title: Age-Related Modulations of AQP4 and Caveolin-1 in the Hippocampus Predispose the Toxic Effect of Phoneutria nigriventer Spider Venom.
abstract: We have previously demonstrated thatPhoneutria nigriventervenom (PNV) causes blood-brain barrier (BBB) breakdown, swelling of astrocytes end-feet and fluid permeation into brain interstitium in rats. Caveolae and water channels respond to BBB alterations by co-participation in shear stress response and edema formation/resolution. Herein, we showed post-natal developmental-related changes of two BBB-associated transporter proteins: the endothelial caveolin-1 (Cav-1), the major scaffolding protein from caveolae frame, and the astroglial aquaporin-4 (AQP4), the main water channel protein expressed in astrocytic peri-vascular end-feet processes, in the hippocampus of rats intraperitoneally-administered PNV. Western blotting protein levels; immunohistochemistry (IHC) protein distribution in CA1, CA2, and CA3 subfields; and gene expression by Real Time-Polymerase Chain Reaction (qPCR) were assessed in post-natal Day 14 (P14) and 8-10-week-old rats over critical periods of envenomation. The intensity and duration of the toxic manifestations indicate P14 neonate rats more vulnerable to PNV than adults. Histologically, the capillaries of P14 and 8-10-week-old rats treated with PNV showed perivascular edema, while controls did not. The intensity of the toxic manifestations in P14 decreases temporally (2 > 5 > 24 h), while inversely the expression of AQP4 and Cav-1 peaked at 24 h when clinically PNV-treated animals do not differ from saline controls. IHC of AQP4 revealed that hippocampal CA1 showed the least expression at 2 h when toxic manifestation was maximal. Subfield IHC quantification revealed that in P14 rats Cav-1 peaked at 24 h when toxic manifestations were absent, whereas in 8-10-week-old rats Cav-1 peaked at 2 h when toxic signs were highest, and progressively attenuated such increases until 24 h, remaining though significantly above baseline. Considering astrocyte-endothelial physical and functional interactions, we hypothesize that age-related modulations of AQP4 and Cav-1 might be linked both to changes in functional properties of astrocytes during post-natal development and in the BBB breakdown induced by the venom ofP. nigriventer.
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas, Campinas, SP 13083-863, Brazil. esiqueirasoares@gmail.com.
authors.forename: Edilene S
authors.initials: ES
authors.lastname: Soares
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas, Campinas, SP 13083-863, Brazil. leilinhabio@yahoo.com.br.
authors.forename: Leila M
authors.initials: LM
authors.lastname: Stávale
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas, Campinas, SP 13083-863, Brazil. mo_padilha@hotmail.com.|Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Campinas, SP 13083-887, Brazil. mo_padilha@hotmail.com.
authors.forename: Monique C P
authors.initials: MC
authors.lastname: Mendonça
authors.affiliation: Laboratory of Cell Signaling, Faculty of Medical Sciences, State University of Campinas, Campinas, SP 13083-887, Brazil. andressacoope@gmail.com.
authors.forename: Andressa
authors.initials: A
authors.lastname: Coope
authors.affiliation: Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas, Campinas, SP 13083-863, Brazil. hofling@unicamp.br.|Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Campinas, SP 13083-887, Brazil. hofling@unicamp.br.
authors.forename: Maria Alice da
authors.initials: MA
authors.lastname: Cruz-Höfling
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D051401:Aquaporin 4 / Q000235:genetics* / Q000378:metabolism; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D001692:Biological Transport; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051242:Caveolin 1 / Q000235:genetics* / Q000378:metabolism; D004487:Edema / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007274:Injections, Intraperitoneal; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D001098:Spider Bites / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D013111:Spider Venoms / Q000008:administration & dosage / Q000302:isolation & purification / Q000633:toxicity*; D013112:Spiders / Q000737:chemistry / Q000472:pathogenicity; D014867:Water / Q000378:metabolism
chemical_list: C496032:Aqp4 protein, rat; D051401:Aquaporin 4; C495537:Cav1 protein, rat; D051242:Caveolin 1; D013111:Spider Venoms; D014867:Water
keywords: aquaporins; caveolin-1; hippocampus; spider venom