Programa de Pós-Graduação em Ciências Biológicas: Bioquímica/Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil; Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil.
Programa de Pós-Graduação em Ciências Biológicas: Bioquímica/Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, Rio Grande do Sul, Brazil.
Appetite. 2020 Oct 1;153:104739. doi: 10.1016/j.appet.2020.104739. Epub 2020 May 18.
Environmental variations can influence eating and motivated behaviors, as well as the brain's feeding circuits to predisposing overweight and obesity. The identification of mechanisms through which a long-term consumption of caloric-dense palatable foods and its association with early life stress can cause neuroadaptations and possible modify motivational behaviors are relevant to elucidate the mechanisms associated with obesity. Here, we investigated the long-term effects of a chronic high-fat diet (HFD), and its interaction with early social isolation on hedonic feeding responses in adult rats. Rats were subjected, or not, to social isolation between postnatal days 21-28 and were fed a control diet or HFD, for 10 weeks post weaning. Hedonic feeding behavior was evaluated during adulthood and parameters related to the dopaminergic, cannabinoid, and opioid systems were measured in the nucleus accumbens. Animals with chronic HFD intake were less motivated to obtain sweet palatable foods. This reduced motivation did not appear to be associated with less pleasure upon tasting sweet food, as no alteration in reactivity to sweet taste was observed. Interestingly, the animals receiving HFD presented decreased immunocontents of the D1 and CB1 receptors, while the stressed group displayed a reduction in dopamine turnover. In summary, chronic HFD causes a significant motivational impairment for sweet palatable foods; these changes may be associated with a decreased dopaminergic and cannabinoid neurotransmission in the nucleus accumbens. In contrast, a brief social isolation during the prepubertal period was unable to alter the behavioral parameters studied but caused a decreased dopaminergic turnover in the nucleus accumbens of adult rats. These findings highlight the importance of long-term HFD exposure on the modulation of hedonic feeding behavior and related neurochemical systems.
环境变化会影响进食和动机行为，以及大脑的进食回路，从而导致超重和肥胖。确定长期摄入高热量美味食物的机制及其与早期生活应激的关联如何导致神经适应，并可能改变动机行为，对于阐明与肥胖相关的机制非常重要。在这里，我们研究了慢性高脂肪饮食（HFD）及其与早期社会隔离对成年大鼠享乐性进食反应的长期影响。大鼠在出生后第 21-28 天接受或不接受社会隔离，并在断奶后 10 周内接受对照饮食或 HFD。在成年期评估享乐性进食行为，并测量伏隔核中的多巴胺能、大麻素和阿片系统相关参数。长期摄入 HFD 的动物对甜味可口食物的获取动机较低。这种动机降低似乎与品尝甜味食物时的快感减少无关，因为对甜味的反应没有观察到改变。有趣的是，接受 HFD 的动物表现出 D1 和 CB1 受体的免疫含量降低，而应激组显示多巴胺周转率降低。总之，慢性 HFD 导致对甜味可口食物的显著动机损害；这些变化可能与伏隔核中多巴胺能和大麻素神经传递的减少有关。相比之下，青春期前短暂的社会隔离不能改变研究中的行为参数，但会导致成年大鼠伏隔核中多巴胺周转率降低。这些发现强调了长期 HFD 暴露对享乐性进食行为和相关神经化学系统的调节作用。
