Anxiolytic and panicolytic effects of escitalopram in the elevated T-maze

Escitalopram is a highly selective inhibitor of serotonin re-uptake that is used to treat anxiety disorders. In the present study, we investigated the effects of acute, sub-chronic ( 14 days) and chronic ( 21 days) administration of escitalopram ( 2, 4 and 8 mg/kg, P0) on the performance of rats in the elevated T-maze. For comparison, imipramine ( 15 mg/ kg, P0) was also studied. The apparatus is made of three elevated arms of equal dimension, one enclosed transversal to the two open arms. Inhibitory avoidance of the open arms, trained in the enclosed arm, has been related to generalised anxiety disorder, while one-way escape from one open arm, to panic disorder. After acute administration, the three doses of escitalopram impaired avoidance ( anxiolytic effect), while imipramine was ineffective. Escape was unaffected by either drug. With sub-chronic administration, both drugs were ineffective on either avoidance or escape. After chronic treatment, avoidance was impaired by imipramine and by the two highest doses of escitalopram. In addition, escape was impaired (panicolytic effect) by imipramine and by the highest dose of escitalopram. Locomotion measured in a square arena was increased by the three doses of escitalopram, given chronically. Therefore, both imipramine and escitalopram had anxiolytic and panicolytic-like effects after chronic administration, but acutely only escitalopram decreased anxiety. Since no such effect was observed following subchronic administration, it is likely that the mechanisms of the early and late anxiolytic actions of escitalopram are different.

Spontaneous reversibility of damage to outer hair cells after sodium salicylate induced ototoxicity

Background: High sodium salicylate doses can cause reversible hearing loss and tinnitus, possibly due to reduced outer hair cell electromotility. Sodium salicylate is known to alter outer hair cell structure and function. This study determined the reversibility and cochlear recovery time after administration of an ototoxic sodium salicylate dose to guinea pigs with normal cochlear function. Study design: Prospective experimental investigation. Methods: All animals received a single 500 mg sodium salicylate dose, but with different durations of action. Function was evaluated before drug administration and immediately before sacrifice. Cochleae were processed and viewed using scanning electron microscopy. Results: Changes in outer hair cell function were observed to be present 2 hours after drug administration, with recovery of normal anatomy beginning after 24 hours. Subsequently, derangement and distortion of cilia reduced, with effects predominantly in row three. At 168 hours, cilia were near-normal but with mild distortions which interfered with normal cochlear physiology. Conclusions: Ciliary changes persisted for up to 168 hours after ototoxic sodium salicylate administration.

Protective effect of Calendula officinalis extract against UVB-induced oxidative stress in skin: Evaluation of reduced glutathione levels and matrix metalloproteinase secretion

Background and purpose: Calendula officinalis flowers have long been employed time in folk therapy, and more than 35 properties have been attributed to decoctions and tinctures from the flowers. The main uses are as remedies for burns (including sunburns), bruises and cutaneous and internal inflammatory diseases of several origins. The recommended doses are a function both of the type and severity of the condition to be treated and the individual condition of each patient. Therefore, the present study investigated the potential use of Calendula officinalis extract to prevent UV irradiation-induced oxidative stress in skin. Methods: Firstly, the physico-chemical composition of marigold extract(ME) (hydroalcoholic extract)was assessed and the in vitro antioxidant efficacy was determined using different methodologies. Secondly, the cytotoxicity was evaluated in L929 and HepG2 cells with the MTT assay. Finally, the in vivo protective effect of ME against UVB-induced oxidative stress in the skin of hairless mice was evaluated by determining reduced glutathione (GSH) levels and monitoring the secretion/activity of metalloproteinases. Results and conclusions: The polyphenol, flavonoid, rutin and narcissin contents found in ME were 28.6 mg/g, 18.8 mg/g, 1.6 mg/g and 12.2 mg/g, respectively and evaluation of the in vitro antioxidant activity demonstrated a dose-dependent effect of ME against different radicals. Cytoxicity experiments demonstrated that ME was not cytotoxic for L929 and HepG2 cells at concentrations less than or equal to of 15 mg/mL However, concentrations greater than or equal to 30 mg/mL, toxic effects were observed. Finally, oral treatment of hairless mice with 150 and 300 mg/kg of ME maintained GSH levels close to non-irradiated control mice. In addition, this extract affects the activity/secretion of matrix metalloproteinases 2 and 9 (MMP-2 and -9) stimulated by exposure to UVB irradiation. However, additional studies are required to have a complete understanding of the protective effects of ME for skin. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Interaction of purinergic and nitrergic mechanisms in the caudal nucleus tractus solitarii of rats

The interaction of purinergic and nitrergic mechanisms was evaluated in the caudal nucleus tractus solitarii (cNTS) using awake animals and brainstem slices. In awake animals, ATP (1.25 nmol/50 nL) was microinjected into the cNTS before and after the microinjection of a selective neuronal nitric oxide synthase (nNOS) inhibitor N-propyl-L-arginine (NPLA, 3 pmoles/50 nL, n=8) or vehicle (saline, n=4), and cardiovascular and ventilatory parameters were recorded. In brainstem slices from a distinct group of rats, the effects of ATP on the NO concentration in the cNTS using the fluorescent dye DAF-2 DA were evaluated. For this purpose brainstem slices (150 pm) containing the cNTS were pre-incubated with ATP (500 mu M; n=8) before and during DAF-2 DA loading. Microinjection of ATP into the cNTS increases the arterial pressure (AP), respiratory frequency (f(R)) and minute ventilation (V(E)), which were significantly reduced by pretreatment with N-PLA, a selective nNOS inhibitor (AP: 39 +/- 3 vs 16 +/- 14 mm Hg; f(R): 75 +/- 14 vs 4 +/- 3 cpm; V(E): 909 159 vs 77 39 mL kg(-1) m(-1)). The effects of ATP in the cNTS were not affected by microinjection of saline. ATP significantly increased the NO fluorescence in the cNTS (62 +/- 7 vs 101 +/- 10 AU). The data show that in the cNTS: a) the NO production is increased by ATP; b) NO formation by nNOS is involved in the cardiovascular and ventilatory responses to microinjection of ATP. Taken together, these data suggest an interaction of purinergic and nitrergic mechanisms in the cNTS. (C) 2009 Elsevier B.V. All rights reserved.

Mechanisms of Action of Eicosapentaenoic Acid in Bladder Cancer Cells In Vitro: Alterations in Mitochondrial Metabolism, Reactive Oxygen Species Generation and Apoptosis Induction

Purpose: Eicosapentaenoic acid has been tested in bladder cancer as a synergistic cytotoxic agent in the form of meglumine-eicosapentaenoic acid, although its mechanism of action is poorly understood in this cancer. The current study analyzed the mechanisms by which eicosapentaenoic acid alters T24/83 human bladder cancer metabolism in vitro. Materials and Methods: T24/83 human bladder cancer cells were exposed to eicosapentaenoic acid for 6 to 24 hours in vitro and incorporation profiles were determined. Effects on membrane phospholipid incorporation, energy metabolism, mitochondrial activity, cell proliferation and apoptosis were analyzed Reactive oxygen species and lipid peroxide production were also determined. Results: Eicosapentaenoic acid was readily incorporated into membrane phospholipids with a considerable amount present in mitochondrial cardiolipin. Energy metabolism was significantly altered by eicosapentaenoic acid, accompanied by decreased mitochondrial membrane potential, and increased lipid peroxide and reactive oxygen species generation. Subsequently caspase-3 activation and apoptosis were detected in eicosapentaenoic acid exposed cells, leading to decreased cell numbers. Conclusions: These findings confirm that eicosapentaenoic acid is a potent cytotoxic agent in bladder cancer cells and provide important insight into the mechanisms by which eicosapentaenoic acid causes these changes. The changes in membrane composition that can occur with eicosapentaenoic acid likely contribute to the enhanced drug cytotoxicity reported previously in meglumine-eicosapentaenoic acid/epirubicin/mitomycin studies. Dietary manipulation of the cardiolipin fatty acid composition may provide an additional method for stimulating cell death in bladder cancer. In vivo studies using intravesical and dietary manipulation of fatty acid metabolism in bladder cancer merit further attention.

Blood Cardioplegia with N-Acetylcysteine May Reduce Coronary Endothelial Activation and Myocardial Oxidative Stress

Objectives: The aim of this prospective study was to compare the efficacy of intermittent antegrade blood cardioplegia with or without n-acetylcysteine (NAC) in reducing myocardial oxidative stress and coronary endothelial activation. Methods: Twenty patients undergoing elective isolated coronary artery bypass graft surgery were randomly assigned to receive intermittent antegrade blood cardioplegia (32 degrees C-34 degrees C) with (NAC group) or without (control group) 300 mg of NAC. For these 2 groups we compared clinical outcome, hemodynamic evolution, systemic plasmatic levels of troponin I, and plasma concentrations of malondialdehyde (MDA) and soluble vascular adhesion molecule 1 (sVCAM-1) from coronary sinus blood samples. Results: Patient demographic characteristics and operative and postoperative data findings in both groups were similar. There was no hospital mortality. Comparing the plasma levels of MDA 10 min after the aortic cross-clamping and of sVCAM-1 30 min after the aortic cross-clamping period with the levels obtained before the aortic clamping period, we observed increases of both markers, but the increase was significant only in the control group (P=.039 and P=.064 for MDA; P=.004 and P=.064 for sVCAM- 1). In both groups there was a significant increase of the systemic serum levels of troponin I compared with the levels observed before cardiopulmonary bypass (P<.001), but the differences between the groups were not significant (P=.570). Conclusions: Our investigation showed that NAC as an additive to blood cardioplegia in patients undergoing on-pump coronary artery bypass graft surgery may reduce oxidative stress and the resultant coronary endothelial activation.

Long-Term Ethanol Consumption Promotes Hepatic Tumorigenesis but Impairs Normal Hepatocyte Proliferation in Rats

Chronic and excessive alcohol consumption has been related to an increased risk of several cancers, including that of the liver; however, studies in animal models have yet to conclusively determine whether ethanol acts as a tumor promoter in hepatic tumorigenesis. We examined whether prolonged alcohol consumption could act as a hepatic tumor promoter after initiation by diethylnitrosamine (DEN) in a rat model. Male Sprague-Dawley rats were injected with 20 mg DEN/kg body weight 1 wk before introduction of either an ethanol liquid diet or an isoenergic control liquid diet. Hepatic pathological lesions, hepatocyte proliferation, apoptosis, PPAR alpha and PPAR gamma, and plasma insulin-like growth factor 1 IGF-1) levels were assessed after 6 and 10 mo. Mean body and liver weights, plasma IGF-1 concentration, hepatic expressions of proliferating cellular nuclear antigen and Ki-67, and cyclin D1 in ethanol-fed rats were all significantly lower after 10 mo of treatment compared with control rats. In addition, levels of hepatic PPAR gamma protein, not PPAR alpha, were significantly higher in the ethanol-fed rats after prolonged treatment. Although ethanol feeding also resulted in significantly fewer altered hepatic foci, hepatocellular adenoma was detected in ethanol-fed rats at 10 mo, but not in control rats given the same dose of DEN. Together, these results indicate that chronic, excessive ethanol consumption impairs normal hepatocyte proliferation, which is associated with reduced IGF-1 levels, but promotes hepatic carcinogenesis. J. Nutr. 141: 1049-1055, 2011.

Glucocorticoid resistance in dialysis patients may impair the kidney allograft outcome

This study examines in vitro steroid sensitivity in chronic renal failure ( CRF) patients and its influence on the allograft outcome. We determined the inhibitory effect of dexamethasone ( DEX) on concanavalin A ( Con-A)-stimulated peripheral blood mononuclear cell ( PBMC) proliferation, and glucocorticoid receptor` ( GR) number of binding sites ( B-max) and affinity ( K-d) in 28 CRF patients and 40 normal healthy controls. Based on K-d values > 95th percentile from controls, patients were divided into two groups: glucocorticoid resistant ( n = 11) and glucocorticoid sensitive ( n = 17). Patients were followed during 18 months post-transplantation observing acute rejection episodes ( ARE), chronic allograft nephropathy ( CAN), allograft failure and death. The DEX concentration that caused 50% inhibition of Con-A-stimulated PBMC proliferation ( IC50) was higher in CRF than in healthy controls ( 2.2 x 10(-5) +/- 1.0 x 10(-5) versus 8.3 x 10(-6) +/- 4.2 x 10(-6) mol/ L, P = 0.02). Values of Kd ( 12.4 +/- 1.8 versus 7.2 +/- 0.9 nM) and Bmax ( 7.7 +/- 1.1 versus 4.1 +/- 0.3 fmol/ mg protein) were higher in CRF patients ( P = 0.02 and P = 0.001, respectively). There were higher incidences of ARE ( P = 0.02) and CAN ( P = 0.002) in the glucocorticoid-resistant group. Univariate and multivariate logistic regression showed that Kd was an independent predictor of ARE ( OR 8.8, P= 0.03) aswell as of CAN ( OR 16.5, P= 0.01). In conclusion, we observed glucocorticoid resistance in a subgroup of CRF patients undergoing dialysis, which led to a higher morbidity due to ARE and CAN in an 18-month follow-up period.

Distinct tumor suppressor mechanisms evolve in rodent species that differ in size and lifespan

Large, long-lived species experience more lifetime cell divisions and hence a greater risk of spontaneous tumor formation than smaller, short-lived species. Large, long-lived species are thus expected to evolve more elaborate tumor suppressor systems. In previous work, we showed that telomerase activity coevolves with body mass, but not lifespan, in rodents: telomerase activity is repressed in the somatic tissues of large rodent species but remains active in small ones. Without telomerase activity, the telomeres of replicating cells become progressively shorter until, at some critical length, cells stop dividing. Our findings therefore suggested that repression of telomerase activity mitigates the increased risk of cancer in larger-bodied species but not necessarily longer-lived ones. These findings imply that other tumor suppressor mechanisms must mitigate increased cancer risk in long-lived species. Here, we examined the proliferation of fibroblasts from 15 rodent species with diverse body sizes and lifespans. We show that, consistent with repressed telomerase activity, fibroblasts from large rodents undergo replicative senescence accompanied by telomere shortening and overexpression of p16(Ink4a) and p21(Cip1/Waf1) cycline-dependent kinase inhibitors. Interestingly, small rodents with different lifespans show a striking difference: cells from small shorter-lived species display continuous rapid proliferation, whereas cells from small long-lived species display continuous slow proliferation. We hypothesize that cells of small long-lived rodents, lacking replicative senescence, have evolved alternative tumor-suppressor mechanisms that prevent inappropriate cell division in vivo and slow cell growth in vitro. Thus, large-bodied species and small but long-lived species have evolved distinct tumor suppressor mechanisms.

Diazepam decreases leukocyte-endothelium interactions in situ

High doses of diazepam reduce the inflammatory paw edema in rats. This effect was attributed to an action of diazepam on the Translocator Protein (TSPO). We evaluated the effects of diazepam (10 mg/kg, intraperitoneally) on leukocyte rolling and migration. In carrageenan-induced acute inflammation, diazepam decreased the interaction of leukocytes with endothelial cells (rolling) and the number of leukocytes in the mesentery (migration). RU486 (antagonist of glucocorticoid receptors) reduced the effects of diazepam on leukocyte rolling and migration, suggesting a participation of endogenous corticosteroids. We also showed that the effects of diazepam on leukocyte-endothelium interactions are mediated by nitric oxide (NO), since prior treatment with l-arginine (precursor of NO) partially precludes the inhibitory effects of diazepam; conversely, pretreatment with L-NAME (false substrate of the NO synthase) somewhat potentiates the effects of diazepam. The pathways that underlie the effects of diazepam remain to be further elucidated, but we believe that both local and systemic mechanisms may overlap to explain the influence of diazepam on leukocyte-endothelium interactions.

Anandamide prior to sensitization increases cell-mediated immunity in mice

The endocannabinoid system has become a topic of great interest in pharmacology due to its remarkable distribution in mammal organisms and capacity to play a modulatory role on several physiological systems, including modulation of immunity. Many studies have shown that administration of cannabinoids causes inhibitory effects on immune cells, including decreased proliferation and antigen-presenting cell (APC) costimulatory activity. In contrast, other groups have shown that some cannabinoids might present stimulatory actions on macrophage activity and T cell activation. Therefore, we aimed to investigate whether a treatment in vivo with a low dose of anandamide (0.1 mg/kg) immediately prior to sensitization would have an immunosuppressive or immunostimulatory effect on cell-mediated immunity (Th1 response) in mice. We report here that anandamide, prior to sensitization, was able to increase the Th1 response to ovalbumin in vivo and ex vivo. Anandamide increased delayed type hypersensitivity (DTH), splenocyte proliferation, and IFN-gamma production in a co-culture of adherent and non-adherent splenocytes. Moreover, anandamide prior to sensitization increased both the expression of DC co-stimulatory molecules (CD80/CD86) and IL-12/IL23 (p40) production ex vivo. We have also assessed direct effects of anandamide in the IFN-gamma/IL-4 balance of ConA-stimulated splenocytes in vitro. Anandamide at nanomolar concentrations increased the production of IFN-gamma, while such production decreased at micromolar range. Thus, anandamide induced both the increment of DC activation and IFN-gamma production, which are likely the mechanisms involved in the increase of Th1 response reported here. (C) 2010 Elsevier B.V. All rights reserved.

Haematological and immunological effects of repeated dose exposure of rats to integerrimine N-oxide from Senecio brasiliensis

This study is the first in the literature to focus attention on the possible immunotoxic effect of integerrimine N-oxide content in the butanolic residue (BR) of Senecio brasiliensis, a poisonous hepatotoxic plant that contains pyrrolizidine alkaloids (PAs). PAs have been reported as a pasture and food contaminant and as herbal medicine used worldwide and are responsible for poisoning events in livestock and human beings. After the plant extraction, BR extracted from Senecio brasiliensis was found to contain approximately 70% integerrimine N-oxide by elemental and spectral analyses ((1)H and (13)C NMR), which was administered to adult male Wistar Hannover rats at doses of 3, 6 and 9 mg/kg for 28 days. Body weight gain, food consumption, lymphoid organs, neutrophil analysis, humoural immune response, cellular immune response and lymphocyte analysis were evaluated. Our study showed that integerrimine N-oxide could promote an impairment in the body weight gain, interference with blood cell counts and a reducing T cell proliferative activity in rats; however, no differences in the neutrophil activities, lymphocytes phenotyping and humoural and cellular immune responses were observed. It is concluded that doses of integerrimine N-oxide here employed did not produce marked immunotoxic effects. (C) 2011 Elsevier Ltd. All rights reserved.

Reproductive toxic effects of Tityus serrulatus scorpion venom in rats

Tityus serrulatus is the most venomous scorpion in Brazil. Little is known about the effect of maternal exposure to the venom on fetal development. We investigated the effect of low to moderate doses of the venom (0.3 or 1.0 mg/kg s.c. on either day 5 or day 10 of gestation) on pregnant rats and on their offspring. For dams, we observed their body weight gain and reproductive parameters. For the offspring, we observed their body weight and weight of internal organs and the number of live and dead fetuses, and we investigated whether the venom caused external, visceral, skeletal or histopathological alterations in the offspring. The offspring were examined on gestational day 21. Injection of the venom on gestational day 5 did not change the reproductive parameters of the dams, their weight or fetuses` weight. Rats that received the high dose of the venom (1.0 mg/kg) on gestational day 10 had heavier placentas and heavier fetuses with heavier lungs. Injections on day 10 of gestation did not alter the reproductive parameters of the dams nor their weight gain at either dose. The venom did not cause malformations of the fetal skeleton or viscera and did not delay fetal development with either dose. In conclusion, subcutaneous administration of 0.3 or 1.0 mg/kg T. serrulatus venom to pregnant Wistar rats at either day 5 or day 10 of gestation did not cause maternal or clear fetal toxicity. Subtle increases in placental weight and fetal body and lung weights observed following treatment with 1.0 mg/kg on day 10 of gestation were not associated with histopathological findings. Whether these observations represent a reaction to treatment and, if so, the underlying mechanisms and their toxicological impact remain to be examined further in future studies. (C) 2008 Elsevier Inc. All rights reserved.

Presence of arsenic in different types of MTA and white and gray Portland cement

Objective. The presence of arsenic in various types of mineral trioxide aggregate (MTA) and Portland cements were evaluated to verify if they comply with the ISO-recommended limit for water-based cements of 2 mg arsenic/kg material. Study design. An amount of 5 mL of hydrochloric acid was added to 2 g each of MTA and Portland cement to be analyzed. After 15 minutes, the material was filtered and the volume of supernatant was diluted with reagent-grade water up to 40 mL. Atomic absorption spectrophotometry readings were performed in triplicate. Results. The following mean values were obtained: CPM (Egeo, Buenos Aires, Argentina) 11.06 mg/kg; CPM sealer (Egeo) 10.30 mg/kg; MTA- Obtura (Angelus, Londrina, PR, Brazil) 0.39 mg/kg; Experimental MTA: 10.30 mg/kg; White MTA- Angelus (Angelus) 1.03 mg/kg; Gray MTA- Angelus (Angelus) 5.91 mg/kg; ProRoot-MTA (Dentsply/Tulsa Dental Specialties, Tulsa, OK) 5.25 mg/kg; Gray Portland cement (Votorantim Cimentos, Cubatao, SP, Brazil): 34.27 mg/kg; and White Portland cement (Cimento Rio Branco, Rio de Janeiro, RJ, Brazil) 0.52 mg/kg. Conclusion. All tested materials presented arsenic in their composition. The form of arsenic was not analyzed nor the toxicity of the arsenic found. Only MTA- Obtura, White MTA- Angelus, and White Portland cement presented arsenic levels below the limit set in the ISO 9917-1 standard. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008; 106: 909-913)