Relationship between initial sensitivity to ethanol and the high alcohol intake in dependent rats

The high spontaneous intake of ethanol, which can be induced in rats after a period of forced administration, may be used to study the altered state created in the C.N.S. by the chronic exposure to ethanol. The relationship between the initial acute sensitivity to ethanol and this induced high oral intake has been examined in rats. Initial sensitivity was determined in two groups of rats either by a test of motor impairment or by alcohol induced hypothermia. After 15 days of daily IG administration of 10 g/kg, rats were submitted to the ethanol presentations which display the high voluntary intake. Two groups of controls were initially tested for their motor impairment or hypothermia respectively under ethanol and then treated for 15 days with saline injections. The results indicate a highly significant negative correlation between initial sensitivity and the level of dependence induced by a chronic treatment and manifested by a voluntary high intake. In control groups, the low intake of ethanol observed in the final test was not correlated to the initial sensitivity to ethanol as tested by hypothermia but weakly correlated to sensitivity measured by motor impairment. The results are discussed in terms of mechanisms which determine the voluntary intake of ethanol in ethanol naive and dependent rats.