Time-dependent metabolome and fatty acid profile changes following a high-fat diet exposure in Drosophila melanogaster

High fat diet induces differential age- and gender-dependent changes in neuronal function in Drosophila linked to redox stress

The prevalence of neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, is steadily increasing, thus posing significant challenges to global healthcare systems. Emerging evidence suggests that dietary habits, particularly consumption of high-fat diets, may play a pivotal role in the development and progression of neurodegenerative disorders. Moreover, several studies have shed light on the intricate communication between the gut and the brain, linking gut health with neuroinflammation and its involvement in neurodegenerative processes. This study aims to assess the effects of a high-fat dietary intake on various aspects of neuronal function during aging in a gender specific manner to help understand the potential contributions of diet to neuronal function. To investigate the effects of a high-fat diet, Drosophila melanogaster was used and exposed to a standard normal food diet (NF) and a high-fat diet (HF). Adults were grouped at 10 and 45 days of age in male and female flies reared under the same conditions starting the HF diet at 5 days of age with data showing differential gender- and HF diet-induced phenotypes. Malondialdehyde (MDA) levels were higher in males at 10 and 45 days (p < 0.05), caspase-3 expression increased at 45 days (p < 0.01) implicating apoptosis induction and a reduced climbing activity at 10 and 45 days was apparent in females only (p < 0.01). Adult lifespan under both dietary conditions was unchanged when reared at 18°C but odour-associated learning ability was reduced in larvae reared in a HF diet throughout their development (p < 0.05). This is the first study to characterise effects of a HF diet on neuronal phenotypes in an age- and gender-specific manner in a Drosophila model. Our findings suggest a HF diet induces differential effects of neuronal dysfunction with age and sex-specific outcomes, characterised by enhanced oxidative stress and cell death impacting on behaviour.

Fasting as a precursor to high-fat diet enhances mitochondrial resilience in Drosophila melanogaster

Changes in diet type and nutrient availability can impose significant environmental stress on organisms, potentially compromising physiological functions and reproductive success. In nature, dramatic fluctuations in dietary resources are often observed and adjustments to restore cellular homeostasis are crucial to survive this type of stress. In this study, we exposed male Drosophila melanogaster to two modulated dietary treatments: one without a fasting period before exposure to a high-fat diet and the other with a 24-h fasting period. We then investigated mitochondrial metabolism and molecular responses to these treatments. Exposure to a high-fat diet without a preceding fasting period resulted in disrupted mitochondrial respiration, notably at the level of complex I. On the other hand, a short fasting period before the high-fat diet maintained mitochondrial respiration. Generally, transcript abundance of genes associated with mitophagy, heat-shock proteins, mitochondrial biogenesis, and nutrient sensing pathways increased either slightly or significantly following a fasting period and remained stable when flies were subsequently put on a high-fat diet, whereas a drastic decrease of almost all transcript abundances was observed for all these pathways when flies were exposed directly to a high-fat diet. Moreover, mitochondrial enzymatic activities showed less variation after the fasting period than the treatment without a fasting period. Overall, our study sheds light on the mechanistic protective effects of fasting prior to a high-fat diet and highlights the metabolic flexibility of Drosophila mitochondria in response to abrupt dietary changes and have implication for adaptation of species to their changing environment.