早期资源匮乏以性和强化物依赖的方式改变了对自然奖励的动机。
Early resource scarcity alters motivation for natural rewards in a sex- and reinforcer-dependent manner.
机构信息
Department of Psychology and Neuroscience Program, Temple University, Philadelphia, PA, 19122, USA.
Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
出版信息
Psychopharmacology (Berl). 2022 Dec;239(12):3929-3937. doi: 10.1007/s00213-022-06264-9. Epub 2022 Oct 27.
RATIONALE
Early life adversity impacts reward-related behaviors, including reward seeking for drugs of abuse. However, the effects of early stress on natural rewards, such as food and social rewards, which have strong implications for symptoms of psychiatric conditions such as major depressive disorder (MDD), are understudied. To fill this gap, we used the limited bedding and nesting (LBN) procedure to assess the impact of early resource scarcity on motivational drive for both food and social rewards in rats.
METHODS
Male and female Long Evans rats were reared in either an LBN environment, with limited nesting materials and no enrichment, from their postnatal day 2-9 or control environment with ample nesting materials and enrichment. As adults, they were tested for reward-seeking behavior on progressive ratio operant tasks: food reward (sucrose) or social reward (access to a same-sex/age conspecific).
RESULTS
We observed sex differences in the impact of LBN on motivation for natural rewards. In males, LBN increased motivation for both a sucrose and social reward. In females, LBN reduced motivation for sucrose but had no effect on social reward.
CONCLUSIONS
These results suggest that the effects of LBN on motivation for natural rewards are both sex- and reinforcer-dependent, with males and females showing differential motivation for food and social rewards following early scarcity. Our previous data revealed an LBN-driven reduction in motivation for morphine in males and no effect in females, highlighting the reinforcer-dependent impact of early resource scarcity on motivated behavior more widely.
背景
早期生活逆境会影响与奖励相关的行为，包括对滥用药物的奖励寻求。然而，早期应激对自然奖励（如食物和社会奖励）的影响，这些奖励对精神疾病症状（如重度抑郁症，MDD）有很强的影响，这方面的研究还很不足。为了填补这一空白，我们使用有限的卧床和筑巢（LBN）程序来评估早期资源匮乏对大鼠食物和社会奖励动机驱动的影响。
方法
雄性和雌性 Long Evans 大鼠在出生后 2-9 天内分别在 LBN 环境（有限的筑巢材料，没有丰富物）或对照环境（充足的筑巢材料和丰富物）中饲养。成年后，它们在渐进比例操作任务中测试对奖励的寻求行为：食物奖励（蔗糖）或社会奖励（与同性别/年龄的同种动物接触）。
结果
我们观察到 LBN 对自然奖励动机的影响存在性别差异。在雄性中，LBN 增加了对蔗糖和社会奖励的动机。在雌性中，LBN 降低了对蔗糖的动机，但对社会奖励没有影响。
结论
这些结果表明，LBN 对自然奖励动机的影响既具有性别依赖性，也具有强化物依赖性，早期资源匮乏后，雄性和雌性对食物和社会奖励的动机不同。我们之前的数据显示，LBN 驱动雄性对吗啡的动机减少，而对雌性没有影响，这突出了早期资源匮乏对动机行为的强化物依赖性影响更为广泛。
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