Behavioural features of alcohol-preferring rats: focus on inbred strains

A recent study conducted a factor analysis on 18 behavioural measures obtained from four alcohol-preferring and five alcohol-non-preferring rat lines/strains. It was concluded that variables such as saccharin intake, ultrasonic vocalizations following an air puff, and defaecation in an open field were associated with voluntary and forced alcohol consumption. In contrast, measures such as time immobile in the forced swim test and time spent in the open arms of the elevated plus maze were not consistently associated with voluntary alcohol intake. The present study focuses on alcohol intake and related measures in four inbred strains of Fawn-Hooded (FH) rats that differ in voluntary alcohol intake and the ACI/N inbred rat strain, which voluntarily consumes very little alcohol. FH rats inbred by Jean Dodds (FH/Wjd) drank significantly more alcohol than FH rats inbred by Gordon Harrington (FH/Har) or selectively inbred by Abraham Provoost (FHH/Eur and FHL/EUR). In contrast, only the FH/Har strain was active in the forced swim test, suggesting that immobility and voluntary alcohol intake may be influenced by different genetic factors. The FH/Wjd rats were also much more immobile than the ACI/N rats in the forced swim test and drank almost 10 times as much alcohol voluntarily. Comparing the two parental lines with reciprocal F1 crosses revealed that alcohol consumption was influenced largely by additive genetic factors (F1 progeny had intermediate scores), whereas immobility was also influenced by dominance genetic factors (F progeny resembled the FH/Wjd parent). Preliminary analysis of 43 F2 progeny indicated that alcohol intake and immobility were not correlated. Thus, immobility in the forced swim test and high voluntary consumption of alcohol, two prominent features of the FH/Wjd rat strain which may be related to its serotonergic dysfunction, appear to be mediated by different genetic factors.