Novelty seeking and harm avoidance in relation to alcohol drinking in intact rats and following axon-sparing lesions to the amygdala and ventral striatum.

Our previous research has pointed to a behavioural pattern in rats similar to the one seen in the prototypic Type 2 alcoholic, where male rats bearing basal forebrain excitotoxin axon-sparing lesions show an increased alcohol intake, lowered responsiveness to threat (harm avoidance) and an enhanced tendency to exploring novel surroundings (novelty seeking). The purpose of the present study was to: (1) examine whether excessive alcohol-consuming rats have a diminished response to potential danger and an enhanced tendency to explore novel surroundings; (2) investigate a possible relationship between the above-mentioned behavioural parameters and two of the emotional motor systems in the basal forebrain, i.e. the extended amygdala and the ventral striato-pallidal system. Thus, we compared the effect of ibotenic axon-sparing lesions (3.5 microg/0.35 microl) to the temporal part of the amygdala with lesions in the ventral striatum on alcohol intake, harm avoidance (stretched attend postures) and novelty seeking (nose pokes), before and after surgery. Our results suggest that: (1) intact animals high in novelty seeking drink more alcohol than rats low on this trait; (2) lesions of the amygdala decrease harm avoidance and fluid intake, especially in animals showing above-average levels of risk assessment pre-operatively; (3) neuronal loss in the ventral striatum stimulates novelty seeking and alcohol intake, particularly in rats which initially show less novelty seeking than average.