ESBRA-Nordmann 1996 Award Lecture: ethanol drinking behaviour in Sardinian alcohol-preferring rats

Abstract

Sardinian alcohol-preferring (sP) rats have been selectively bred for high ethanol preference and consumption over 16 years and 39 generations. The present paper briefly reviews some recent studies from this laboratory characterizing ethanol drinking behaviour in this rat line. Under the two-bottle regimen of free choice between 10% (v/v) ethanol and water, sP rats consume daily >4 g of ethanol/kg and avoid water almost completely. Relevant features of ethanol drinking behaviour in sP rats are: (a) attainment of high ethanol intake from the first day of exposure to ethanol, suggestive of an immediate disclosure and acquisition of ethanol reinforcement; (b) titration of daily ethanol intake in distinct binges during the nocturnal phase of the light/dark cycle, indicative of their ability to regularize both ethanol dose and administration time; (c) achievement of pharmacologically relevant blood ethanol levels at each drinking episode; (d) substitution of the calories provided by ethanol for a part of those taken from food; (e) maintenance of constant ethanol intake (in g/kg/day) in the presence of ethanol concentrations varying from 7 to 30% (v/v). These results suggest that voluntary ethanol intake in sP rats is sustained by the search for specific pharmacological effects of ethanol. Anxiolysis is likely to be one of these effects; indeed, voluntarily consumed ethanol reversed the innate, high levels of anxiety in sP rats. These results portray sP rats as a valid model for investigating the association between ethanol drinking and anxiety. Finally, the breeding programme as well as results of neurochemical studies are also described.