Differential ethanol intake in Tryon maze-bright and Tryon maze-dull rats: implications for the validity of the animal model of selectively bred rats for high ethanol consumption.

The search for a genetically based "animal model of alcoholism" has led to the creation of extensive research programs using various combinations of initial ethanol preference screening techniques and breeding methods to yield rodents with primary genetic differences that contribute to high or low ethanol preference. The present experiment examined the ethanol intake of the Tryon rat strain, which were bred for high and low maze learning scores. It was observed that the Tryon Maze Bright rats displayed an unprecedented affinity for ethanol with stable intakes between 12.7 and 13.7 g/kg per day and preference ratios exceeding 0.75 for ethanol concentrations ranging between 15 and 29%. The pattern of ethanol intake of the Tryon Maze Dull rats resembled the ethanol intake pattern of other, non-selectively bred strains of rats, approximately 2-3 g/kg of absolute ethanol at preference ratios between 0.11 and 0.28. The affinity for ethanol observed for the Tryon Maze Bright rats seems to exceed the reported consumption patterns of rat strains specifically bred for high ethanol consumption although the Tryon rats were selectively bred for variables that were seemingly unrelated to ethanol intake.