Olfactory sensitivity, behaviors, and transcriptional profiling by high fat diet-induced stress in Drosophila melanogaster

Abstract

Energy homeostasis is essential to most organisms for survival affected by internal state and external factors. Unbalanced nutrient supplies cause obesity and give detrimental effects on a sensory system. In particular, sensory-mediated responses are crucial to maintain energy balance as involved in a metabolic regulation. However, investigating effects and relationship between HFD-induced stress and its effects on the sensory system have yet to be elucidated. To gain insights into how HFD-induced stress affects olfactory sensitivity and behavioral responses, we used a male Drosophila melanogaster model to test this hypothesis involving olfactory and nutrient-related signaling by using physiological, behavioral and transcriptional analysis. Here we demonstrated that lifespan and climbing ability in HFD-treated flies were decreased and moreover olfactory sensitivity and behavioral responses to odorants were modified after HFD treatment. Overall, flies showed reduction of olfactory sensitivity to most odorants after HFD treatment. Interestingly, flies showed increased behavioral attraction to benzaldehyde in both 7-day and 14-day HFD treatment. This behavioral and physiological modulation in HFD-treated flies were accompanied by a significant decreased DmOrco gene expression in antennae organ, suggesting some mediators might regulate olfactory processing through the actions of metabolic and sensory signals. The gene expression profiles of antennae indicated significantly differences in olfactory receptors, odorant-binding proteins, and insulin signaling-related genes. These transcriptional changes affected the genes in functional gene ontology. Taken together, olfactory sensitivity and behavioral responses by HFD-induced stress might be in modulation through olfactory and nutrient-related signaling in Drosophila, reflecting to functional variation of genes and modification the sensory processing from antennae to brains.