Behavioral functions of octopamine in adult insects under stressful conditions

Abstract

Octopamine (OA) functions as a neurotransmitter, neuromodulator, and neurohormone in the insect body. Octopaminergic neurons were found in the nervous system of all studied insect species. OA acts on nerve, muscle, glandular and fat cells through receptors associated with G-proteins, preparing and providing intense physical activity. The concentration of octopamine in the hemolymph increases in response to a wide range of stressful factors, from infection to physical activity, which is consistent with the well-known idea of OA as a “stress hormone” in insects. However, for more than 10 years there has been no analysis of publications on the modulating role of octopamine in connection with various types of complex behavior in insects, including stressful conditions. The current data suggest that the activity of the octopaminergic system is associated with adaptation to physical activity, modulation of aggressive behavior in a situation of intraspecific conflict, avoidance behavior when meeting a predator, feeding and search behavior in conditions of hunger. It is concluded that octopamine at different levels (from modulation of neural ensembles and receptors to energy metabolism) is involved in providing adaptive responses of insects to a wide range of stressful situations.