Neuropharmacological effects of Phoneutria nigriventer venom on astrocytes.
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 Ca(2+) 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™ 488-conjugated phalloidin probe), the G-actin/F-actin ratio was determined, and the expression level of connexin 43 (Cx43) was assessed. Incubation in Ca(2+)-free buffer did not change the Ca(2+) responses. However, pre-incubation in thapsigargin/caffeine completely abolished these responses, suggesting that PNV-evoked Ca(2+) transients were from intracellular Ca(2+) stores. Pretreatment with a Na(+)/K(+)-ATPase antagonist (ouabain) or a TLR4 antagonist (LPS-RS) decreased or increased the Ca(2+)-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.
Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), 13 083-970 Campinas, SP, Brazil.
Catarina
C
Rapôso
Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, SE 413 45 Gothenburg, Sweden.
Ulrika
U
Björklund
Department of General Biology, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), 31270-901 Belo Horizonte, MG, Brazil.
Evanguedes
E
Kalapothakis
Department of Anaesthesiology and Intensive Care Medicine, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, SE 413 45, Gothenburg, Sweden.
Björn
B
Biber
Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), 13 083-970 Campinas, SP, Brazil.
Maria
M
Alice da Cruz-Höfling
Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, SE 413 45 Gothenburg, Sweden. Electronic address: elisabeth.hansson@neuro.gu.se.
Elisabeth
E
Hansson
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D005260:Female; D008297:Male; D009479:Neuropeptides / Q000302:isolation & purification / Q000633:toxicity*; D009498:Neurotoxins / Q000302:isolation & purification / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013112:Spiders
D009479:Neuropeptides; D009498:Neurotoxins; C064022:Tx1 neurotoxin
Arthropod venom; Astrocytes; Ca(2+) responses; Glutamate; Stress fibers; TLR4