908 resultados para NMDA-receptor antagonist
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The search for reconsolidation blockers may uncover clinically relevant drugs for disrupting memories of significant stressful life experiences, such as those underlying the posttraumatic stress disorder. Considering the safety of systemically administered cannabidiol (CBD), the major non-psychotomimetic component of Cannabis sativa, to animals and humans, the present study sought to investigate whether and how this phytocannabinoid (3-30 mg/kg intraperitoneally; i.p.) could mitigate an established memory, by blockade of its reconsolidation, evaluated in a contextual fear-conditioning paradigm in rats. We report that CBD is able to disrupt 1- and 7-days-old memories when administered immediately, but not 6 h, after their retrieval for 3 min, with the dose of 10 mg/kg being the most effective. This effect persists in either case for at least 1 week, but is prevented when memory reactivation was omitted, or when the cannabinoid type-1 receptors were antagonized selectively with AM251 (1.0 mg/kg). Pretreatment with the serotonin type-1A receptor antagonist WAY100635, however, failed to block CBD effects. These results highlight that recent and older fear memories are equally vulnerable to disruption induced by CBD through reconsolidation blockade, with a consequent long-lasting relief in contextual fear-induced freezing. Importantly, this CBD effect is dependent on memory reactivation, restricted to time window of <6h, and is possibly dependent on cannabinoid type-1 receptor-mediated signaling mechanisms. We also observed that the fear memories disrupted by CBD treatment do not show reinstatement or spontaneous recovery over 22 days. These findings support the view that reconsolidation blockade, rather than facilitated extinction, accounts for the aforementioned CBD results in our experimental conditions. Neuropsychopharmacology (2012) 37, 2132-2142; doi:10.1038/npp.2012.63; published online 2 May 2012
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Cohabitation for 14 days with Ehrlich tumor-bearing mice was shown to increase locomotor activity, to decrease hypothalamic noradrenaline (NA) levels, to increase NA turnover and to decrease innate immune responses and decrease the animals' resistance to tumor growth. Cage mates of a B16F10 melanoma-bearer mice were also reported to show neuroimmune changes. Chemosignals released by Ehrlich tumor-bearing mice have been reported to be relevant for the neutrophil activity changes induced by cohabitation. The present experiment was designed to further analyze the effects of odor cues on neuroimmune changes induced by cohabitation with a sick cage mate. Specifically, the relevance of chemosignals released by an Ehrlich tumor-bearing mouse was assessed on the following: behavior (open-field and plus maze); hypothalamic NA levels and turnover; adrenaline (A) and NA plasmatic levels; and host resistance induced by tumor growth. To comply with such objectives, devices specifically constructed to analyze the influence of chemosignals released from tumor-bearing mice were employed. The results show that deprivation of odor cues released by Ehrlich tumor-bearing mice reversed the behavioral, neurochemical and immune changes induced by cohabitation. Mice use scents for intraspecies communication in many social contexts. Tumors produce volatile organic compounds released into the atmosphere through breath, sweat, and urine. Our results strongly suggest that volatile compounds released by Ehrlich tumor-injected mice are perceived by their conspecifics, inducing the neuroimmune changes reported for cohabitation with a sick companion. (C) 2011 Elsevier Inc. All rights reserved.
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The present work aimed to investigate the effects of acute sucrose treatment on the perception of painful stimuli. Specifically, we sought to determine the involvement of the endogenous opioid peptide-mediated system as well as the role of the mu(1)-opioid receptor in antinociception organisation induced by acute sucrose intake. Nociception was assessed with the tail-flick test in rats (75, 150 and 250 g) of different ages acutely pre-treated with 500 mu L. of a sucrose solution (25, 50, 150 and 250 g/L) or tap water. Young and Adult rats (250 g) showed antinociception after treatment with 50 g/L (during 5 min) and 150 g/L and 250 g/L (during 20 min) sucrose solutions. Surprisingly, this antinociception was more consistent in mature adult rodents than in pups. To evaluate the role of opioid systems, mature adult rodents were pre-treated with different doses (0.25, 1 or 4mg/kg) of the non-selective opioid receptor antagonist naloxone, the selective pi-opioid receptor antagonist naloxonazine or vehicle followed by 250 g/L sucrose solution treatment. Sucrose-induced antinociception was reduced by pre-treatment with both naloxone and naloxonazine. The present findings suggest that sweet substance-induced hypo-analgesia is augmented by increasing sucrose concentrations in young and adult rodents. Acute oral sucrose treatment inhibits pain in laboratory animal by mediating endogenous opioid peptide and mu(1)-opioid receptor actions. (C) 2011 Elsevier Inc. All rights reserved.
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Changes in brain-derived neurotrophic factor (BDNF)mediated signaling in the hippocampus have been implicated in the etiology of depression and in the mode of action of antidepressant drugs. There is also evidence from animal studies to suggest that BDNF-induced changes in the hippocampus may play a role in another stress-related pathology: anxiety. However, it is still unknown whether this neurotrophin plays a differential role in defensive responses associated with distinguished subtypes of anxiety disorders found in the clinic, such as generalized anxiety and panic disorder. In the present study, we investigated the effect of an acute BDNF injection into the rat dorsal hippocampus (DH) on inhibitory avoidance acquisition and escape expression measured in the elevated T-maze (ETM). We also assessed whether serotonergic neurotransmission may account for such effects. Intra-DH BDNF injection (200 pg) facilitated inhibitory avoidance in ETM. BDNF was equally anxiogenic in the light/dark transition test. Preadministration of the 5-HT1A receptor antagonist WAY-100635 fully counteracted the anxiogenic effect of BDNF in both tests. Intra-DH midazolam administration (10 nmol) impaired avoidance acquisition in ETM, suggesting an anxiolytic effect. Therefore, in the DH, facilitation of BDNF signaling seems to enhance 5-HT1A receptor-mediated neurotransmission to exert an anxiogenic effect associated with generalized anxiety. Behavioural Pharmacology 23:80-88 (C) 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.
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Cannabinoid receptor 1 (CB1) agonists usually induce dose-dependent biphasic effects on anxiety-related responses. Low doses induce anxiolytic-like effects, whereas high doses are ineffective or anxiogenic, probably due to activation of Transient Receptor Potential Vanilloid Type 1 (TRPV1) channels. In this study we have investigated this hypothesis by verifying the effects of the CB1/TRPV1 agonist ACEA injected into the prelimbic medial prefrontal cortex (PL) and the participation of endocannabinoids in the anxiolytic-like responses induced by TRPV1 antagonism, using the elevated plus-maze (EPM) and the Vogel conflict test (VCT). Moreover, we verified the expression of these receptors in the PL by double labeling immunofluorescence. ACEA induced anxiolytic-like effect in the intermediate dose, which was attenuated by previous injection of AM251, a CB1 receptor antagonist. The higher and ineffective ACEA dose caused anxiogenic- and anxiolytic-like effects, when injected after AM251 or the TRPV1 antagonist 6-iodonordihydrocapsaicin (6-I-CPS), respectively. Higher dose of 6-I-CPS induced anxiolytic-like effects both in the EPM and the VCT, which were prevented by previous administration of AM251. In addition, immunofluorescence showed that CB1 and TRPV1 receptors are closely located in the PL These results indicate that the endocannabinoid and endovanilloid systems interact in the PL to control anxiety-like behavior. (C) 2012 Elsevier Ltd. All rights reserved.
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Endothelin mediates neutrophil recruitment during innate inflammation. Herein we address whether endothelin-1 (ET-1) is involved in neutrophil recruitment in adaptive inflammation in mice, and its mechanisms. Pharmacological treatments were used to determine the role of endothelin in neutrophil recruitment to the peritoneal cavity of mice challenged with antigen (ovalbumin) or ET-1. Levels of ET-1, tumour necrosis factor a (TNF alpha), and CXC chemokine ligand 1 (CXCL1) were determined by enzyme-linked immunosorbent assay. Neutrophil migration and flow cytometry analyses were performed 4 h after the intraperitoneal stimulus. ET-1 induced dose-dependent neutrophil recruitment to the peritoneal cavity. Treatment with the non-selective ETA/ETB receptor antagonist bosentan, and selective ETA or ETB receptor antagonists BQ-123 or BQ-788, respectively, inhibited ET-1- and ovalbumin-induced neutrophil migration to the peritoneal cavity. In agreement with the above, the antigen challenge significantly increased levels of ET-1 in peritoneal exudates. The ET-1- and ovalbumin-induced neutrophil recruitment were reduced in TNFR1 deficient mice, and by treatments targeting CXCL1 or CXC chemokine receptor 2 (CXCR2); further, treatment with bosentan, BQ-123, or BQ-788 inhibited ET-1- and antigen-induced production of TNFa and CXCL1. Furthermore, ET-1 and ovalbumin challenge induced an increase in the number of cells expressing the Gr1(+) markers in the granulocyte gate, CD11c+ markers in the monocyte gate, and CD4(+) and CD45(+) (B220) markers in the lymphocyte gate in an ETA-and ETB-dependent manner, as determined by flow cytometry analysis, suggesting that ET-1 might be involved in the recruitment of neutrophils and other cells in adaptive inflammation. Therefore, the present study demonstrates that ET-1 is an important mediator for neutrophil recruitment in adaptive inflammation via TNF alpha and CXCL1/CXCR2-dependent mechanism.
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Objectives: This study aimed to evaluate a panel of proinflammatory and antiinflammatory cytokines in noncomplicated and complicated parapneumonic pleural effusions and to correlate their levels with pleural fluid biochemical parameters. Methods: Serum and pleural effusion were collected from 60 patients with noncomplicated (n = 26) or complicated (n = 34) parapneumonic effusions and assayed for cytologic, biochemical, and proinflammatory and antiinflammatory cytokines. Student t test was used to compare serum and pleural fluid values, Spearman correlation to analyze the relationship between pleural fluid cytokines and biochemical parameters, and accuracy of pleural fluid cytokine levels to determine the optimal cutoff value for identification of complicated effusions. Corrections for multiple comparisons were applied and a P value < .05 was accepted as significant. Results: Serum and pleural fluid cytokine levels of IL-8, vascular endothelial growth factor (VEGF), IL-10, and tumor necrosis factor (TNF) soluble receptor (sR) II were similar between groups. In contrast, complicated effusions had higher levels of pleural fluid IL-1 beta, IL-1 receptor antagonist (ra), and TNF sRI. Negative correlations were found between pleural fluid glucose with IL-1 beta and TNF sRI and positive correlations between lactic dehydrogenate (LDH) with IL-1 beta, IL-8, and VEGF. Pleural fluid levels of IL-1 beta, IL-1ra, and TNF sRI were more accurate than IL-8, VEGF, IL-10, and TNF sRII in discriminating complicated effusions. Conclusions: Both proinflammatory and antiinflammatory cytokine levels in pleural fluid are elevated in complicated in comparison with noncomplicated parapneumonic pleural effusions, and they correlate with both pleural fluid glucose and LDH levels. IL-1 beta, IL-1ra, and TNF sRI had higher sensitivity and specificity than IL-8, VEGF, IL-10, and TNF sRII in discriminating complicated effusions. CHEST 2012; 141( 1):183-189
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Objective: The aim of this study was to investigate the effects of PRP on SAOS-2 cells in terms of cytokine expression, cell activity and oxidative stress. Design: Cell line SAOS-2 (1 x 10(5) cells/mL) were grown in culture medium alpha-MEM with 10% FBS for 24 h and stimulated (or not) with PRP at concentrations of 3, 10 and 20%, LPS (E. coli, 10 g/mL) and IL-1 beta (1 mg/mL) for 24 h. The supernatant was collected and analyzed for the expression of cytokines in a panel array, ALP using a commercial kit and NO2- with Griess reaction method. Also, the cells were analyzed using Western blot for RANKL and slot blotting for nitrotyrosine expression. Result: There were no significant differences amongst the groups in terms of NO2-, protein nitrotyrosine content and RANKL expression. However, all stimuli increased ALP activity and in case of PRP, it was in a dose-dependent manner (p < 0.001). Also, all stimuli induced an increase in cytokines and chemokines expression, but only PRP promoted an increase of component C5, sICAM-1 and RANTES expression. Whilst IL-1 receptor antagonist (IL-1ra) expression was down-regulated by PRP, both LPS and IL-1 beta caused up-regulation of this cytokine. Conclusions: PRP can stimulate osteoblast activity and cytokine/chemokine release, as well as indicate some of the mediators that can (and cannot) be involved in this activation. (C) 2012 Elsevier Ltd. All rights reserved.
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Interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha, and IL-6 have been established as important mediators of fever induced by lipopolysaccharide (LPS) from Gram-negative bacteria. Whether these pro-inflammatory cytokines are also important in mediating fever induced by live bacteria remains less certain. We therefore investigated the following: (1) the synthesis of TNF-alpha, IL-1 beta, and IL-6 during E. coli-induced fever and (2) the effect of blocking the action of cytokines within the brain on E. coli-induced fever. Body or tail skin temperature (bT or Tsk, respectively) was measured by biotelemetry or telethermometry, every 30 min, during 6 or 24 h. Depending on the number of colony-forming units (CFU) injected i.p., administration of E. coli induced a long-lasting increase in bT of male Wistar rats. The duration of fever did not correlate with the number of CFU found in peritoneal cavity or blood. Because 2.5 x 10(8) CFU induced a sustained fever without inducing a state of sepsis/severe infection, this dose was used in subsequent experiments. The E. coli-induced increase in bT was preceded by a decrease in Tsk, reflecting a thermoregulatory response. TNF-alpha, IL-1 beta, and IL-6 were detected at 3 h in serum of animals injected i.p. with E. coli. In the peritoneal exudates, TNF-alpha, IL-1 beta, and IL-6 were detected at 0.5 and 3 h after E. coli administration. Moreover, both IL-1 beta and IL-6, but not TNF-alpha, were found in the cerebrospinal fluid (CSF) and hypothalamus of animals injected with E. coli. Although pre-treatment (i.c.v., 2 mu l, 15 min before) with anti-IL-6 antibody (anti-IL-6, 5 mu g) reduced E. coli-induced fever, pre-treatment with either IL-1 receptor antagonist (IL-1ra, 200 mu g) or soluble TNF receptor I (sTNFRI, 500 ng) had no effect on the fever response. In conclusion, replicating E. coli promotes an integrated thermoregulatory response in which the central action of IL-6, but not IL-1 and TNF, appears to be important.
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Aim: It has been suggested that the medullary raphe (MR) plays a key role in the physiological responses to hypoxia. As opioid mu-receptors have been found in the MR, we studied the putative role of opioid mu-receptors in the rostral MR (rMR) region on ventilation in normal and 7% hypoxic conditions. Methods: We measured pulmonary ventilation ((V) over dotE) and the body temperatures (Tb) of male Wistar rats before and after the selective opioid l-receptor antagonist CTAP ( d-Phe-Cys-Tyr-d-Trp-Arg-Thr-Pen-Thr-NH2, cyclic, 0.1 mu g per 0.1 mu L) was microinjected into the rMR during normoxia or after 60 min of hypoxia. Results: The animals treated with intra-rMR CTAP exhibited an attenuation of the ventilatory response to hypoxia ( 430 +/- 86 mL kg) 1 min) 1) compared with the control group ( 790 +/- 82 mL kg) 1 min) 1) ( P < 0.05). No differences in the Tb were observed between groups during hypoxia. Conclusion: These data suggest that opioids acting on l-receptors in the rMR exert an excitatory modulation of hyperventilation induced by hypoxia.
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We previously reported that melatonin modulates the Plasmodium falciparum erythrocytic cycle by increasing schizont stage population as well as diminishing ring stage population. In addition, the importance of calcium and cAMP in melatonin signaling pathway in P. falciparum was also demonstrated. Nevertheless, the molecular effectors of the indoleamine signaling pathway remain elusive. We now demonstrate by real-time PCR that melatonin treatment up-regulates genes related to ubiquitin/proteasome system (UPS) components and that luzindole, a melatonin receptor antagonist, inhibits UPS transcription modulation. We also show that protein kinase PfPK7, a P. falciparum orphan kinase, plays a crucial role in the melatonin transduction pathway, since following melatonin treatment of P. falciparum parasites where pfpk7 gene is disrupted (pfpk7- parasites) (i) the ratio of asexual stages remain unchanged, (ii) the increase in cytoplasmatic calcium in response to melatonin was strongly diminished and (iii) up-regulation of UPS genes did not occur. The wild-type melatonin-induced alterations in cell cycle features, calcium rise and UPS gene transcription were restored by re-introduction of a functional copy of the pfpk7 gene in the pfpk7- parasites.
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We investigated whether interleukin-4 (IL-4) is present and capable of reducing inflammatory changes seen in ifosfamide-induced hemorrhagic cystitis. Male Swiss mice were treated with saline or ifosfamide alone or ifosfamide with the classical protocol with mesna and analyzed by changes in bladder wet weight (BWW), macroscopic and microscopic parameters, exudate, and hemoglobin quantification. In other groups, IL-4 was administered intraperitoneally 1 h before ifosfamide. In other experimental groups, C57BL/6 WT (wild type) and C57BL/6 WT IL-4 (-/-) knockout animals were treated with ifosfamide and analyzed for changes in BWW. Quantification of bladder IL-4 protein by ELISA in control, ifosfamide-, and mesna-treated groups was performed. Immunohistochemistry to tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) as well as protein identification by Western blot assay for inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was carried out on ifosfamide- and IL-4-treated animals. In other experimental groups, antiserum against IL-4 was given 30 min before ifosfamide. In IL-4-treated animals, the severity of hemorrhagic cystitis was significantly milder than in animals treated with ifosfamide only, an effect that was reverted with serum anti-IL-4. Moreover, knockout animals for IL-4 (-/-) exhibit a worse degree of inflammation when compared to C57BL/6 wild type. Exogenous IL-4 also attenuated TNF-alpha, IL-1 beta, iNOS, and COX-2 expressions in ifosfamide-treated bladders. IL-4, an anti-inflammatory cytokine, attenuates the inflammation seen in ifosfamide-induced hemorrhagic cystitis.
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Leishmania parasites, the causative agent of leishmaniasis, are transmitted through the bite of an infected sand fly. Leishmania parasites present two basic forms known as promastigote and amastigote which, respectively, parasitizes the vector and the mammalian hosts. Infection of the vertebrate host is dependent on the development, in the vector, of metacyclic promastigotes, however, little is known about the factors that trigger metacyclogenesis in Leishmania parasites. It has been generally stated that "stressful conditions" will lead to development of metacyclic forms, and with the exception of a few studies no detailed analysis of the molecular nature of the stress factor has been performed. Here we show that presence/absence of nucleosides, especially adenosine, controls metacyclogenesis both in vitro and in vivo. We found that addition of an adenosine-receptor antagonist to in vitro cultures of Leishmania amazonensis significantly increases metacyclogenesis, an effect that can be reversed by the presence of specific purine nucleosides or nucleobases. Furthermore, our results show that proliferation and metacyclogenesis are independently regulated and that addition of adenosine to culture medium is sufficient to recover proliferative characteristics for purified metacyclic promastigotes. More importantly, we show that metacyclogenesis was inhibited in sand flies infected with Leishmania infantum chagasi that were fed a mixture of sucrose and adenosine. Our results fill a gap in the life cycle of Leishmania parasites by demonstrating how metacyclogenesis, a key point in the propagation of the parasite to the mammalian host, can be controlled by the presence of specific purines.
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Systemic administration of cannabidiol (CBD) attenuates cardiovascular and behavioral changes induced by re-exposure to a context that had been previously paired with footshocks. Previous results from our group using cFos immunohistochemistry suggested that the bed nucleus of the stria terminalis (BNST) is involved in this effect. The mechanisms of CBD effects are still poorly understood, but could involve 5-HT1A receptor activation. Thus, the present work investigated if CBD administration into the BNST would attenuate the expression of contextual fear conditioning and if this effect would involve the activation of 5-HT1A receptors. Male Wistar rats with cannulae bilaterally implanted into the BNST were submitted to a 10 min conditioning session (six footshocks, 1.5 mA/3 s). Twenty-four hours later freezing and cardiovascular responses (mean arterial pressure and heart rate) to the conditioning box were measured for 10 min. CBD (15, 30 or 60 nmol) or vehicle was administered 10 min before the re-exposure to the aversive context. The second experiment was similar to the first one except that animals received microinjections of the 5-HT1A receptor antagonist WAY100635 (0.37 nmol) 5 min before CBD (30 nmol) treatment. The results showed that CBD (30 and 60 nmol) treatment significantly reduced the freezing and attenuated the cardiovascular responses induced by re-exposure to the aversive context. Moreover, WAY100635 by itself did not change the cardiovascular and behavioral response to context, but blocked the CBD effects. These results suggest that CBD can act in the BNST to attenuate aversive conditioning responses and this effect seems to involve 5-HT1A receptor-mediated neurotransmission.
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We have previously reported that stimulation of alpha-1 adrenoceptors by noradrenaline (NA) injected into the lateral septal area (LSA) of anaesthetized rats causes pressor and bradycardic responses that are mediated by acute vasopressin release into the circulation through activation of the paraventricular nucleus (PVN). Although the PVN is the final structure of this pathway, the LSA has no direct connections with the PVN, suggesting that other structures may connect these areas. To address this issue, the present study employed c-Fos immunohistochemistry to investigate changes caused by NA microinjection into the LSA in neuronal activation in brain structures related to systemic vasopressin release. NA microinjected in the LSA caused pressor and bradycardic responses, which were blocked by intraseptal administration of alpha-1 adrenoceptor antagonist (WB4101, 10 nmol/200 nL) or systemic V-1 receptor antagonist (dTyr(CH2)5(Me)AVP, 50 mu g/kg). NA also increased c-Fos immunoreactivity in the prelimbic cortex (PL), infralimbic cortex (IL), dorsomedial periaqueductal gray (dmPAG), bed nucleus of the stria terminalis (BNST), PVN, and medial amygdala (MeA). No differences in the diagonal band of Broca, cingulate cortex, and dorsolateral periaqueductal gray (dlPAG) were found. Systemic administration of the vasopressin receptor antagonist dTyr AVP (CH2)5(Me) did not change the increase in c-Fos expression induced by intra-septal NA. This latter effect, however, was prevented by local injection of the alpha-1 adrenoceptor antagonist WB4101. These results suggest that areas such as the PL, IL, dmPAG, BNST, MeA, and PVN could be part of a circuit responsible for vasopressin release after activation of alpha-1 adrenoceptors in the LSA.