Neural basis of aversive taste in a blood-sucking insect

BERON DE ASTRADA, MARTÍN; GUTIÉRREZ, MARÍA LAURA; BARROZO, ROMINA

Buenos Aires

Congreso; 2nd FALAN Congress; 2016

Sociedad Argentina de Neurociencias; IBRO-LAC; FALAN

Taste provides animals information about the quality of potential food and allows them to discriminate nutritive and harmful food. Rhodnius prolixus is a vector of Chagas disease in Latin America. They use gustatory sense to evaluate the quality of substrate and consequently make a decision: to bite or not to bite. At this point, salt and bitter perception inhibits feeding of these bugs. This inhibition disappeared when the distal segments of the antennae were ablated, indicating that the gustatory receptor neurons (GRNs) involved in such feeding deterrence are housed in taste sensilla of the antennae. Here, we examined the responses to salts (NaCl/KCl) and to bitter compounds (caffeine) of taste sensilla using extracellular electrophysiology. Three types of GRNs were identified in each sensilla, although only two of them responded to salts and caffeine. GRN1 elicited phasi-tonic dose-dependent responses to both salts and caffeine, whereas GRN2 was inhibited by caffeine and showed tonic excitation to NaCl. GRN1 and GRN2 sensitivity to salts were modulated by amiloride, showing that ENaC receptors might be involved. Besides, we traced the projections of their neuronal axons into the brain using a neuronal marker. Back-fills from individual sensilla revealed that axons target the antennal lobes, suggesting that taste information might be integrated together with olfactory inputs. Aversive taste has an essential function in helping insects to avoid toxic or harmful food sources.