Effect of lipopolysaccharide and cytokines on oxidative metabolism in neonatal rat hepatocytes

The Effects of Ionotropic GABA Receptor Blockage on the Brain in Rats with Induced Sepsis

Encephalopathy following sepsis is defined as life-threatening organ failure due to the irregular response of the host to infection and has high mortality and morbidity rates. The present study aimed to investigate the effects of inflammation and the gamma-aminobutyric acid-A (GABAA) receptor antagonist, bicuculline, on brain tissue in rats with sepsis. Sepsis was experimentally generated using lipopolysaccharide (LPS). The rats were divided into four groups: control, LPS (10 mg/kg i.p.), bicuculline (1.5 mg/kg s.c.), and LPS+Bic. Electrophysiologic recordings and body temperature measurements were completed at the 24th hour, and samples were taken. TNF-α, IL-10, GABA, and MDA levels were measured. Tissue imaging was performed using S100-ß, NEUN, and synaptophysin antibodies. One-way ANOVA followed by the Tukey test was performed for statistical analysis. Inflammatory parameters significantly increased in brain tissue in the LPS group compared with the other groups (TNF-α, [F (3.14) = 6.015, p = 0.042]; IL-10, [F (3.15) = 9.013, p = 0.02]). Tissue imaging results were as follows: S100-ß involvement increased, and NeuN and synaptophysin involvement decreased in the LPS group [F (3.21) = 18.016, p = 0.006, for S100-ß; F (3.21) = 19.071, p = 0.003, for NeuN; F (3.21) = 18.098, p = 0.005, for synaptophysin]. In electrophysiologic recordings, we observed activity consistent with acute non-focal seizures in the LPS group. Contrarily, the control and other comparison groups exhibited normal resting neural activity. Bicuculline may be used as a therapeutic agent in sepsis to maintain the neurotransmitter and pro- and anti-inflammatory cytokine balance and reduce lipid peroxidation with its effects of acetylcholine esterase inhibition and GABAA receptor antagonism.

Impaired energy metabolism during neonatal sepsis: the effects of glutamine

Neonatal sepsis is an important cause of morbidity and mortality as a result of multiple organ system failure, particularly in neonates requiring total parenteral nutrition. Suitable therapies and support are needed both to prevent sepsis and to prevent multiple organ failure. After bacterial infection, pro-inflammatory cytokines trigger the antimicrobial activity of macrophages and neutrophils, resulting in production of reactive species such as H2O2, NO, superoxide and peroxynitrite. However, excess production can lead to host tissue damage. Incubation of either hepatocytes or heart mitochondria from neonatal rats with these reactive species, or with cytokines, leads to impairment of mitochondrial oxidative function, and in an animal model of neonatal sepsis similar results to thein vitrofindings have been demonstrated. Recentin vivostudies, using indirect calorimetry of suckling rat pups, show that during endotoxaemia there is a profound hypometabolism, associated with hypothermia. Having determined that cellular oxidative function may be impaired during sepsis, it is of great importance to try to identify therapeutic measures. Much interest has been shown in glutamine, which may become essential during sepsis. It has been shown that hepatic glutamine is rapidly depleted during endotoxaemia. When hepatocytes from endotoxaemic rats were incubated with glutamine, there was a restoration of mitochondrial structure and metabolism.In vivo, intraperitoneal injection of glutamine into endotoxic suckling rats partially reversed hypometabolism, markedly reduced the incidence of hypothermia and improved clinical status. These results suggest that glutamine has a beneficial effect during sepsis in neonates.

Involvement of nitric oxide in gastric protection of epinephrine in endotoxin intoxication in rats

Reduction in blood pressure may cause gastric mucosal hypoxia and injury during endotoxin intoxication. Epinephrine is found to increase gastric mucosal perfusion while managing hypotension. Nitric oxide plays an important role in regulating gastric mucosal perfusion and maintaining gastric integrity. The aim of this study was to investigate the involvement of nitric oxide in the gastric protection of epinephrine by determining gastric mucosal lipid peroxidation, ulceration, and hemorrhage levels in endotoxin intoxication in rats. Epinephrine significantly increased gastric mucosal nitrite levels, decreased gastric mucosal lipid peroxidation levels, and ameliorated gastric ulceration and hemorrhage in endotoxin-treated rats. Furthermore, nitric oxide synthase inhibitors potently reversed the effects of epinephrine on gastric mucosa in endotoxin-treated rats. It was suggested that nitric oxide might be involved in the protective effect of epinephrine on gastric mucosal injury in endotoxin intoxication in rats.

BICUCULLINE METHIODIDE ATTENUATES HEPATIC INJURY AND DECREASES MORTALITY IN SEPTIC RATS: ROLE OF CYTOKINES

Bicuculline methiodide attenuates inflammation by inhibiting the production of proinflammatory cytokines, such as tumor necrosis factor-alpha, and by increasing the production of the anti-inflammatory cytokine interleukin-10, both of which play important roles in the pathogenesis of sepsis. The aim of this study was to examine the effects of bicuculline methiodide on sepsis in the cecal ligation and puncture septic-rat model. Cytokine production was measured by enzyme-linked immunosorbent assay. Oxidative stress was assessed by determining serum lipid peroxidation and nitrite levels. Hepatic injury was evaluated by determining the levels of serum aspartate aminotransferase, alkaline phosphatase, and total bilirubin. Mortality was recorded within 24 h. Bicuculline methiodide potently decreased the production of tumor necrosis factor-alpha and interleukin-1beta but increased interleukin-10 in serum. Bicuculline methiodide significantly decreased serum lipid peroxidation and nitrite levels. Further, bicuculline methiodide attenuated hepatic injury and reduced mortality after cecal ligation and puncture. Therefore, the alteration of cytokine production may be involved in the effects of bicuculline methiodide on hepatic injury and mortality in septic rats.

Effect of GABAA receptor antagonist bicuculline methiodide on hypotension in endotoxin-intoxicated rats

Gamma-aminobutyric acid (GABA) receptor plays an important regulatory role in human and animal blood pressure; however, whether a GABAergic mechanism is involved in endotoxin intoxication-associated hypotension has never been reported. In vivo effect of the GABA(A) receptor antagonist bicuculline methiodide (BMI) on mean arterial pressure (MAP), heart rate (HR), and serum nitrite levels were investigated in endotoxin (lipopolysaccharide; LPS)-treated rats. BMI increased MAP and decreased HR in LPS-stimulated rats. DOAV ([deamino-Pen, O-Me-Tyr, Arg3]-vasopressin), an arginine vasopressin (AVP) antagonist, reversed the hemodynamic improvement resulted from BMI in LPS-intoxicated rats. Based on a two-factor (BMI treatment by LPS dose) factorial design, BMI reduced the serum nitrite production induced by LPS. DOAV plus BMI, however, did not affect the serum nitrite level in LPS-intoxicated rats. Thus, GABA receptor antagonist BMI might attenuate hypotension in endotoxin intoxication in rats.

Epr analysis reveals three tissues responding to endotoxin by increased formation of reactive oxygen and nitrogen species

The excessive formation of reactive oxygen and nitrogen species (RONS) in tissue has been implicated in the development of various diseases. In this study we adopted ex vivo low temperature EPR spectroscopy combined with spin trapping technique to measure local RONS levels in frozen tissue samples. CP-H (1-hydroxy-3-carboxy-pyrrolidine), a new nontoxic spin probe, was used to analyze RONS in vivo. In addition, nitrosyl complexes of hemoglobin were determined to trace nitric oxide released into blood. By this technique we found that RONS formation in tissue of control animals increased in the following order: liver < heart < brain < cerebellum < lung < muscle < blood < ileum < kidney < duodenum < jejunum. We also found that endotoxin challenge, which represents the most common model of septic shock, increased the formation of RONS in rat liver, heart, lung, and blood, but decreased RONS formation in jejunum. We did not find changes in RONS levels in other parts of gut, brain, skeletal muscles, and kidney. Scavenging of RONS by CP-H was accompanied by an increase in blood pressure, indicating that LPS-induced vasodilatation may be due to RONS, but not due to nitric oxide. Experiments with tissue homogenates incubated in vitro with CP-H showed that ONOO(-) and O(2)(*)(-), as well as other not identified RONS, are detectable by CP-H in tissue. In summary, low-temperature EPR combined with CP-H infusion allowed detection of local RONS formation in tissues. Increased formation of RONS in response to endotoxin challenge is organ specific.