Caffeine is the most widely consumed psychoactive substance in the world. However, there is controversy about whether becoming addicted to caffeine is possible and a lack of well-established animal models to examine caffeine consumption. The present study sought to establish a model of caffeine consumption in Wistar rats, identify different rat populations based on caffeine preference, and determine whether extended voluntary caffeine consumption produces compulsive-like caffeine intake and withdrawal symptoms.

Male Wistar rats were used throughout the experiment. The optimal concentration of caffeine to maximize caffeine consumption and caffeine preference was determined. Rats were then given continuous access to caffeine, followed by intermittent access. Rats were tested for signs of withdrawal-like behavior by measuring mechanical nociception and irritability-like behavior. Rats were further examined for compulsive-like caffeine consumption using quinine adulteration.

Dose-response testing indicated an optimal caffeine concentration of 0.3 mg/mL. During intermittent access to caffeine, the rats did not escalate their caffeine intake and instead exhibited a decrease in intake over sessions. Three groups of rats were identified based on caffeine preference (high, medium, and low) across continuous and intermittent access. These three groups of rats matched low (1 cup), medium (2 cups), and high (4 cups) levels of daily coffee consumption in humans. Caffeine-consuming rats did not exhibit differences in mechanical nociception or irritability-like behavior compared with controls. In high caffeine-preferring rats but not in medium or low caffeine-preferring rats, compulsive-like caffeine consumption was observed.

The present study established a rodent model of caffeine consumption that resulted in large individual differences in caffeine intake, similar to humans. Compulsive-like caffeine consumption in high caffeine-preferring rats and differences in caffeine preference between groups suggest that caffeine may result in compulsive-like intake in a subpopulation of subjects. Further testing is necessary to determine the factors that contribute to differences in caffeine preference and compulsive-like intake.

咖啡因是世界上消费最广泛的精神活性物质。然而，关于是否可能对咖啡因上瘾存在争议，并且缺乏完善的动物模型来检查咖啡因的摄入量。本研究试图建立 Wistar 大鼠的咖啡因摄入模型，根据咖啡因偏好识别不同的大鼠群体，并确定长期自愿摄入咖啡因是否会产生类似强迫性的咖啡因摄入和戒断症状。

在整个实验过程中使用雄性 Wistar 大鼠。确定了最大化咖啡因消耗和咖啡因偏好的最佳咖啡因浓度。然后让大鼠连续摄入咖啡因，然后间歇性摄入。通过测量机械性伤害感受和烦躁样行为来测试大鼠的戒断样行为迹象。使用奎宁掺假进一步检查大鼠的强迫性咖啡因消耗情况。

剂量反应测试表明最佳咖啡因浓度为 0.3 mg/mL。在间歇性摄入咖啡因期间，老鼠并没有增加咖啡因的摄入量，而是在整个过程中表现出摄入量的减少。根据连续和间歇性摄入的咖啡因偏好（高、中和低），确定了三组大鼠。这三组老鼠的日常咖啡摄入量与人类的低（1 杯）、中（2 杯）和高（4 杯）水平相匹配。与对照组相比，摄入咖啡因的大鼠在机械性伤害感受或易激惹行为方面没有表现出差异。在高咖啡因偏好的大鼠中，但在中度或低度咖啡因偏好的大鼠中，没有观察到强迫性的咖啡因消耗。

本研究建立了啮齿动物的咖啡因摄入模型，该模型导致咖啡因摄入量存在很大的个体差异，与人类相似。高咖啡因偏好大鼠的强迫性咖啡因摄入量以及各组之间咖啡因偏好的差异表明，咖啡因可能会导致受试者亚群出现强迫性摄入。需要进一步的测试来确定导致咖啡因偏好和强迫性摄入差异的因素。