Neuropeptides and neurotransmitters in the central nervous system of a disease vector insect. Effect of jaburetox-2EC

SETTEMBRINI BEATRIZ P; GALVANI GERÓNIMO L.; AGUIRRE SA; CANAVOSO LILIAN; CARLINI CÉLIA

New Orleans

Congreso; 42nd annual meeting of the Society for Neuroscience; 2012

Society for Neuroscience

Triatoma infestans is the main insect vector of Chagas´ disease in southern-cone countries. The objective of the presence work was to study the distribution of neuropeptides and neurotransmitters which might be related to activities of the insect involved in the transmission of the disease. The effect of the administration of the entomotoxic peptide jaburetox-2EC (J-2EC), on the expression of these neuroactive molecules was also evaluated. Allatostatin (ALA) is one of these candidates. Its distribution in the brain was analyzed by means of immunocytochemistry. In the protocerebrum, ALA-like immunoreactive (Li) somata were present in the calices of the mushroom bodies and in the pars intercerebralis. The antennal lobe contained numerous immunopositive somata and the glomeruli showed immunostained varicose fibers. Stained cell bodies were also detected in the antennal mechanosensory and motor center. The finding of immunoreactivity in areas related to olfactory behaviour suggested us to combine the analysis of ALA-Li with that of nitric oxide synthase (NOS) the enzyme which catalyzes the formation of NO, a molecule with a recognized function in insect olfaction and chemoreception. The possible coexistence of both markers was evaluated by incubating brain sections with ALA antiserum followed by NADPH-diaphorase histochemical reaction. It was found that both markers coexisted in specific somata of the antennal lobe. Catechols derived from tyrosine are generated by the activity of tyrosine hydroxilase. Two isoforms of this enzyme are present in insects; the shorter form is expressed in neural cells. Using an antiserum directed against Manduca sexta recombinant TH we observed, immunoreactive somata in the anteromedial protocerebum, the optic lobe and the lateral cell body layer of the antennal lobe. When analyzing the expression ALA, TH and NOS in bugs treated with J-2EC only the expression of NOS was affected. The number of NOS-Li somata decreased in treated insects while the activity of the enzyme decreased 75% in brain homogenates incubated with the peptide. These results confirm that NOS is a main early target of J-2EC in T. infestans.