Dopamine (DA) is essential for both physiological and behavioral responses including the regulation of sexuality. Our previous studies have revealed that activity of PPL2ab neurons enhances male courtship sustainment through DA transmission in Drosophila. We showed that increasing DA levels in PPL2ab neurons also prompted visual cue-dependent inter-male courtship behavior, but that sexual preference for females remained unchanged. In addition, males with low DA levels in PPL2ab neurons attracted higher sex drive males with high DA levels in PPL2ab neurons. In this scenario, inter-male courtship was observed even in a visual cue-blocked condition. Thus, we demonstrated that PPL2ab neurons modulate male sexual motivation towards other males in conditions without female targets. Moreover, PPL2ab neurons were found to mediate the response to male cuticular sex pheromone composition, which promoted significant inter-male courtship activity. These findings imply that masculine and feminine roles in male homosexual responses are modulated by the same class of neurons through DA activity. Together, our data provide an evolutionary perspective of sex that incorporates mechanisms related to modulation of active or passive sexuality in flies. This concept represents an important advance in understanding how the brain acts to aid libido levels and sexual motivation.

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