Evaluation of Tick Abundance and Pyrethroid Resistance Via Determination of Glutathione-S-Transferases Activity.

Controlling the number of ticks as carriers of infectious diseases is very important. The process is sometimes compromised by activating the protective mechanisms of the tick itself. Glutathione-S-transferases activity (GSTs) was the subject of our investigation of tick abundance after pyrethroid treatment. We determined GSTs activity in ticks collected from six locations in Belgrade before and after pyrethroid treatment and correlated it with the number of ticks in the locations. The results showed that tick abundance correlated with GSTs activity. On the other hand, treatment efficiency was location-dependent, being similar in each particular location in both April (spring) and October (autumn). Our results suggest that GSTs activity reflects the influence of both present local allelochemicals from different environmental seasonal vegetation and applied pyrethroid. We can conclude that by evaluating GSTs activity in ticks from particular locations as well as during the treatment with acaricides tick removal practice could be improved.

The humanised CYP2C19 transgenic mouse exhibits cerebellar atrophy and movement impairment reminiscent of ataxia.

AIMS: CYP2C19 transgenic mouse expresses the human CYP2C19 gene in the liver and developing brain, and it exhibits altered neurodevelopment associated with impairments in emotionality and locomotion. Because the validation of new animal models is essential for the understanding of the aetiology and pathophysiology of movement disorders, the objective was to characterise motoric phenotype in CYP2C19 transgenic mice and to investigate its validity as a new animal model of ataxia. METHODS: The rotarod, paw-print and beam-walking tests were utilised to characterise the motoric phenotype. The volumes of 20 brain regions in CYP2C19 transgenic and wild-type mice were quantified by 9.4T gadolinium-enhanced post-mortem structural neuroimaging. Antioxidative enzymatic activity was quantified biochemically. Dopaminergic alterations were characterised by chromatographic quantification of concentrations of dopamine and its metabolites and by subsequent immunohistochemical analyses. The beam-walking test was repeated after the treatment with dopamine receptor antagonists ecopipam and raclopride. RESULTS: CYP2C19 transgenic mice exhibit abnormal, unilateral ataxia-like gait, clasping reflex and 5.6-fold more paw-slips in the beam-walking test; the motoric phenotype was more pronounced in youth. Transgenic mice exhibited a profound reduction of 12% in cerebellar volume and a moderate reduction of 4% in hippocampal volume; both regions exhibited an increased antioxidative enzyme activity. CYP2C19 mice were hyperdopaminergic; however, the motoric impairment was not ameliorated by dopamine receptor antagonists, and there was no alteration in the number of midbrain dopaminergic neurons in CYP2C19 mice. CONCLUSIONS: Humanised CYP2C19 transgenic mice exhibit altered gait and functional motoric impairments; this phenotype is likely caused by an aberrant cerebellar development.

Antipsychotic Drug-Mediated Adverse Effects on Rat Testicles May Be Caused by Altered Redox and Hormonal Homeostasis.

Sexual dysfunction, as a noticeable adverse effect of atypical antipsychotic drugs (APDs) for the treatment of schizophrenia, has not been investigated in detail. A study was undertaken to investigate whether 28-day long treatment with clozapine, ziprasidone or sertindole (using a recommended daily dose for atypical antipsychotic therapy), induced histopathological changes both in rat testicles and prostate, changed the activity of the antioxidant defence system and altered blood testosterone and prolactin. Clozapine, ziprasidone and sertindole induced histopathological changes in rat testicular tissue, which could be attributed to a disturbed testicular antioxidant defence system in addition to an altered prolactin to testosterone ratio. None of the APD treatments induced histopathological changes in prostate. Our results demonstrate that APDs have the capacity to change both redox and endocrinological balance. One or both outcomes could underline testicular degeneration and disturbed spermatogenesis.

Ibogaine-Mediated ROS/Antioxidant Elevation in Isolated Rat Uterus Is ß-Adrenergic Receptors and KATP Channels Mediated.

Ibogaine effects are mediated by cellular receptors, ATP depletion followed by ROS production and antioxidant enzyme activity elevation in a dose and time dependent manner. Since the role of KATP channels and ß-adrenoceptors in ROS cellular circuit was established here we explored their role in ibogaine pro-antioxidant effectiveness. Single dose of ibogaine (10 mg/L i.e., 28.8 µmol/L) was applied to isolated rat uterus (spontaneous and Ca2+-stimulated) and contractility and antioxidant enzymes activity were monitored during 4 h. Ibogaine increased amplitude and frequency of spontaneous active uteri immediately after addition that was prevented by propranolol (ß1 and ß2 adrenoceptors selective antagonists) and glibenclamide (KATP sensitive channels inhibitor; only frequency) pre-treatment. In Ca2+-stimulated uteri, ibogaine decreased both amplitude and frequency after 4 h. Pre-treatment with propranolol abolished ibogaine induced amplitude lowering, while glibenclamide had no effect. In both types of active uterus, ibogaine induced a decrease in SOD1 and an increase in CAT activity after 2 h. In Ca2+-stimulated uterus, there was also a decrease of SOD2 activity after 2 h. After 4 h, SOD1 activity returned to the baseline level, but GSH-Px activity increased. Pre-treatment with both propranolol and glibenclamide abolished observed changes of antioxidant enzymes activity suggesting that ibogaine pro-antioxidative effectiveness is ß-adrenergic receptors and KATP channels mediated.

Ibogaine Has Sex-Specific Plasma Bioavailability, Histopathological and Redox/Antioxidant Effects in Rat Liver and Kidneys: A Study on Females.

Ibogaine induces rapid changes in cellular energetics followed by the elevation of antioxidant activities. As shown earlier in male rats, ibogaine treatment with both 1 and 20 mg/kg b.w. per os led to significant glycogenolytic activity in the liver. In this work, female rats treated with the same doses of ibogaine per os displayed lower liver glycogenolytic activity relative to males, dilatation of the central vein and branches of the portal vein, and increased concentration of thiols 6 h after treatment. These changes were followed by increased catalase activity and lipid peroxidation, and decreased xanthine oxidase activity after 24 h. In kidneys, mild histopathological changes were found in all treated animals, accompanied by a decrease of glutathione reductase (after 6 and 24 h at both doses) and an increase of catalase (6 h) and xanthine oxidase activity (6 and 24 h). Ibogaine did not affect antioxidant enzymes activity in erythrocytes. Bioavailability of ibogaine was two to three times higher in females than males, with similar kinetic profiles. Compared to previous results in males, ibogaine showed sex specific effect at the level of antioxidant cellular system. Effects of ibogaine in rats are sex- and tissue-specific, and also dose- and time-dependent.

Effects of several atypical antipsychotics closapine, sertindole or ziprasidone on hepatic antioxidant enzymes: Possible role in drug-induced liver dysfunction.

Chronic use of atypical antipsychotics may produce hepatic damage. Atypical antipsychotics, including clozapine, sertindole, and ziprasidone, are extensively metabolized by the liver and this process generates toxic-free radical metabolic intermediates which may contribute to liver damage. The aim of this study was to investigate whether clozapine, sertindole, or ziprasidone affected hepatic antioxidant defense enzymes which consequently led to disturbed redox homeostasis. The expression and activity of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), and glutathione-S-transferases (GST) were measured in rat livers at doses corresponding to human antipsychotic therapy. Clozapine increased activity of SOD types 1 and 2, GR and GST, but reduced CAT activity. Sertindole elevated activities of both SODs. In ziprasidone-treated rats only decreased CAT activity was found. All three antipsychotics produced mild-to-moderate hepatic histopathological changes categorized as regenerative alterations. No apparent signs of immune cell infiltration, microvesicular or macrovesicular fatty change, or hepatocytes in mitosis were observed. In conclusion, a 4-week long daily treatment with clozapine, sertindole, or ziprasidone altered hepatic antioxidant enzyme activities and induced histopathological changes in liver. The most severe alterations were noted in clozapine-treated rats. Data indicate that redox disturbances may contribute to liver dysfunction after long-term atypical antipsychotic drug treatment.

Edaravone May Prevent Ferroptosis in ALS.

Radicava™ (Edaravone) was approved the Food and Drug Administration (FDA) as a new treatment for amyotrophic lateral sclerosis (ALS). Edaravone is a synthetic antioxidant that specifically targets oxidative damage interacting with lipid radicals in the cell. In ALS disease the multiple cell types are involved in devastating loss of motor neurons. Mutations and biochemical changes in various cell types jointly contribute to motor neuron death, disease onset, and disease progression. The overall mechanism of neurodegeneration in ALS is still not completely understood. Dying motor neurons have been reported to exhibit features of apoptosis. However, non-apoptotic features of dying motor neurons have also been reported such as ferroptosis. The role of Edaravone in the prevention of ferroptosis in parallel with other therapeutic approaches to ALS therapy is discussed.

Clozapine, ziprasidone, and sertindole-induced morphological changes in the rat heart and their relationship to antioxidant enzymes function.

Atypical antipsychotics produce severe side effects including myocarditis that may be attributed to oxidative stress. The aim of this study was to investigate the influence of clozapine, ziprasidone, and sertindole on rat heart morphology and determine whether redox imbalane plays a role in development of histopathological changes. Adult 3-month-old male Wistar rats were treated with recommended daily dose for selected drugs. After 4 week treatment histopathological analysis of the heart was performed and expression and activity of antioxidant enzymes determined. All examined drugs induced histopathological changes that were characterized as toxic myocarditis. Degenerative changes in cardiomyocytes were accompanied by lymphocytic infiltration as well as pericardial histopathological alterations in all treated groups. The least prominent changes were observed in sertindole-treated animals, and most severe with clozapine. Clozapine increased superoxide dismutase 1 (SOD1) activity while ziprasidone reduced glutathione reductase (GR) activity. Sertindole exerted no marked effect on antioxidant enzyme function in the heart even though myocardial degeneration was noted. In conclusion, treatment with clozapine or ziprasidone induced pathophysiological alterations in rat heart, which appeared to be associated disturbances in antioxidant capacity. Abbreviation: AAP, Atypical antipsychotics; ROS, reactive oxygen species; SOD1, Copper-zinc superoxide dismutase; SOD2, Manganese superoxide dismutase; CAT, Catalase; GPx, Glutathione peroxidase; GR, Glutathione reductase; H&E, hematoxylin and eosin stain; TNF- α, tumor necrosis factor alpha.

The Effects of Ibogaine on Uterine Smooth Muscle Contractions: Relation to the Activity of Antioxidant Enzymes.

Ibogaine is an indole alkaloid originally extracted from the root bark of the African rainforest shrub Tabernanthe iboga. It has been explored as a treatment for substance abuse because it interrupts drug addiction and relieves withdrawal symptoms. However, it has been shown that ibogaine treatment leads to a sharp and transient fall in cellular ATP level followed by an increase of cellular respiration and ROS production. Since contractile tissues are sensitive to changes in the levels of ATP and ROS, here we investigated an ibogaine-mediated link between altered redox homeostasis and uterine contractile activity. We found that low concentrations of ibogaine stimulated contractile activity in spontaneously active uteri, but incremental increase of doses inhibited it. Inhibitory concentrations of ibogaine led to decreased SOD1 and elevated GSH-Px activity, but doses that completely inhibited contractions increased CAT activity. Western blot analyses showed that changes in enzyme activities were not due to elevated enzyme protein concentrations but posttranslational modifications. Changes in antioxidant enzyme activities point to a vast concentration-dependent increase in H2O2 level. Knowing that extracellular ATP stimulates isolated uterus contractility, while H2O2 has an inhibitory effect, this concentration-dependent stimulation/inhibition could be linked to ibogaine-related alterations in ATP level and redox homeostasis.

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.

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

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.

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.

Ex vivo effects of ibogaine on the activity of antioxidative enzymes in human erythrocytes.

ETHNOPHARMACOLOGICAL RELEVANCE: Ibogaine is a naturally occurring alkaloid with psychotropic and metabotropic effects, derived from the bark of the root of the West African Tabernanthe iboga plant. The tribes of Kongo basin have been using iboga as a stimulant, for medicinal purposes, and in rite of passage ceremonies, for centuries. Besides, it has been found that this drug has anti-addictive effects. AIM OF THE STUDY: Previous studies have demonstrated that ibogaine changed the quantity of ATP and energy related enzymes as well as the activity of antioxidant enzymes in cells thus altering redox equilibrium in a time manner. In this work, the mechanism of its action was further studied by measuring the effects of ibogaine in human erythrocytes in vitro on ATP liberation, membrane fluidity and antioxidant enzymes activity. MATERIALS AND METHODS: Heparinized human blood samples were incubated with ibogaine (10 and 20 µM) at 37°C for 1h. Blood plasma was separated by centrifugation and the levels of ATP and uric acid were measured 10 min after the addition of ibogaine using standard kits. The activity of copper-zinc superoxide dismutase (SOD1), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were measured in erythrocytes after incubation period. The stability of SOD1 activity was further tested through in vitro incubation with H2O2 and scanning of its electrophoretic profiles. Membrane fluidity was determined using an electron paramagnetic resonance spin-labelling method. RESULTS: Results showed that ibogaine treatment of erythrocytes in vitro increased ATP concentration in the blood plasma without changes in neither erythrocytes membrane fluidity nor uric acid concentration. Ibogaine also increased SOD1 activity in erythrocytes at both doses applied here. Treatment with 20 µM also elevated GR activity after in vitro incubation at 37°C. Electrophoretic profiles revealed that incubation with ibogaine mitigates H2O2 mediated suppression of SOD1 activity. CONCLUSION: Some of the effects of ibogaine seem to be mediated through its influence on energy metabolism, redox active processes and the effects of discrete fluctuations of individual reactive oxygen species on different levels of enzyme activities. Overall, ibogaine acts as a pro-antioxidant by increasing activity of antioxidative enzymes and as an adaptagene in oxidative distress.

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 ß-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 ß-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.

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.

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 infant's 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.

Reversible oxidation of myometrial voltage-gated potassium channels with hydrogen peroxide.

The uteri, spontaneously active or Ca(2+) (6 mM) induced, were allowed to equilibrate, and to inhibit voltage-gated potassium (K(V)) channels 1 mM 4-amino pyridine (4-AP) was applied for 15 min before adding H(2)O(2). H(2)O(2) was added cumulatively: 2 µM, 20 µM, 200 µM, 400 µM, and 3 mM. Average time for H(2)O(2) concentrations (2, 20, 200, and 400) µM to reach its full effect was 15 min. H(2)O(2) 3 mM had a prolonged effect and therefore was left to act for 30 min. Two-way ANOVA showed significant differences in time dependency between spontaneous and Ca(2+)-induced rat uteri after applying 3 mM H(2)O(2) (type of contraction, P = 0.0280), but not 400 µM H(2)O(2) (P = 0.9271). Our results indicate that H(2)O(2) oxidises channel intracellular thiol groups and activates the channel, inducing relaxation. Cell antioxidative defence system quickly activates glutathione peroxidase (GSHPx) defence mechanism but not catalase (CAT) defence mechanism. Intracellular redox mechanisms repair the oxidised sites and again establish deactivation of K(V) channels, recuperating contractility. In conclusion, our results demonstrate that K(V) channels can be altered in a time-dependent manner by reversible redox-dependent intracellular alterations.

Tianeptine's effects on spontaneous and Ca2+-induced uterine smooth muscle contraction.

Tianeptine is a novel anti-depressant with an efficacy equivalent to that of classical anti-depressants. Additional beneficial effects include neuroprotection, anti-stress and anti-ulcer properties whose molecular mechanisms are still not completely understood but may involve changes in the anti-oxidant defence system. Herein, we have studied the effects of tianeptine on both contractile activity of isolated rat uteri and components of the endogenous anti-oxidative defence system. Tianeptine-induced dose-dependent inhibition of both spontaneous and Ca2+-induced contraction of uterine smooth muscle. The effect was more pronounced in the latter. Tianeptine treatment increased glutathione peroxidase (GSH-Px) and catalase (CAT) activities in spontaneous and Ca2+-stimulated uteri. A significant decrease in glutathione-reductase (GR) activity in both spontaneous and Ca2+-induced uterine contractions after tianeptine treatment indicated a reduction in reduced glutathione and consequently a shift toward a more oxidised state in the treated uteri. In spontaneously contracting uteri, tianeptine caused a decrease in copper-zinc SOD (CuZnSOD) activity. Tianeptine's anti-depressant effects may be accomplished by triggering a cascade of cellular adaptations including inhibition of smooth muscle contractility and an adequate anti-oxidative protection response.

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 ß-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.