Neuroendocrine Regulation of Postprandial Diuresis in Rhodnius prolixus

CAPRIOTTI, NATALIA

CORDOBA

Congreso; XXXIII Congress of the Argentine Society for Research in Neuroscience; 2018

Argentine Society for Research in Neurosciences

Given that hematophagous insects ingest large quantities of blood in a single meal, they should undergo a rapid postprandial diuresis to maintain the homeostasis. The diuresis is regulated by serotonin and neuropeptides, which modulate the secretory activity of the malpighian tubules and the fluid transport and peristaltic waves in the anterior midgut. Diuresis finishes 4 hr postbloodmeal (PBM), when anti-diuresis processes begin. CCHamide is a brain gut neuropeptide precursor conserved in insect genomes. The physiological role of CCHamide has been studied in Drosophila melanogaster and Bombyx mori, where it modulates feeding behavior as an orexigenic factor. Here, we report that the neuropeptide RhoprCCHamide (RhoprCCHa) is involved in the regulation of the postprandial diuresis in Rhodnius prolixus, a triatomine insect which is a vector of Chagas disease. The expression of RhoprCCHa gene was downregulated by RNA interference in this insect, obtaining an 85% of gene silencing and we found a dual effect of RhoprCCHa in the diuresis. Our results point to an inhibition of immediate excretion (10?45 min PBM) and a stimulation of dieresis toward the end of the process (90?240 min PBM). Using in vitro approaches, we confirmed an effect of RhoprCCHa inhibiting the fluid transport by the anterior midgut stimulated with 5HT and an increasing in the secretion rate by stimulated malpighian tubules. The opposite role in different structures was not reported previously for any neuropeptidergic system in insects. It seems to reflect the necessity of a tight regulation of the volumes excreted in hematophagous, and thus avoiding defects in the diuresis that would endanger the homeostasis.