Corticosterone evaluation in Wistar rats infected with the Y strain of Trypanosoma cruzi during the chronic phase

Understanding the mechanisms responsible for mediating the effects of stress on Trypanosoma cruzi infection is crucial for determining the full impact of stress on Chagas` disease and for devising effective interventions. Dehydroepiandrosterone (DHEA), a steroid hormone synthesized from pregnenolone, is secreted by the adrenal cortex in response to stress. Although its physiologic role has not been fully defined, DHEA has been shown to modulate immune function. In the present study, we evaluated the levels of corticosterone and the ability of T. cruzi infection to modulate the expression of Th2 cytokines in Wistar rats with chronic Chagas` disease submitted to repetitive stress. The animals submitted to stress displayed enhanced levels of corticosterone as compared to control counterparts. Stress and infection triggered the most elevated concentrations of corticosterone. DHEA significantly reduced corticosterone levels for infected and stressed animals with DHEA. The infected animals displayed enhanced levels of IL-10 and IL-4 as compared to control ones. Stress combined with infection triggered the higher levels of IL-10 and IL-4. DHEA alone and combined with infection and stress significantly increased IL-10 and IL-4 levels. Then, this study might provide additional clues about factors that regulate some of the immunoregulatory aspects of T. cruzi infection and might offer new opportunities for therapeutic interventions. (C) 2010 Elsevier Inc. All rights reserved.

Immunomodulatory effects of zinc and DHEA on the Th-1 immune response in rats infected with Trypanosoma cruzi

Chagas` disease is considered the sixth most important neglected tropical disease worldwide. Considerable knowledge has been accumulated concerning the role of zinc on cellular immunity. The steroid hormone dehydroepiandrosterone (DHEA) is also known to modulate the immune system. The aims of this paper were to investigate a possible synchronization of their effects on cytokines and NO production and the resistance to Trypanosoma cruzi during the acute phase of infection. It was found that zinc, DHEA or zinc and DHEA supplementation enhanced the immune response, as evidenced by a significant reduction in parasitemia levels. Zinc and DHEA supplementation exerted additive effects on the immune response by elevation of macrophage counts, and by increasing concentrations of IFN-gamma and NO. (C) 2009 Elsevier GmbH. All rights reserved.

Histamine Plays an Essential Regulatory Role in Lung Inflammation and Protective Immunity in the Acute Phase of Mycobacterium tuberculosis Infection

The course and outcome of infection with mycobacteria are determined by a complex interplay between the immune system of the host and the survival mechanisms developed by the bacilli. Recent data suggest a regulatory role of histamine not only in the innate but also in the adaptive immune response. We used a model of pulmonary Mycobacterium tuberculosis infection in histamine-deficient mice lacking histidine decarboxylase (HDC(-/-)), the histamine-synthesizing enzyme. To confirm that mycobacterial infection induced histamine production, we exposed mice to M. tuberculosis and compared responses in C57BL/6 (wild-type) and HDC(-/-) mice. Histamine levels increased around fivefold above baseline in infected C57BL/6 mice at day 28 of infection, whereas only small amounts were detected in the lungs of infected HDC(-/-) mice. Blocking histamine production decreased both neutrophil influx into lung tissue and the release of proinflammatory mediators, such as interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha), in the acute phase of infection. However, the accumulation and activation of CD4(+) T cells were augmented in the lungs of infected HDC(-/-) mice and correlated with a distinct granuloma formation that contained abundant lymphocytic infiltration and reduced numbers of mycobacteria 28 days after infection. Furthermore, the production of IL-12, gamma interferon, and nitric oxide, as well as CD11c(+) cell influx into the lungs of infected HDC(-/-) mice, was increased. These findings indicate that histamine produced after M. tuberculosis infection may play a regulatory role not only by enhancing the pulmonary neutrophilia and production of IL-6 and TNF-alpha but also by impairing the protective Th1 response, which ultimately restricts mycobacterial growth.

Trypanosoma cruzi: Dehydroepiandrosterone (DHEA) and immune response during the chronic phase of the experimental Chagas` disease

Dehydroepiandrosterone (DHEA) has long been considered as a precursor for many steroid hormones. It also enhances the immune responses against a wide range of viral, bacterial, and parasitic pathogens. The aims of this work were to evaluate the influences of exogenous DHEA treatment on Wistar rats infected with the Y strain of Trypanosoma cruzi during the acute and its influence on the chronic phase of infection. Animals were subcutaneous treated with 40 mg/kg body weight/day of DHEA. DHEA treatment promoted increased lymphoproliferative responses as well as enhanced concentrations of NO and IL-12. So, we point in the direction that our results validate the utility of the use of DHEA as an alternative therapy candidate against T cruzi. (C) 2009 Published by Elsevier B.V.

Control of experimental pulmonary tuberculosis depends more on immunostimulatory leukotrienes than on the absence of immunosuppressive prostaglandins

Prostaglandins (PGs) and leukotrienes (LTs) are produced in Mycobacterium tuberculosis (Mtb)-infected lungs and have immune suppressive and protective effects, respectively. Considering that both of these mediators are produced during mycobacterial infection, we investigated the specific and relative biological importance of each in regulating host response in experimental tuberculosis. Administration of celecoxib, which was found to reduce lung levels of PGE(2) and increase LTB(4), enhanced the 60-day survival of Mtb-infected mice in 14%. However administration of MK-886, which reduced levels of LTB(4) but did not enhance PGE(2), reduced 60-day survival from 86% to 43% in Mtb-infected mice, and increased lung bacterial burden. MK-886 plus celecoxib reduced survival to a lesser extent than MK-886 alone. MK-886- and MK-886 plus celecoxib-treated animals exhibited reduced levels of the protective interleukin-12 and gamma-interferon. Our findings indicate that in this model, the protective effect of LTs dominates over the suppressive effect of PGs. (C) 2011 Elsevier Ltd. All rights reserved.

Genetic interactions of the Ashergillus nidulans atmA(ATM) homolog with different components of the DNA damage response pathway

Ataxia telangiectasia mutated (ATM) is a phosphatidyl-3-kinase-related protein kinase that functions as a central regulator of the DNA damage response in eukaryotic cells. In humans, mutations in ATM cause the devastating neurodegenerative disease ataxia telangiectasia. Previously, we characterized the homolog of ATM (AtmA) in the filamentous fungus Aspergillus nidulans. In addition to its expected role in the DNA damage response, we found that AtmA is also required for polarized hyphal growth. Here, we extended these studies by investigating which components of the DNA damage response pathway are interacting with AtmA. The AtmA(ATM) loss of function caused synthetic lethality when combined with mutation in UvsB(ATR). Our results suggest that AtmA and UvsB are interacting and they are probably partially redundant in terms of DNA damage sensing and/or repairing and polar growth. We identified and inactivated A. nidulans chkA(CHK1) and chkB(CHK2) genes. These genes are also redundantly involved in A. nidulans DNA damage response. We constructed several combinations of double mutants for Delta atmA, Delta uvsB, Delta chkA, and Delta chkB. We observed a complex genetic relationship with these mutations during the DNA replication checkpoint and DNA damage response. Finally, we observed epistatic and synergistic interactions between AtmA, and bimE(APCI), ankA(WEE1) and the cdc2-related kinase npkA, at S-phase checkpoint and in response to DNA-damaging agents.

Spectroelectrochemistry and investigation of charge transport mechanisms of iron poly(pyridyl) redox polymers

In this work, we describe the characterization of the complex [Fe(tpy-NH2)(2)](PF6)(2) (tpy-NH2 = bis[4`-(3-aminophenyl)-2, 2`:6`,2 ``-terpyridine]. The complex was oxidatively electropolymerized on glassy.-carbon electrodes in CH3CN/0.1 M tetraethylammonium perchlorate (TEAP) to generate polymer films that exhibit reversible oxidative electrochemical behavior in a wide potential range (0.0-1.6 V), as well as high conductivity and stability/durability. In situ spectrocyclic voltammetry of this modified electrode was carried out on a photodiode array spectrophotometer attached to a potentiostat, which provided UV-Vis absorption spectra of the redox species during the potential sweep. We determined charge transport parameters as a function of time and thickness of the modified electrode, and the results showed that poly-[[Fe(tpy-NH2)(2)](2+)](n) can be made to exhibit three regimes of charge transport behavior by manipulation of the film thickness and the experimental time-scale. Morphological characterization of the film was provided by atomic force microscopy. (C) 2008 Elsevier Ltd. All rights reserved.

L-Allylglycine dissociates the neural substrates of fear in the periaqueductal gray of rats

The dorsal (dPAG) and ventral (vPAG) regions of the periaqueductal gray are well known to contain the neural substrates of fear and anxiety. Chemical or electrical stimulation of the dPAG induces freezing, followed by a robust behavioral reaction that has been considered an animal model of panic attack. In contrast, the vPAG is part of a neural system, in which immobility is the usual response to its stimulation. The defense reaction induced by the stimulation of either region is accompanied by anti nociception. Although GABAergic mechanisms are known to exert tonic inhibitory control on the neural substrates of fear in the dPAG, the role of these mechanisms in the vPAG is still unclear. The present study examined defensive behaviors and antinociception induced by microinjections of an inhibitor of gamma-aminobutyric acid synthesis, L-allylglycine (L-AG; 1, 3, and 5 mu g/0.2 mu l), into either the dPAG or vPAG of rats subjected to the open field and tail-flick tests. Passive or tense immobility was the predominant behavior after L-AG (1 or 3 mu g) microinjection into the vPAG and dPAG, respectively, which was replaced with intense hyperactivity, including jumps or rearings, after injections of a higher dose (5 mu g/0.2 mu l) into the dPAG or vPAG. Moreover, whereas intra-dPAG injection of 3 mu g L-AG produced intense antinociception, only weak antinociception was induced by intra-vPAG injections of 5 mu g L-AG. These findings suggest that GABA mechanisms are involved in the mediation of antinociception and behavioral inhibition to aversive stimulation of the vPAG and exert powerful control over the neural substrates of fear in the dPAG to prevent a full-blown defense reaction possibly associated with panic disorder. (C) 2009 Elsevier Inc. All rights reserved.

Antidepressant-Like Effects of Medial Prefrontal Cortex Deep Brain Stimulation in Rats

Background: Subcallosal cingulate gyrus (SCG) deep brain stimulation (DBS) is being investigated as a treatment for major depression. We report on the effects of ventromedial prefrontal cortex (vmPFC) DBS in rats, focusing on possible mechanisms involved in an antidepressant-like response in the forced swim test (FST). Methods: The outcome of vmPFC stimulation alone or combined with different types of lesions, including serotonin (5-HT) or nore-pineprhine (NE) depletion, was characterized in the FST. We also explored the effects of DBS on novelty-suppressed feeding, learned helplessness, and sucrose consumption in animals predisposed to helplessness. Results: Stimulation at parameters approximating those used in clinical practice induced a significant antidepressant-like response in the FST. Ventromedial PFC lesions or local muscimol injections did not lead to a similar outcome. However, animals treated with vmPFC ibotenic acid lesions still responded to DBS, suggesting that the modulation of fiber near the electrodes could play a role in the antidepressant-like effects of stimulation. Also important was the integrity of the serotonergic system, as the effects of DBS in the FST were completely abolished in animals bearing 5-HT, but not NE, depleting lesions. In addition, vmPFC stimulation induced a sustained increase in hippocampal 5-HT levels. Preliminary work with other models showed that DBS was also able to influence specific aspects of depressive-like states in rodents, including anxiety and anhedonia, but not helplessness. Conclusions: Our study suggests that vmPFC DES in rats maybe useful to investigate mechanisms involved in the antidepressant effects of SCG DBS.

Selective involvement of GABAergic mechanisms of the dorsal periaqueductal gray and inferior colliculus on the memory of the contextual fear as assessed by the fear potentiated startle test

The inferior colliculus (IC) together with the dorsal periaqueductal gray (dPAG), the amygdala and the medial hypothalamus make part of the brain aversion system, which has mainly been related to the organization of unconditioned fear. However, the involvement of the IC and dPAG in the conditioned fear is still unclear. It is certain that GABA has a regulatory role on the aversive states generated and elaborated in these midbrain structures. In this study, we evaluated the effects of injections of the GABA-A receptor agonist muscimol (1.0 and 2.0 nmol/0.2 mu L) into the IC or dPAG on the freezing and fear-potentiated startle (FPS) responses of rats submitted to a context fear conditioning. Intra-IC injections of muscimol did not cause any significant effect on the FPS or conditioned freezing but enhanced the startle reflex in non-conditioned animals. In contrast, intra-dPAG injections of muscimol caused significant reduction in FPS and conditioned freezing without changing the startle reflex in non-conditioned animals. Thus, intra-dPAG injections of muscimol produced the expected inhibitory effects on the anxiety-related responses, the FPS and the freezing whereas these injections into the IC produced quite opposite effects suggesting that descending inhibitory pathways from the IC, probably mediated by GABA-A mechanisms, exert a regulatory role on the lower brainstem circuits responsible for the startle reflex. (C) 2008 Elsevier Inc. All rights reserved.

GABAergic REGULATION OF AUDITORY SENSORY GATING IN LOW- AND HIGH-ANXIETY RATS SUBMITTED TO A FEAR CONDITIONING PROCEDURE

The inferior colliculus (IC) is primarily involved in the processing of acoustic stimuli, being in a position to send auditory information to motor centers that participate in behaviors such as prey catching and predators` avoidance The role of the central nucleus of the IC (CIC) on fear and anxiety has been suggested on the basis that rats are able to engage in tasks to decrease the aversiveness of CIC stimulation, increased Fos immunolabeling during diverse aversive states and increased CIC auditory evoked potentials (AEP) induced by conditioned fear stimuli Additionally it was shown that brainstem AEP, represented by wave V, for which the main generator is the IC, is increased during experimentally induced anxiety Rats segregated according to their low or high emotional reactivity have been used as an important tool in the study of fear and anxiety The IC contains a high density of GABA receptors Since the efficacy of an anxiolytic compound is a function of the animal`s anxiety level, it is possible that GABA-benzodiazepine (Bzp) agents affect LA and HA animals differently In this study we investigated the GABA-Bzp influence on the modulation of AEP in rats with low (LA) or high-anxiety (HA) levels, as assessed by the elevated plus maze test (EPM) GABA-Bzp modulation on the unconditioned AEP response was analyzed by using intra CIC injections (0 2 mu l) of the GABA-Bzp agonists muscimol (121 ng) and diazepam (30 mu g) or the GABA inhibitors bicuculline (10 ng) and semicarbazide (7 mu g) In a second experiment, we evaluate the effects of contextual aversive conditioning on AEP using foot shocks as unconditioned stimuli On the unconditioned fear paradigm GABA inhibition in creased AEP in LA rats and decreases this measure in HA counterparts Muscimol was effective in reducing AEP in both LA and HA rats Contextual fear stimuli increased the magnitude of AEP In spite of no effect obtained with diazepam in LA rats the drug inhibited AEP in HA animals The specificity of the regulatory mechanisms mediated by GABA Bzp for the ascending neurocircuits responsible for the acquisition of aversive information in LA and HA animals shed light on the processing of sensory information underlying the generation of defensive reactions (C) 2010 IBRO Published by Elsevier Ltd All rights reserved

Overshadowing in conditioned taste aversion or in conditioned emotional response after neonatal ventral hippocampal lesions in rats

The neonatal hippocampus lesion thought to model schizophrenia should show the same modifications in behavioural tests as other models, especially pharmacological models. namely decreased latent inhibition, blocking and overshadowing. The present study is set out to evaluate overshadowing in order to complement our previous studies, which had tested latent inhibition. ""Overshadowing"" refers to the decreased conditioning that occurs when the to-be-conditioned stimulus is combined with another stimulus at the conditioning stage. We used the same two Pavlovian conditioning paradigms as in our previous works, namely conditioned taste aversion (CTA) and conditioned emotional response (CER). A sweet taste overshadowed a salty conditioned stimulus, and a tone overshadowed a flashing light. Totally different stimuli were used to counter possible sensory biases. The protocols were validated with two groups of Sprague Dawley rats. The same two protocols were then applied to a cohort of rats whose ventral hippocampus had been destroyed when they were 7 days old. Only rats with extended ventral hippocampus lesions were included. The overall effect of Pavlovian conditioning was attenuated, significantly so in the conditioned emotional response paradigm, but overshadowing appeared not to be modified in either the conditioned emotional response or the conditioned taste aversion paradigm. (C) 2008 Elsevier B.V. All rights reserved.

Central substance P NK(1) receptors are involved in fever induced by LPS but not by IL-1 beta and CCL3/MIP-1 alpha in rats

Substance P (SP) is a neuropeptide that can modulate inflammatory mediator release through activation of NK(1) receptors (NK(1)R). Some studies have also suggested the involvement of SP in lipopolysaccharide (LPS)-induced fever. However, the precise contribution of this neuropeptide to the pathways activated during fever is unknown. In this study we investigated the effect of a selective NK(1)R antagonist, SR140333B, on the febrile response induced by LPS and cytokines. Our results show that the systemic injection of SR140333B did not modify the fever induced by LPS at a dose that is able to reduce protein extravasation induced by SP in the skin. On the other hand, intracerebroventricular administration of 5R140333B significantly reduced the fever induced by peripheral injection of LPS. These data emphasize an important role for SP in the central nervous system during the febrile response to LPS, and are reinforced by the fact that intracerebroventricular injection of SP also induced fever in a dose-dependent manner in captopril-treated rats. Considering that the febrile response can result from the generation of several endogenous pyrogens, among them interleukin (IL)-1 beta and macrophage inflammatory protein-1 alpha (CCL3/MIP-1 alpha), we also examined the effect of SR140333B on the fever induced by these cytokines which act through prostaglandin-dependent and independent mechanisms, respectively. Surprisingly, SR140333B did not modify the febrile response to IL-1 beta or CCL3/MIP-1 alpha. Altogether these data suggest that the central action of SP is essential for LPS-, but not for IL-1 beta- or CCL3/MIP-1 alpha-induced fever. (C) 2011 Elsevier B.V. All rights reserved.

Glucose and Fructose Fermentation by Wine Yeasts in Media Containing Structurally Complex Nitrogen Sources

Glucose and fructose fermentations by industrial yeasts strains are strongly affected by both the structural complexity of the nitrogen Source and the availability of oxygen. In this Study two Saccharomyces cerevisiae industrial wine strains were grown, under shaken and static conditions, in a media containing either a) 20% (w/v) glucose, or b) 10% (w/v) fructose and 10% (w/v) glucose or c) 20% (w/v) fructose, all supplemented with nitrogen Sources varying from a single ammonium salt (ammonium Sulfate) to free amino acids (casamino acids) and peptides (peptone). Data Suggest that 1 complex Structured nitrogen source is not submitted to the same control mechanisms as those involved in the utilization of simpler structured nitrogen Sources, and mutual interaction between carbon and nitrogen Sources, including the mechanisms involved ill the regulation of aerobic/anaerobic metabolism, may play in important role in defining yeast fermentation performance and the differing response to the structural complexity of the nitrogen Source, with a strong impact oil fermentation performance.

Improvement in Insulin Sensitivity and B-Cell Function Following Ileal Interposition with Sleeve Gastrectomy in Type 2 Diabetic Patients: Potential Mechanisms

Bariatric surgery in morbidly obese type 2 diabetic (T2DM) patients is associated with high rates of diabetes remission. We investigated the mechanisms of the anti-diabetic effect of the laparoscopic ileal interposition with sleeve gastrectomy (LII-SG) in normal weight (NW), overweight (OW) and obese (OB) T2DM patients. Ninety-four patients (aged 54 +/- 8 years) with long-standing (median 10 years), treated diabetes (median HbA(1c) = 8.6%), who were NW (15), OW (64) or OB (15) based on BMI, underwent LII-SG. Insulin sensitivity and parameters of -cell function were measured from an Oral Glycaemic Tolerance Test pre- and post-operatively. At a median of 13.4 months post-operatively, weight loss averaged 9.4 +/- 1.3, 16.8 +/- 0.8 and 23.2 +/- 1.7 kg in NW, OW and OB subjects, respectively (p < 0.0001). Insulin sensitivity was fully restored (395 [108] vs 208 [99] ml min(-1) m(-2)), fasting insulin secretion rate decreased (68 [52] vs 146 [120] pmol min(-1) m(-2)) and total insulin output increased (52 [26] vs 39 [28] nmol m(-2), all p a parts per thousand currency signaEuro parts per thousand 0.001). -cell glucose sensitivity doubled (37 [33] vs 18 [24] mol min(-1) m(-2) mM(-1), p < 0.0001). The only parameter predicting remission of diabetes was a lower baseline insulin sensitivity (p = 0.005). LII-SG induced changes on T2DM by mechanisms in part distinct from weight loss, principally involving restoration of insulin sensitivity and improvement of -cell function.