Influence of brain and azadirachtin on Trypanosoma cruzi development in the vector, Rhodnius prolixus

Studies on the effects of decapitation, head transplantation, azadirachtin, and ecdysone therapy on the ultrastructural organization of the midgut of Rhodnius prolixus, a vector of the protozoan Trypanosoma cruzi, show a dist inct effect on the organization of the epithelial cells. When insects are d ecapitated or treated with azadirachtin, the ultrastructural organization o f these compartments changed significantly and drastically blocked the deve lopment of T. cruzi infection. In converse experiments, head transplantatio n or oral therapy with ecdysone significantly reversed the T. cruzi infecti vity and reestablished the organization of the stomach and intestine in dec apitated or azadirachtin-treated insects. These results indicat that a brai n factor, possibly the prothoracicotropic hormone which stimulates ecdyster oid production on the prothoracic glands, may act directly or indirectly on both the midgut cell organization and the intestinal microenvironment inte rfering in the trypanosome survival and infection of the vector R prolixus. (C) 1999 Academic Press.