Gustatory Receptor Neurons in Manduca sexta Contain a TrpA1-Dependent Signaling Pathway that integrates Taste and Temperature

摘要

Temperature modulates the peripheral taste response of many animals, in part by activating transient receptor potential (Trp) cation channels. We hypothesized that temperature would also modulate peripheral taste responses in larval Manduca sexta. We recorded excitatory responses of the lateral and medial styloconic sensilla to chemical stimuli at 14, 22, and 30 °G. The excitatory responses to 5 chemical stimuli-a salt (KCI), 3 sugars (sucrose, glucose, and inositol) and an alkaloid (caffeine)-were unaffected by temperature. In contrast, the excitatory response to the aversive compound, aristolochic acid (AA), increased robustly with temperature. Next, we asked whether TrpAl mediates the thermally dependent taste response to AA. To this end, we 1) identified a TrpAl gene in M. sexta; 2) demonstrated expression of TrpAl in the lateral and medial styloconic sensilla; 3) determined that 2 TrpAl antagonists (HC-030031 and mecamylamine) inhibit the taste response to AA, but not caffeine; and then 4) established that the thermal dependence of the taste response to AA is blocked by HC-030031. Taken together, our results indicate that TrpAl serves as a molecular integrator of taste and temperature in M. sexta.