Avaliação do perfil glicídico e da biologia reprodutiva de Biomphalaria glabrata (Mollusca) experimentalmente co-infectada por Angiostrongylus cantonensis (Nematoda) e Echinostoma paraensei (Trematoda)

Abstract

The interaction between intermediate hosts and helminths can cause metabolic and reproductive changes in the host snail, they start using their reserves to maintain its vital functions, immune system activation, repair of tissue damage and also to supply the necessary energy for the parasites development. Investigations of co-infection by different helminths can provide essential information about the biology of their co-existence. Our aims are investigate the reproductive changes, evaluate the activity of lactate dehydrogenase and the concentrations of glucose in the hemolymph and glycogen in the digestive gland complex and cephalopedal mass, and also verify histological and histochemical changes of Biomphalaria glabrata experimentally co-infected with Echinostoma paraensei and Angiostrongylus cantonensis. Five groups of snails i.e. uninfected, with single and double infections, either E. paraensei first (E+A) or A. cantonensis first (A+E) were followed; three times a week during four weeks the numbers of egg masses, eggs and hatched snails were counted. Histological and histochemical samples of the ovotestis, albumen gland, digestive gland complex and cephalopedal mass were collected after four weeks as well samples for the biochemical analysis. The number of egg masses/snail, eggs/snail and hatched snails showed significant differences comparing the control group to all infected groups, especially in group E + A, with the majority of values of parameters analyzed lower than 50% of those observed for control snails. A significant decrease in glucose levels and glycogen content, in contrast an increase of lactate dehydrogenase activity was observed in the infected snails. These results indicate intense energy demand that takes the snail increasing the anaerobic degradation of carbohydrates in the infected snails to obtain energy in an attempt to maintain homeostasis. The histological analysis showed that presence of both parasites in the all organs analyzed and the parasites were associated with cell disorganization.