Similar mechanisms may underlie the acquisition of Ethanol and Lithium Chloride-mediated conditioned taste aversions in preweanling rats

ARIAS, C; PAUTASSI, R; MURPHY, H; MOLINA, J.C.; SPEAR, N.E.

Chicago

Congreso; 30thAnnual Scientific Meeting of the Resarch Society on Alcoholism; 2007

Resarch Society on Alcoholism

Rats display taste avoidance (i.e., suppressed consumption) and aversive orofacial reactions (e.g., reduced mouthing) when stimulated with a novel tastant (conditioned stimulus, CS) previously paired with moderate to high ethanol doses. Emetic properties of ethanol (EtOH) have been suggested as possible mediators in the acquisition of these conditioned taste aversions (CTAs). This experiment was aimed to scrutinize the mechanisms underlying ethanol-mediated CTA in the infant rat. Preweanlings pups were assessed in terms of consumption and orofacial responsiveness towards a taste CS previously paired with either EtOH or lithium chloride (LiCl), an emetic agent.  Drugs doses were selected as a function of a preliminary dose-response study indicating similar effects in terms of their capability to induce conditioned taste avoidance in preweanlings. On postnatal day 13 (PD13) paired pups (P) were intraorally infused with saccharin (7.5 m, 2.5 % of body weight, BW). Immediately after they received EtOH (2.5 g/kg, i.g.) or LiCl (0.5% of BW, 0.3 M, i.p). Unpaired controls (UP) experienced these stimuli in an explicitly unrelated manner. Intake and taste reactivity tests (TRTs) were conducted on PDs 14 and 15. Statistical analyses (ANOVAs) revealed that, regardless drug treatment during acquisition, paired pups consumed less saccharin on PD 14, relative to control animals. Paired pups also showed, independently of whether they had received EtOH or LiCl, an enhanced amount of conditioned rejection reactions in the TRT. Specifically, these pups exhibited, when compared with UP controls, increased amounts of grooming, general activity, head shaking and wall climbing as well as a reduced frequency of mouthing movements. No other quantitative or qualitative differences in taste reactivity were observed between paired conditions. On PD 15, aversive conditioned orofacial reactions were still evident in P rats, even when differences in saccharin intake were no longer observed between P and UP conditions. In conclusion, a taste CS experimented in contiguity with postabortive effects of EtOH and LiCl elicited similar patterns of conditioned rejection patterns in young animals, even when employing drug doses titrated in terms of their capability to support conditioned taste avoidance. These results suggest that similar mechanisms may be underlying CTAs induced by both LiCl and a high EtOH dose in preweanling rats.