Zorana Oreščanin-Dušić

Beyond H2S and NO interplay: hydrogen sulfide and nitroprusside react directly to give nitroxyl (HNO). A new pharmacological source of HNO.

Hydrogen sulfide (H2S) has been increasingly recognized as an important signaling molecule that regulates both blood pressure and neuronal activity. Attention has been drawn to its interactions with another gasotransmitter, nitric oxide (NO). Here, we provide evidence that the physiological effects observed upon the application of sodium nitroprusside (SNP) and H2S can be ascribed to the generation of nitroxyl (HNO), which is a direct product of the reaction between SNP and H2S, not a consequence of released NO subsequently reacting with H2S. Intracellular HNO formation has been confirmed, and the subsequent release of calcitonin gene-related peptide from a mouse heart has been demonstrated. Unlike with other thiols, SNP reacts with H2S in the same way as rhodanese, i.e., the cyanide transforms into a thiocyanate. These findings shed new light on how H2S is understood to interact with nitroprusside. Additionally, they offer a new and convenient pharmacological source of HNO for therapeutic purposes.

Hydrogen peroxide affects contractile activity and anti‐oxidant enzymes in rat uterus

Background and purpose:  The effects of hydrogen peroxide (H2O2) on uterine smooth muscle are not well studied. We have investigated the effect and the mechanism of action of exogenous hydrogen peroxide on rat uteri contractile activity [spontaneous and calcium ion (Ca2+)‐induced] and the effect of such treatment on anti‐oxidative enzyme activities.

Citrus flavanones naringenin and hesperetin improve antioxidant status and membrane lipid compositions in the liver of old-aged Wistar rats

This study aimed to investigate effects of citrus flavanones naringenin (NAR) and hesperetin (HES) on liver antioxidant status and membrane phospholipid composition in 24-month-old rats. NAR and HES (15mg/kg) were administrated orally to male Wistar rats, once per day, for 4weeks. Control group received either vehicle (sunflower oil) or remained intact. The results showed decreased (p<0.05) activity of antioxidant enzymes (AOE), specifically catalase (CAT), superoxide dismutase (SOD) 1 and glutathione reductase (GR) in the liver of intact control old-aged rats in comparison to young intact controls. Flavanone administration to old-aged males increased (p<0.05) examined AOE activities in comparison to vehicle-administered animals. Namely, NAR was more potent in comparison to HES regarding the increase (p<0.05) in activities of examined antioxidant enzymes (SOD 1 and 2, glutathione peroxidase-GPx and GR) and the liver glutathione (GSH), while HES elevated (p<0.05) only activity of CAT and GR. Both flavanones significantly decreased (p<0.05) TBARS and improved (p<0.05) membrane phospholipid composition in favor of n-3 PUFA and n-6/n-3 PUFA ratio. Both flavanones did not affect liver histology and reduced (p<0.05) alanine aminotransferase and aspartate aminotransferase levels in serum. The results of this study indicate beneficial potential of citrus flavanones in the old-aged rat liver.

Differences in direct pharmacologic effects and antioxidative properties of mature breast milk and infant formulas

OBJECTIVE Early-onset and exclusive breast-feeding provides a significant health benefit to infants compared with infant formulas. The aim of this study was to compare mature breast milk with standard infant formulas by examining their effects on non-vascular smooth muscle contraction and their antioxidative properties. METHODS The pharmacologic effects of breast milk and formulas were examined using a model system of the rat uterine smooth muscle contraction. Electron paramagnetic resonance spin-trapping spectroscopy was used to compare the antioxidative capacities of breast milk (obtained in the ninth week of lactation) with commercial infant formulas against hydroxyl radical production in the Fenton reaction. The activities of superoxide dismutase, glutathione peroxidase, and the sulfhydryl group were determined in the breast milk and infant formulas. RESULTS In contrast to the infant formulas, breast milk exerted a relaxing effect on isolated non-vascular smooth muscle. In general, breast milk showed higher antioxidative activity compared with the infant formulas. In all samples, the generation of hydroxyl radicals led to the formation of carbon-centered and ascorbyl radicals. CONCLUSIONS Human milk exerts direct pharmacologic relaxation effects and provides better antioxidant protection compared with infant formulas because of the presence of specific enzymatic components, such as human superoxide dismutase. We propose that these effects should be advantageous to an infants gastrointestinal tract by supporting the normal work of the smooth musculature and maintaining redox homeostasis and may represent one of the mechanisms by which breast-feeding benefits health.

Methanolic extract of Origanum vulgare ameliorates type 1 diabetes through antioxidant, anti-inflammatory and anti-apoptotic activity

Type 1 diabetes (T1D), an autoimmune inflammatory disorder, develops as a consequence of pancreatic β-cell destruction and results in hyperglycaemia. Since current T1D therapy mainly involves insulin replacement, the aim of the present study was to evaluate the therapeutic potential of Origanum vulgare L. ssp. hirtum (Greek oregano) leaf extract rich in biophenols for the treatment of T1D. The phytochemical profile of methanolic oregano extract (MOE) and aqueous oregano extract (AOE) was determined by liquid chromatography/electrospray ion-trap tandem MS (LC/DAD/ESI-MSn), while their main compounds were quantified by HPLC with diode array detection. After establishing their potent in vitro antioxidant activity, the extracts were administered to C57BL/6 mice treated with multiple low doses of streptozotocin for diabetes induction. While prophylactic AOE therapy had no impact on diabetes induction, MOE reduced diabetes incidence and preserved normal insulin secretion. In addition, MOE scavenged reactive oxygen and nitrogen species and, therefore, alleviated the need for the up-regulation of antioxidant enzymes. MOE treatment specifically attenuated the pro-inflammatory response mediated by T helper 17 cells and enhanced anti-inflammatory T helper 2 and T regulatory cells through the impact on specific signalling pathways and transcription factors. Importantly, MOE preserved β-cells from in vitro apoptosis via blockade of caspase 3. Finally, rosmarinic acid, a predominant compound in MOE, exhibited only partial protection from diabetes induction. In conclusion, acting as an antioxidant, immunomodulator and in an anti-apoptotic manner, MOE protected mice from diabetes development. Seemingly, there is more than one compound responsible for the beneficial effect of MOE.

Comparison of the effects of methanethiol and sodium sulphide on uterine contractile activity

BACKGROUND Our aim was to investigate the effect of methanethiol (CH3SH) on contractility of rat uterus and activities of redox-active enzymes, and to compare them with the effect of sodium sulphide (Na2S), a hydrogen sulphide (H2S/HS(-)) donor. METHODS Uteri were isolated from virgin Wistar rats, divided into six groups, controls (untreated uteri allowed to contract spontaneously and in the presence of Ca(2+)(6mM)), CH3SH treated (spontaneously active and Ca(2+) induced) and Na2S treated (spontaneously active and Ca(2+) induced). Underlying antioxidative enzyme activities (superoxide dismutase--SOD, glutathione peroxidase--GSHPx, glutathione reductase--GR) in CH3SH- or Na2S-treated uteri were compared to controls. RESULTS Our experiments showed that CH3SH and Na2S provoked reversible relaxation of both spontaneous and Ca(2+)-induced uterine contractions. The dose-response curves differed in shape, and CH3SH curve was shifted to higher concentration compared to H2S/HS(-). The effects of Na2S fitted sigmoid curve, whereas those of CH3SH fitted linearly. CH3SH provoked increased SOD activity and decreased GR activity. However, Na2S (H2S/HS(-)) provoked an increase in SOD activity exclusively in Ca(2+)-stimulated uteri, while the activity of GSHPx was increased in both types of active uteri. CONCLUSION Our results imply that CH3SH may have a constructive role in the control of muscle function and metabolism. Observed differences between CH3SH and H2S/HS(-) could be attributed to a larger moiety that is present in CH3SH compared to H2S, but they are more likely to be a consequence of the specific actions of HS(-), in relation to its negative charge.

Diethyldithiocarbamate potentiates the effects of protamine sulphate in the isolated rat uterus

Abstract Protamine sulphate causes potassium ion channel-mediated relaxation of spontaneous and calcium ion-induced contractions of the isolated rat uterus. Diethyldithiocarbamate (DDC) potentiated the effect of protamine sulphate. A mechanism for DDCs action was postulated on the basis of its interactions with divalent iron ions and Cu,Zn-SOD. DDC chelates divalent iron ions creating DDC-iron (Fe-DDC) complexes. Fe-DDC forms stable NO-Fe-DDC2 complexes by NO scavenging and de-nitrosylation processes, which in combination with DDC (5 mM) provoke inhibition of Cu,Zn-SOD resulting in specific oxidative conditions culminating in potassium ion channel opening, membrane hyperpolarisation, inhibition of calcium ion influx and subsequent muscle relaxation. As Fe-DDC and NO-Fe-DDC2 complexes exclude divalent iron ions from participating in the hydroxyl radical generating Fenton reaction, DDC can also prevent iron-related pathophysiological manifestations. Such permissive roles of DDC open the possibility for application of its pharmacological form (disulfiram) to a wider spectrum of pathophysiological conditions related to smooth muscles.

The effects of N-acetylcysteine on cisplatin-induced changes of cardiodynamic parameters within coronary autoregulation range in isolated rat hearts.

The aim of this study was to evaluate the effects of chronic NAC administration along with cisplatin on cisplatin-induced cardiotoxicity by means of coronary flow (CF), cardiodynamic parameters, oxidative stress markers and morphological changes in isolated rat heart. Isolated hearts of Wistar albino rats (divided into four groups: control, cisplatin, NAC and cisplatin+NAC group) were perfused according to Langendorff technique at constant coronary perfusion pressure starting at 50 and gradually increased to 65, 80, 95 and 110 cm H2O to evaluate cardiodynamic parameters within autoregulation range. Samples of coronary venous effluent (CVE) were collected for determination of CF and biochemical assays, and heart tissue samples for biochemical assays and histopathological examination. Cisplatin treatment decreased CF and heart rate, and increased left ventricular systolic pressure and maximum left ventricular pressure development rate. Cisplatin increased H2O2 and TBARS, but decreased NO2(-) levels in CVE. In tissue samples, cisplatin reduced pathological alterations in myocardium and coronary vessels, with no changes in the amount of total glutathione, as well as in activity of glutathione peroxidase and glutathione reductase. NAC coadministration, by reducing oxidative damage, attenuated cisplatin-induced changes of cardiodynamic and oxidative stress parameters, as well as morphological changes in myocardium and coronary vasculature.

Effect of indometacin pretreatment on protamine sulfate-mediated relaxation of the isolated rat uterus: the role of the antioxidative defense system

Previous results in this laboratory indicate that protamine sulfate (PS) evokes dose-dependent relaxation of both spontaneous and calcium ion-induced uterus activity mediated predominantly by potassium channels and, to a small extent, via β-adrenergic receptors or nitric oxide (NO)-dependent pathways. Indometacin is a nonselective inhibitor of cyclooxygenase (COX 1 and COX 2) that has the ability to delay premature labor by reducing uterine contractions through the inhibition of prostanglandin synthesis in the uterus. This study investigates the effects of indometacin (0.1 and 1 μg/ml) pretreatment on the PS-induced relaxation of isolated uterine smooth muscle. Indometacin pretreatment per se did not change the activity of the uteri. However, indometacin significantly increased PS-induced relaxation of spontaneous uterine contractions. Indometacin pretreatment significantly decreased the magnitude and slope of PS-induced relaxation of calcium ion-induced uterine contractions. Indometacin pretreatment increased CuZnSOD activity and slightly increased GR activity during spontaneous uterine contractions when compared to PS alone. In calcium ion-induced contractions, indometacin pretreatment increased CuZnSOD, GSH-Px and GR activities. These results suggest that, in addition to its COX inhibitory effects, indometacin influences the effects of PS. Therefore, it is possible that indometacin regulates diverse cell functions via its association with lipid membranes by altering micro-environments within the membranes. The above-mentioned processes appear to be partly mediated by redox processes involving ROS, lipid peroxides and antioxidant enzymes. The extent of the PS-mediated effect as different in spontaneous versus calcium ion-induced active uteri.

Effects of antipsychotic drug administration on antioxidative defense enzymes in male rat kidney

ABSTRACT The use of atypical antipsychotic drugs (APD) was reported to be associated with adverse effects on the kidneys. Thus, the aim of this study was to examine whether APD exerted their adverse effects by interfering with the renal antioxidant defense system. Male 3-mo-old Wistar rats were treated for 28 d with ziprasidone (ZIP), clozapine (CLO), or sertindole (SER) using a daily dose recommended for antipsychotic drug therapy. The expression and activities of antioxidant enzymes superoxide dismutase (SOD) type 1 and type 2, catalase (CAT), glutathione reductase (GR), and glutathione S-transferases (GSTs) activity were measured in the kidneys. Changes in the kidneys were also evaluated histologically. Ziprasidone, CLO, and SER reduced renal SOD type 1 and type 2 activities. Decreased CAT activity was observed only in SER-treated rats. An inhibition in GR activity and increased activity of GST was found only after treatment with CLO. Histological analysis showed dilatation of proximal tubules in kidneys with all three drugs. In conclusion, data indicate that redox disturbances may contribute to renal morphologic alterations in proximal tubules in rats treated with all APD.