Figure 6
From: The Neuropeptide Allatostatin A Regulates Metabolism and Feeding Decisions in Drosophila
AstA is affected differentially by protein and sugar and regulates preference for these nutrients and food intake.
(A–D) Expression of genes related to AstA signaling and metabolism in wild type (w1118) male (A,C) and female (B,D) flies fed on cornmeal (Ctrl), a restricted diet of 1% sucrose for 48 hours (Sucrose only) or re-fed for 24 hours after dietary restriction with either cornmeal (Sucrose + Cornmeal) (A,B) or yeast (Sucrose + Yeast) (C,D). After nutrient restriction, a carbohydrate rich cornmeal diet strongly induced AstA and Dar-2 expression, while a protein rich yeast diet only had a moderate effect on expression of AstA with no effects of Dar-2 transcripts. Error bars indicate standard errors (n = 4). (E) Yeast preference index indicating the preference for dietary protein. Males and females with increased (AstA > NaChBac) AstA neuron activation were tested in a two choice feeding assay for their preference for sucrose versus yeast (protein). Negative values indicate a preference for sucrose and positive values indicate a preference for yeast. Ad-libitum-fed AstA > NaChBac flies had a stronger preference for protein rich yeast compared to the control. Ctrl: AstA-Gal4/+. Error bars indicate standard errors (n = 3). (F) Sucrose consumption of adult males lacking AstA (AstASK1 and AstASK1/Df(3R)BSC519) compared to control animals (y2 cho2 v1, y1 w1118 and y2 cho2 v1 x y1 w1118: offspring from crossing these lines). Sucrose intake was measured using the Capillary Feeding (CAFE) assay. Error bars indicate standard errors (n = 10). *: P < 0.05; **: P < 0.01; ***: P < 0.001 (Student’s t-test). (G) Model: The proposed role of AstA in coordinating metabolism and feeding decision to balance nutrient intake according the internal nutrient state. AstA is affected differentially by dietary sugar and protein and guide metabolic programs, through the balance between AKH and DILPs, important to maintain homeostasis on food with different sugar:protein ratios. Activation of AstA neurons change the preference for protein rich food, showing that AstA plays a key role in the decision-making processes that assign value to dietary sugar and protein and guide food choice.
