Abstract: 5-Hydroxytryptamine (5-HT) is an important biogenic amine in insects, which is synthesized in both neuronal and peripheral tissues and can be reuptaken by serotonin transporter into presynaptic neuron. 5-HT plays various important physiological roles in insects through specific G protein-coupled receptors, such as feeding, circadian behavior, aggregation, learning and memory. There are five types of 5-HT receptors in insects, i.e., 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2B and 5-HT7. 5-HT1A and 5-HT1B inhibit intracellular cAMP production, 5-HT2A and 5-HT2B  increase Ca²⁺ level, and 5-HT7 induces cAMP production. In recent years, great progress has been made in the research of 5-HT in insects, especially their receptors. More and more 5-HT receptor genes have been cloned, and their functions and pharmacological properties have been analyzed. The pharmacological differences of 5-HT receptors from different insects will provide fundamental basis for designing and developing new specific insecticides for pest management.  

Key words: Insects, neuron, biogenic amine, 5-hydroxytryptamine (5HT), G protein-coupled receptors, pharmacology