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- Nunes, A. K. D., et al.
(författare)
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Sildenafil (Viagra (R)) prevents and restores LPS-induced inflammation in astrocytes
- 2016
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Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940. ; 630, s. 59-65
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Tidskriftsartikel (refereegranskat)abstract
- Astrocytes are effectively involved in the pathophysiological processes in the central nervous system (CNS) and may contribute to or protect against development of inflammatory and degenerative diseases. Sildenafil is a potent and selective phosphodiesterase-5 (PDE-5) inhibitor, which induces cyclic GMP accumulation. However, the mechanisms of actions on glial cells are not clear. The aim of the present work is to evaluate the role of sildenafil in lipopolysaccharide (LPS)-stimulated astrocytes. The cytoskeleton integrity and Ca2+ waves were assessed as indicators of inflammatory state. Two main groups were done: (A) one prevention and (B) one restoration. Each of these groups: A1: control; A2: LPS for 24h; A3: sildenafil 1 or 10 mu M for 4h and then sildenafil 1 or 10 mu M + LPS for 24 h. B1: control; B2: LPS for 24 h; B3: LPS for 24 h and then LPS + sildenafil 1 or 10 mu M for 24 h. Cytoskeleton integrity was analyzed through GFAP immunolabeling and actin labeling with an Alexa 488-conjugated phalloidin probe. Calcium responses were assessed through a Ca2+-sensitive fluorophore Fura-2/AM. The results show that both preventive and restorative treatments with sildenafil (in both concentrations) reduced the Ca2+ responses in intensity and induced a more organized actin fiber pattern, compared to LPS treated cells. This work demonstrated for the first time that astrocytes are a key part of the sildenafil protective effects in the CNS.
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- Raposo, C., et al.
(författare)
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Neuropharmacological effects of Phoneutria nigriventer venom on astrocytes
- 2016
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Ingår i: Neurochemistry International. - : Elsevier BV. - 0197-0186. ; 96, s. 13-23
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Tidskriftsartikel (refereegranskat)abstract
- Bites from genus Phoneutria (Ctenidae, Araneomorpha) are the second most frequent source of spider accidents in Southeast Brazil. Severe envenoming from Phoneutria nigriventer produces vision disturbance, tremor and convulsion, suggesting that the CNS is involved; however, the mechanisms by which P. nigriventer venom (PNV) affects the CNS remain poorly understood. The present study aimed to investigate whether PNV directly impairs astrocytes. Cultured astrocytes were exposed to PNV, and intracellular Ca2+ release and signaling were measured (Fura-2/AM), Na+/K+-ATPase and Toll-like receptor 4 (TLR4) involvement were investigated, actin filaments were stained (Alexa (TM) 488-conjugated phalloidin probe), the G-actin/F-actin ratio was determined, and the expression level of connexin 43 (Cx43) was assessed. Incubation in Ca2+-free buffer did not change the Ca2+ responses. However, pre-incubation in thapsigargin/caffeine completely abolished these responses, suggesting that PNV-evoked Ca2+ transients were from intracellular Ca2+ stores. Pretreatment with a Na+/K+-ATPase antagonist (ouabain) or a TLR4 antagonist (LPS-RS) decreased or increased the Ca2+-evoked transients, respectively. Astrocytes showed altered actin filament structure after PNV exposure. PNV treatment increased the expression levels of Na+/K+-ATPase and Cx43 but decreased those of TLR4. The present results suggest that PNV directly affects astrocytes. Na+/K+-ATPase may thus represent a more specific drug target for controlling the neurotoxicity of PNV. (C) 2016 Elsevier Ltd. All rights reserved.
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