Interaction between 5-HT1B receptors and nitric oxide in zebrafish responses to novelty

AbstractNitric oxide (NO) and serotonin (5-HT) interact at the molecular and systems levels to control behavioral variables, including agression, fear, and reactions to novelty. In zebrafish, the 5-HT1B receptor has been implicated in anxiety and reactions to novelty, while the 5-HT1A receptor is associated with anxiety-like behavior; this role of the 5-HT1A receptor is mediated by NO. This work investigated whether NO also participates in the mediation of novelty responses by the 5-HT1B receptor. The 5-HT1B receptor inverse agonist SB 224,289 decreased bottom-dwelling and erratic swimming in zebrafish; the effects on bottom-dwelling, but not on erratic swimming, were blocked by pre-treatment with the nitric oxide synthase inhibitor L-NAME. These effects underline a novel mechanism by which 5-HT controls zebrafish reactivity to novel environments, with implications for the study of neotic reactions, exploratory behavior, and anxiety-like states

Local inhibition of nitrergic activity in tenotomized rats accelerates muscle regeneration by increasing fiber area and decreasing central core lesions

Muscular atrophy is a progressive degeneration characterized by muscular proteolysis, loss of mass and decrease in fiber area. Tendon rupture induces muscular atrophy due to an intrinsic functional connection. Local inhibition of nitric oxide synthase (NOS) by No-nitro-L-arginine methyl ester (L-NAME) accelerates tendon histological recovery and induces functional improvement. Here we evaluate the effects of such local nitrergic inhibition on the pattern of soleus muscle regeneration after tenotomy. Adult male Wistar rats (240 to 280 g) were divided into four experimental groups: control (n=4), tenotomized (n=6), vehicle (n=6), and L-NAME (n=6). Muscular atrophy was induced by calcaneal tendon rupture in rats. Changes in muscle wet weight and total protein levels were determined by the Bradford method, and muscle fiber area and central core lesion (CCL) occurrence were evaluated by histochemical assays. Compared to tenotomized (69.3±22%) and vehicle groups (68.1%±17%), L-NAME treatment induced an increase in total protein level (108.3±21%) after 21 days post-injury. A reduction in fiber areas was observed in tenotomized (56.3±1.3%) and vehicle groups (53.9±3.9%). However, L-NAME treatment caused an increase in this parameter (69.3±1.6%). Such events were preceded by a remarkable reduction in the number of fibers with CCL in L-NAME-treated animals (12±2%), but not in tenotomized (21±2.5%) and vehicle groups (19.6±2.8%). Altogether, our data reveal that inhibition of tendon NOS contributed to the attenuation of atrophy and acceleration of muscle regeneration

Entamoeba histolytica : ouabain-insensitive Na+-ATPase activity

6 p. : il.Our aim was to determine the presence of sodium pumps in Entamoeba histolytica. It is shown through the measurement of ouabainsensitive ATPase activity and immunoblotting that E. histolytica does not express (Na++K+)ATPase. On the other hand, we observed a Na+-ATPase with the following characteristics: (1) stimulated by Na+ or K+, but these effects are not addictive; (2) the apparent affinity is similar for Na+ and K+ (K0.5 = 13.3 ± 3.7 and 15.4 ± 3.1 mM, respectively), as well as the Vmax (24.9 ± 1.5 or 27.5 ± 1.6 nmol Pi mg 1 min 1, respectively); (3) insensitive up to 2 mM ouabain; and (4) inhibited by furosemide with an IC50 of 0.12 ± 0.004 mM. Furthermore, this enzyme forms a Na+- or K+-stimulated, furosemide- and hydroxylamine-sensitive ATP-driven acylphosphate phosphorylated intermediate

Entamoeba histolytica : an ecto-phosphatase activity regulated by oxidation–reduction reactions

7 p. : il.In this work, an ecto-phosphatase activity of Entamoeba histolytica was characterized using intact cells. This activity presented the following biochemical characteristics: (i) it hydrolyzes p-NPP with Vmax of 8.00 ± 0.22 nmol p-NP · h 1 · 10 5 cells and Km of 2.68 ± 0.25 mM; (ii) it is inhibited by acid phosphatase inhibitors, such as sodium molybdate (Ki = 1.70 ± 0.24 lM) and sodium fluoride (Ki = 0.25 ± 0.02 mM); (iii) it also showed high sensitivity to phosphotyrosine phosphatase inhibitors, such as sodium orthovanadate (Ki = 1.07 ± 0.14 lM), bpV-PHEN (Ki = 0.38 ± 0.02 lM) and mpV-PIC (Ki = 0.39 ± 0.04 lM). Zn2+, an oxidizing agent, decreased the enzymatic activity in 50%. DTT and GSH, two reducing agents, enhanced the activity twofold. The non-invasive E. histolytica and free-living E. moshkovskii were less efficient in hydrolyzing p-NPP than the pathogenic E. histolytica suggesting that this enzyme could represent a virulence marker for this cell

Receptors A3A modulam o comportamento e o sistema serotonérgico no zebrafish: Mediação pela via do óxido nítrico

<p>Poster presented at 36th meeting from the Brazilian Neurosciences and Behavior Society</p

A3 adenosine receptors modulate behavior and serotonergic system in zebrafish: Mediation by the nitric oxide pathway

<p>Extracellular serotonin (5-HT) levels in the brain are thought to mediate many different behavioral functions, including anxiety and stress; the main mechanism to regulate extracellular 5-HT levels is through reuptake, which are regulated by a plethora of mechanisms. Here, we demonstrate that activation of A3 adenosine receptors by IB-MECA decreases scototaxis, geotaxis, neophobia and arousal in zebrafish in vivo, increases extracellular brain 5-HT levels ex vivo, and increases 5-HT uptake in vitro. The effects of IB-MECA on 5-HT uptake, on extracellular 5-HT concentrations and on scototaxis are dependent on L-type calcium channels, nitric oxide synthase, and serotonin transporters; the effects of IB-MECA on geotaxis, on the other hand, are dependent on nitric oxide synthase, but not on serotonin transporters or calcium channels. These results underline a potential target to control 5-HT uptake and its behavioral consequences.</p

Occurrence of strongyloidiasis among patients with HTLV-1/2 seen at the outpatient clinic of the Núcleo de Medicina Tropical, Belém, State of Pará, Brazil

Introduction This study investigated the occurrence of Strongyloides stercoralis infestation and coinfection with HTLV-1/2 in Belém, Brazil. Methods S. stercoralis was investigated in stool samples obtained from individuals infected with HTLV-1/2 and their uninfected relatives. Results The frequency of S. stercoralis was 9% (9/100), including six patients infected with HTLV-1 (14.3%), two patients infected with HTLV-2 (11.1%), and one uninfected relative. Two cases of hyperinfestation by S. stercoralis were characterized as HTLV-1. Conclusions These results support the need for the routine investigation of S. stercoralis in patients with HTLV-1, in an attempt to prevent the development of severe forms of strongyloidiasis

Análise das variáveis comportamentais em diferentes linhagens selvagens de zebrafish: Papel das monoaminas cerebrais

<p>Poster presented at the 36th Meeting of the Brazilian Society for Neurosciences and Behavior (SBnEC)</p

Ação da fluoxetina e WAY100,635 nos processos neuroquímicos, ativação simpática e analgesia induzida pela substância de alarme em paulistinhas adultos (Danio rerio)

<p>Poster presented at SBnEC 2014</p