Behavioral similarities and differences among alcohol-preferring and -nonpreferring rats: confirmation by factor analysis and extension to additional groups

Thirteen behavioral variables from six tasks were measured in alcohol-preferring (AA, FH, and P) and -nonpreferring (ANA, FRL, and NP) rat lines/strains and subjected to Factor Analysis. Four Independent factors accounted for > 90% of the variance. Defecation in the open field and ultrasonic vocalizations after an air puff were negatively correlated with alcohol intake and preference, whereas the increase in daily fluid intake in the presence of saccharin was positively correlated. Other factors could be labeled Activity, Emotionality, and immobility Factors, and each was independent of the Alcohol Factor. When an additional alcohol-preferring rat line (HAD) and two additional nonpreferring groups (LAD and ACI) were tested, they were found to differ on most behaviors that were associated with alcohol intake and preference in the Factor Analysis; vocalizations and saccharin-induced increase in fluid intake, but not defection. A new Factor Analysis was then performed incorporating these three new groups and including five new behavioral measures. The following measures had high loadings on the Alcohol Factor: alcohol intake under choice conditions; alcohol preference; forced alcohol intake; alcohol acceptance (forced alcohol intake/basal water intake x 100); ultrasonic vocalization; saccharin intake; saccharin-induced increase in daily fluid intake; defecation in the open field test; and immobility in a modified forced swim test. These findings indicate that there are indeed certain behavioral characteristics that are common among alcohol-preferring rat lines/strains, but there are also substantial group differences on other behavioral measures. For those behavioral measures reflecting emotionality (defecation and ultrasonic vocalization) that loaded highly on the Alcohol Factor, the alcohol-preferring rats had lower scores.