Alcoholism is a serious mental disorder caused from both genetics and the environment. There are many animal models of alcoholism which focus on aspects of alcohol abuse and dependence. The rodent model manipulates genetic and environmental/behavioural factors aiming to increase the rodent self-administration of alcohol. After the lights were turned off the water feeders were replaced with a feeder containing 20% ethanol. The mice were allowed to drink from this on their own free will for four hours. Genetic manipulation such as inbred mice did not yield genotypes that regularly drank alcohol on their own free will. However changing behaviours such as adding a sweetener caused the mice to drink until intoxicated, however the mice in the first generation required food and water restriction to force them into drinking the alcohol, while the succeeding generations developed a higher genetic preference to drink excessively. Mice have high reproduction rates and short gestation times. These mice were specifically breed for high blood ethanol concentrations. Throughout the experiment the blood ethanol concentration increased in each subsequent generation, increasing the following generations genetic preference to alcohol, as they would self administer on their own free will unlike generations who had not been predisposed. Mice in generations which hadn’t been previously exposed to alcohol would drink until they were still able to metabolize the ethanol; generations exposed would drink until intoxication, thus having a tendency to drink excessively. After 11 generations of selection more than 56% of the mice exceeded the blood ethanol concentration of 100mg% after being allowed to drink for four hours a night from a bottle containing 20% ethanol. Human who have a genetic preference towards alcohol generally stop drinking by the time they reach the legal driving limit (50-70mg %), however there are many who drink dependantly. This model shows the biological and genetic involvement in excessive drinking, this will help with further understanding alcoholism in humans.
Reference: Crabbe, JC, Metten, P,
& Finn, DA 2009, ‘A Line of Mice Selected for High Blood Ethanol Concentrations Shows Drinking in the Dark to Intoxication’, Biol Psychiatry, Vol. 65, pp. 662-670. Viewed 25 April 2009.
Summarised by Zoe Williams (42083469)
