Sexual identity affects the development and mature function of a defined neural circuit in Drosophila melanogaster. Parag Bhatt, Selma Advagic, Harsha Swamy. Pharmcological and Physiological Science, Saint Louis University School of Medicine, St Louis, MO.

   In the fruit fly, Drosophila melanogaster, serotonin (5-HT) functions both as a neurotransmitter to regulate larval feeding, and as a trophic factor in the development of the stomatogastric feeding circuit. We have shown an inverse relationship between developmental 5-HT levels and the complexity of the 5-HT axonal fibers projecting from the brain to the foregut, which correlates with perturbations in feeding, the functional output of the circuit (Neckameyer, 2010). These effects are distinct from the actions of 5-HT as a neurotransmitter. We have also shown that although dopamine (DA) neurotransmission does not modulate feeding, perturbed levels of neuronal DA during development affect 5-HT innervation of the gut as well as larval feeding behavior (Neckameyer and Bhatt, 2012). Although feeding does not differ between male and female larvae, it is differentially sensitive to the trophic, or developmental, actions of neuronal 5-HT and DA. We have identified a subset of neurons, using Gal4 drivers, that are at least partially responsible for the sexually dimorphic effects in the feeding response. Using transgenic approaches, we have manipulated the sexual identity of the brain during CNS development, and have established that it is sensitive to the actions of DA and 5-HT function.