Stimulation of peripheral Kappa opioid receptors inhibits inflammatory hyperalgesia via activation of the PI3Kγ/AKT/nNOS/NO signaling pathway

<p>Abstract</p> <p>Background</p> <p>In addition to their central effects, opioids cause peripheral analgesia. There is evidence showing that peripheral activation of kappa opioid receptors (KORs) inhibits inflammatory pain. Moreover, peripheral μ-opioid receptor (MOR) activation are able to direct block PGE₂-induced ongoing hyperalgesia However, this effect was not tested for KOR selective activation. In the present study, the effect of the peripheral activation of KORs on PGE₂-induced ongoing hyperalgesia was investigated. The mechanisms involved were also evaluated.</p> <p>Results</p> <p>Local (paw) administration of U50488 (a selective KOR agonist) directly blocked, PGE₂-induced mechanical hyperalgesia in both rats and mice. This effect was reversed by treating animals with L-NMMA or N-propyl-L-arginine (a selective inhibitor of neuronal nitric oxide synthase, nNOS), suggesting involvement of the nNOS/NO pathway. U50488 peripheral effect was also dependent on stimulation of PI3Kγ/AKT because inhibitors of these kinases also reduced peripheral antinociception induced by U50488. Furthermore, U50488 lost its peripheral analgesic effect in PI3Kγ null mice. Observations made in vivo were confirmed after incubation of dorsal root ganglion cultured neurons with U50488 produced an increase in the activation of AKT as evaluated by western blot analyses of its phosphorylated form. Finally, immunofluorescence of DRG neurons revealed that KOR-expressing neurons also express PI3Kγ (≅ 43%).</p> <p>Conclusions</p> <p>The present study indicates that activation of peripheral KORs directly blocks inflammatory hyperalgesia through stimulation of the nNOS/NO signaling pathway which is probably stimulated by PI3Kγ/AKT signaling. This study extends a previously study of our group suggesting that PI3Kγ/AKT/nNOS/NO is an important analgesic pathway in primary nociceptive neurons.</p

Dual role of hydrogen sulfide in mechanical inflammatory hypernociception

Hydrogen Sulfide (H2S) is an endogenous gas involved in several biological functions, including modulation of nociception. However, the mechanisms involved in such modulation are not fully elucidated. The present Study demonstrated that the pretreatment of mice with PAG, a H2S synthesis inhibitor, reduced LPS-induced mechanical paw hypernociception. This inhibition of hypernociception was associated with the prevention of neutrophil recruitment to the plantar tissue. Conversely, PAG had no effect on LPS-induced production of the hypernociceptive cytokines, TNF-alpha, IL-1 beta and CXCL1/KC and on hypernociception induced by PGE(2), a directly acting hypernociceptive mediator. In contrast with the pro-nociceptive role of endogenous H2S. systemic administration of NaHS, a H2S donor, reduced LPS-induced mechanical hypernociception in mice. Moreover, this treatment inhibited mechanical hypernociception induced by PGE(2), suggesting a direct effect of H2S on nociceptive neurons. The antinociceptive mechanism of exogenous H2S depends on K-(ATP)(+) channels since the inhibition of PGE(2) hypernociception by NaHS was prevented by glibenclamide (K-(ATP)(+) channel blocker). Finally, NaHS did not alter the thermal nociceptive threshold in the hot-plate test, confirming that its effect is mainly peripheral. Taken together, these results suggest that H2S has a dual role in inflammatory hypernociception: 1. an endogenous pro-nociceptive effect due to up-regulation of neutrophil migration. and 2. an antinociceptive effect by direct blockade of nociceptor sensitization modulating K-(ATP)(+) channels. (c) 2008 Elsevier B.V. All rights reserved.FAPESPCNP

Opinião e conhecimento de pacientes e familiares sobre o uso da eletroconvulsoterapia: implicações para a enfermagem Opinion and knowledge of pacients and their relativies of the electroconvulsive therapy: implication for nursing

Neste trabalho verificou-se a opinião e o conhecimento de pacientes internados em uma unidade psiquiátrica e seus familiares, sobre a aceitação do uso da eletroconvulsoterapia. Através de análise quantitativa constatou-se a aprovação da maioria ao tratamento, apesar do escasso conhecimento sobre este, apresentado pelos indivíduos estudados. Constatou-se também que o conhecimento desse tratamento e a confiança depositada no profissional médico que indica o tratamento, parece influir na opinião dos indivíduos sobre seu uso. Desta forma existe a importância do papel do enfermeiro na educação dos indivíduos em relação à eletroconvulsoterapia.<br>The aim of this report was to verify in-patients and their relative's opinion and knowledge of the use of electroconvulsive therapy. By means of a quantitative analysis, the use of this treatment was shown to be accepted despite the individuals knew little about it. It was observed taht the knowledge of this treatment had influence over individual's opinion about it. Thus nurses play an important role on the instruction of these individuals regarding this treatment