ABSTRACT
The armyworm, Spodoptera frugiperda, is the principal pest of corn in Brazil. Control is achieved primarily by synthetic insecticides, which cause problems for the agro-ecosystem. Alternative methods of control are under investigation and citronella (Cymbopogon winterianus) essential oil appears to be a promising agent. We investigated the effects of citronella oil using histological, histochemical and immunohistochemical methods. The midgut of larvae treated with citronella exhibited altered epithelium including cytoplasmic protrusions, columnar cell extrusion, pyknotic nuclei, and increased periodic acid-Schiff positive granules. Regenerative cells in the epithelium of the midgut increased in number, which facilitated subsequent regeneration of this tissue. After exposure to citronella, trophocytes, the principal cell type of the fat body, possessed enlarged vacuoles and mitotic bodies, and contained reduced amounts of glycogen, lipid, and protein. Citronella oil caused morphological changes of the midgut and reduction of stored resources in the fat body, which may adversely affect insect reproduction and survival.
Subject(s)
Digestive System/drug effects , Plant Oils/pharmacology , Spodoptera/drug effects , Animals , Biological Assay , Chromatography, Gas , Dose-Response Relationship, Drug , Fat Body , Mass Spectrometry , Reference StandardsABSTRACT
Avaliou-se o efeito da administração de dexametasona no início e no meio da gestação de ratas, sobre os perfis glicídicos e hematológicos materno e da prole. Os animais foram submetidos aos seguintes tratamentos: dexametasona do primeiro ao sétimo dia e placebo do oitavo ao 14º dia; placebo do primeiro ao sétimo dia e dexametasona do oitavo ao 14º dia; dexametasona do primeiro ao 14º dia e placebo do primeiro ao 14º dia de gestação. A dexametasona foi administrada por via intraperitoneal, na dose de 0,8mg/kg. Foram coletadas amostras de sangue no sétimo, 14º e 21º dias de gestação, e de sangue e tecido hepático da prole no quinto, 10º e 15º dias pós-natal. Para a verificação das reservas de glicogênio hepático da prole, cortes histológicos foram corados pelo ácido periódico de Schiff. Os resultados apontam para um efeito tempo-dependente da administração de dexametasona durante a gestação, levando a alterações temporais distintas na hematologia e na concentração plasmática de carboidratos nas matrizes e na prole.
The effect of the administration of dexamethasone at the beginning and middle of the pregnancy in rats on hematological and glicidic maternal and offspring profile was evaluated. The animals underwent the following treatments: dexamethasone from the first to the seventh day and placebo from the 8th to the 14th day, placebo from the first to the seventh day and dexamethasone from the 8th to the 14th day; dexamethasone from the 1st to the 14th day, and placebo treatment from the first to the 14th day of gestation. Dexamethasone was administered intraperitoneally at a dose of 0.8 mg/kg. Blood samples were collected on the 7th, 14th and 21st days of pregnancy, and blood and liver tissue of offspring on the fifth, 10th and 15th days postnatal. For verification of the reserves of liver glycogen on the offspring, histological sections were stained with periodic acid-Schiff. The results point to a time-dependent effect of dexamethasone during pregnancy, leading to different temporal changes in hematology and plasma levels of carbohydrates in headquarters and in the offspring.
