Long-term ethanol self-administration with repeated ethanol deprivation episodes changes ethanol drinking pattern and increases anxiety-related behaviour during ethanol deprivation in rats.
In order to study the dynamics of ethanol drinking behaviour, male Wistar rats were given the free choice between tap water, and 5, 10 and 20% ethanol solutions. After 8 weeks of continuous access, the animals were repeatedly deprived of the ethanol solutions for 3 days every 4 weeks. In the first experiment, drinking patterns were recorded for 24 h with an electronic drinkometer device, at different time-points of ethanol experience and after an ethanol deprivation episode. The preference for more highly concentrated ethanol solutions as well as ethanol consumption increased with continuing ethanol experience. Furthermore, after the ethanol deprivation episode, the animals immediately and preferentially drank from the 20% ethanol solution, the most highly concentrated ethanol solution offered. Additionally, the number of drinking bouts, particularly at the 10 and 20% ethanol solutions, was increased during the first hour after ethanol re-presentation. In a second experiment, the effects of repeated ethanol deprivation experience, inherent in this self-administration paradigm, on anxiety-related behaviour were tested on the elevated plus-maze. Repeated ethanol deprivation proved to be more anxiogenic than the first deprivation experience. Taken together, these findings suggest that ethanol deprivation is anxiogenic in long-term voluntarily ethanol-drinking rats, which is increased by repeated ethanol deprivation experience. The possibility that anxiety during ethanol deprivation might contribute to the 'relapse'-like drinking behaviour is discussed.