title: Histopathological findings in rabbits after experimental acute exposure to the Loxosceles intermedia (brown spider) venom.
abstract: Loxoscelism, the term used to describe envenomation with brown spiders, is characterized by a dermonecrotic lesion at the bite site. In the present investigation we submitted albino rabbits to an acute experimental envenomation protocol using Loxosceles intermedia (brown spider) venom, with in order to determine the pathogenesic features of the lesion induced by this spider, which is the cause of several accidents throughout the world. Rabbits received intradermal injections of the venom and were monitored over the first 4 h, and then at 12 h and 1, 2 and 5 days after envenomation. Histological specimens from 3 rabbits per time point were collected from euthanized animals and processed for histological examination by light microscopy. Major findings observed during the first 4 h were oedema, haemorrhage, degeneration of blood vessel walls, plasma exudation, thrombosis, neutrophil accumulation in and around blood vessels with an intensive diapedesis, a diffuse collection of inflammatory cells (polymorphonuclear leucocytes) in the dermis, and subcutaneous muscular oedema. Over the following hours and up to 5 days after envenomation the changes progressed to massive neutrophil infiltration (with no other leucocytes) into the dermis and even into subcutaneous muscle tissue, destruction of blood vessels, thrombosis, haemorrhage, myonecrosis, and coagulative necrosis on the 5th day.
authors.affiliation: Department of Cell Biology, Federal University of Parana, Jardim das Américas, 81531-990 Curitiba, Parana, Brazil.
authors.forename: Katia Zoghbi
authors.initials: KZ
authors.lastname: Ospedal
authors.forename: Marcia Helena
authors.initials: MH
authors.lastname: Appel
authors.forename: José
authors.initials: J
authors.lastname: Fillus Neto
authors.forename: Oldemir Carlos
authors.initials: OC
authors.lastname: Mangili
authors.forename: Silvio
authors.initials: S
authors.lastname: Sanches Veiga
authors.forename: Waldemiro
authors.initials: W
authors.lastname: Gremski
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000473:pathology; D004487:Edema / Q000139:chemically induced / Q000473:pathology; D006470:Hemorrhage / Q000139:chemically induced; D007271:Injections, Intradermal; D018482:Muscle, Skeletal / Q000276:immunology / Q000473:pathology*; D009336:Necrosis; D020556:Neutrophil Infiltration; D011817:Rabbits; D012867:Skin / Q000276:immunology / Q000473:pathology*; D001098:Spider Bites / Q000473:pathology*; D013111:Spider Venoms / Q000633:toxicity*; D013927:Thrombosis / Q000139:chemically induced; D013997:Time Factors
chemical_list: D013111:Spider Venoms