Neural basis of aversive taste in a blood-sucking insect

GUTIERREZ, L; BERON DE ASTRADA, M; BARROZO, RB

Buenos Aires

Congreso; 2nd FALAN; 2016

Tasteprovides animals information about the quality of potential food and allowsthem to discriminate nutritiveand harmful food. Rhodnius prolixus is a vector of Chagas disease in Latin America. They use gustatory sense toevaluate the quality of substrate and consequently make a decision: to bite ornot to bite. At this point, salt and bitter perception inhibits feeding ofthese bugs. This inhibition disappeared when the distal segments of theantennae were ablated, indicating that the gustatory receptor neurons (GRNs) involvedin 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 typesof GRNs were identified in each sensilla, although only two of them respondedto salts and caffeine. GRN1 elicited phasi-tonic dose-dependent responses toboth salts and caffeine, whereas GRN2 was inhibited by caffeine and showedtonic excitation to NaCl. GRN1 and GRN2 sensitivity to salts were modulated by amiloride,showing that ENaC receptors might be involved. Besides, we traced theprojections of their neuronal axons into the brain using a neuronal marker. Back-fillsfrom individual sensilla revealed that axons target the antennal lobes, suggestingthat taste information might be integrated together with olfactory inputs. Aversivetaste has an essential function in helping insects to avoid toxic or harmful food sources.