Induction of aversive taste memory by azadirachtin and its effects on dopaminergic neurons of Drosophila

Objective  To investigate the inductive effects of azadirachtin on taste memory in Drosophila melanogaster (fruit fly) and the regulation of dopamine signaling in such memory formation.

Method Aversive taste memory induced by azadirachtin was tested by proboscis extension reflex (PER). Effects of azadirachtin on membrane excitability and receptor currents of dopaminergic neurons in D. melanogaster brain were studied using pressure injection combined with whole-cell patch clamp recording.

Result Both azadirachtin A and the azadirachtin dry powder could significantly inhibit the probability of PER, which were 60.34% and 17.24% respectively(P < 0.007). The effect of dry powder was more obvious. Different clusters of dopaminergic neurons responded variously to azadirachtin. PPL1, PAM and PPM2 subgroups showed increasing trends in excitability, in which the changes of PPL1 cluster neurons were most pronounced. Azadirachtin showed agonistic effect on D1 receptor, and such effect could be inhibited by D1 receptor specific antagonists.

Conclusion Azadirachtin can induce aversive taste memory in Drosophila, and such memory is regulated by dopaminergic signals in the brain.