Biological functions of α2-adrenergic-like octopamine receptor in Drosophila melanogaster

Octopamine regulates various physiological phenomena including memory, sleep, grooming and aggression in insects. In Drosophila, four types of octopamine receptors have been identified: Oamb, Oct/TyrR, Oct beta R and Oct alpha 2R. Among these receptors, Oct alpha 2R was recently discovered and pharmacologically characterized. However, the effects of the receptor on biological functions are still unknown. Here, we showed that Oct alpha 2R regulated several behaviors related to octopamine signaling. Oct alpha 2R hypomorphic mutant flies showed a significant decrease in locomotor activity. We found that Oct alpha 2R expressed in the pars intercerebralis, which is a brain region projected by octopaminergic neurons, is involved in control of the locomotor activity. Besides, Oct alpha 2R hypomorphic mutants increased time and frequency of grooming and inhibited starvation-induced hyperactivity. These results indicated that Oct alpha 2R expressed in the central nervous system is responsible for the involvement in physiological functions.