Vesna Jacevic

Amifostine protection against doxorubicin cardiotoxicity in rats

Aminothiol amifostine (AMI) protects against toxic effects of both ionizing radiation and numerous anticancer drugs. The aim of this study was to investigate the potential protective effects of AMI against doxorubicin (DOX)-induced cardiotoxicity in rats. Male Wistar rats were treated with AMI (75 mg/kg i.p.) and/or DOX (1.25 mg/kg i.p.), 4 times per week, for 4 weeks. Mortality, general condition and body weight of the animals were observed during the whole treatment, and for a further 4 weeks, until the end of experiment. Evaluation of cardioprotective efficacy of AMI was performed by analyzing the electrocardiographic parameters and response to the pro-arrhythmic agent aconitine, as well as activity registration of the in situ rat heart preparations. Necropsy was also performed at the end of the experiment, and heart excision, weight and macroscopic examination were done before histological evaluation. Doxorubicin caused rat heart disturbances manifested by prominent electrocardiographic changes (S&agr;–T prolongation and T-wave flattening), significantly enhanced response to aconitine, decrease of the heart rate and contractility, as well as histopathologically verified myocardial lesions. The heart changes were accompanied by 40% mortality rate, significant decline in body mass and severe effusion intensity score in 66.6% of the animals. Application of AMI before each dose of DOX significantly reduced or completely prevented its toxic effects. Therefore, since AMI had very good protective effects against a high dose of DOX given as a multiple, low, unitary dose regimen, not only on the heart but on the whole rat as well, it could be recommended for further investigation in this potentially new indication for clinical application.

Fullerenol C60(OH)24 prevents doxorubicin-induced acute cardiotoxicity in rats

Results obtained in vitro suggested that fullerenols antiproliferative properties and protective effects against doxorubicin (DOX) cytotoxicity are mediated by antioxidative and hydroxyl radical scavenger activity. The aim of this study was to examine the influence of fullerenol on acute cardiotoxicity after the administration of a single high dose of DOX in vivo. The experiment was performed on male Wistar rats randomly divided into five groups, each containing eight individuals, that were treated as follows: I) 0.9% NaCl, II) 10 mg/kg DOX, III) 50 mg/kg fullerenol 30 min before 10 mg/kg DOX, IV) 100 mg/kg fullerenol 30 min before 10 mg/kg DOX, and V) 100 mg/kg fullerenol. A functional, biochemical, hematological, and pathomorphological examination of the heart as well as an evaluation of oxidative stress parameters was conducted on days 2 and 14 after DOX administration. The function of the heart was investigated by monitoring heart contractility after the adrenaline infusion. Fullerenol, applied alone, did not alter basal values of investigated animals. Both doses of fullerenol, used as a pretreatment, did not alter the basal parameters of the animals. The 100 mg/kg dose of fullerenol showed better protection. Considering the mechanisms of DOX toxicity, fullerenol likely exerts its protective role as a free radical sponge and/or by removing free iron through the formation of a fullerenol-iron complex. Our results suggest that fullerenol might be a potential cardioprotective agent in DOX-treated individuals.

The impact of prolonged cadmium exposure and co-exposure with polychlorinated biphenyls on thyroid function in rats.

Endocrine-disrupting chemicals currently represent one of the major concerns and this study was aimed to investigate the effects of different doses of cadmium, widespread toxic metal, on the levels of thyroid hormones and to calculate Benchmark doses for these effects. Furthermore, the effects of co-exposure to cadmium and polychlorinated biphenyls on thyroid function were investigated. Six orally-treated groups of rats were receiving 0.3, 0.6, 1.25, 2.5, 5 and 10mgCd/kgb.w./day, five groups were orally treated with 0.5, 1, 2, 4 and 8mgPCBs/kgb.w./day, while nine groups of rats were orally-treated with different dose combinations of Cd and PCBs (0.6, 1.25 and 2.5mgCd/kgb.w. and 2, 4 and 8mgPCBs/kgb.w./day), during 28 days. Thyroid hormones were adversely affected by cadmium, with most prominent effect observed on triiodothyroxine levels indicating Cd interference with thyroid function at extrathyroidal level. Calculated Benchmark doses for Cd effects on thyroid hormones indicate triiodothyroxine as the most sensitive one that can be used as a basis for risk assessment. This study also implicates possible synergistic effects of Cd and PCBs on thyroid function as a consequence of their interference at different levels of thyroid homeostasis.

Combined effects of cadmium and decabrominated diphenyl ether on thyroid hormones in rats.

The aim of this study was to see how a mixture of cadmium (Cd) and decabrominated diphenyl ether (BDE209) affect thyroid function, namely thyroid-stimulating hormone (TSH), thyroxin (T4), free thyroxin (FT4), triiodothyronin (T3), and free triiodothyronin (FT3) in Wistar rats (eight per group) receiving either a single substance or their combination by gavage for 28 days. Three groups were receiving Cd alone in the doses of 2.5 mg kg-1, 7.5 mg kg-1, or 15 mg kg-1 b. w. a day, three groups were receiving BDE209 in the doses of 1000 mg kg-1, 2000 mg kg-1, or 4000 mg kg-1 b. w. a day, while nine groups were receiving different mixtures of Cd and BDE209 in these doses (3x3 design). The results have indicated that the Cd+BDE209 mixtures more potently disrupt thyroid hormone homeostasis than would be expected from these chemicals alone.

Design, Synthesis, and Local Anti‐Inflammatory Activity of 17β‐Carboxamide Derivatives of Glucocorticoids

Molecular docking studies were performed on 18 17β‐carboxamide steroids in order to select compounds with potential local anti‐inflammatory activity. These derivatives are amides of cortienic acids (obtained from hydrocortisone, prednisolone, and methylprednisolone) with methyl or ethyl esters of six amino acids. Interactions with the glucocorticoid receptor (GR), binding energies and ligand efficiency values of these compounds were compared with dexamethasone and cortienic acid obtained from prednisolone (inactive metabolite). On the basis of molecular docking studies, seven compounds were selected and their binding affinities for the GR were predicted by use of the exponential model created in this study. Subsequently, selected compounds were synthesized in good yields by use of modified N,N′‐dicyclohexylcarbodiimide (DCC)/1‐hydroxybenzotriazole (HOBt) coupling procedure. Finally, the local anti‐inflammatory activity of the synthesized compounds was examined by use of the croton oil‐induced ear edema test. In vivo evaluation of systemic side effects as well as in silico prediction of metabolism were performed on the derivative with the best local anti‐inflammatory activity. The combination of molecular docking studies and the exponential model for the GR binding affinity prediction could be used as an in silico tool for the rational design of novel 17β‐carboxamide steroids with potentially better biological profile than dexamethasone.

Synthesis, crystal structure and local anti-inflammatory activity of the L-phenylalanine methyl ester derivative of dexamethasone-derived cortienic acid

The L-phenylalanine methyl ester derivative of dexamethasone- derived cortienic acid (DF) was synthesized and its crystal structure charac- terized by the X-ray diffraction method. The crystal system is orthorhombic with space group P212121 and cell constants a = 8.2969(3) A, b = 18.9358(8) A, c = 20.0904(6) A, V = 3156.4(2) A 3 and Z = 4. Ring A of the steroid nucleus and phenyl ring in the 17β-side chain are almost planar. Rings B and C have a slightly distorted chair conformation, whereas ring D has an envelope con- formation. The packing of DF is characterized by a network of intermolecular hydrogen bonds involving the O4 atom from one side of the steroid nucleus and O1 and F1 atoms from the other side as hydrogen bond acceptors. Apart from the intermolecular hydrogen bonds in the crystal packing, there are also numerous intramolecular hydrogen bonds of the N-H … O, C-H … O and C-H … F type. The local anti-inflammatory activity of DF was evaluated using

Gastroprotective effects of novel antidotal combination in rats acutely poisoned by T-2 toxin

The purpose of this experiment was to evaluate the antidotal potencies of methylprednisolone (soluble form, Lemod-solu®), nimesulide, N-acetylcysteine (Fluimucil®) and their combinations in rats treated with 1.0 LD50 (0.23 mg/kg) of trichothecene mycotoxin, T-2 toxin. Their antidotal efficacy was investigated by monitoring their effects on general condition, 24-hour-survival, body weight gain, food and water consumption and pathohistological changes in the gut of Wistar rats acutely treated with a single injection of T-2 toxin during a 4-week period. The highest protective index was obtained with methylprednisolone (2.43). Initial loss of body weight (after first 7 days) was found only in T-2 toxin group. During the whole experiment, in poisoned rats protected by methylprednisolone or methylprednisolone and nimesulide, a significant increase (p<0.001) in body weight gain, food and water consumption in comparison with T-2 toxin group was found. At the end of the experiment, N-acetylcysteine, nimesulide and their combination assured higher (p<0.05) weight gain, food and water consumption in comparison with T-2 toxin group. Signs of hemorrhagic diathesis and necrosis of the gut crypt epithelium and lymphoid tissues were found in the T-2 toxin group. Some of these histological alterations were presented in the gut of poisoned rats treated by nimesulide, Nacetylcysteine and their combination. The gut of T-2 toxin rats treated with a combination of methylprednisolone and nimesulide and especially methylprednisolone alone had a histological structure similar to the control group. These results clearly show that methylprednisolone, a well-known anti-inflammatory and immunosuppressive drug, exerts the best antidotal effect against T-2 toxin intoxication in rats.

Simvastatin Protects Cardiomyocytes Against Endotoxin-induced Apoptosis and Up-regulates Survivin/NF-κB/p65 Expression

This study is aimed to investigate whether simvastatin induces cardiomyocytes survival signaling in endotoxin (lipopolysaccharide, LSP)-induced myocardial injury, and if so, further to determine a role of survivin in simvastatin-anti-apoptotic effect. Wistar rats were pretreated with simvastatin (10–40 mg/kg po) before a single non-lethal dose of LPS. In myocardial tissue, LPS induced structural disorganization of myofibrils with significant inflammatory infiltrate (cardiac damage score, CDS = 3.87 ± 0.51, p < 0.05), whereas simvastatin dose-dependently abolished structural changes induced by LPS (p < 0.01). Simvastatin in 20 mg/kg and 40 mg/kg pretreatment, dose dependently, attenuated myocardial apoptosis determined as apoptotic index (28.8 ± 4.5% and 18.9 ± 3.5, p < 0.05), decreased cleaved caspase-3 expression (32.1 ± 5.8%, p < 0.01), along with significant Bcl-xL expression in the simvastatin groups (p < 0.01). Interestingly, in the simvastatin groups were determined significantly increased expression of survivin (p < 0.01), but in negative correlation with cleaved caspase-3 and apoptotic indices (p < 0.01). Simvastatin has a cardioprotective effects against LPS induced apoptosis. The effect may be mediated by up-regulation of survivin via activation of NF-κB, which leads to reduced activation of caspase-3 and consequent apoptosis of cardiomyocytes in experimental sepsis.

The Efficacy of Amifostine against Multiple-Dose Doxorubicin-Induced Toxicity in Rats

Amifostine is well known cytoprotector which is efficient when administered before a wide range of antineoplastic agents. The aim of our study was to investigate amifostine effects on doxorubicin-induced toxic changes in rats. Amifostine (75 mg/kg ip) was given 30 min before each dose of doxorubicin (cumulatively 20 mg/kg ip, for 28 days). The animals’ whole-body, liver, and kidney weight, serum biochemical examination, as well as microscopic examination of bone marrow, peripheral blood, liver, and kidney, were done on day 56 of the study. Hepatic and renal alterations were carefully quantified by semiquantitative grading scales—hepatic and renal damage score, respectively. In amifostine-pretreated rats, the number of peripheral blood leukocytes was significantly higher in comparison to doxorubicin-only treated group, preferentially protecting neutrophils. In the same group of rats, hepatic and renal alterations associated with polymorphonuclear cell infiltrates were significantly less severe than those observed in animals receiving only doxorubicin. Our results showed that amifostine successfully protected rats against multiple-dose doxorubicin-induced toxicity by complex, and still not fully elucidated mechanisms of action.

Pharmacodynamic and pharmacokinetic effects of flumazenil and theophylline application in rats acutely intoxicated by diazepam

BACKGROUND/AIM The majority of symptoms and signs of acute diazepam poisoning are the consequence of its sedative effect on the CNS affecting selectively poli-synaptic routes by stimulating inhibitory action of GABA. The aim of the present study was to examine the effects of combined application of theophylline and flumazenil on sedation and impaired motor function activity in acute diazepam poisoning in rats. METHODS Male Wistar rats were divided in four main groups and treated as follows: group I--with increasing doses of diazepam in order to produce the highest level of sedation and motor activity impairment; group II--diazepam + different doses of flumazenil; group III--diazepam + different doses of theophylline; group IV--diazepam + combined application of theophylline and flumazenil. Concentrations of diazepam and its metabolites were measured with LC-MS. The experiment was performed on a commercial apparatus for spontaneous motor-activity registration (LKB-Farad, Sweden). Assessment of diazepam-induced neurotoxic effects and effects after theophylline and flumazenil application was performed with rotarod test on a commercial apparatus (Automatic treadmill for rats, Ugo Basile, Italy). RESULTS Diazepam in doses of 10 mg/kg and 15 mg/kg produced long-time and reproducible pharmacodynamic effects. Single application of flumazenil or theophylline antagonized effects of diazepam, but not completely. Combined application of flumazenile and theophylline resulted in best effects on diazepam-induced impairment of motoric activity and sedation. As a result of theopylline application there was better elimination of diazepam and its metabolites. CONCLUSION Combined application of flumazenil and theophylline resulted in the best antidotal effects in the treatment of diazepam poisoned rats. These effects are a result of different mechanisms of their action, longer half-life of theophylline in relation to that of flumezenil and presumably the diuretic effect of theophylline.