tcv-309 and Disease-Models--Animal

Platelet-activating factor (PAF)-a potent activator of neutrophils-plays an important role in the pathogenesis of endotoxin-induced tissue injury. However, the role of PAF in hepatic damage during alcoholic hepatitis remains unclear. The aims of the present study were to test whether PAF contributes to hepatic injury in an animal model of alcoholic hepatitis and to investigate the involvement of the Fas-receptor/Fas-ligand system in this process.. Male Sprague-Dawley rats were pair-fed with Lieber-DeCarli ethanol liquid diet or isocaloric control diet for 6 weeks. Liver injury was induced by the intravenous (i.v.) injection of lipopolysaccharide (LPS) (1 mg/kg). Rats were pretreated with a specific PAF receptor antagonist (TCV-309; 100 mg/kg i.v.) or vehicle 1 h before LPS treatment.. Chronic ethanol administration remarkably sensitized the rats to the effects of LPS, with resultant severe hepatocellular injury, accompanied by significant increases in serum levels of alanine aminotransferase (ALT), tumour necrosis factor (TNF)-alpha and interleukin (IL)-8 (CINC/gro). Histological examination of the damaged livers showed hepatocyte apoptosis and necrosis with extensive infiltration by neutrophils, whereas immunohistochemical studies revealed enhanced Fas-receptor expression on hepatocytes and hepatic accumulation of neutrophils expressing Fas-ligand. Pretreatment with the PAF receptor antagonist protected against hepatic injury, suppressing hepatocyte apoptosis and necrosis, infiltration of neutrophils, expression of Fas-receptor and Fas-ligand, and serum TNF-alpha levels.. Our study suggests that PAF is an important mediator of hepatic injury in the ethanol/endotoxin model of alcoholic hepatitis.

Topics: Animals; Apoptosis; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Drug Therapy, Combination; Escherichia coli; Ethanol; Fas Ligand Protein; fas Receptor; Hepatitis, Alcoholic; Immunoenzyme Techniques; In Situ Nick-End Labeling; Isoquinolines; Lipopolysaccharides; Liver; Male; Membrane Glycoproteins; Necrosis; Platelet Activating Factor; Pyridinium Compounds; Rats; Rats, Sprague-Dawley; Tetrahydroisoquinolines

In this study, we evaluated the time course of the alterations in left ventricular (LV) dimensions, LV wall thickness, and LV systolic function in rats with endotoxemia by using echocardiography as well as myocardial histopathologic assessments. Our second goal was to examine whether pretreatment with a platelet-activating factor (PAF) antagonist would ameliorate the lipopolysaccharide (LPS)-induced cardiovascular collapse during the early phase.. A prospective, controlled, in vivo animal laboratory study.. Research laboratory at a university.. Male, Wistar rats (8-9 wks old; n = 83).. In pentobarbital-anesthetized rats, the right carotid artery was cannulated to measure the arterial blood pressure and to sample blood. The right jugular vein also was catheterized for the administration of drugs. LPS (2 mg/kg) derived from Klebsiella pneumoniae or physiologic saline was administered in the presence or absence of pretreatment with TCV-309, a specific potent PAF antagonist. Echocardiographic studies were performed with an 8- to 13-MHz transducer.. LPS administration immediately induced progressive hypotension. The maximal hypotensive response was observed at 10 mins after LPS infusion with mean arterial pressure decreasing from 119 +/- 2 to 56 +/- 3 mm Hg (p < .001). LV end-diastolic internal dimensions decreased from 6.4 +/- 0.1 to 3.1 +/- 0.1 mm (p < .001) at 30 mins after LPS and remained significantly reduced compared with control rats. LV end-systolic dimensions also decreased dramatically from 3.5 +/- 0.2 to 0.5 +/- 0.1 mm (p < .001) at 30 mins after LPS and remained significantly reduced throughout the experiment. LV fractional shortening increased from 45 +/- 1% to 84 +/- 2% (p < .001) at 30 mins after LPS and remained elevated compared with control rats. LV wall thickness increased strikingly from 15 mins until 2 hrs after LPS infusion. Pathologic studies demonstrated marked congestion of capillaries and mild edema in the LV myocardium. The hematocrit increased after the administration of LPS. LPS markedly increased sympathetic tone as demonstrated by the elevation of plasma concentrations of epinephrine and norepinephrine. There was no elevation of concentrations of nitrite and nitrate. Pretreatment with TCV-309, a specific potent PAF antagonist, reduced LPS-induced hypotension and attenuated LV functional and structural changes. TCV-309 administration reduced the LPS-induced adrenergic activation and hemoconcentration.. The hypotension that occurred during the initial phase of LPS-induced shock was accompanied by LV functional and structural alterations. The marked increase in LV wall thickness can be ascribed to the congestion of capillaries and edema in the LV myocardium. Pretreatment with a PAF antagonist reduced LPS-induced alterations. PAF may play a pivotal role during the initial phase of LPS-induced cardiovascular responses.

Topics: Animals; Disease Models, Animal; Drug Evaluation, Preclinical; Echocardiography; Electrocardiography; Endotoxemia; Epinephrine; Hematocrit; Isoquinolines; Klebsiella Infections; Klebsiella pneumoniae; Lipopolysaccharides; Male; Nitrates; Nitrites; Norepinephrine; Platelet Activating Factor; Platelet Aggregation Inhibitors; Prospective Studies; Pyridinium Compounds; Rats; Rats, Wistar; Systole; Tetrahydroisoquinolines; Time Factors; Ventricular Dysfunction, Left

This swine model was designed to elucidate the role of platelet-activating factor in regional myocardial ischemia-reperfusion injury.. In groups 1 and 2 (n = 12 each), the left anterior descending coronary artery was ligated for 60 minutes to induce regional myocardial ischemia followed by 6 hours of reperfusion. Group 1 received the platelet-activating factor antagonist TCV-309 before ischemia, whereas group 2 did not. Group 3 (n = 3) had a sham operation.. Animals in group 2 exhibited significant (p < 0.05) hemodynamic instability and myocardial depression during the reperfusion period. Despite preventive measures, 7 of the 12 animals experienced severe dysrhythmias in the form of atrial and ventricular fibrillation leading to cardiac arrest. In contrast, animals in group 1 in whom the effects of platelet-activating factor were blocked by the specific platelet-activating factor receptor antagonist TCV-309 were hemodynamically stable and had significantly (p < 0.05) better myocardial function. This significant difference in global myocardial function between the groups was observed in the presence of similar morphologic findings and regional myocardial function.. These results suggest that platelet-activating factor has a definite influence on global myocardial dysfunction associated with regional myocardial ischemia-reperfusion injury.

Topics: Animals; Arrhythmias, Cardiac; Atrial Fibrillation; Blood Pressure; Cardiac Output; Cardiac Volume; Disease Models, Animal; Female; Heart Arrest; Hemodynamics; Isoquinolines; Myocardial Contraction; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Neutrophils; Platelet Activating Factor; Platelet Aggregation Inhibitors; Pyridinium Compounds; Random Allocation; Stroke Volume; Swine; Tetrahydroisoquinolines; Ventricular Fibrillation; Ventricular Function

We investigated the effects of TCV-309, a novel platelet activating factor (PAF) antagonist, on circulatory dysfunction and hematological abnormalities in experimental canine endotoxin (ET) shock. ET caused biphasic hypotension with a decrease in cardiac output (CO), left ventricular systolic pressure (LVP) and its dp/dt(max). The first hypotensive phase occurred within 15 min, and the second phase between 90 and 180 min following the injection of ET. Pulmonary vascular resistance (PVR) abruptly increased at 15 min with a partial recovery, and was then sustained at twice the basal value throughout the experiment. TCV-309 attenuated the hypotension, the decrease in CO, LVP and its dp/dt(max), and the increase in PVR. TCV-309 had no significant effect on the increase in TPR. The decrease in plasma fibrinogen and the increase in hematocrit and plasma lactate were significantly attenuated by TCV-309. These data suggest that PAF may be a key mediator leading to shock in sepsis.

Topics: Animals; Blood Circulation; Blood Pressure; Disease Models, Animal; Dogs; Heart; Hematologic Diseases; Hemodynamics; Isoquinolines; Male; Platelet Activating Factor; Platelet Count; Pyridinium Compounds; Shock, Septic; Tetrahydroisoquinolines; Time Factors

Platelet-activating factor (PAF) has been postulated to play a role in the pathogenesis of sepsis. Additionally, in vitro studies have revealed tight interactions between PAF and the cytokine network, and PAF is considered to be an important stimulator of neutrophil functions. To assess the intermediate role of PAF in the induction of cytokines and neutrophil degranulation in endotoxemia in vivo, 12 healthy adult chimpanzees were i.v. injected with a bolus dose of Escherichia coli endotoxin (4 ng/kg); four animals received endotoxin alone, whereas the other chimpanzees were infused with the specific and potent PAF antagonist TCV-309 (bolus of 100 micrograms/kg, followed by either 100 micrograms/kg/h (n = 4) or 500 micrograms/kg/h (n = 4) for 5 h). At both doses TCV-309 significantly inhibited the endotoxin-induced rise in cytokine levels. Peak TNF concentrations after injection of endotoxin alone were 366 +/- 96 pg/ml, vs 105 +/- 47 and 115 +/- 56 pg/ml after administration of endotoxin together with the lower or higher dose of TCV-309, respectively (p < 0.05). TCV-309 also reduced the appearance of soluble TNFRs. Maximal levels of the type I soluble TNFR were diminished from 2.53 +/- 0.27 ng/ml (endotoxin alone) to 1.69 +/- 0.36 ng/ml (high dose TCV-309; p < 0.05); peak values of the type II soluble TNFR were diminished from 8.62 +/- 1.19 ng/ml to 5.76 +/- 0.92 ng/ml (p < 0.05). Furthermore, TCV-309 attenuated the endotoxin-induced release of IL-6 (160 +/- 82 pg/ml after endotoxin alone, vs 63 +/- 30 pg/ml in the low dose TCV-309 group (p < 0.05) and 65 +/- 29 pg/ml in the high dose group (p = 0.07) as well as that of IL-8 (279 +/- 168, vs 71 +/- 15 and 46 +/- 17 pg/ml, respectively; both p < 0.05). TCV-309 tended to reduce the endotoxin-provoked rise in serum IL-1R antagonist levels. In contrast, TCV-309 did not affect the neutrophilic leukocytosis elicited by endotoxin, nor did it inhibit endotoxin-induced neutrophil degranulation, as monitored by the plasma levels of elastase-alpha 1-antitrypsin complexes. We conclude that PAF plays a role, either directly or indirectly, in the stimulation of the cytokine network and in the shedding of soluble TNFR in endotoxemia. PAF does not seem to be an important intermediate factor in endotoxin-induced neutrophilia or neutrophil degranulation.

Topics: alpha 1-Antitrypsin; Animals; Cytokines; Disease Models, Animal; Endotoxins; Interleukin 1 Receptor Antagonist Protein; Interleukin-6; Interleukin-8; Isoquinolines; Leukocyte Count; Leukocyte Elastase; Neutrophils; Pan troglodytes; Pancreatic Elastase; Platelet Activating Factor; Pyridinium Compounds; Receptors, Tumor Necrosis Factor; Sialoglycoproteins; Tetrahydroisoquinolines; Toxemia; Tumor Necrosis Factor-alpha

The study was designed to demonstrate the time course of neutrophil chemotactic factor (NCF) release from blood-free isolated rat hearts and to clarify the characteristics of NCF in order to facilitate its identification.. Coronary effluents were collected every minute from Langendorff perfused rat hearts during ligation of the left coronary artery for 40 min and reperfusion for 60 min. The neutrophil chemotactic activity in the effluents was assayed using modified Boyden's chambers with rat neutrophils isolated from peripheral blood as the indicator cells.. The NCF release started at 10 min of coronary artery occlusion. During the reperfusion period, NCF release peaked at 5 min (230% of preischaemic value). To clarify the characteristics of NCF, the changes in chemotactic activity were examined using various inhibitors and inactivators of possible NCF candidates (LTB4, PAF, 5-lipoxygenase, and thromboxane synthase). The heat stability of NCF was also examined to exclude heat labile molecules such as adenosine or complements appearing as NCF. Among the various substances examined, only PAF antagonists (CV-6209 and TCV-309 at concentrations of 10(-6) M and 10(-5) M respectively) abolished the chemotactic activity. However direct measurement of PAF in the effluents was unsuccessful.. NCF is released from the heart early after ischaemic insult, with the highest peak occurring at 5 min of reperfusion. PAF related substances might be the primary NCF in the effluent but this remains to be determined.

Topics: Animals; Chemotaxis; Disease Models, Animal; Hot Temperature; Interleukin-8; Isoquinolines; Male; Myocardial Reperfusion Injury; Myocardium; Phenylpropionates; Platelet Activating Factor; Pyridinium Compounds; Rats; Rats, Wistar; Tetrahydroisoquinolines; Time Factors

The possible involvement of platelet activating factor (PAF) in the pathogenesis of endotoxin-induced disseminated intravascular coagulation (DIC) was investigated in rats using a novel potent PAF antagonist, TCV-309. TCV-309 (> 1 mg/kg, i.v.) showed beneficial effects in rats with experimental DIC induced by a 4-hour sustained infusion of endotoxin (1 mg/kg) in a dose-dependent manner. TCV-309 (1 mg/kg) significantly ameliorated the decrease in platelet count and plasma fibrinogen, the prolongation of prothrombin time (PT) and activated partial thromboplastin time (APTT) and the increase in fibrin and fibrinogen degradation products (FDP) and inhibited glomerular fibrin deposition. Furthermore, plasma tissue factor (TF) activity was greatly increased in the DIC rats, and this was also significantly decreased by TCV-309 (1 mg/kg). TCV-309 (1 mg/kg) did not affect these parameters in normal rats. A 4-hour sustained infusion of PAF (60 micrograms/kg) caused mild but significant changes in some DIC parameters such as PT, fibrinogen and FDP concentration and increased the plasma TF activity. TCV-309 (1 mg/kg) inhibited all these PAF-induced changes. TCV-309 (0.1 mM) itself had no direct in vitro effects on the blood coagulation system including TF activity. These results strongly suggest that PAF plays a role in the pathogenesis of endotoxin-induced DIC via the generation of TF. Prophylactic use of PAF antagonists may therefore be useful for the treatment of DIC with sepsis.

Topics: Animals; Disease Models, Animal; Disseminated Intravascular Coagulation; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Isoquinolines; Male; Platelet Activating Factor; Pyridinium Compounds; Rats; Rats, Sprague-Dawley; Tetrahydroisoquinolines; Thromboplastin