The endocannabinoid system (ECs) is a well known contributor to the hedonic regulation of food intake (FI) in mammals whereas in fish, the knowledge regarding hedonic mechanisms that control FI is limited. Previous studies reported the involvement of ECs in FI regulation in fish since anandamide (AEA) treatment induced enhanced FI and changes of mRNA abundance of appetite-related neuropeptides through cannabinoid receptor 1 (cnr1). However, no previous studies in fish evaluated the impact of palatable food like high-fat diets (HFD) on mechanisms involved in hedonic regulation of FI including the possible involvement of ECs. Therefore, we aimed to evaluate the effect of feeding a HFD on the response of ECs in rainbow trout (Oncorhynchus mykiss). First, we demonstrated a higher intake over 4 days of HFD compared with a control diet (CD). Then, we evaluated the postprandial response (1, 3 and 6 h) of components of the ECs in plasma, hypothalamus, and telencephalon after feeding fish with CD and HFD. The results obtained indicate that the increased FI of HFD occurred along with increased levels of 2-arachidonoylglycerol (2-AG) and AEA in plasma and in brain areas like hypothalamus and telencephalon putatively involved in hedonic regulation of FI in fish. Decreased mRNA abundance of EC receptors like cnr1, gpr55 and trpv1 suggest a feed-back counter-regulatory mechanism in response to the increased levels of EC. Furthermore, the results also suggest that neural activity players associated to FI regulation in mammals as cFOS, γ-Amino butyric acid (GABA) and brain derived neurotrophic factor (BDNF)/neurotrophic receptor tyrosine kinase (NTRK) systems could be involved in the hedonic eating response to a palatable diet in fish.

内源性大麻素系统（EC）是哺乳动物对食物摄入（FI）的享乐调节的众所周知的贡献，而在鱼类中，有关控制FI的享乐机制的知识是有限的。先前的研究报道了ECs参与鱼的FI调节，因为通过anandamide（AEA）处理可增强FI并通过大麻素受体1（cnr1）改变食欲相关神经肽的mRNA含量。但是，以前没有任何鱼类研究评估高脂肪饮食（HFD）等可口食物对FI享乐性调节机制的影响，包括EC的参与。因此，我们旨在评估饲喂HFD对虹鳟鱼（Oncorhynchus mykiss） EC反应的影响）。首先，我们证明了与对照饮食（CD）相比，HFD在4天的摄入量更高。然后，我们在给鱼类喂食CD和HFD后评估了血浆，下丘脑和端脑中EC的餐后反应（1、3和6小时）。获得的结果表明，血浆和脑下区域（如下丘脑和端脑）的HFD的增加与2-花生四烯酰甘油（2-AG）和AEA的水平升高有关，可能与鱼类FI的享乐调节有关。EC受体（如cnr1，gpr55和trpv1）的mRNA丰度降低提出对EC水平升高的反馈反调节机制。此外，结果还表明，与哺乳动物FI调控相关的神经活动参与者，如cFOS，γ-氨基丁酸（GABA）和脑源性神经营养因子（BDNF）/神经营养受体酪氨酸激酶（NTRK）系统，可能参与了享乐主义饮食对鱼类可口饮食的反应。