Silvio Trivulzio

Ellagitannins from Rubus Berries for the Control of Gastric Inflammation: In Vitro and In Vivo Studies

Ellagitannins have shown anti-inflammatory and anti-Helicobacter pylori properties; however, their anti-inflammatory activity at gastric level was not previously investigated. The aim of this research was to evaluate the effects of ellagitannins from Rubus berries on gastric inflammation. Ellagitannin enriched extracts (ETs) were prepared from Rubus fruticosus L. (blackberry) and Rubus idaeus L. (raspberry). The anti-inflammatory activity was tested on gastric cell line AGS stimulated by TNF-α and IL-1β for evaluating the effect on NF-kB driven transcription, nuclear translocation and IL-8 secretion. In vivo the protective effect of ellagitannins was evaluated in a rat model of ethanol-induced gastric lesions. Rats were treated orally for ten days with 20 mg/kg/day of ETs, and ethanol was given one hour before the sacrifice. Gastric mucosa was isolated and used for the determination of IL-8 release, NF-kB nuclear translocation, Trolox equivalents, superoxide dismutase and catalase activities. In vitro, ETs inhibited TNF-α induced NF-kB driven transcription (IC50: 0.67–1.73 µg/mL) and reduced TNF-α-induced NF-kB nuclear translocation (57%–67% at 2 µg/mL). ETs inhibited IL-8 secretion induced by TNF-α and IL-1β at low concentrations (IC50 range of 0.7–4 µg/mL). Sanguiin H-6 and lambertianin C, the major ETs present in the extracts, were found to be responsible, at least in part, for the effect of the mixtures. ETs of blackberry and raspberry decreased Ulcer Index by 88% and 75% respectively and protected from the ethanol induced oxidative stress in rats. CINC-1 (the rat homologue of IL-8) secretion in the gastric mucosa was reduced in the animals receiving blackberry and raspberry ETs. The effect of ETs on CINC-1 was associated to a decrease of NF-κB nuclear translocation in ETs treated animals. The results of the present study report for the first time the preventing effect of ETs in gastric inflammation and support for their use in dietary regimens against peptic ulcer.

Activity of a new hydrogen sulfide-releasing aspirin (ACS14) on pathological cardiovascular alterations induced by glutathione depletion in rats.

We investigated the effects of the hydrogen sulfide (H₂S)-releasing derivatives of aspirin (ACS14) and salicylic acid (ACS21) in a rat model of metabolic syndrome induced by glutathione (GSH) depletion, causing hypertension and other pathological cardiovascular alterations. GSH depletion was induced in normal rats by the GSH-synthase inhibitor buthionine sulfoximine (BSO, 30 mmol/L day for seven days in the drinking water). Systolic blood pressure and heart rate were measured daily by the tail-cuff method, and plasma thromboxane B₂, 6-keto-prostaglandin F(2α), 8-isoprostane, GSH, insulin and glucose were determined at the end of the seven-day BSO schedule. In addition, ischemia/reperfusion-induced myocardial dysfunction and endothelial dysfunction were assayed on isolated heart and aortic rings, respectively. Unlike aspirin and salicylic acid, ACS14 and ACS21 reduced BSO-induced hypertension, also lowering plasma levels of thromboxane B₂, 8-isoprostane and insulin, while GSH remained in the control range. Neither ACS14 nor ACS21 caused gastric lesions. Both restored the endothelial dysfunction observed in aortic rings from BSO-treated rats, and in ischemia/reperfusion experiments they lowered left ventricular end-diastolic pressure, consequently improving the developed pressure and the maximum rise and fall of left ventricular pressure. Together with this improvement of heart mechanics there were reductions in the activity of creatine kinase and lactate dehydrogenase in the cardiac perfusate. This implies that H₂S released by both ACS14 and ACS21 was involved in protecting the heart from ischemia/reperfusion, and significantly limited vascular endothelial dysfunction in aortic tissue and the related hypertension.

Effects of ondansetron administration on opioid withdrawal syndrome observed in rats

This study tested whether a 5-HT3 receptor antagonist could reverse the signs of precipitated opioid withdrawal. Rats were treated with either saline or morphine for 4 days. After the four days, half of the rats in each group received naloxone and half received saline. Each animal also received one of four doses of ondansetron (0, 1, 2 and 4 mg/kg i.p.). Administration of ondansetron to rats receiving naloxone after chronic morphine decreased the intensity of withdrawal signs such as increased defecation, jumping and wet-dog shakes, elevated the nociceptive threshold values which were decreased by precipitated withdrawal, but produced no change in urination, rectal temperature or salivation. The effects exhibited by ondansetron administration may be explained through interference of its 5-HT3 receptor antagonist activity with serotoninergic mechanisms involved in the regulation of these withdrawal symptoms. The use of this drug is thus suggested as a possible treatment of opioid withdrawal signs in heroin addicts.

Myocardial infarction non-invasively induced in rabbits by administering isoproterenol and vasopressin: protective effects exerted by verapamil

Myocardial infarction is usually induced in small animals by means of invasive procedures: the aim of this study was to cause heart necrosis lesions by non‐invasive means. We injected rabbits with isoproterenol (3 mg/kg, i.p.) and vasopressin (0.3 mg/kg/5 min, i.v.) alone and in combination, and studied their effects on myocardial histology, electrocardiographic profiles, the appearance of the plasma cardiac necrosis marker c‐troponin I (c‐TPN I), hemodynamic parameters (blood pressure, heart rate), the coagulative process partial throboplastine time (PTT), and plasma nitric oxide (NO) levels. In the rabbits treated with vasopressin alone, the ischemic damage was associated with a decrease in NO values, and the appearance of electrocardiographic T‐wave inversion and low plasma c‐TPN I levels, whereas the animals treated with isoproterenol alone had necrotic bands in the myocardium, plasma c‐TPN I, and electrocardiographic modifications (ST‐segment changes and T‐wave inversion). Combined treatment increased myocardial alterations such as contraction band necrosis, induced the appearance of specific hypoxic lesions such as areas of coagulative necrosis and leukocyte infiltration, and led to higher plasma c‐TPN I levels and altered ECG profiles. Both drugs favored a decrease in plasma NO values and further alterations in hemodynamic parameters, such as higher blood pressure and greater procoagulant activity. The myocardial necrosis and modified cardiovascular parameters were attributed to calcium activated processes and the decrease in NO levels. As this model of myocardial damage involves the use of drugs that facilitate the opening of L‐calcium channels, we also investigated their effects on cardiovascular parameters and heart histology after pretreatment with the calcium antagonist verapamil; this drug protected against the appearance of histological myocardial lesions, electrocardiographic alterations and high plasma c‐TPN I levels, and prevented the hemodynamic and procoagulation changes, but did not affect the decrease in plasma NO values. The protective effects were attributed to the drugs calcium antagonist activity. In conclusion, the injection of isoproterenol and vasopressin induces a myocardial infarction non‐invasively and seems to be suitable for studying early myocardial ischemic lesions and the effects of drugs interfering with myocardial damage and its related phenomena.

Omegaconotoxin binding decreases in aged rat brain

Omegaconotoxin binding was studied in young (3 months) and old (24 months) male Sprague-Dawley rats. In both groups omegaconotoxin binding displayed high affinity, was specific and saturable. The age-related changes are mainly a decrease in the Bmax in striatum and cortex (-29% and -31%, respectively). Binding parameters were unmodified in hippocampus of the two age groups. These data are consistent with the decrease of calcium uptake and neurotransmitter release observed in the brain of aged rodents.

Plasma malondialdehyde levels and opiate withdrawal signs observed in rats treated with morphine plus naloxone: effects of α‐lipoic acid administration

A number of experimental studies have found that reactive oxygen species are involved during morphine treatment or withdrawal. The aims of this study were to analyse whether morphine administration and/or removal are related to peroxide generation and/or signs of withdrawal in rats, and whether the changes in antioxidant status induced by the administration of an antioxidant may modify peroxide levels and behavioural signs. We injected morphine or morphine and naloxone into rats and evaluated the plasma levels of peroxide malondialdehyde (MDA) and the appearance of withdrawal signs. We also investigated the effects on these parameters induced by the administration of the antioxidant α‐lipoic acid (LA). Morphine treatment increased MDA levels. Abrupt naloxone‐induced morphine withdrawal caused a further and significant increase in MDA, and the appearance of withdrawal signs such as abnormal fecal excretion, shortened latency times and jumping. The administration of LA lowered MDA levels in the rats treated with morphine or morphine plus naloxone, and also decreased MDA values and abstinence signs in the animals treated with morphine plus naloxone. The effects of LA were attributed to its capacity to scavenge peroxides and interfere with the biogenesis of the arachidonic acid metabolites involved in the expression of abstinence symptoms.

Drugs modifying nitric oxide metabolism affect plasma cholesterol levels, coagulation parameters, blood pressure values and the appearance of plasma myocardial necrosis markers in rabbits: opposite effects of L-NAME and nitroglycerine.

AbstractVarious experiments have shown that decreased nitric oxide values alter plasma lipid levels or coagulation parameters or blood pressure values or cause myocardial necrosis phenomena, but it is not clear whether these alterations are reciprocally connected, or whether nitric oxide changes are involved in the appearance of some coronary disease risk factors (lipid, coagulation, blood pressure alterations) and myocardial necrosis. Aims. We modified nitric oxide levels in rabbits using L-NAME (a NO synthase blocker) or nitroglycerine (a NO donor), and simultaneously evaluated variations in total and HDL cholesterol levels, some coagulation parameters, mean blood pressure values and myocardial necrosis patterns. Results. L-NAME lowered plasma nitric oxide values, increased plasma total cholesterol and decreased HDL cholesterol levels, enhanced the amount of plasma fibrinogen, shortened prothrombin times, elevated the mean blood pressure values and caused the appearance of cardiac necrosis markers (c-troponin I, creatine kinase) in plasma and coagulative necrosis lesions in the myocardium. The administration of nitroglycerine to rabbits treated with L-NAME increased plasma nitric oxide levels and reversed the biochemical lesions caused by L-NAME. Conclusions. Our data show that the studied alterations in cholesterol values, coagulation parameters, increased mean blood pressure values and myocardial necrosis markers are strictly related to modified plasma nitric oxide levels, and that the regulation of nitric oxide metabolism affects the presence or absence of some coronary disease risk factors (lipid, coagulation and blood pressure alterations) and plasma indicators of myocardial necrosis.

Kynurenine may directly interact with GABA receptors in rat brain

Previous studies have shown that kynurenine may have convulsant activity. In the present investigation the intracerebroventricular injection of L- but not D-kynurenine induced convulsions in the rat. In vitro, L- but not D-kynurenine was able to displace 3H-GABA from rat brain membrane preparations. The action was specific for 3H-GABA and was not observed with other ligands. The data suggest that the convulsant activity of L-kynurenine might be due to an interaction with GABA receptors.

Effects of Carbamazepine Treatment on Pain Threshold Values and Brain Serotonin Levels in Rats

The administration of carbamazepine to rats caused a significant increase in pain threshold values. Furthermore, treatment with carbamazepine lowered the concentration of tryptophan bound to plasma proteins and elevated the brain serotonin values. The high brain serotonin levels, observed in carbamazepine-treated rats, are probably attributable to an increased availability of brain tryptophan, since this amino acid has been substantially removed from the plasma protein compartment by carbamazepine treatment, which exhibits a high binding capacity to plasma proteins. The analgesic effects caused by carbamazepine administration have been attributed to increased levels of brain serotonin which is involved in the control of pain transmission.

Anti-convulsant effects by reduced glutathione and related aminoacids in rats treated with isoniazid

Rats were treated with different doses of isoniazid (INH) causing convulsions. Lethal dose (DL50) and effective convulsant dose (ED50) were calculated. Reduced glutathione (GSH) and related aminoacids were administered to rats receiving INH: the latency and duration of convulsions were recorded; cerebral gamma-aminobutyric acid (GABA) concentrations were determined in rats receiving INH and an association of GSH and INH. GSH and its related aminoacids as cysteine and glycine greatly decreased the duration of INH-induced seizures, while glutamic acid did not protect against convulsions caused by INH. Furthermore, INH causes a decrease in cerebral GABA levels to about half and GSH repeated pretreatment did, however, not prevent the INH induced decline of GABA content: hence, the anticonvulsant effect of GSH can not be ascribed to the restoration of normal levels of anti-epilectically acting GABA, but can be attributed to cysteine and glycine, aminoacids linked to GSH.