First-order tactile conditioning induced by ethanol in infant rats.

NIZHNIKOV M; PAUTASSI RM; MOLINA J.C.,; SPEAR, N.E.

Washington, DC, USA

Congreso; Society for Neuroscience (SFN); 2008

Society for Neuroscience

In infant rats, ethanol’s pharmacological consequences are capable of supporting appetitive learning when assessed in operant and second-order conditioning techniques. However, in rats, it has been difficult to find evidence of ethanol reinforcement in terms of conditioned place preference as when directly assessing preference for tactile cues previously paired with ethanol intoxication. Two experiments tested expression of ethanol-mediated conditioned preference in two-week old rats. Experiment 1 included a pre-exposure phase (postnatal day 12, PD 12) involving brief experience with low-dose ethanol from vapor or uncontaminated air. During daily conditioning sessions (PDs 13-14), pups were given a discrimination training procedure: ethanol intoxication (1.0 g/kg, intragastrically or intraperitoneally delivered) was paired with a distinctive tactile stimulus (sandpaper, CS+), whereas an alternative texture (CS-) signaled the absence of ethanol’s effects. Unpaired controls had experience with both textures and with ethanol’s postabsorptive effects, but in a completely unrelated fashion. Tactile preferences were assessed on PD 15. Analysis (ANOVA) revealed a significant interaction between treatment at conditioning and time spent on each texture [F (1, 62) = 5.28 ; p < 0.05]. Paired animals spent significantly more time on the ethanol-related CS than on the alternative texture, whereas unpaired controls showed equivelent preference for both textures. This pattern, which was not significantly affected by pre-exposure manipulations or route of ethanol administration, was replicated in a follow-up experiment. These results indicate that rat pups can express first-order appetitive learning mediated by the postabsortive effects of ethanol. The discrimination conditioning procedure that included an explicit CS- may be a critical factor in this outcome.