title: Are Synchronized Changes in Connexin-43 and Caveolin-3 a Bystander Effect in a Phoneutria nigriventer Venom Model of Blood-Brain Barrier Breakdown?
abstract: Upregulation of caveolin-3 (Cav-3) or connexin-43 (Cx43) in astrocytes has been associated with important brain pathologies. We used Phoneutria nigriventer spider venom (PNV), which induces blood-brain barrier breakdown in rats, in order to investigate Cav-3 and Cx43 expression in the cerebellum over critical periods of rat envenomation. By immunofluorescence, western blotting (WB), and transmission electron microscopy (TEM), we assessed changes at 1, 2, 5, 24, and 72 h post-venom. WB showed immediate increases in Cav-3 and Cx43 at 1 h (interval of greatest manifestations of envenomation) that persisted at 5 h (when there were signs of recovery) and peaked at 24 h when no signs of envenomation were detectable. At 2 and 72 h, Cav-3 was downregulated and Cx43 had returned to baseline. PNV markedly intensified Cx43 in molecular, Purkinje and granular layers and Cav-3 in astrocytes whose colocalization to increased GFAP suggests interaction between reactive astrogliosis and Cav-3 upregulation. TEM showed swollen perivascular astrocytic end-feet and synaptic contact alterations that had generally resolved by 72 h. It is uncertain whether such PNV-induced synchronized changes are an interactive effect between Cav-3 and Cx43, or a bystander effect. Evidences indicate that Cav-3 downregulation coupled to Cx43 return to baseline at 72 h when no signs of envenomation were visible, suggesting homeostasis reestablishment. This experimental model is relevant to studying mechanisms involved in neurological disorders associated with Cav-3 overexpression.
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
authors.forename: Edilene Siqueira
authors.initials: ES
authors.lastname: Soares
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil.|Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
authors.forename: Monique Culturato Padilha
authors.initials: MC
authors.lastname: Mendonça
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil.|Multidisciplinary Research Laboratory, São Francisco University (USF), Bragança Paulista, SP, Brazil.
authors.forename: Thalita
authors.initials: T
authors.lastname: Rocha
authors.affiliation: Department of General Biology, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
authors.forename: Evanguedes
authors.initials: E
authors.lastname: Kalapothakis
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil. hofling@unicamp.br.|Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil. hofling@unicamp.br.
authors.forename: Maria Alice
authors.initials: MA
authors.lastname: da Cruz-Höfling
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D051244:Caveolin 3 / Q000235:genetics / Q000378:metabolism*; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D009498:Neurotoxins / Q000494:pharmacology* / Q000633:toxicity; D051381:Rats; D013111:Spider Venoms / Q000494:pharmacology* / Q000633:toxicity; D013569:Synapses / Q000187:drug effects / Q000378:metabolism
chemical_list: D051244:Caveolin 3; D018031:Connexin 43; D009498:Neurotoxins; D013111:Spider Venoms
keywords: Astrocytes; Caveolin-3; Gap junctions; Phoneutria nigriventer; Ultrastructural changes