Ipomoea carnea toxicity study in rats during perinatal period. Evaluation of possible harmful effects on the placental tissue

Author(s)

Luciana Lucinio Lippi

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2009-09-10

Examining board members

Silvana Lima Górniak; Estela Maris Andrade Forell Bevilacqua; Helenice de Souza Spinosa

• Advisor: Silvana Lima Górniak

Abstract

Ipomoea carnea is a toxic plant widely distributed in Brazil and other tropical countries. During periods of drought, animals graze on this plant which grows even in the presence of adverse climatic conditions. After prolonged periods of plant intake, the animals exhibit a variety of clinical signs as depression, general weakness, body weight loss, staggering gait, muscle tremors, ataxia, posterior paresis, and paralysis. Two kinds of toxic principles were isolated from the plant, the nortropane alkaloids calystegines B1, B2, B3 and C1 and mainly the indolizidine alkaloid swainsonine. The latter alkaloid is a potent inhibitor of two distinct intracellular enzymes, the lysosomal α-mannosidase which results in lysosomal accumulation of incompletely processed oligosaccharides moieties inside vacuoles, which progresses to cellular function loss and, ultimately, to cell death and the Golgi mannosidase II enzyme causes alteration of the N-linked glycoprotein process, modifying the glycoprotein synthesis, processing and carrier. Histologically, cellular vacuolization of Purkinje cells, thyroid follicles, exocrine pancreas, liver and kidney cells have been observed. Recently, many studies in our laboratory have shown that Ipomoea carnea have teratogenic effects in rats, goats and rabbits. However, it is not known yet if the alterations observed in the fetuses are due to alterations in the placenta or if they can be directly related to the transplacental transfer of the active principle. The present study was performed to evaluate the effects of Ipomoea carnea in the placental tissue and in the litter of female rats treated during. Pregnant rats of the experimental groups were treated orally by gavage, once a day from GD6 to GD19, with 1,0; 3,0; 7,0 g/kg of Ipomoea carnea AF. The control and peer-feeding group received tap water by gavage. Total body weight gain, water and food consumption were measured each three days during the experimental period. At the end of pregnancy period some animals were, for cesarean section, mainly for evaluation of placental tissue and the other animals followed the pregnancy until the birth to the term analysis of offspring. From the animals that came from the cesarean section, were collected the fetuses and their placental, those being collected for anatomopathological, histochemistry (lectins and TUNEL) and morphometric analysis, as the fetuses measured about their sizes and weight and assessed to external malformation and bone and visceral analysis and performed the reproductive performance of those females. The pregnants that followed up to the birth of their offspring, which were assessed regarding their physical and reflexology development daily and at days 4, 8, 15 e 22 of lactation, an offspring of each mother was euthanized so representatives fragments of the liver, kidney, SNC and pancreas could be collected for a histopathological assessment, this procedure was also performed at those mothers submitted to the cesarean section at the 20th pregnancy day, as well as at the breastfeeding at the 22nd lactation day. The obtained results clearly show the teratogenic potential produced by the Ipomoea carnea, because both the fetuses as the pups had some congenital anomalies, decrease in birth weight and the delayed negative geotaxis. At both the mother and offsprings liver and kidneys was observed a vacuolar degeneration, showing the maternal and fetal toxicity promoted by the plant exposed during the pregnancy period. An important data noted here refers to the placental tissue assessment, which showed some histopathological alterations, as the labirinth zone thickening and the reduction of the junctional zone thickness, however the vacuolar degeneration was not observed in this organ, although when performed the lectin-histochemistry technique, it was possible to observe the accumulation of some sugars in some cells located at several regions of the placenta, this way showing that this tissue has also suffered some injury promoted by the plant action, not being possible anymore to consider this organs just as a plac of passage for these toxic active principle. (AU)