Periodicity of chronic ethanol administration as a variable in the induction of dependence in rats.

The effect of periodicity of chronic ethanol intragastric administrations on the induction of physical and behavioral dependence on ethanol has been assessed in two groups of rats. In the two groups, rats initially selected for an identical sensitivity to ethanol, were administered daily 10 g per kg b.w. during 15 days. In one group, this daily dose was administered in six intragastric pulses of 1.7 g/kg each, 3 hours apart. In the other group, the same 10 g/kg daily dose was administered in three pulses of 3.33 g/kg, 6 hours apart. In control rats determinations of blood ethanol level in these two treatment conditions showed that the daily area of blood alcohol was 2.5 times higher in the first condition than in the second one. After the 15 days of chronic forced administration, experimental rats were subjected during 6 days to an alternate eight hours single bottle presentation of 10% ethanol solution and water. In this final test of the induced behavioral dependence, rats chronically treated by small frequent doses, displayed the highest intake of ethanol solution versus water. It is concluded that periodicity of a chronic administration or intake of ethanol is an important parameter in the induction of dependence, and the frequent administration of a small daily dose distributed in higher and less frequent unitary administrations.