Shteyn Rebecca, Lafferty Danielle S, Petrovich Gorica D
Department of Psychology & Neuroscience, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA, 02467, USA.
Department of Psychology & Neuroscience, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA, 02467, USA.
Physiol Behav. 2025 Sep 1;298:114935. doi: 10.1016/j.physbeh.2025.114935. Epub 2025 May 1.
Hedonic and memory mechanisms can stimulate food cravings and consumption in sated individuals, promoting binge eating and obesity. Despite that, how satiety impacts learning and memory about cues for palatable food in males and females remains unclear. This is the first study to directly compare food associative learning, extinction, and memory renewal between hungry and sated subjects of both sexes. Food-restricted and sated male and female adult Sprague Dawley rats were trained in Pavlovian cue-food conditioning sessions, followed by cue-only presentations during extinction in a different context. They were then tested for renewal of conditioned responding to the food cue by return to the conditioning context. Conditioned responding was assessed through foodcup approach behavior. These rats were also tested for consumption of palatable food and chow before and after the learning and memory protocol. Sated rats demonstrated learning, extinction, and renewal of conditioned responding, indicating that physiological hunger is not required for learning and memory of palatable food cues. There were differences during cue-food acquisition, food-deprived rats learned faster and reached a plateau in conditioned responding sooner than sated rats. However, there were no differences after the fourth session, when sated rats reached the same level of responding as the food-deprived rats. There were sex differences during early acquisition under sated but not hungry states. Sated females had higher conditioned responding than sated males, while food-deprived rats of both sexes responded similarly. Extinction and renewal tests showed that both hungry and sated rats successfully decreased and subsequently renewed their conditioned responses. These results demonstrate the durability of learning and persistence of food-cue memory regardless of hunger state. Consumption tests found that all rats prefer palatable food compared to chow. Females, particularly when sated, consumed more palatable food compared to males. Higher palatable food consumption and learning in females suggest an enhanced sensitivity to palatable rewards. Correlation analyses found a positive relation between the amounts of food rats consumed and their conditioned responding in both sexes. These results demonstrate robust associative learning and memory under satiety and add evidence of sex differences in hedonic food motivation.
享乐和记忆机制可刺激饱腹感个体产生食物渴望并促使其进食，从而导致暴饮暴食和肥胖。尽管如此，饱腹感如何影响男女对美味食物线索的学习和记忆仍不清楚。这是第一项直接比较饥饿和饱腹状态下男女受试者食物联想学习、消退和记忆恢复的研究。对食物受限和饱腹的成年雄性和雌性斯普拉格·道利大鼠进行巴甫洛夫线索 - 食物条件反射训练，随后在不同环境下进行仅线索呈现的消退训练。然后通过回到条件反射环境来测试它们对食物线索的条件反应恢复情况。通过食物杯接近行为评估条件反应。这些大鼠在学习和记忆实验前后还接受了美味食物和普通食物的消费测试。饱腹大鼠表现出条件反应的学习、消退和恢复，表明对美味食物线索的学习和记忆不需要生理饥饿。在线索 - 食物习得过程中存在差异，饥饿大鼠学习更快，条件反应比饱腹大鼠更快达到平稳状态。然而，在第四阶段后没有差异，此时饱腹大鼠的反应水平与饥饿大鼠相同。在饱腹但非饥饿状态下的早期习得过程中存在性别差异。饱腹雌性大鼠的条件反应高于饱腹雄性大鼠，而饥饿的两性大鼠反应相似。消退和恢复测试表明，饥饿和饱腹大鼠都成功降低并随后恢复了它们的条件反应。这些结果证明了无论饥饿状态如何，学习的持久性和食物线索记忆的持续性。消费测试发现，与普通食物相比，所有大鼠都更喜欢美味食物。雌性，尤其是在饱腹时，比雄性消耗更多的美味食物。雌性对美味食物更高的消费和学习表明其对美味奖励的敏感性增强。相关分析发现，两性大鼠消耗的食物量与它们的条件反应之间存在正相关。这些结果证明了饱腹感下强大的联想学习和记忆，并增加了享乐性食物动机中性别差异的证据。
