Animal Models of the Binge/Intoxication Stage of the Addiction Cycle
Genetic Animal Models of High Alcohol Drinking
Many genetically selected lines of rats have been bred that have high and low drinking preferences. Some of these genetic lines include University of Chile A and B rats, Alko alcohol and non-alcohol rats, University of Indiana alcohol-preferring and non-preferring rats, University of Indiana high-alcohol-drinking and low-alcohol-drinking rats, and Sardinian alcohol-preferring and non-preferring rats. The alcohol-preferring animals can voluntarily consume 6.5 g/kg alcohol per day when given a free choice between alcohol and water, attaining blood alcohol levels in the 50–200 mg% range.
FIGURE 3.4 Intracranial self-stimulation threshold procedure. A rat is trained to turn a wheel (usually a quarter turn) to receive rewarding electrical stimulation directly in the brain. Panels I, II, and III illustrate the timing of events during three hypothetical discrete trials. Panel I shows a trial during which the rat responded within the 7.5 s following the delivery of the noncontingent stimulus (positive response). Panel II shows a trial during which the animal did not respond (negative response). Panel III shows a trial during which the animal responded during the intertrial interval (negative response). For demonstration purposes, the intertrial interval was set at 10 s. In reality, however, the interresponse interval has an average duration of 10 s, ranging from 7.5 to 12.5 s. The table at the bottom shows a hypothetical session and demonstrates how thresholds are defined for the four individual series. The threshold of the session is the mean of the four series’ thresholds. [Taken with permission from Markou A, Koob GF. Construct validity of a self-stimulation threshold paradigm: effects of reward and performance manipulations. Physiology and Behavior, 1992, (51), 111–119.]