The cloning, phylogenetic relationship and distribution pattern of two new putative GPCR-type octopamine receptors in the desert locust (Schistocerca gregaria)

The biogenic amine octopamine functions as a neuromodulator, neurotransmitter and neurohormone in insect nervous systems. It plays a prominent role in modulating multiple physiological and behavioural processes in invertebrates. Octopamine exerts its effects by binding to specific receptor proteins that belong to the superfamily of G protein-coupled receptors. We found two partial sequences of putative octopamine receptors in the desert locust Schistocerca gregaria (SgOctαR and SgOctβR) and investigated their transcript levels in males and females of both phases and during the transition between long-term solitarious and gregarious locusts. The transcript levels of SgOctαR are the highest in the central nervous system, whereas those of SgOctβR are the highest in the flight muscles, followed by the central nervous system. Both SgOctαR and SgOctβR show higher transcript levels in long-term gregarious locusts as compared to solitarious ones. The rise of SgOctβR transcript levels already appears during the first 4 h of gregarisation, during which also the behavioural changes take place.