associated with vagus nerve activity. This study explored the effects of electroacupuncture (EA) at ST36 on severe thermal injury-induced remote acute lung injury in rats. INTERVENTIONS Forty male Sprague-Dawley (SD) rats were randomly divided into five groups: (1) the sham (S) group, (2) the thermal injury (TEM) group subjected to 30% total body surface area (30% TBSA) third-degree scald, (3) the EA at ST36 group subjected to EA stimulation at ST36 (3V, 2ms, and 3Hz) after 30% TBSA scald, (4) the EA at non-acupoint group subjected to EA stimulation at non-acupoint after 30% TBSA scald, and (5) the α-bungarotoxin (α7 nicotinic acetylcholine receptor subunit antagonist) group administered 1.0 μg kg(-1) α-bungarotoxin before EA at ST36. MEASUREMENTS AND MAIN RESULTS Thermal injury of 30% TBSA induced leukocytosis in the alveolar space, interstitial edema, and the pro-inflammatory cytokines interleukin (IL)-1β, IL-6, and high-mobility group box 1 (HMGB-1); the expression of both HMGB-1 messenger RNA (mRNA) and protein in lung tissue was significantly enhanced. EA at ST36 significantly downregulated the levels of inflammatory cytokines and improved lung tissue injury. However, pretreatment with α-bungarotoxin reversed the effects of electrical stimulation of ST36. CONCLUSIONS EA at ST36 might have a potential protective effect on severe thermal injury-induced remote acute lung injury via limitation of inflammatory responses in rats.

Ketamine ameliorates ischemia–reperfusion injury after liver autotransplantation by suppressing activation of Kupffer cells in rats

This study aimed to investigate the protective effects of ketamine against hepatic ischemia-reperfusion (I/R) injury by suppressing activation of Kupffer cells (KCs) in rat liver autotransplantation. Male Sprague-Dawley rats were randomized into 3 groups (n = 10 each). Group I, the sham group, received saline. Group II received saline and underwent orthotopic liver autotransplantation (OLAT). Group III received 10 mg/kg ketamine and underwent OLAT. Blood samples were obtained at 3, 6, 12, and 24 h after I/R, and following ALT, AST, LDH, IL-6, TNF-α, IL-1β, and IL-10 in serum were detected. Model rats were sacrificed at the indicated time points and the graft liver tissues were evaluated histologically. KCs were isolated from rat liver tissues, and inflammatory products and proteins of NF-κB signaling pathway were detected using quantitative RT-PCR and Western blotting. Our results showed that ketamine significantly decreased ALT, AST, LDH, IL-6, TNF-α, and IL-1β levels and increased IL-10 level. Furthermore, ketamine alleviated the histopathology changes, by less KC infiltration and lower hepatocyte apoptosis. Moreover, activity of NF-κB signaling pathway in KCs was suppressed. In addition, production of pro- and anti-inflammatory factors is consistent with the results in tissues. Ketamine ameliorated I/R injury after liver transplantation by suppressing activation of KCs in rats.

Muramyl dipeptide enhances thermal injury-induced inflammatory cytokine production and organ function injury in rats.

ABSTRACT The bacterial infection following thermal injury is a very important factor of excessive inflammatory response and multiple organ damage. Muramyl dipeptide (MDP) is the key structure of gram-positive bacteria and gram-negative bacteria triggering the innate immune system. The aim of the present study was to determine the effect of MDP on thermal injury–induced inflammatory responses, organ function injury, and mortality in rats. Fifty male Sprague-Dawlay rats were randomly divided into three groups: normal control group, scald group, and MDP group. Scald group only suffered 20% total body surface area third-degree thermal injury. Muramyl dipeptide 5 mg·kg−1 was administered through the femoral vein at 24 h after thermal injury in the MDP group. Plasma inflammatory cytokine levels were measured by enzyme-linked immunosorbent assay. An additional 90 male Sprague-Dawley rats were randomly divided into three groups to observe the survival rate in 72 h. Plasma levels of interleukin-6, interleukin-10, interferon-&ggr;, and high-mobility group box 1; the white blood cell counts; the serum concentrations of alanine aminotransferase, aspartate aminotransferase, total bilirubin, creatine kinase isoenzyme-MB, blood urea nitrogen, and creatinine; and the activity of lung tissue myeloperoxidase significantly increased after thermal injury alone. Compared with the scald group, MDP led to more serious inflammatory responses and organ function damage and higher mortality (P < 0.05, respectively). These data indicate that MDP exacerbates thermal injury–induced inflammatory cytokine production, accompanied by multiple organ dysfunction syndrome and high mortality in rats.