Food restriction augments drug seeking in abstinent rats. The underlying motivational mechanisms, however, remain unclear. We hypothesized that caloric restriction enhances the incentive value attributed to drug-associated cues and, in turn, augments drug seeking. Male rats were trained to lever-press for heroin, and then moved to the animal colony for a forced-abstinence period. Rats were maintained on free access to food (Sated) or subjected to 14 days of food restriction (FDR). In a series of experiments, we assessed the effect of food-restriction on the incentive value of heroin-associated cues. Tests included performance under a progressive ratio (PR) schedule of reinforcement maintained by heroin-associated cues, acquisition of a novel operant response reinforced by drug-associated cues, effect of food-restriction on operant response reinforced by neutral cues, acquisition of a novel operant response reinforced by drug-associated or neutral cues, and the effect of food-restriction on operant response reinforced by drug-associated or neutral cues, under a discrete choice procedure.

Food-restriction did not change breakpoints in PR maintained by heroin-associated cues. FDR rats acquired the novel response at a greater level compared to the Sated group. Food-restriction-induced increase in novel-response rate was observed for both heroin-paired and the neutral cue. Responding for a heroin-associated cue was greater than for the neutral cue in both Sated and FDR groups. Response rate for the neutral cue, however, was greater in the FDR versus Sated group.

Our findings suggest that food restriction increases the conditioned motivational properties of environmental stimuli, including, but not exclusive to, heroin-paired cues.

食物限制会增加戒断大鼠的药物寻求。然而，潜在的动机机制仍不清楚。我们假设热量限制会增强药​​物相关线索的激励价值，进而增加药物寻求。雄性老鼠被训练为海洛因按下杠杆，然后转移到动物群体进行强制戒酒期。使大鼠自由进食（Sated）或进行14天的食物限制（FDR）。在一系列实验中，我们评估了食物限制对海洛因相关线索的激励价值的影响。测试包括海洛因相关线索维持的渐进比例（PR）强化计划下的表现、药物相关线索强化的新操作反应的获得、中性线索强化的食物限制对操作反应的影响、新操作反应的获得在离散选择程序下，药物相关或中性线索强化的操作反应，以及药物相关或中性线索强化的食物限制对操作反应的影响。

食物限制并没有改变由海洛因相关线索维持的公关断点。与 Sated 组相比，FDR 大鼠获得了更高水平的新反应。对于海洛因配对和中性线索，都观察到食物限制引起的新反应率增加。在“饱和”组和“罗斯福”组中，对海洛因相关线索的反应大于对中性线索的反应。然而，FDR 组对中性提示的反应率高于 Sated 组。

我们的研究结果表明，食物限制会增加环境刺激的条件动机特性，包括但不限于海洛因配对线索。