Pharmacological characterization and functional roles of the 5-HT7 receptor for pheromone sensitivity and mating in Helicoverpa armigera

Background: Serotonin (5-hydroxytryptamine, 5-HT) is an important biogenic amine in insects, which regulates and controls many important physiological and behavioral processes by binding to different G protein-coupled receptors. The physiological functions of 5-HT and its receptors in olfactory learning and memory, courtship, and mating behaviors, have been reported in the model insect Drosophila melanogaster. However, little is known about the molecular properties, pharmacological characterization, and physiological functions of 5-HT receptors in the important agricultural pest Helicoverpa armigera.

Results: In this study, 5-HT₇ receptor gene was identified for the first time in H. armigera. Bioinformatics analysis showed that H. armigera 5-HT₇ shared a higher homology with 5-HT₇ from Spodoptera litura and Mythimna separata. The expression profile showed that Harm5-HT₇ receptor gene is highly expressed in the larval and adult developmental stages, and is mainly expressed in the gut of the larva, and is male-biased expressed in antennae and labial palps. Moreover, we investigated the pharmacological characterization of Harm5-HT₇ receptor, 5-HT could activate the Harm5-HT₇ receptor and increase the production of cyclic adenosine monophosphate (cAMP) in a dose-dependent manner [half maximal effective concentration (EC₅₀) = 0.54 μM]. In addition, we investigated the function of Harm5-HT₇ through in vivo pharmacological and RNA interference methodology. The results showed that interference of Harm5-HT₇ signaling pathway caused defects in pheromone sensitivity and mating behavior of male H. armigera.

Conclusion: Our results provide the first comprehensive understanding of the pharmacological characterization and functional roles of the Harm5-HT₇ receptor in olfactory sensitivity and mating behavior of male H. armigera. Our findings may facilitate the identification of potential target genes or chemical compounds for application in the mating disruption control of H. armigera. © 2025 Society of Chemical Industry.

Helicoverpa armigera; cAMP level; courtship and mating; olfactory perception; serotonin receptor.