Inhibition of lipid peroxidation restores impaired vascular endothelial growth factor expression and stimulates wound healing and angiogenesis in the genetically diabetic mouse.

Impaired wound healing is a well-documented phenomenon in experimental and clinical diabetes. Experimental evidence suggests that a defect in vascular endothelial growth factor (VEGF) regulation might be associated with wound-healing disorders. We studied the involvement of lipid peroxidation in the pathogenesis of altered VEGF expression in diabetes-related healing deficit by using an incisional skin-wound model produced on the back of female diabetic C57BL/KsJ db+/ db+ mice and their normal (db+/+m) littermates. Animals were then randomized to the following treatment: raxofelast (15 mg.kg(-1).day(-1) i.p.), an inhibitor of lipid peroxidation, or its vehicle (DMSO/NaCl 0.9%, 1:1 vol: vol). The animals were killed on different days (3, 6, and 12 days after skin injury), and the wounded skin tissues were used for histological evaluation, for analysis of conjugated dienes (CDs), as an index of lipid peroxidation and wound breaking strength. Furthermore, we studied the time course of VEGF mRNA expression throughout the skin-repair process (3, 6, and 12 days after skin injury), by means of reverse transcriptase-polymerase chain reaction, as well as the mature protein in the wounds. Diabetic mice showed impaired wound healing with delayed angiogenesis, low breaking strength, and increased wound CD content when compared with their normal littermates. In healthy control mice, a strong induction of VEGF mRNA was found between day 3 and day 6 after injury, while no significant VEGF mRNA expression was observed at day 12 after injury. In contrast, VEGF mRNA levels, after an initial increase (day 3), were significantly lower in diabetic mice than in normal littermates, and light induction of VEGF mRNA expression was also present at day 12 after injury. Similarly, the wound content of the angiogenic factor was markedly changed in diabetic mice. Administration of raxofelast did not modify the process of wound repair in normal mice, but significantly improved the impaired wound healing in diabetic mice through the stimulation of angiogenesis, re-epithelization, and synthesis and maturation of extracellular matrix. Moreover, raxofelast treatment significantly reduced wound CD levels and increased the breaking strength of the wound. Lastly, the inhibition of lipid peroxidation restored the defect in VEGF expression during the process of skin repair in diabetic mice and normalized the VEGF wound content. The current study provides evidence that lipid peroxidation inhibition restores wound healing to nearly normal levels in experimental diabetes-impaired wounds and normalizes the defect in VEGF regulation associated with diabetes-induced skin-repair disorders.

The reduction of myocardial damage and leukocyte polymorphonuclear accumulation following coronary artery occlusion by the tyrosine kinase inhibitor tyrphostin AG 556.

We investigated the effects of tyrophostin AG 556, a tyrosine kinase inhibitor, on the phenomenon of leukocyte accumulation during ischaemia and reperfusion of the myocardium. Male anaesthetized rats were subjected to total occlusion (45 min) of the left main coronary artery followed by 5 h reperfusion (MI/R). Sham myocardial ischaemia-reperfusion rats (Sham MI/R) were used as controls. Myocardial necrosis, myocardial myeloperoxidase activity (MPO), serum creatinine phosphokinase activity (CPK) serum Tumor Necrosis Factor (TNF-alpha) and Interleukin 6 (IL-6), cardiac intercellular adhesion molecule-1 (ICAM-1) and TNF-alpha expression and myocardial contractility (left ventricle dP/dt(max)) were evaluated. Myocardial ischaemia plus reperfusion in untreated rats produced marked myocardial necrosis, increased serum CPK activity (196.5 +/- 19 U/100 ml, at the end of reperfusion) and myeloperoxidase activity (MPO, a marker of leukocyte accumulation) both in the area-at-risk (4.5 +/- 0.5 U/g/tissue) and in necrotic area (8.2 +/- 1.2 U/g/tissue), reduced myocardial contractility (1,706 +/- 52 mmHg/s, at the end of reperfusion) and induced a marked increase in the serum levels of TNF-alpha (1,950 +/- 97 pg/ml, at 1 h of reperfusion) and IL-6 (998 +/- 16 U/ml, at the end of reperfusion). Finally, myocardial ischaemia-reperfusion injury also increased cardiac mRNA for TNF-alpha and ICAM-1 in the myocardium-at risk. Tyrphostin AG 556 (0.5, 1 and 2 mg/kg subcutaneously 5 min after the onset of reperfusion) lowered myocardial necrosis and myeloperoxidase activity in the area-at-risk (1.5 +/- 0.2 U/g/tissue, following the highest dose) and in necrotic area (2.9 +/- 0.3 U/g/tissue following the highest dose), decreased serum CPK activity (96 +/- 9 U/100 ml, at the end of reperfusion), lowered serum TNF-alpha and IL-6, increased myocardial contractility (2,096 +/- 88 mmHg s, at the end of reperfusion) and reduced cardiac mRNA levels for TNF-alpha and ICAM-1. The present data suggest that tyrosine kinase inhibitors protect against myocardial ischaemia-reperfusion injury by reducing leukocyte accumulation to the ischaemic myocardium.

Protective effects of cyclosporin-A in splanchnic artery occlusion shock.

Cyclosporin A (CsA) is an immunosuppressant drug that inhibits nitric oxide (NO) synthase induction in vascular smooth muscle cells. Splanchnic artery occlusion (SAO) shock is a lethal type of shock characterized by a marked vascular dysfunction in which the L-arginine/nitric oxide pathway plays an important role. We investigated whether CsA exerts protective effects in SAO shock by interfering with the L-arginine/nitric oxide pathway. Male anaesthetized rats (n=156) were subjected to clamping of the splanchnic arteries for 45 min. This surgical procedure resulted in an irreversible state of shock (SAO shock). Sham operated animals were used as controls. SAO shocked rats had a decreased survival (86+/-6 min, while sham shocked rats survived more than 240 min), marked hypotension, increased serum levels of TNF-alpha, enhanced plasma nitrite/nitrate concentrations (75+/-7.1 microM; sham shocked rats=1.6+/-0.5 microM) and enhanced inducible NO synthase (iNOS) protein induction and activity in the aorta. Moreover aortic rings from shocked rats showed a marked hyporeactivity to phenylephrine (PE, 1 nM - 10 microM). CsA (0.25, 0.5 and 1 mg kg(-1), 5 min after reperfusion) increased survival rate (SAO+CsA=236+/-9 min following the highest dose), reverted the marked hypotension, reduced plasma nitrite/nitrate concentration (11+/-5.2 microM following the highest dose), restored to control values the hyporeactivity to PE, and blunted iNOS protein induction and activity in aortic rings. The present data indicate that in an experimental rat model CsA may have antishock properties related to inhibition of L-arginine/nitric oxide pathway.

The lazaroid, U-74389G, inhibits inducible nitric oxide synthase activity, reverses vascular failure and protects against endotoxin shock.

The aim of our study was to investigate the effect of the 21-aminosteroid U-74389G [21- < 4-(2,6-di-1-pyrrolidinyl-4-pyrimidinyl)-1-piperazinyl-pregna-1,4,9,(11) triene-3,20-dione(z)-2-butenedionate] on the l-arginine-nitric oxide (NO) pathway in a rat model of endotoxin shock. Endotoxin shock was produced in male rats by a single intravenous (i.v.) injection of 20 mg/kg of Salmonella Enteritidis lipopolysaccharide (LPS). Rats were treated with U-74389G (7.5, 15 and 30 mg/kg i.v.) or vehicle (1 ml/kg i.v.) 5 min after endotoxin challenge. Lipopolysaccharide administration reduced survival rate (0%, 72 h after endotoxin administration) decreased mean arterial blood pressure, enhanced plasma concentration of bilirubin and alanine aminotransferase and increased plasma nitrite concentrations. Lipopolysaccharide injection also increased the activity of inducible NO synthase in the liver and in the aorta. Furthermore aortic rings from shocked rats showed a marked hyporeactivity to phenylephrine (1 nM-10 microM). In addition lipopolysaccharide (50 microg/ml for 4 h) in vitro stimulation significantly increased nitrite production in peritoneal macrophages harvested from normal rats. Treatment with U-74389G (15 and 30 mg/kg i.v., 5 min after endotoxin challenge) significantly protected against lipopolysaccharide-induced lethality (90% survival rate 24 h and 80% 72 h after lipopolysaccharide injection, respectively, following the highest dose of the drug), reduced hypotension, ameliorated liver function, decreased plasma nitrite levels, restored the hyporeactivity of aortic rings to their control values and inhibited the activity of inducible NO synthase in the liver and in the aorta. Finally, U-74389G in vitro (12.5, 25 and 50 microM) significantly inhibited nitrite production in endotoxin stimulated peritoneal macrophages. The data suggest that U-74389G may exert beneficial effects in an experimental model of septic shock by inhibiting the activity of the inducible NO synthase.

Effect of sulfatide on acute lung injury during endotoxemia in rats.

Experimental studies have shown that intrapulmonary leukocyte sequestration and activation is implicated in the pathogenesis of acute lung injury during endotoxemia. Selectins are involved in the adhesion of leukocyte to the endothelium. Sulfatide is recognized by P selectin and blocks this adhesion molecule. We studied the effects of sulfatide on endotoxin-induced lung damage in rats. Endotoxin shock was produced in male rats by a single intravenous (i.v.) injection of 20 mg/kg of Salmonella enteritidis lipopolysaccharide (LPS). LPS administration reduced survival rate (0%, 72 h after endotoxin challenge) decreased mean arterial blood pressure (MAP), produced leukopenia (Controls = 11,234+/-231 cells/mL, LPS = 4,567+/-123 cells/mL) and increased lung myeloperoxidase activity (MPO; a marker of leukocyte accumulation) in the lung (Controls = 0.35+/-0.1 U/g/tissue; LPS = 10+/-1.2 U/g/tissue). Furthermore LPS administration markedly impaired the concentration-response curves for acetylcholine and sodium nitroprusside in isolated pulmonary arterial rings. There was also an increased staining for P-selectin in the pulmonary arteries. Sulfatide treatment (10 mg/kg, 30 min. after LPS challenge), significantly protected against LPS-induced lethality (90% survival rate and 70% survival rate 24 h and 72 h after LPS injection), reduced LPS induced hypotension, reverted leukopenia (8,895+/-234 cells/ml) and lowered lung MPO activity (1.7+/-0.9 U/g/tissue). Furthermore sulfatide restored to control values the LPS-induced impairment in arterial pulmonary vasorelaxation and reduced P-selectin immunostaining. Our data indicate that sulfatide attenuates LPS-induced lung injury and protects against endotoxin shock.

Inhibition of tumour necrosis factor and reversal of endotoxin-induced shock by U-83836E, a 'second generation' lazaroid in rats.

1. Antioxidants can exert protective effects in endotoxic shock by either a reduction of the oxidant damage or attenuation of Tumour Necrosis Factor (TNF-alpha) production. 2. Lazaroids are a family of compounds that inhibit lipid peroxidation. Besides, they can also reduce TNF-alpha. U-83836E is a new lazaroid lacking the glucocorticoid ring. 3. Aim of our study was to investigate the effect of U-83836E on TNF-alpha production either in vivo or in vitro. Endotoxic shock was produced in male rats by a single intravenous (i.v.) injection of 20 mg kg(-1) of S. enteritidis lipopolysaccharide (LPS). LPS administration reduced survival rate (0% survival, 72 h after endotoxin administration), decreased mean arterial blood pressure, increased serum and macrophage TNF-alpha and enhanced plasma malonylaldehyde (MAL) levels. Furthermore aortic rings from shocked rats showed a marked hyporeactivity to phenylephrine (PE 1 nM-10 microM). 4. Treatment with U-83836E (7.5, 15 and 30 mg kg(-1), i.v.) 5 min after endotoxin challenge significantly protected against LPS induced lethality (90% survival rate and 80% survival rate 24 h and 72 h after LPS injection respectively, following the highest dose of the drug), reduced hypotension, blunted plasma MAL, decreased serum and macrophage TNF-alpha and restored the hyporeactivity of aortic rings to control values. In vitro LPS stimulation (50 microg ml(-1) for 4 h) significantly increased cytokine production in macrophages (Mphi) harvested from untreated normal rats. Pretreatment with pertussis toxin (PT; 0.1, 1 and 10 ng ml(-1) 4 h before LPS) significantly increased TNF-alpha production. PT effects on these LPS responses were correlated with a PT mediated ADP ribosylation of a 41 kDa protein. U-83836E (50 microM) reduced, in a dose dependent manner, LPS induced TNF-alpha production and inhibited the PT effects on cytokine production and on ADP ribosylation of the protein. 5. Our data suggest that lazaroids may affect the early events associated with LPS receptor mediated activation of a G protein in LPS induced TNF-alpha production. These molecular events may explain, at least in part, the in vivo inhibition of cytokine production and reversal of endotoxic shock.

Monocytes and lymphocytes as active participants in the pathogenesis of experimental shock.

We investigated the role played by monocytes and lymphocytes in the pathogenesis of experimental shock. Splanchnic artery occlusion (SAO) shock was induced in anaesthetized rats by clamping splanchnic arteries for 45 min followed by reperfusion. Sham operated animals were used as controls. SAO shocked rats had a decreased survival time (80 +/- 11 min, while sham shocked rats survived more than 4 h), increased serum (248 +/- 21 U/ml) and macrophage (145 +/- 15 U/ml) levels of TNF-alpha, enhanced myeloperoxidase (MPO) activity in the ileum (3.38 +/- 0.2 U x 10(-3)/g tissue), decreased number of monocytes, lymphocytes and neutrophils and a profound hypotension. In addition we found an increased expression of vascular cell adhesion molecule-1 (VCAM-1) on aortic endothelium and a reduced percentage of VLA-4 positive monocytes and lymphocytes. Inhibition of TNF-alpha synthesis, reversed the increased endothelial expression of VCAM-1, increased the percentage of integrin VLA-4 positive leukocytes and improved monocyte, lymphocyte and neutrophil count. Furthermore a passive immunization with specific antibodies raised against VCAM-1 (2 mg/kg, i.v. 3 h before SAO) increased survival, reduced MPO activity in the ileum (0.034 +/- 0.04 U x 10(-3)/g tissue) and improved mean arterial blood pressure. Our data suggest that monocytes and lymphocytes participate in the pathogenesis of splanchnic ischaemia-reperfusion injury and may amplify the adhesion of neutrophils to peripheral tissues.

Endotoxin tolerance impairs a pertussis-toxin-sensitive G-protein regulating tumour necrosis factor release by macrophages from tumour-bearing rats.

The aim of this work was to study whether a G-protein regulates lipopolysaccharide (LPS) induced TNF-alpha production in tumour-bearing rat peritoneal macrophages differently to in normal rats. We also investigated whether a state of 'early endotoxin tolerance' affects LPS induced TNF-alpha release via a G-protein-mediated phenomenon. LPS-stimulated (50 micrograms ml-1 of Salmonella enteritidis LPS) TNF-alpha release was investigated in peritoneal macrophages harvested from both normal rats and tumour-bearing rats. Cholera toxin (10, 100 and 1000 ng ml-1) did not significantly modify LPS-induced TNF-alpha release. In contrast pertussis toxin (0.1, 1.0 and 10 ng ml-1) significantly increased LPS-induced TNF-alpha release and inhibited LPS-stimulated prostaglandin E2 (PGE2) production in both normal rat macrophages and tumour-bearing rat macrophages. Pertussis toxin effects on these LPS responses were correlated with a pertussis-toxin-mediated ADP-ribosylation of a 41 kDa protein(s). The LPS-mediated responses were significantly greater in macrophages from tumour-bearing rats than in macrophages from normal rats. PGE2 (10(-9), 10(-8) and 10(-7) M) suppressed LPS-induced TNF-alpha production in a dose-dependent fashion. A state of 'early endotoxin tolerance' was then induced in tumour-bearing rats by a single intravenous injection of 125 micrograms rat-1 of LPS, and experiments were performed on peritoneal macrophages harvested 24 h after LPS injection. In tolerant macrophages pertussis toxin induced an increase in LPS-stimulated TNF-alpha release and an inhibition in LPS-stimulated PGE2 release significantly lower than in macrophages harvested from non-tolerant tumour bearing rats. Our results suggest that a pertussis-toxin-sensitive G-protein may serve to regulate the synthesis of TNF-alpha in rat peritoneal macrophages and that the activity of this pertussis-sensitive G-protein is increased in macrophages from tumour-bearing rats. Furthermore, our experiments would indicate that a 'state of endotoxin tolerance', caused by altering the function of presumably a Gi-protein, may exert beneficial effects on the functions of macrophages in tumour-bearing rats.

G 619, a dual thromboxane synthase inhibitor and thromboxane A2 receptor antagonist, inhibits tumor necrosis factor-alpha biosynthesis.

G 619 is 3-carbamyl-(3'-picolyl)-4-methoxy-1-benzamide. The compound is structurally related to picotamide, a previously reported dual thromboxane synthase inhibitor/thromboxane A2 receptor antagonist, which displays inhibitory activity on tumor necrosis factor-alpha. The aim of the present work was to study the effect of G 619 on tumor necrosis factor-alpha synthesis both in vivo and in vitro. Salmonella enteritidis lipopolysaccharide was used to induce tumor necrosis factor-alpha production. Septic shock was produced in male rats by a single intravenous (i.v.) injection of 20 mg/kg (LD90) of Salmonella enteritidis lipopolysaccharide. Rats were pretreated with G 619 (50 mg/kg, i.v.) or vehicle (1 ml/kg, i.v.) 1 h before endotoxin challenge. Salmonella enteritidis lipopolysaccharide administration dramatically reduced survival rate (0%, 72 h after endotoxin administration), reduced mean arterial blood pressure, increased plasma levels of thromboxane B2 and 6-keto-prostaglandin F1 alpha and enhanced serum levels of tumor necrosis factor. Furthermore, endotoxic shock produced characteristic gastric damage, consisting of haemorrhagic infiltrates. Pretreatment with G 619 in vivo significantly protected against Salmonella enteritidis lipopolysaccharide-induced lethality (80% survival rate and 60% survival rate 24 h and 72 h after Salmonella enteritidis lipopolysaccharide injection, respectively), reduced hypotension, decreased plasma thromboxane B2 and serum tumor necrosis factor-alpha levels and enhanced blood levels of 6-keto-prostaglandin F1 alpha. In rat peritoneal macrophages, G 619 in vitro (25, 50 and 100 microM) significantly blunted (P < 0.001) Salmonella enteritidis lipopolysaccharide-stimulated production of tumor necrosis factor-alpha, whereas it increased 6-keto-prostaglandin F1 alpha and cyclic AMP levels. The present data indicate that G 619 may be useful during disease states characterized by elevated tumor necrosis factor-alpha levels.

Beneficial effects of BAY u3405, a novel thromboxane A2 receptor antagonist, in splanchnic artery occlusion shock.

Splanchnic artery occlusion shock was induced in male anaesthetized rats by clamping the splanchnic artery for 45 min. The arteries were then released and survival rate, mean survival time, mean arterial blood pressure, plasma levels of thromboxane B2 and 6-keto-PGF1 alpha, macrophage phagocytosis activity and plasma levels of myocardial depressant factor were evaluated. In addition, the neutrophilic infiltrate was quantified in the ileum and lung using a myeloperoxidase (MPO) assay. Sham splanchnic-artery-occlusion-shocked rats were used as controls. Splanchnic-artery-occlusion-shocked rats died within 93 +/- 7 min, while all sham-shocked animals survived more than 3 h. Splanchnic artery occlusion shock caused changes in mean arterial blood pressure, significantly increased the plasma levels of thromboxane B2 (7.5 +/- 1.3 ng/ml; p < 0.001 vs. sham), 6-keto-PGF1 alpha (8.9 +/- 1.7 ng/ml; p < 0.001 vs. sham) and myocardial depressant factor (114 +/- 11 U/ml), and reduced macrophage phagocytosis. Furthermore, MPO activity was significantly elevated (0.12 +/- 0.03 x 10(-3) and 1.8 +/- 0.5 x 10(-3) U/g protein in the ileum and lung, respectively) 70 min after starting reperfusion. Administration of BAY u3405, a novel thromboxane A2 receptor antagonist (30 mg/kg i.v., 30 min before occlusion), significantly increased survival time (187 +/- 3.7 min) and survival rate, improved mean arterial blood pressure, reduced the plasma levels of myocardial depressant factor (54 +/- 3 U/ml), partially restored macrophage phagocytosis and lowered MPO activity in both the ileum and the lung. Our data are consistent with an involvement of thromboxane A2 in splanchnic artery occlusion shock and suggest that BAY u3405 might be of benefit in low-flow states such as circulatory shock.

TCV-309, a novel platelet activating factor antagonist, inhibits leukocyte accumulation and protects against splanchnic artery occlusion shock.

The aim of this study was to evaluate: (1) the accumulation of leukocytes in the ileum and the lung during splanchnic artery occlusion (SAO) shock; (2) the role of platelet-activating factor (PAF) and tumor necrosis factor (TNF-alpha) in this phenomenon. Untreated anesthesized rats subjected to total occlusion of the celiac, superior and inferior mesenteric arteries for 45 min, followed by reperfusion, uniformly died within 90 min after reperfusion. The mean survival time was 93 +/- 7 min. The neutrophilic infiltrate was quantitated in the ileum and in the lung using a myeloperoxidase (MPO) assay. MPO activity in the ileum and in the lung averaged 0.05 +/- 0.03 and 0.4 +/- 0.02 U x 10(-3)/g protein in animals killed before occlusion. MPO activity did not change in rats killed immediately before reperfusion and was significantly elevated (0.11 +/- 0.02 and 1.7 +/- 0.6 U x 10(-3)/g protein in the ileum and the lung, respectively) in those killed 80 min after the beginning of the reperfusion. The histological examination confirmed the accumulation of leukocytes in the mucosa of the ileum and the lung over the 80 min. SAO shocked rats exhibited leukopenia and increased serum levels of TNF-alpha. In order to evaluate the role of PAF and TNF-alpha in SAO shock, a powerful PAF receptor antagonist, TCV-309 (5 micrograms/kg i.v.), was injected 5 min after reperfusion. TCV-309 increased survival time, lowered serum TNF-alpha, reduced MPO activity in both the ileum and the lung and ameliorated leukopenia induced by SAO shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effects of BAY U 3405, a thromboxane A2 receptor antagonist, in endotoxin shock.

The present study was designed to investigate the effects of BAY U 3405, a new thromboxane A2 (TxA2) receptor antagonist, in endotoxin shock. Endotoxin shock (ES) was induced in male rats by an i.v. injection of Salmonella enteritidis lipopolysaccharide (LPS; 20 mg kg-1). LPS administration caused animal death (survival = 0%, 48 h after endotoxin challenge), systemic hypotension, depressed phagocytosis and increased blood levels of TNF-alpha, TxB2 and 6-keto-PGF1 alpha, reduced white blood cell (WBC) count (ES = 5.9 +/- 1 x 10(3) mm-3; CTRL = 13.4 +/- 5 x 10(3) mm-3) and enhanced myeloperoxidase (MPO) activity, studied as a quantitative means for assessing leukocyte accumulation, in the ileum (ES = 0.24 +/- 0.7 U g-1 fresh tissue; CTRL = 0.13 +/- 0.04 U g-1 fresh tissue), in the heart (ES = 0.41 +/- 0.1 U g-1 fresh tissue; CTRL = 0.16 +/- 0.08 U g-1 fresh tissue) and in the lung (ES = 0.68 +/- 0.11 U g-1 fresh tissue; CTRL = 0.19 +/- 0.05 U g-1 fresh tissue). Furthermore, endotoxin administration produced characteristic damage of the gastric mucosa consisting of haemmorrhagic infiltrates. BAY U 3405 (30 mg kg-1 i.v., 30 min before endotoxin challenge) increased survival rate (45% survival rate 48 h after endotoxin challenge), reduced hypotension, decreased TNF-alpha levels in serum, enhanced phagocytic activity (ES = 25.6 +/- 1.9%, BAY U 3405 = 45.9 +/- 0.4%, P < 0.001) and lowered MPO activity in the ileum (0.14 +/- 0.05 U g-1 fresh tissue), in the heart (0.18 +/- 0.08 U g-1 fresh tissue) and in the lung (0.44 +/- 0.09 U g-1 fresh tissue). Finally, the gastric alterations were significantly reduced in rats pretreated with BAY U 3405. These data suggest that this thromboxane receptor antagonist might be a useful drug in shock conditions.

Protective effects of L-659,989, a platelet-activating factor receptor antagonist, in myocardial ischemia and reperfusion in rats.

The cardioprotective effects of L-659,989, a specific platelet-activating factor (PAF) receptor antagonist, were investigated in an ischemia/reperfusion model in rats. Pentobarbital-anesthetized rats were subjected to left main coronary artery occlusion (1 h) followed by reperfusion (1 h) (MI/R); Sham-operated rats were used as controls (Sham MI/R). Rats receiving vehicle showed reduced survival rate (60%), marked myocardial injury (necrotic area/total area = 54.5 +/- 6%; necrotic area/area at risk 76.6 +/- 6.7%), high serum creatine phosphokinase (CPK) activity (150 +/- 10 U/ml), and increased myocardial myeloperoxidase (MPO) activity in the area at risk (AR, 6.2 +/- 0.5 U x 10(-3)/g protein) and in the necrotic area (6.6 +/- 0.7 U x 10(-3)/g protein). PAF plasma levels increased significantly during reperfusion and peaked at 15 min of reperfusion. Administration of L-659,989 enhanced survival rate (80%), reduced myocardial damage (necrotic area/total area 25.6 +/- 3.5%; necrotic area/AR 34.6 +/- 5.4%), attenuated the increase in serum CPK (50 +/- 6 U/ml) and decreased MPO activity both in the AR (2.8 +/- 0.3 U x 10(-3)/g tissue) and in the necrotic area (2.3 +/- 0.5 U x 10(-3)/g tissue). Our results suggest that PAF-inducing adhesion and activation of polymorphonuclear leukocytes (PMN) plays a significant role in the injury associated with ischemia/reperfusion.

Anorectic activity of NG-nitro-L-arginine, an inhibitor of brain nitric oxide synthase, in obese Zucker rats.

We investigated the effects of NG-nitro-L-arginine (L-NO Arg) administration (12.5, 25 and 50 mg/kg i.p.) on food consumption and body weight of male obese Zucker rats (fa/fa) and in their lean age-matched controls (FA/?; FA/FA), both groups aged 14 weeks. Acute or repeated administration of L-NO Arg reduced food intake and body weight in both obese and lean rats. However the lean rats showed tolerance to the L-NO Arg effects after 5 days of treatment. L-NO Arg anorexia was suppressed by pretreatment with metergoline. These results suggest that L-NO Arg may represent a new anorectic drug.

Protective effects of G 619, a dual thromboxane synthase inhibitor and thromboxane A2 receptor antagonist, in splanchnic artery occlusion shock.

Splanchnic artery occlusion (SAO) shock was induced in anesthetized rats by clamping the celiac trunk and the superior mesenteric artery for 45 min. The arteries were then released and survival rate, mean survival time, mean arterial blood pressure (MAP), plasma levels of thromboxane B2 (TxB2) and 6-keto-PGF1 alpha, and the phagocytotic activity of peritoneal macrophages were evaluated. Shocked animals died within 89 +/- 10 min, while all sham-shocked rats survived greater than 3 h. SAO shock produced relevant changes in MAP, significantly increased plasma levels of TxB2 and 6-keto-PFG1 alpha, and decreased peritoneal macrophage phagocytotic activity. The administration of G 619, a dual thromboxane synthase inhibitor/thromboxane A2 receptor antagonist (50 mg/kg, 15 min before SAO shock) significantly increased survival time (190 +/- 13 min) and survival rate, reduced plasma levels of TxB2, and partially restored the impairment in peritoneal macrophage phagocytosis. Finally, the administration of G 619 had beneficial effects on changes in MAP-induced bay SAO shock. These data further confirm the involvement of TxA2 in SAO shock and suggest that G 619 may have positive effects in low-flow states.

[Changes in blood viscosity after administration of vitamin E in the rabbit]. / Modificazione della viscosita' ematica dopo somministrazione di vitamina E nel coniglio.

Vitamin E is an essential factor to maintain biological membranes stability and its lack may affect membranes structures and reduce erythrocyte life-span. Vitamin E also play a role in the maintenance of a normal platelet aggregation. A.A. studied the effects of a ten days supply of d-1-alpha tocopherol acetate (50 mg/Kg/die) on blood viscosity in 8 rabbits. Results obtained show a significant reduction of blood viscosity on 6th day of treatment in the male rabbits and a progressive reduction of values from the 6th till the 10th day in female rabbits. The most significant decrease of blood viscosity were obtained at the lowest shear-rates, due to an increased red cells deformability to the antioxidative action of vitamin E on the erythrocytes membrane and to a reduced red cells aggregation. Such modifications on the red blood cells caratheristics can be determined by vitamin E through different mechanism: a) inhibiting red cell membrane's polyunsaturable fatty acids oxidation; b) by removal of abnormal lipids from erythrocyte membrane; c) physical and chemical stabilization of membrane's surface.

Lack of relation between dopaminergic and gabaergic mechanisms in chick retina.

The effects of apomorphine and bromocriptine on GABA content, GAD and GABA-T activities in the chick retina, both in conditions of a light cycle of 12 h/day and in conditions of light deprivation for 72 h, were studied. In addition, the effects of a treatment with 2 neuroleptics, having a different action on dopamine receptors, i.e. haloperidol and sulpiride, on the same biochemical parameters were examined. The present results show that all the pharmacological manipulations at the dopaminergic transmission by means of agonists and antagonists at dopamine receptors did not affect GABAergic mechanisms in the chick retina and seem to suggest a lack of relations between dopaminergic and GABAergic mechanisms at this level.

Optic tectum adenylate cyclase activity from goldfish (Carassius auratus) as a model to assess dopamine receptor agonists and antagonists.

The distribution of adenylate cyclase activity in several discrete areas of brain in the goldfish (Carassius auratus) and the responsiveness of this activity in the optic tectum to various neurotransmitters were studied. Adenylate cyclase activity was found to have an uneven distribution in the brain, the highest concentrations occurring in the telencephalon. A dopamine-sensitive adenylate cyclase was found in the optic tectum. The increase in cAMP formation induced by dopamine was selectively prevented by antagonists at post-synaptic dopamine receptors linked to adenylate cyclase.

[Modifications in the feeding behavior of the rat, induced by antimitotic drugs: effects of hydroxyurea]. / Modificazioni del comportamento alimentare del ratto indotte da farmaci antimitotici: effetti dell'idrossiurea.

The effects of Hydroxyurea treatment on food intake and on the self-selection between a protein free diet and a complete one are different from those observed during Cyclophosphamide and Mustine Hydrochloride treatment and appear to be similar to those observed during Methotrexate treatment; these may be referred exclusively to a toxic action of the drug on the liver and on the mucous membranes of digestive apparatus. The urea, a product of Hydroxyurea metabolism, does not seem to induce modifications on food intake both as to the quantitative and qualitative aspect.