The Role of Monoaminergic Neurotransmission for Metabolic Control in the Fruit Fly .

Hormones control various metabolic traits comprising fat deposition or starvation resistance. Here we show that two invertebrate neurohormones, octopamine (OA) and tyramine (TA) as well as their associated receptors, had a major impact on these metabolic traits. Animals devoid of the monoamine OA develop a severe obesity phenotype. Using flies defective in the expression of receptors for OA and TA, we aimed to decipher the contributions of single receptors for these metabolic phenotypes. Whereas those animals impaired in , 2r and share the obesity phenotype of OA-deficient (-deficient) animals, the 1r, 2r deficient flies showed reduced insulin release, which is opposed to the situation found in -deficient animals. On the other hand, OAMB deficient flies were leaner than controls, implying that the regulation of this phenotype is more complex than anticipated. Other phenotypes seen in animals, such as the reduced ability to perform complex movements tasks can mainly be attributed to the 2r. Tissue-specific RNAi experiments revealed a very complex interorgan communication leading to the different metabolic phenotypes observed in OA or OA and TA-deficient flies.