Intravenous Administration Of Lipopolysaccharide Research Articles

Influence of Acute Inflammation on the Expression of Clock Genes in the Ovine Pars Tuberalis Under Different Photoperiodic Conditions.

The pars tuberalis (PT) plays an important role in the photoperiodic regulation of the secretory activity of the pituitary gland. Additionally, PT secretory activity may be influenced by the animal's immune status. The melatonin signal processing in PT cells occurs through the presence of melatonin receptors and the expression of molecular clock genes. This study aimed to define the effects of acute inflammation induced by intravenous administration of lipopolysaccharide (LPS) on the expression of clock genes in the PT of ewes under different photoperiodic conditions. Two analogous experiments were conducted in different photoperiods: short-day and long-day. Both experiments included 24 sheep divided into two groups: day (n = 12) and night (n = 12), further subdivided into a control group (n = 6) and a group treated with LPS (n = 6) at a dose of 400 ng/kg. Under short-day conditions, the expression of clock circadian regulator, basic helix-loop-helix ARNT like 1, cryptochrome circadian regulator (CRY) 1, 2, and casein kinase 1 epsilon genes was lower during inflammation. LPS injection increased expression of the period circadian regulator 1 gene during the night. Under long-day conditions, CRY1 mRNA level was lower during the night, while diurnal CRY2 mRNA expression was decreased after LPS injection. Our results showed that inflammation disturbed the expression of molecular clock genes in the PT; however, this influence was partly dependent on photoperiod conditions.

New Insights into Hepatic and Intestinal Microcirculation and Pulmonary Inflammation in a Model of Septic Shock and Veno-Arterial Extracorporeal Membrane Oxygenation in the Rat.

Despite significant efforts toward improving therapy for septic shock, mortality remains high. Applying veno-arterial (V-A) extracorporeal membrane oxygenation (ECMO) in this context remains controversial. Since the cannulation of the femoral artery for V-A ECMO return leads to lower body hyperoxia, this study investigated the impact of V-A ECMO therapy on the intestinal and hepatic microcirculation during septic shock in a rodent model. Thirty male Lewis rats were randomly assigned to receive V-A ECMO therapy with low (60 mL/kg/min) or high (90 mL/kg/min) blood flow or a sham procedure. Hemodynamic data were collected through a pressure-volume catheter in the left ventricle and a catheter in the lateral tail artery. Septic shock was induced by intravenous administration of lipopolysaccharide (1 mg/kg). The rats received lung-protective ventilation during V-A ECMO therapy. The hepatic and intestinal microcirculation was measured by micro-lightguide spectrophotometry after median laparotomy for two hours. Systemic and pulmonary inflammation was detected via enzyme-linked immunosorbent assays (ELISA) of the plasma and bronchoalveolar lavage (BAL), respectively, measuring tumor necrosis factor-alpha (TNF-α), interleukins 6 (IL-6) and 10 (IL-10), and C-X-C motif ligands 2 (CXCL2) and 5 (CXCL5). Oxygen saturation and relative hemoglobin concentration were reduced in the hepatic and intestinal microcirculation during V-A ECMO therapy, independent of the blood flow rate. Further, rats treated with V-A ECMO therapy also presented elevated systolic, diastolic, and mean arterial blood pressure and increased stroke volume, cardiac output, and left ventricular end-diastolic volume. However, left ventricular end-diastolic pressure was only elevated during high-flow V-A ECMO therapy. Blood gas analysis revealed a dilutional anemia during V-A ECMO therapy. ELISA analysis showed an elevated plasma CXCL2 concentration only during high-flow V-A ECMO therapy and elevated BAL CXCL2 and CXCL5 concentrations only during low-flow V-A ECMO therapy. Rats undergoing V-A ECMO therapy exhibited impaired microcirculation of the intestine and liver during septic shock despite increased blood pressure and cardiac output. Increased pulmonary inflammation was detected only during low-flow V-A ECMO therapy in septic shock.

Evaluation of the Effect of Induced Endotoxemia on ROTEM S® and Platelet Parameters in Beagle Dogs Anaesthetized with Sevoflurane.

Endotoxemia is thought to induce severe changes in coagulation status. In this study, blood samples from six beagle dogs receiving 1 mg/kg E. coli lipopolysaccharide (LPS) intravenously were analyzed to describe the concurrent changes in platelet count, platelet function assessed with impedance thromboaggregometry, thromboelastometry and d-dimers during artificially induced endotoxemia and its therapy with fluids and vasopressors at five timepoints (baseline, after LPS and 30 mL/kg Ringer's acetate, during noradrenaline ± dexmedetomidine infusion, after a second fluid bolus and a second time after vasopressors). Results were analyzed for changes over time with the Friedman test, and statistical significance was set at p < 0.05. We found decreased platelet count and function and changes in all platelet-associated rotational thromboelastometry (ROTEM) variables indicating hypocoagulability, as well as increases in d-dimers indicating fibrinolysis within one hour of intravenous administration of LPS, with partial recovery of values after treatment and over time. The fast changes in platelet count, platelet function and ROTEM variables reflect the large impact of endotoxemia on the coagulation system and support repeated evaluation during the progress of endotoxemic diseases. The partial recovery of the variables after initiation of fluid and vasopressor therapy may reflect the positive impact of the currently suggested therapeutic interventions during septic shock in dogs.

Effects of acute intravenous lipopolysaccharide administration on the plasma lipidome and metabolome in lactating Holstein cows experiencing hyperlipidemia.

The effects of lipopolysaccharides (i.e., endotoxin; LPS) on metabolism are poorly defined in lactating dairy cattle experiencing hyperlipidemia. Our objective was to explore the effects of acute intravenous LPS administration on metabolism in late-lactation Holstein cows experiencing hyperlipidemia induced by intravenous triglyceride infusion and feed restriction. Ten non-pregnant lactating Holstein cows (273 ± 35 d in milk) were administered a single bolus of saline (3 mL of saline; n [Formula: see text] 5) or LPS (0.375 [Formula: see text]g of LPS/kg of body weight; n [Formula: see text] 5). Simultaneously, cows were intravenously infused a triglyceride emulsion and feed restricted for 16 h to induce hyperlipidemia in an attempt to model the periparturient period. Blood was sampled at routine intervals. Changes in circulating total fatty acid concentrations and inflammatory parameters were measured. Plasma samples were analyzed using untargeted lipidomics and metabolomics. Endotoxin increased circulating serum amyloid A, LPS-binding protein, and cortisol concentrations. Endotoxin administration decreased plasma lysophosphatidylcholine (LPC) concentrations and increased select plasma ceramide concentrations. These outcomes suggest modulation of the immune response and insulin action. Lipopolysaccharide decreased the ratio of phosphatidylcholine to phosphatidylethanomanine, which potentially indicate a decrease in the hepatic activation of phosphatidylethanolamine N-methyltransferase and triglyceride export. Endotoxin administration also increased plasma concentrations of pyruvic and lactic acids, and decreased plasma citric acid concentrations, which implicate the upregulation of glycolysis and downregulation of the citric acid cycle (i.e., the Warburg effect), potentially in leukocytes. Acute intravenous LPS administration decreased circulating LPC concentrations, modified ceramide and glycerophospholipid concentrations, and influenced intermediary metabolism in dairy cows experiencing hyperlipidemia.

EFFECT OF DIRECT ORAL ANTICOAGULANTS ON THE HEMOSTASIS SYSTEM 142 IN BACTERIAL SEPSIS

The inflammatory reaction that arises in patients with sepsis is interconnected with the coagulation system and leads to the development of hypercoagulable changes in the body. Therefore, in this study, we studied the effect of direct oral anticoagulants dabigatran etexilate and apixaban on the hemostasis system without and under conditions of a systemic inflammatory response. Hypercytokinemia was created by intravenous administration of lipopolysaccharide into the tail vein of a rat. The anticoagulant activity of the studied drugs was assessed by their effect on the parameters of the rat blood coagulogram. Dabigatran etexilate showed a pronounced antithrombin effect, increasing the thrombin time by 10.5 times relative to the control in intact animals. Under conditions of hypercytokinemia, this activity increased by 12.8 times. Apixaban did not cause changes in thrombin time, but it increased the prothrombin time index both in intact animals and animals with a systemic inflammatory response by 7 and 8.6 times, respectively. Thus, an increase in the anticoagulant effect of dabigatran etexilate and apixaban under conditions of hypercytokinemia indicates that they may have anti-inflammatory activity.

Hemodynamic resuscitation with fluids bolus and norepinephrine increases severity of lung damage in an experimental model of septic shock

ObjectiveHemodynamic resuscitation is considered a cornerstone of the initial treatment of septic shock. However, there is growing concern about its side effects. Our objective was to assess the relationship between fluid administration and norepinephrine infusion and the development of lung injury. DesignRandomized in vivo study in rabbits. SettingUniversity animal research laboratory. PatientsEighteen New Zealand rabbits. Control group (SHAM, n=6), Sepsis group with or without hemodynamic resuscitation (ETX-R, n=6; ETX-NR, n=6). InterventionsSepsis was induced by intravenous lipopolysaccharide administration and animals were followed-up for 4h. Hemodynamic resuscitation with Ringer lactate (20mL·kg−1) was administered and later norepinephrine was initiated 3h after sepsis induction. At the end, the left lung was excised. Main variables of interestAn indwelling arterial catheter and an esophageal Doppler were placed. Lung mechanics were monitored with side stream spirometry. Lung damage was analyzed by histopathological examination. ResultsThe SHAM group did not show hemodynamic or respiratory changes. Lipopolysaccharide administration aimed an increase in cardiac output and arterial hypotension. In the ETX-NR group, animals remained hypotensive until the end of the experiment. Resuscitation with fluids and norepinephrine reversed arterial hypotension. Compared to the ETX-NR group, the remaining lung of the ETX-R group showed greater accumulation of neutrophils and reactive type-II pneumocytes, thicker alveolar wall, alveolar hemorrhage and non-aerated pulmonary areas. Lung injury score was larger in the ETX-R group. ConclusionsIn our experimental study, following a strategy with bolus fluids and late norepinephrine used in the early phase of endotoxic septic shock has a negative influence on the development of lung injury.

Intravenous administration of LPS activates the kynurenine pathway in healthy male human subjects: a prospective placebo-controlled cross-over trial

BackgroundAdministration of lipopolysaccharide (LPS) from Gram-negative bacteria, also known as the human endotoxemia model, is a standardized and safe model of human inflammation. Experimental studies have revealed that peripheral administration of LPS leads to induction of the kynurenine pathway followed by depressive-like behavior and cognitive dysfunction in animals. The aim of the present study is to investigate how acute intravenous LPS administration affects the kynurenine pathway in healthy male human subjects.MethodsThe present study is a prospective, single-blinded, randomized, placebo-controlled cross-over study to investigate the effects of intravenously administered LPS (Escherichia coli O113, 2 ng/kg) on tryptophan and kynurenine metabolites over 48 h and their association with interleukin-6 (IL-6) and C-reactive protein (CRP). The study included 10 healthy, non-smoking men (18–40 years) free from medication. Statistical differences in tryptophan and kynurenine metabolites as well as associations with IL-6 and CRP in LPS and placebo treated subjects were assessed with linear mixed-effects models.ResultsSystemic injection of LPS was associated with significantly lower concentrations of plasma tryptophan and kynurenine after 4 h, as well as higher concentrations of quinolinic acid (QUIN) after 48 h compared to the placebo injection. No differences were found in kynurenic acid (KYNA) or picolinic acid plasma concentrations between LPS or placebo treatment. The KYNA/kynurenine ratio peaked at 6 h post LPS injection while QUIN/kynurenine maintained significantly higher from 3 h post LPS injection until 24 h. The kynurenine/tryptophan ratio was higher at 24 h and 48 h post LPS treatment. Finally, we report an association between the kynurenine/tryptophan ratio and CRP.ConclusionsOur findings strongly support the concept that an inflammatory challenge with LPS induces the kynurenine pathway in humans, activating both the neurotoxic (QUIN) and neuroprotective (KYNA) branch of the kynurenine pathway.Trial registrationThis study is based on a study registered at ClinicalTrials.gov, NCT03392701. Registered 21 December 2017.

Role of the Transcription Factor BTB and CNC Homology 1 in a Rat Model of Acute Liver Injury Induced by Experimental Endotoxemia.

Hepatic oxidative stress plays an important role in the pathogenesis of several acute liver diseases, and free heme is thought to contribute to endotoxemia-induced acute liver injury. The heme oxygenase 1 (HO-1) gene is upregulated and the δ-aminolevulinate synthase (ALAS1) gene is downregulated in the rat liver following lipopolysaccharide (LPS) treatment. BTB and CNC homology 1 (Bach1) is a heme-responsive transcription factor that normally represses HO-1 expression. In this study, we evaluated the changes in HO-1, ALAS1, and Bach1 expression and nuclear Bach1 expression in rat livers following intravenous LPS administration (10 mg/kg body weight). LPS significantly upregulated HO-1 mRNA and downregulated ALAS1 mRNA in the rat livers, suggesting that hepatic free heme concentrations are increased after LPS treatment. Bach1 mRNA was strongly induced after LPS injection. In contrast, nuclear Bach1 was significantly but transiently decreased after LPS treatment. Rats were also administered hemin (50 mg/kg body weight) intravenously to elevate heme concentrations, which decreased nuclear Bach1 levels. Our results suggest that elevated hepatic free heme may be associated with a decline of nuclear Bach1, and induction of Bach1 mRNA may compensate for the decreased nuclear Bach1 after LPS treatment in the rat liver.

Hemodynamic resuscitation with fluids bolus and norepinephrine increases severity of lung damage in an experimental model of septic shock.

Hemodynamic resuscitation is considered a cornerstone of the initial treatment of septic shock. However, there is growing concern about its side effects. Our objective was to assess the relationship between fluid administration and norepinephrine infusion and the development of lung injury. Randomized in vivo study in rabbits. University animal research laboratory. Eighteen New Zealand rabbits. Control group (SHAM, n=6), Sepsis group with or without hemodynamic resuscitation (ETX-R, n=6; ETX-NR, n=6). Sepsis was induced by intravenous lipopolysaccharide administration and animals were followed-up for 4h. Hemodynamic resuscitation with Ringer lactate (20mL·kg-1) was administered and later norepinephrine was initiated 3h after sepsis induction. At the end, the left lung was excised. An indwelling arterial catheter and an esophageal Doppler were placed. Lung mechanics were monitored with side stream spirometry. Lung damage was analyzed by histopathological examination. The SHAM group did not show hemodynamic or respiratory changes. Lipopolysaccharide administration aimed an increase in cardiac output and arterial hypotension. In the ETX-NR group, animals remained hypotensive until the end of the experiment. Resuscitation with fluids and norepinephrine reversed arterial hypotension. Compared to the ETX-NR group, the remaining lung of the ETX-R group showed greater accumulation of neutrophils and reactive type-II pneumocytes, thicker alveolar wall, alveolar hemorrhage and non-aerated pulmonary areas. Lung injury score was larger in the ETX-R group. In our experimental study, following a strategy with bolus fluids and late norepinephrine used in the early phase of endotoxic septic shock has a negative influence on the development of lung injury.

Increased Lipopolysaccharide‐Induced Hypothermia in Neurogenic Hypertension is caused by Reduced Hypothalamic PGE2 Production and Increased Heat Loss

Brain‐mediated thermoregulatory changes in systemic inflammation (SI) induced by lipopolysaccharide (LPS) at a septic‐like model are characterized by hypothermia followed by fever which are associated with inadequate tissue oxygenation, multiple organs dysfunctions, and death. Hypertension is a prevalent chronic disease characterized by autonomic‐induced elevated and sustained blood pressure levels and spontaneously hypertensive rats (SHR) also have abnormal body core temperature (Tb) regulation and metabolic adjustments, by unknown mechanisms. The rationale of the present study was to find out the mechanisms involved in the thermoregulatory changes observed during SI in SHR. We combined Tb and skin temperature (Tsk) analysis, assess prostaglandin (PG) E2 levels in the anteroventral region of the hypothalamus (AVPO), indirect calorimetry, cardiovascular recordings, assays of inflammatory markers and evaluation of oxidative stress status in male Wistar and SHR that receive intravenous administration of LPS (1.5 mg.kg−1) or saline (CEUA #2017.1.585.58.9). As expected, LPS induced hypothermia followed by fever in Wistar whereas in SHR increased hypothermia and no fever were observed. These changes were associated with an increased Tsk in SHR in relation to Wistar (P &lt; 0.05). Oxygen consumption and carbon dioxide production were significantly and similarly reduced in both SHR and Wistar rats during SI (P &lt; 0.05). Interestingly, we measured increased AVPO PGE2 levels in Wistar during SI (P &lt; 0.05), but not in SHR. LPS‐induced drop in MAP was significantly higher in SHR than in Wistar rats. Besides, LPS‐induced plasma and brain cytokines surges were blunted whereas oxidative stress was higher in SHR (P &lt; 0.05). The present data are consistent with the notion that in SHR LPS‐induced SI leads to thermoregulatory changes mediated by the thermo effector mechanisms in the skin but not in energy expenditure and these events are associated with reduced hypothalamic PGE2.Support or Funding InformationFAPESP, CAPES and CNPq

Pre-eclamptic Fetal Programming Alters Neuroinflammatory and Cardiovascular Consequences of Endotoxemia in Sex-Specific Manners.

Pre-eclampsia (PE)-induced fetal programming predisposes offspring to health hazards in adult life. Here, we tested the hypothesis that pre-eclamptic fetal programming elicits sexually dimorphic inflammatory and cardiovascular complications to endotoxemia in adult rat offspring. PE was induced by oral administration of L-NAME (50 mg/kg per day for seven consecutive days) starting from day 14 of conception. Cardiovascular studies were performed in conscious adult male and female offspring preinstrumented with femoral indwelling catheters. Compared with non-PE male counterparts, intravenous administration of lipopolysaccharide (LPS, 5 mg/kg) to PE male offspring caused significantly greater 1) falls in blood pressure, 2) increases in heart rate, 3) rises in arterial dP/dtmax, a correlate of left ventricular contractility, and 4) decreases in time- and frequency-domain indices of heart rate variability (HRV). By contrast, the hypotensive and tachycardic actions of LPS in female offspring were independent of the pre-eclamptic state and no clear changes in HRV or dP/dtmax were noted. Measurement of arterial baroreflex activity by vasoactive method revealed no sex specificity in baroreflex dysfunction induced by LPS. Immunohistochemical studies showed increased protein expression of toll-like receptor 4 in heart as well as in brainstem neuronal pools of the nucleus of solitary tract and rostral ventrolateral medulla in endotoxic PE male, but not female, offspring. Enhanced myocardial, but not neuronal, expression of monocyte chemoattractant protein-1 was also demonstrated in LPS-treated male offspring. Together, pre-eclamptic fetal programming aggravates endotoxic manifestations of hypotension and autonomic dysfunction in male offspring via exacerbating myocardial and neuromedullary inflammatory pathways. SIGNIFICANCE STATEMENT: Current molecular and neuroanatomical evidence highlights a key role for pre-eclamptic fetal programming in offspring predisposition to health hazards induced by endotoxemia in adult life. Pre-eclampsia accentuates endotoxic manifestations of hypotension, tachycardia, and cardiac autonomic dysfunction in male offspring via exacerbating myocardial and central inflammatory pathways. The absence of such detrimental effects in female littermates suggests sexual dimorphism in the interaction of pre-eclamptic fetal programming with endotoxemia.

Study of thermo-regulation as a worsening marker of experimental sepsis in an animal model.

Objective: to analyze variations in body temperature and in plasma nitrate and lactate concentrations in rats submitted to the experimental sepsis model.Method: a total of 40 rats divided equally into five groups. The induction of endotoxemia was performed with intravenous administration of lipopolysaccharide, 0.5 mg/Kg, 1.5 mg/Kg, 3.0 mg/Kg, and 10 mg/Kg, respectively. The control group received 0.5 mL of saline solution. The experiment lasted six hours, with evaluations performed at 0 (baseline data), 2nd, 4th, and 6thhours.Results: The animals that received doses up to 3.0 mg/kg showed a significant increase in body temperature compared to the group with 10 mg/kg, which showed a decrease in these values. The increase in plasma nitrate and lactate concentrations in the groups with lipopolysaccharide was significantly higher than in the group that received the saline solution and was correlated with the increase in body temperature.Conclusion: the variations in body temperature observed in this study showed the dose-dependent effect of lipopolysaccharide and were correlated with the increase in the concentrations of nitrate and plasma lactate biomarkers. The implications of this study are the importance of monitoring body temperature, together with the assessment of these pathophysiological markers, which suggest worsening in the prognosis of sepsis.

Cytoglobin Attenuates Neuroinflammation in Lipopolysaccharide-Activated Primary Preoptic Area Cells via NF-κB Pathway Inhibition.

Cytoglobin (Cygb) is a hexacoordinate protein, associated with the transport of oxygen, nitric oxide scavenging, tumor suppression and protection against oxidative stress and inflammation. This protein is expressed in brain areas including the preoptic area (POA) of the anterior hypothalamus, the region responsible for the regulation of body temperature. In this study, we show that Cygb is upregulated in the rat hypothalamus 2.5 h and 5 h after intravenous administration of lipopolysaccharide (LPS). We investigated the effect of treatment with Cygb in POA primary cultures stimulated with LPS for 4 h. The levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) were measured and the results showed that Cygb reduced the concentrations of both cytokines. We further observed a decrease in immunoreactivity of the inflammatory transcription factor nuclear factor-κB (NF-κB), but not NF-IL6 and STAT3, in the nucleus of Cygb-treated POA cells. These findings suggest that Cygb attenuates the secretion of IL-6 and TNF-α in LPS-stimulated POA primary cultures via inhibition of the NF-κB signaling pathway, indicating that this protein might play an important role in the control of neuroinflammation and fever.

Effects of Landiolol in Lipopolysaccharide-Induced Acute Kidney Injury in Rats and In Vitro.

The mechanisms by which landiolol, an ultra-short-acting, selective β-1 blocker, could improve septic acute kidney injury and how inflammation might affect mitochondrial function and cause the renal injury were examined. Male Wistar rats (250 g-300 g) were randomly allocated to three groups: a sham control group (n = 8); a lipopolysaccharide (LPS) group (n = 8); and an LPS + landiolol group (n = 8). LPS was administered intravenously at the start of the experiments; the LPS + landiolol group rats received LPS and continuous intravenous landiolol. Serum creatinine and lactate concentrations and hemodynamic parameters were measured 3 and 6 h after the experiments started. TNF-α, IL-1β, and IL-6 levels and urinary 8-OHdG concentrations were determined. The extent of LPS-induced renal injury and recovery with landiolol were examined histopathologically. Metabolic analysis in human embryonic kidney cells was performed using Seahorse analysis. The effects of landiolol on cytokine-induced mitochondrial stress and glycolytic stress were examined. Treatment with landiolol was shown to normalize serum creatinine and lactate levels following intravenous LPS administration (Cr: LPS group 0.8 ± 0.6 mg/mL, LPS + landiolol group 0.5 ± 0.1 mg/mL; P < 0.05). In the in vitro experiments, TNF-α induced an increase in mitochondrial oxygen consumption, which was attenuated by landiolol, which could represent a mechanism for renal protection. Landiolol may have protective effects on the cells and tissues of the kidney by inhibiting oxygen consumption and hypoxia caused by TNF-α in renal cells. These results suggest that landiolol may be an important new therapeutic target for treating inflammation-associated kidney injury.

Curcumin and Selenium Prevent Lipopolysaccharide/Diclofenac-Induced Liver Injury by Suppressing Inflammation and Oxidative Stress.

Diclofenac (DCL), an anti-inflammatory drug used to reduce pain and inflammation, ranks in the top causes of drug-induced liver injury. The inflammatory stress induced by inflammagens is implicated in DCL-induced liver injury. Curcumin (CUR) and selenium (Se) possess anti-inflammatory effects; therefore, this study evaluated their protective potential against lipopolysaccharide (LPS)/DCL-induced liver injury. Rats received CUR and/or Se for 7 days followed by a single intravenous administration of LPS 2 h before a single injection of DCL and two other doses of CUR and/or Se 2 and 8 h after DCL. Administration of nontoxic doses of LPS and DCL resulted in liver damage evidenced by the significantly elevated liver function markers in serum. LPS/DCL-induced liver injury was confirmed by histological alterations, increased lipid peroxidation and nitric oxide, and diminished glutathione and superoxide dismutase. CUR and/or Se prevented liver injury, histological alterations, and oxidative stress and boosted antioxidant defenses in LPS/DCL-induced rats. In addition, CUR and/or Se reduced serum C-reactive protein, liver pro-inflammatory cytokines, and the expression of TLR4, NF-κB, JNK, and p38, and upregulated heme oxygenase-1 (HO-1). In conclusion, CUR and/or Se mitigated LPS/DCL-induced liver injury in rats by suppressing TLR4 signaling, inflammation, and oxidative stress and boosting HO-1 and other antioxidants. Therefore, CUR and Se can hinder the progression and severity of liver injury during acute inflammatory episodes.

Qualitative Determination of Hemoglobin in Rats with Septic Shock by Photoacoustic Spectroscopy

Septic shock is the main cause of death in patients in the intensive care unit. Nowadays, few methods exist in the clinical area that provide an early diagnosis of this condition, and these methods even deliver imprecise values on the concentration of hemoglobin. Photoacoustic spectroscopy (PAS) has been previously used to determine the concentration of hemoglobin in blood, based on the identification of the γ, β, and α peaks in the optical absorption spectrum, located at approximately 412 nm, 550 nm, and 580 nm, respectively. The absorption peak γ/β and γ/α ratios have been reported to be inversely proportional to the concentration of hemoglobin, which could be related to the severity of septic shock. The main goal of this work was to analyze the evolution of the γ/β and γ/α ratios, obtained by PAS, in blood samples of rats with septic shock induced through the intravenous administration of lipopolysaccharide (LPS, 6 mg·Kg−1). Ratios of γ/β and γ/α increased as a function of time, implying a decrease in the hemoglobin concentration. Hemoglobin identified by PAS seems to be a prognostic biomarker in shock.

Cardiovascular Reflexes Control Hemodynamic Responses During LPS‐induced Systemic Inflammation in Conscious Rats

Lipopolysaccharide (LPS)‐induced systemic inflammation (SI) is associated with hypotension, tachycardia, and multiple organs dysfunctions. SI, a hallmark of sepsis can lead to cardiovascular impairment and death. Considering that the nervous system regulates immunity and that cardiovascular reflexes, i.e. baroreflex, chemoreflex, and Bezold‐Jarish reflex, are important regulators of hemodynamic function, we investigated these cardiovascular reflexes control acutely and 24 hours after LPS‐induced SI. We combined cardiovascular recordings, immunofluorescence and molecular approaches in male Wistar rats that received intravenous administration of LPS (1.5 or 2.5 mg.kg−1, CEUA #2017.1.585.58.9). LPS induced hypotension and tachycardia and reduction in baroreflex gain. On the other hand, SI caused no significant impairment in hemodynamic responses to chemoreflex and Bezold‐Jarish reflexes, despite an increased number of activated microglia and IL‐1β levels in the nucleus tractus solitarius. The present data are consistent with the notion that cardiovascular reflexes are kept functional even with central nervous system inflammation. These findings provide insights into the mechanisms that regulate the cardiovascular system during SI and indicate that the improvement of these reflexes responsiveness can be useful for the therapeutic management of sepsis.Support or Funding InformationFAPESP, CAPES and CNPqThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Central serotonin prevents hypotension and hypothermia and reduces plasma and spleen cytokine levels during systemic inflammation

An exceptionally high mortality rate is observed in sepsis and septic shock. Systemic administration of lipopolysaccharide (LPS) has been used as an experimental model for sepsis resulting in an exacerbated immune response, brain neurochemistry adjustments, hypotension, and hypothermia followed by fever. Central serotonergic pathways not only modulate systemic inflammation (SI) but also are affected by SI, including in the anteroventral region of the hypothalamus (AVPO), which is the hierarchically most important region for body temperature (Tb) control. In this study, we sought to determine if central serotonin (5-HT) plays a role in SI induced by intravenous administration of LPS (1.5 mg/kg) in male Wistar rats (280–350 g) by assessing 5-HT levels in the AVPO, mean arterial pressure, heart rate, and Tb up to 300 min after LPS administration, as well as assessing plasma and spleen cytokine levels, nitric oxide (NO) plasma levels, and prostaglandin (PG) E2 levels in the AVPO at 75 min and 300 min after LPS administration. We observed reduced AVPO 5-HT levels, hypotension, tachycardia, hypothermia followed by fever, as well as observing increased plasma NO, plasma and spleen cytokines and AVPO PGE2 levels in SI. Intracerebroventricular (icv) administration of 5-HT 30 min before LPS administration prevented hypotension and hypothermia, which were accompanied by reduced plasma NO, as well as plasma TNF-α, IL-1β, IL-6, and IL-10 and spleen TNF-α and IL-10 levels. We suggest that SI reduced 5-HT levels in the AVPO favor an increased pro-inflammatory status both centrally and peripherally that converge to hypotension and hypothermia. Moreover, our results are consistent with the notion that exogenous 5-HT given icv prevents hypotension and hypothermia probably activating the splenic anti-inflammatory pathway.

Arbutin attenuates LPS-induced lung injury via Sirt1/ Nrf2/ NF-κBp65 pathway

The main goal of this study was to evaluate the effects of arbutin (AR) on lipopolysaccharide (LPS)-induced lung injury. A lung injury rat model was established by intravenous LPS administration. We found that levels of inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) in both serum and lung tissue were significant increased after LPS challenge. In addition, pathological conditions were examined in rat lungs, and it was demonstrated that AR-pretreatment reduced LPS-induced malondialdehyde (MDA) levels and increased LPS-induced superoxide dismutase (SOD) activity. Moreover, the expression of sirtuin1 (SIRT1), nuclear erythroid factor 2-related factor 2 (Nrf-2), heme oxygenase-1 (HO-1) as well as the phosphorylation of NF-κBp65 and IκBα were increased with LPS-induced lung injury, and were significantly restored by AR treatment. Together, our results indicated that SIRT1 is a potential therapeutic target in LPS-induced lung injury, and that AR may be a novel therapeutic in patients with acute lung injury.

Abstract P287: Time Course of Hemodynamic Responses to Different Doses of Lipopolysaccharide Administration in Unanesthetized Rats

Introduction: Intravenous administration of lipopolysaccharide (LPS) from Escherichia coli is an experimental model of systemic inflammation that has been widely used for investigating new therapeutic strategies for sepsis, which is characterized by clinical manifestations such as hypo or hyperthermia, tachycardia, hypotension and tachypnea. However, there is a number of doses of LPS used in several studies, and the hemodynamic responses were not well characterized. Thus, the aim of the present study was to evaluate the hemodynamic (arterial pressure and heart rate) responses from unanesthetized rats to different doses of LPS over time. Methods and Results: Femoral artery and vein catheters were inserted into anaesthetized Wistar Hannover male rats for arterial pressure recording and LPS administration, respectively. On the next day, the arterial pressure was recorded before (baseline) and after (90, 180 and 360 min) LPS injection in the unanesthetized subjects. Four different doses of LPS were tested: 0.06 mg/kg (n = 8), 20 mg/kg (n = 4), 30 mg/kg (n = 4), and 40 mg/kg (n = 5). As compared to baseline, the dose of 0.06 mg/kg of LPS decreased the mean arterial pressure at 360 min after its administration (113 ± 4 vs. 103 ± 7 mmHg, p = 0.007). However, the doses of 20, 30 and 40 mg/kg increased the mean arterial pressure at 360 min after LPS, compared to baseline values ( 20 mg/kg: 101 ± 2 vs. 121 ± 4 mmHg, p &lt; 0.001; 30 mg/kg: 115 ± 6 vs. 130 ± 0.4 mmHg, p = 0.023; 40 mg/kg: 92 ± 2 vs. 107 ± 3 mmHg, p = 0.005). In addition, all doses tested increased the heart rate at 360 min after LPS administration ( 0.06 mg/kg: 342 ± 19 vs. 435 ± 11 bpm, p &lt; 0.001; 20 mg/kg: 388 ± 6 vs. 588 ± 24 bpm, p &lt; 0.001; 30 mg/kg: 366 ± 15 vs. 569 ± 8 bpm p &lt; 0.001; 40 mg/kg: 426 ± 27 vs. 606 ± 24 bpm, p &lt; 0.001). Nevertheless, the dose of 0.06 mg/kg promoted a smaller tachycardia as compared to the other doses evaluated ( 0.06 mg/kg: 435 ± 11 bpm; 20 mg/kg: 588 ± 24 bpm; 30 mg/kg: 569 ± 8 bpm; 40 mg/kg: 606 ± 24 bpm, p &lt; 0.001). Conclusions: These findings indicate that it is important to choose the correct dose of LPS, depending on the aim of the study. The current data indicate that each dose of LPS may promote different hemodynamic (mean arterial pressure and heart rate) responses, affecting the therapeutic strategy, for instance, for sepsis.