Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
PLoS Biol. 2023 Oct 17;21(10):e3002332. doi: 10.1371/journal.pbio.3002332. eCollection 2023 Oct.
Thermosensation is critical for the survival of animals. However, mechanisms through which nutritional status modulates thermosensation remain unclear. Herein, we showed that hungry Drosophila exhibit a strong hot avoidance behavior (HAB) compared to food-sated flies. We identified that hot stimulus increases the activity of α'β' mushroom body neurons (MBns), with weak activity in the sated state and strong activity in the hungry state. Furthermore, we showed that α'β' MBn receives the same level of hot input from the mALT projection neurons via cholinergic transmission in sated and hungry states. Differences in α'β' MBn activity between food-sated and hungry flies following heat stimuli are regulated by distinct Drosophila insulin-like peptides (Dilps). Dilp2 is secreted by insulin-producing cells (IPCs) and regulates HAB during satiety, whereas Dilp6 is secreted by the fat body and regulates HAB during the hungry state. We observed that Dilp2 induces PI3K/AKT signaling, whereas Dilp6 induces Ras/ERK signaling in α'β' MBn to regulate HAB in different feeding conditions. Finally, we showed that the 2 α'β'-related MB output neurons (MBONs), MBON-α'3 and MBON-β'1, are necessary for the output of integrated hot avoidance information from α'β' MBn. Our results demonstrate the presence of dual insulin modulation pathways in α'β' MBn, which are important for suitable behavioral responses in Drosophila during thermoregulation under different feeding states.
热感觉对于动物的生存至关重要。然而，营养状况调节热感觉的机制尚不清楚。在此，我们发现饥饿的果蝇与吃饱的果蝇相比表现出强烈的热回避行为（HAB）。我们发现热刺激会增加α'β'蘑菇体神经元（MBns）的活性，在吃饱的状态下活性较弱，而在饥饿的状态下活性较强。此外，我们还发现α'β' MBn 在吃饱和饥饿状态下通过胆碱能传递从 mALT 投射神经元接收相同水平的热输入。热刺激后，食物充足和饥饿的果蝇之间α'β' MBn 活性的差异受不同的果蝇胰岛素样肽（Dilps）调节。Dilp2 由胰岛素产生细胞（IPCs）分泌，在饱食时调节 HAB，而 Dilp6 由脂肪体分泌，在饥饿时调节 HAB。我们观察到 Dilp2 诱导α'β' MBn 中的 PI3K/AKT 信号通路，而 Dilp6 诱导 Ras/ERK 信号通路，以在不同的进食条件下调节 HAB。最后，我们发现 2 个与α'β'相关的 MB 输出神经元（MBONs），MBON-α'3 和 MBON-β'1，对于从α'β' MBn 输出整合的热回避信息是必要的。我们的研究结果表明，α'β' MBn 中存在双胰岛素调节途径，这对于果蝇在不同进食状态下的热调节过程中产生适当的行为反应非常重要。
