Shoaib M, Almeida O F
Department of Neuroendocrinology, Max-Planck Institute of Psychiatry, Munich, Germany.
Alcohol. 1996 Mar-Apr;13(2):175-80. doi: 10.1016/0741-8329(95)02039-x.
Depending on the situation, ethanol can serve as a reinforcer in one paradigm and an aversive stimulus in another. The relationships between the two stimuli are not clear, particularly the behavioural adaptation following chronic ethanol exposure. We report on two experiments using an oral-self administration (OSA) paradigm and a conditioned taste aversion (CTA) paradigm. Male Wistar rats were exposed to ethanol using either the OSA or the CTA paradigm, and the consequences were examined in the same groups of rats by performing the other corresponding experiment. Thus, sensitisation or tolerance to the respective stimulus properties of ethanol would be detectable. For OSA experiments, rats were presented, under a free-choice setting, tap water and an ascending series of ethanol concentrations (2-10%) for up to 4 days per concentration. The amounts of ethanol and water consumed in 23-h sessions were measured. For CTA, a two-bottle procedure was employed. Distinctively flavoured solutions (saccharin or saline) were paired with IP injections of either ethanol (1.5 g/kg) or saline (1 ml/kg). Tests for aversion were made after two pairings, when both solutions were presented simultaneously for 10 min. At low concentrations of ethanol, drinking solution consumption was high, decreasing gradually with increasing concentrations; however, daily intake of orally self-administered ethanol remained stable. No significant differences could be established between the two groups tested. Ethanol preference [EtOH/EtOH + H2O] was attenuated in rats experienced with the CTA procedure before the OSA experiment. Injections of ethanol produced marked CTAs, even in rats that had consumed ethanol in the OSA experiment. The absence of tolerance to the aversive stimulus effects suggests that this stimulus property may not play a significant role in the consumption of ethanol.
根据具体情况，乙醇在一种实验范式中可作为强化物，而在另一种范式中则作为厌恶刺激物。这两种刺激之间的关系尚不清楚，尤其是慢性乙醇暴露后的行为适应性。我们报告了两项实验，分别使用口服自我给药（OSA）范式和条件性味觉厌恶（CTA）范式。雄性Wistar大鼠通过OSA或CTA范式接触乙醇，并通过对同一组大鼠进行另一个相应实验来检查其后果。因此，对乙醇各自刺激特性的敏化或耐受性将是可检测的。对于OSA实验，在自由选择的环境下，给大鼠提供自来水和一系列浓度递增的乙醇溶液（2%-10%），每种浓度持续4天。测量23小时内消耗的乙醇和水的量。对于CTA实验，采用双瓶法。将具有独特风味的溶液（糖精或盐水）与腹腔注射乙醇（1.5 g/kg）或盐水（1 ml/kg）配对。在两次配对后进行厌恶测试，此时同时呈现两种溶液10分钟。在低浓度乙醇时，饮用溶液的消耗量很高，随着浓度增加逐渐减少；然而，口服自我给药的乙醇每日摄入量保持稳定。在测试的两组之间未发现显著差异。在进行OSA实验之前，经历过CTA程序的大鼠对乙醇的偏好[乙醇/乙醇+水]减弱。即使在OSA实验中消耗过乙醇的大鼠中，注射乙醇也会产生明显的CTA。对厌恶刺激效应缺乏耐受性表明，这种刺激特性可能在乙醇消耗中不发挥重要作用。
