Pharmacological characterization of dopamine receptors in the rice striped stem borer, Chilo suppressalis

- Three types of dopamine receptor genes were cloned and examined in C. suppressalis.
- CsDOP1, CsDOP2 and CsDOP3 genes were all expressed at high levels in the central nervous system.
- CsDOP1 and CsDOP2 couple to Gs protein, and CsDOP3 couples to Gi protein.
- CsDOP1, CsDOP2 and CsDOP3 were dose-dependently activated by dopamine and dopaminergic agonists.
- The antagonist profiles of CsDOP1, CsDOP2 and CsDOP3 were diverse.

Dopamine is an important neurotransmitter and neuromodulator in both vertebrates and invertebrates and is the most abundant monoamine present in the central nervous system of insects. A complement of functionally distinct dopamine receptors mediate the signal transduction of dopamine by modifying intracellular Ca2+ and cAMP levels. In the present study, we pharmacologically characterized three types of dopamine receptors, CsDOP1, CsDOP2 and CsDOP3, from the rice striped stem borer, Chilo suppressalis. All three receptors show considerable sequence identity with orthologous dopamine receptors. The phylogenetic analysis also clusters the receptors within their respective groups. Transcript levels of CsDOP1, CsDOP2 and CsDOP3 were all expressed at high levels in the central nervous system, indicating their important roles in neural processes. After heterologous expression in HEK 293 cells, CsDOP1, CsDOP2 and CsDOP3 were dose-dependently activated by dopamine and synthetic dopamine receptor agonists. They can also be blocked by different series of antagonists. This study offers important information on three dopamine receptors from C. suppressalis that will provide the basis for forthcoming studies investigating their roles in behaviors and physiology, and facilitate the development of new insecticides for pest control.

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