Neuropeptides and nitric oxide in the brain of a disease vector insect

SETTEMBRINI BP; TORBIDONI ANA V; GONZALEZ A; GALVANI GL

Florencia

Congreso; 8th World Congress of Neuroscience; 2011

International Brain Research Organization

Triatoma infestans is the main insect vector of Chagas disease in southern cone countries. Several neuropeptides have been localized in the cephalic ganglia of this insect species. One of them is allatostatin, which has been detected in the central nervous of several insect species. Using an antibody directed against the amino acid sequence of the cockroach, AYSYVSEYKALPVYNFLG-NH2, the presence of allatostatin and its coexistence with other neuroactive molecules has been analyzed. In the brain of T. infestans, allatostatin-like immunoreactive somata were found in relationship to 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. A high density of immunoreactive fibers were present in the tritocerebral neuropil. Tthe optic medulla and lobula neuropils showed allatostatin-like immunoreactivity while stained somata at the level of the lobula and in the proximal optic lobe. Coexistence of allatostatin with nitric oxide synthase was evaluated by incubating sections of the brain with the anti-allatostatin antibody followed by the NADPH-diaphorase histochemical reaction. It was found that both markers were present in somata of the antennal lobe and at the base of the optic lobes. It was also found that the expression of NO synthase decreased when the insects were treated with urease-derived peptides. The coexistence between allatostatin and serotonin as well as that of allatostatin and small cardioactive peptide B was analyzed using double labeling immunohistochemistry.It was found that no soma expressed allatostatin and serotonin simultaneously. Instead, somata expressing both allatostatin- and small cardioactive peptide B-like immunoreactivities were detected in the posterior protocerebrum and in the pars intercerebralis. The distribution of allatostatin in the brain of this insect species suggests neuroendocrine and neurotransmitter roles for the neuropeptide in this species.