Agradecimentos: The authors thank Miguel Silva and Antonio Vilson dos Santos for excellent animal care. The work was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior (CAPES), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, grant no. 2005/53625-1) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, grant nos. 508806/ 2010-0 and 486142/2012-4). ESS was supported by a studentship from CNPq, and MCPM was supported by a studentship from FAPESP. MACH is a CNPq level 1A Research Fellow (grant no. 302206/2008- 6). This study was part of an MSc dissertation by ESS. The authors thank the National Institute of Science and Technology on Photonics Applied to Cell Biology (INFABIC/UNICAMP) for assistance and access to equipment (FAPESP grant no. 08/57906-3; CNPq grant no. 573913/2008-0) Ver menos

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 Ver menos