998 resultados para Induced polarization
Resumo:
Recently, superior cervical ganglionectomy has been performed to investigate a variety of scientific topics from regulation of intraocular pressure to suppression of lingual tumour growth. Despite these recent advances in our understanding of the functional mechanisms underlying superior cervical ganglion (SCG) growth and development after surgical ablation, there still exists a need for information concerning the quantitative nature of the relationships between the removed SCG and its remaining contralateral ganglion and between the remaining SCG and its modified innervation territory. To this end, using design-based stereological methods, we have investigated the structural changes induced by unilateral ganglionectomy in sheep at three distinct timepoints (2, 7 and 12 weeks) after surgery. The effects of time, and lateral (left-right) differences, were examined by two-way analyses of variance and paired t-tests. Following removal of the left SCG, the main findings were: (i) the remaining right SCG was bigger at shorter survival times, i.e. 74% at 2 weeks, 55% at 7 weeks and no increase by 12 weeks, (ii) by 7 weeks after surgery, the right SCG contained fewer neurons (no decrease at 2 weeks, 6% fewer by 7 weeks and 17% fewer by 12 weeks) and (iii) by 7 weeks, right SCG neurons were also larger and the magnitude of this increase grew substantially with time (no rise at 2 weeks, 77% by 7 weeks and 215% by 12 weeks). Interaction effects between time and ganglionectomy-induced changes were significant for SCG volume and mean perikaryal volume. These findings show that unilateral superior cervical ganglionectomy has profound effects on the contralateral ganglion. For future investigations, it would be interesting to examine the interaction between SCGs and their innervation targets after ganglionectomy. Is the ganglionectomy-induced imbalance between the sizes of innervation territories the milieu in which morphoquantitative changes, particularly changes in perikaryal volume and neuron number, occur? Mechanistically, how would those changes arise? Are there any grounds for believing in a ganglionectomy-triggered SCG cross-innervation and neuroplasticity? (C) 2011 ISDN. Published by Elsevier Ltd. All rights reserved.
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Background: The protective effect of carvedilol on multiple organ damage induced by angiotensin II (Ang II) remains unclear. The aim of this study was to evaluate the protective effect of carvedilol on the heart, liver, and kidney in rats infused with Ang II. Material/Methods: Wistar rats were randomly distributed into three groups: control (no treatment), continuously infused with Ang II (150 eta g/min for 72 hr), and treated with Ang II + carvedilol (90 mg/kg/d). Histological sections of the myocardium, kidney, and liver were analyzed for the presence of necrosis. Results: Ang II induced arterial hypertension which was not affected by carvedilol treatment (tail-cuff blood pressures, control: 125 +/- 13.6, Ang II: 163 +/- 27.3, Ang II + CV: 178 +/- 39.8 mmHg, p<0.05). Also, there were perivascular inflammation and necrosis in the myocardium, kidney, and hepatocytes necrosis around the terminal vein. Carvedilol treatment fully prevented damage to the heart and kidney and attenuated liver lesions induced by the Ang II infusion. Conclusions: The protective effect of carvedilol on perivascular damage induced by Ang II infusion depended on the target organ. The prevention of heart damage occurred independently of the antihypertensive effects of carvedilol.
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This study was undertaken to test whether the structural remodelling of pulmonary parenchyma can be sequentially altered in a model and method that demonstrate the progression of the disease and result in remodelling within the lungs that is typical of idiopathic pulmonary fibrosis. Three groups of mice were studied: (i) animals that received 3-5-di-tert-butyl-4-hydroxytoluene (BHT) and were killed after 2 weeks (early BHT = 9); (ii) animals that received BHT and were killed after 4 weeks (late BHT = 11); (iii) animals that received corn oil solution (control = 10). The mice were placed in a ventilated Plexiglas chamber with a mixture of pure humidified oxygen and compressed air. Lung histological sections underwent haematoxylin-eosin, immunohistochemistry (epithelial, endothelial and immune cells) and specific staining (collagen/elastic fibres) methods for morphometric analysis. When compared with the control group, early BHT and late BHT groups showed significant decrease of type II pneumocytes, lower vascular density in both and higher endothelial activity. CD4 was increased in late BHT compared with early and control groups, while CD8, macrophage and neutrophil cells were more prominent only in early BHT. The collagenous fibre density were significantly higher only in late BHT, whereas elastic fibre content in late BHT was lower than that in control group. We conclude that the BHT experimental model is pathologically very similar to human usual interstitial pneumonia. This feature is important in the identification of animal models of idiopathic pulmonary fibrosis that can accurately reflect the pathogenesis and progression of the human disease.
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We have previously shown that bracken fern (Pteridium aquilinum) has immunomodulatory effects on mouse natural killer (NK) cells by reducing cytotoxicity. Alternatively, it has been demonstrated that selenium can enhance NK cell activity. Therefore, the aims of the present study were to evaluate if ptaquiloside, the main toxic component found in P. aquilinum, is responsible for the immunotoxic effects observed in mice, and if selenium supplementation could prevent or even reverse these effects. Male C57BL/6 mice were administered the P. aquilinum extract by daily gavage for 30 days, and histological analyses revealed a significant reduction in splenic white pulp area that was fully reversed by selenium treatment. In addition, mice administered ptaquiloside by daily gavage for 14 days demonstrated the same reduction of NK cell activity as the P. aquilinum extract, and this reduction was prevented by selenium co-administration. Lastly, non-adherent splenic cells treated in vitro with an RPM! extract of P. aquilinum also showed diminished NM cell activity that was not only prevented by selenium co-treatment but also fully reversed by selenium post-treatment. The results of this study clearly show that the immunosuppressive effects of P. aquilinum are induced by ptaquiloside and that selenium supplementation can prevent as well as reverse these effects. (C) 2010 Elsevier Ltd. All rights reserved.
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The periaqueductal gray (PAG) has been reported as a potential site for opioid regulation of behavioral selection. Opioid-mediated behavioral and physiological responses differ between nulliparous and multiparous females. This study addresses the effects of multiple reproductive experiences on mu-, kappa- and delta-opioid receptor (Oprm1, Oprk1, and Oprd1 respectively) gene activity and mu, kappa and delta protein expression (MOR, KOR and DOR respectively) in the PAG of the female rats. This was done by evaluating the opioid gene expression using real-time (RT-PCR) and quantification of each protein receptor by Western blot analysis. The RT-PCR results show that multiple reproductive experiences increase Oprm1 and Oprk1 gene expression. Western blot analysis revealed increased MOR and KOR while DOR protein was decreased in multiparous animals. Taken together, these data suggest that multiple reproductive experiences influence both gene activity and opioid receptor expression in the PAG. Post-translational mechanisms seem particularly relevant for DOR expression. Thus, opioid transmission in the PAG might be modulated by different mechanisms of multiparity-induced plasticity according to the opioid receptor type.
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Objectives: The effects of short-term 5-day and long-term 30-day hyperprolactinemia induced by domperidone (1.7 mg/kg/day, s.c.) or ectopic pituitary graft on the acute inflammatory response induced by carrageenan were evaluated in male rats. Both models of hyperprolactinemia effectively increased serum prolactin (PRL) levels. Methods: The volume in milliliters of inflammatory edema was measured by plethysnnography 1, 2, 3, 4, 6, 8 and 24 h after carrageenan injection. The areas under the inflammatory time-response curves were compared. Additionally, the effects of hyperprolactinemia on body weight and serum corticosterone levels were evaluated. Results: In both domperidone-treated and pituitary graft-implanted animals, short-term 5-day hyperprolactinemia increased the inflammatory response, while long-term 30-day hyperprolactinemia had anti-inflammatory effects. Body weight was not affected by either short- or long-term hyperprolactinennia. Conclusion: These results show that PRL has biphasic effects on the carrageenan-induced inflammatory response. Copyright (C) 2011 S. Karger AG, Basel
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Background/Aims: Antidepressants are reported to exhibit antiinflammatory effects. However, mechanisms involved in this action have not been elucidated. Thus, the objectives of the present study were (a) to evaluate the effects of amitriptyline on the acute inflammatory process, and (b) to investigate the participation of alpha(1)-adrenergic receptors and glucocorticoids as possible mechanisms implicated in the amitriptyline action on inflammation. Methods and Results: Single and multiple doses of amitriptyline were administered to rats submitted to the carrageenan-induced paw edema model. The results showed a significant antiedematous reaction to amitriptyline, mainly when administered at each elimination half-life. The next step was to evaluate its effects on leukocyte behavior, using intravital microscopy. Amitriptyline produced a significant effect on leukocyte behavior. To investigate possible mechanisms involved, a glucocorticoid receptor antagonist (RU-486) and an alpha(1)-adrenergic receptor antagonist (prazosin) were used. RU-486 administration lacked the ability to decrease the amitriptyline antiinflammatory effects in the carrageenan-induced paw edema model. Prazosin pretreatment potentiated the amitriptyline antiinflammatory effect without presenting an effect per se. Conclusion:The present study shows the ability of amitriptyline to decrease edema and affect leukocyte behavior in an acute inflammatory process; and, for the first time to our knowledge, we suggest the involvement of alpha(1)-adrenoceptors in the antiinflammatory effects of amitriptyline. Copyright (C) 2010 S. Karger AG, Basel
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In this study, we report the protective effects of IAA on diethylnitrosamine (DEN)-induced hepatocarcinogenesis. BALB/c mice received daily IAA at 50 (T(50)), 250 (T(250)), and 500 (T(500)) mg K(-1) per body mass by gavage for 15 days. At day 15, animals were administered DEN and sacrificed 4 h later. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were analyzed in sera. In addition., hepatomorphologic alterations, activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR), gene expression of antioxidant enzymes and DNA integrity were evaluated in the liver. IAA administration did not show any alterations in any of the parameters available, except for a reduction of the gene expression for antioxidant enzyrries by 55, 56, 27, and 28% for SOD, CAT, GPx, and GR upon T(500). respectively compared with the control. Several hepatic alterations were observed by DEN exposure. Moreover, IAA administration at 3 doses was shown to provide a total prevention of the active reduction of CAT and GR induced by DEN exposure compared with the control. IAA at T5(00) was shown to give partial protection (87, 71, 57, and 90% for respectively SOD, CAT. GPx. and GR) on the down-regulation of the enzymes induced by DEN and this auxin showed a partial protection (50%) on DEN-induced DNA fragmentation for both parameters when compared to DEN alone. This work showed IAA hepatocarcinogenesis protection for the first time by means of a DEN-protective effect on CAT and GR activity. and by affecting antioxidant gene expression and DNA fragmentation. Copyright (C) 2008 John Wiley & Sons, Ltd.
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Background: Mice allergic to ovalbumin (OVA) avoid drinking a solution containing this antigen. This was interpreted as related to IgE-dependent mast cell degranulation and sensory C fiber activation. Methods: We employed pharmacological manipulation to further investigate the mediators involved in immune-induced food aversion. Results: While nonimmunized rats preferred a sweetened OVA solution, immunized rats avoided it. We also employed a paradigm in which rats are conditioned to drink water for two 10-min sessions a day. Tolerant rats presented lower IgE titers, and this manipulation abrogated food aversion. Dexamethasone (1.0 mg/kg) prevented the aversion of OVA-immunized rats to the antigen-containing solution. Combined blockade of H(1) and 5-hydroxytryptamine (5-HT)(2) receptors by promethazine (3.0 mg/kg) plus methysergide (5.0 mg/kg) was unable to alter food aversion. Blockade of 5-HT(3) receptors by ondansetron (1.0 mg/kg) caused a twofold increase in the ingestion of the sweetened OVA solution by immunized rats, suggesting the involvement of 5-HT(3) receptors in food aversion. Finally, we showed that dexamethasone or promethazine plus methysergide, but not ondansetron, effectively prevented the IgE-dependent mast-cell-degranulation-induced increase in vascular permeability in rats. Conclusion: We suggest that regardless of whether or not they cause edema, IgE-mediated mast cell degranulation and consequent 5-HT(3) signaling are involved in the process that triggers avoidance to the source of the allergen in allergic rats. Copyright (C) 2008 S. Karger AG, Basel
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The relevance and property of studies related to stress effects on immune function are undisputable. All studies conducted on stress-immune relationships, however, provide from physical and/or psychological stressors. Indeed, as far as it is of our knowledge brain-innate immune responses were not analyzed after anxiogenic-like drugs use. The present experiment was then undertaken to analyze the effects of picrotoxin (0.3, 0.6 and 1.0 mg/kg doses) on behavior, macrophage activity, serum corticosterone and noradrenaline (NE) levels and turnover in the brain of adult mice. Results showed that picrotoxin treatment in mice: (1) decreased motor and rearing activities in an open-field; (2) decreased the number of entries into the plus-maze open-arms and decreased the time spent in the exploration of the plus-maze open-arms; (3) decreased both motor activity and the level of holes exploration in the hole-board; (4) increased the levels of serum corticosterone in dose-dependent way; (5) increased noradrenaline (NE) and MHPG levels and NE turnover in the hypothalamus; and (6) increased Staphylococcus aureus and PMA-induced macrophage oxidative burst. However, and contrary to that reported after physical or psychological stress, this drug induced no effects on macrophage phagocytosis and NE levels and turnover in the frontal cortex. The present results are thus showing that picrotoxin induces some but not all neuro-innate immunity changes previously reported for inescapable foot-shock and psychological stressors in mice. These facts suggest that this chemical stressor triggers CNS pathways that might be somehow different from those fired by inescapable foot-shock and psychological stressors, leading to different neuro-innate immune responses. (C) 2007 Elsevier Ltd. All fights reserved.
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The susceptibility of cattle and buffalos to chronic copper poisoning (CCP) was compared by using cattle (n = 10) and buffalo (n = 10) steers distributed into two copper supplemented (n = 6) and two control (n = 4) groups. Supplemented animals received 2 mg copper (Cu)/kg body weight daily for one week, with an additional 2 mg weekly until the end of the experiment (day 105). Three liver biopsies (day 0, 45, and 105) were obtained for mineral analyses; clinical examinations and blood samples were obtained every 15 days. Three supplemented cattle and two buffalos with typical manifestations of CCP died. There were no differences in the frequency of mortality between cattle and buffalos; hepatic copper concentration was higher in cattle than buffalos. These findings suggest that buffalos and cattle might be equally susceptible to CCP. However, buffalos accumulate less liver copper than cattle and have a lower threshold of hepatic Cu accumulation, which leads to clinical manifestation of CCP. (c) 2009 Elsevier Ltd. All rights reserved.
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Considering, that there is limited information about the preovulatory LH surge in Zebu Cattle (Bos indicus). the purpose of the present work was to assess the LH surge in Nelore cows during the estrous cycle and after ovarian superestimulation of ovarian follicular development with FSH. This information is particularly important to improve superovulatory protocols associated with fixed-time artificial insemination. Nelore cows (n = 12) had their estrus synchronized with all intravaginal device containing progesterone (CIDR-B (R)) associated with estradiol benzoate administration (EB, 2.5 mg, i.m., Day 0). Eight days later all animals were treated with PGF2 alpha (Day 8) in the morning (8:00 h) and at night, when CIDR devices were removed (20:00 11). Starting 38 h after the first PGF2 alpha injection, blood sampling and ovarian ultrasonography took place every 4 h, during 37 consecutive hours. Frequent handling may have resulted in a stress-induced suppression of LH secretion resulting in only 3 of 12 cows having ovulations at 46.7 +/- 4.9 and 72.3 +/- 3.8 h, respectively, after removal of CIDR-B. Thirty days later, the same animals received the described hormonal treatment associated with FSH (Folltropin (R) total dose = 200 mg) administered twice a day, during 4 consecutive days, starting on Day 5. Thirty-six hours after the first injection of PGF2 alpha, to minimize stress. only seven blood samples were collected at 4 h interval each. and ultrasonography was performed every 12 h until ovulation. In 11 of 12 cows (92%) the LH surge and ovulation were observed 34.6 +/- 1.6 and 59.5 +/- 1.9 h. respectively. after removal of progesterone source. The maximum values for LH in those animals were 19.0 +/- 2.6 ng/ml (mean +/- S.E.M.). It is concluded that, in Nelore COWS submitted to a ovarian superstimulation Protocol, the LH surge occurs approximately 35 It after removal of intravaginal device containing progesterone, and approximately 12h before the LH surge observed after an induced estrus without ovarian superstimulation (C) 2008 Elsevier B.V. All rights reserved.
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Gap junction channels, formed by connexins (Cx), are involved in the maintenance of tissue homeostasis, cell growth, differentiation, and development. Several studies have shown that Cx43 is involved in the control of wound healing in dermal tissue. However, it remains unknown whether Cx43 plays a role in the control of liver fibrogenesis. Our study investigated the roles of Cx43 heterologous deletion on carbon tetrachloride (CCl(4))-induced hepatic fibrosis in mice. We administered CCl(4) to both Cx43-deficient (Cx43(+/-)) and wild-type mice and examined hepatocellular injury and collagen deposition by histological and ultrastructural analyses. Serum biochemical analysis was performed to quantify liver injury. Hepatocyte proliferation was analyzed immunohistochemically. Protein and messenger RNA (mRNA) expression of liver connexins were evaluated using immunohistochemistry as well as immunoblotting analysis and quantitative real-time PCR. We demonstrated that Cx43(+/-) mice developed excessive liver fibrosis compared with wild-type mice after CCl(4)-induced chronic hepatic injury, with thick and irregular collagen fibers. Histopathological evaluation showed that Cx43(+/-) mice present less necroinflammatory lesions in liver parenchyma and consequent reduction of serum aminotransferase activity. Hepatocyte cell proliferation was reduced in Cx43(+/-) mice. There was no difference in Cx32 and Cx26 protein or mRNA expression in fibrotic mice. Protein expression of Cx43 increased in CCl(4)-treated mice, although with aberrant protein location on cytoplasm of perisinusoidal cells. Our results demonstrate that Cx43 plays an important role in the control and regulation of hepatic fibrogenesis. Microsc. Res. Tech. 74:421-429, 2011. (C) 2010 Wiley-Liss, Inc.
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Background and Objective: Oral mucositis is a dose-limiting and painful side effect of radiotherapy (RT) and/or chemotherapy in cancer patients. The purpose of the present study was to analyze the effect of different protocols of laser phototherapy (LPT) on the grade of mucositis and degree of pain in patients under RT. Patients and Methods: Thirty-nine patients were divided into three groups: G1, where the irradiations were done three times a week using low power laser; G2, where combined high and low power lasers were used three time a week; and G3, where patients received low power laser irradiation once a week. The low power LPT was done using an InGaAlP laser (660 nm/40 mW/6 J cm(-2)/0.24 J per point). In the combined protocol, the high power LPT was done using a GaAlAs laser (808 nm, 1 W/cm(2)). Oral mucositis was assessed at each LPT session in accordance to the oral-mucositis scale of the National Institute of the Cancer-Common Toxicity criteria (NIC-CTC). The patient self-assessed pain was measured by means of the visual analogue scale. Results: All protocols of LPT led to the maintenance of oral mucositis scores in the same levels until the last RT session. Moreover, LPT three times a week also maintained the pain levels. However, the patients submitted to the once a week LPT had significant pain increase; and the association of low/high LPT led to increased healing time. Conclusions: These findings are desired when dealing with oncologic patients under RT avoiding unplanned radiation treatment breaks and additional hospital costs. Lasers Surg.Med. 41:264-270,2009. (C) 2009Wiley-Liss, Inc.
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Hyperglycemia induces overproduction of superoxide and it is related to diabetic complications. In this study, we analyzed the antioxidant enzymatic defense and the lipid peroxidation of rat salivary glands in six different periods of diabetic condition. Ninety-six rats were divided into 12 groups: C7/14/21128/45/60 (non-diabetic animals) and D7/14/21/28/45/60 (diabetic animals). Diabetes was induced by streptozotocin and the rats were euthanized after 7, 14, 21, 28, 45, or 60 days. Their parotid (PA) and submandibular (SM) glands were removed soon after the sacrifice and the total protein and malondialdehyde (MDA) concentrations, as well as, the superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities were determined. Twenty-one days after the diabetes induction, the SM glands showed an increase in SOD, CAT, and GPx activities, as well as, MDA concentration. Concerning the PA glands, an increase in the CAT activity and MDA content was observed throughout the observation period. The results suggest that diabetes can cause alterations on the salivary glands and that PA and SM glands react differently when exposed to diabetes condition. However, no impairment of antioxidant system was observed in the group whose diabetic condition had been induced 60 days earlier, herein named 60-day group. Copyright (C) 2010 John Wiley & Sons, Ltd.