Appetitive, Aversive And Negative Reinforcing Effects Of Ethanol In Infant Rats (PARTE 2).

PAUTASSI RM

San Diego, CA, USA

Congreso; 32a Reunión Científica Anual de la Research Society on Alcoholism (RSA); 2009

Research Society on Alcoholism (RSA)

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> APPETITIVE, AVERSIVE AND NEGATIVE REINFORCING EFFECTS OF ETHANOL IN INFANT RATS.  -- SUNY at Binghamton, NY, USA. *   The presentation will make a case for the use of the infant (preweanling) rat as a model to study ethanol reinforcement and intake. This model provides an alternative to the highly successful approach that aims at breeding lines of rodents genetically selected for features associated with ethanol abuse and dependence (McBride and Li, 1998). By using an immature rat model, genetic differences are substituted by ontogenetic differences in structure and function. The utility of this model will be exemplified by a series of recent studies (Pautassi, Molina and Spear, 2008; Nizhnikov, Pautassi, et al., under review) that assessed ethanol reinforcement in two-week old rats by means of a variant of the conditioned place preference procedure. Ethanol-mediated appetitive reinforcement was found at low (1.0 g/kg) but not moderate ethanol doses (2.0 g/kg) and only when conditioning procedures captured the rising limb of the blood ethanol curve. Subsequent experiments replicated this result, assessed corticosterone release during training and, perhaps more important, found that ethanol-mediated preference was inhibited by pre-treatment with either a general opioid antagonist (naloxone, 0.75 -- 1.5 mg/kg) or with antagonists specific for mu- and delta receptors (CTOP and naltrindole, respectively. These results fit well with human research (Peterson et al., 2006) indicating the involvement of the endogenous opioid system in the positive reinforcing effects of ethanol occurring soon after ethanol ingestion, when blood alcohol levels are rising.  The relevance of the ontogenetic approach will also be highlighted by a description of recent findings indicating that adolescent, but not adult, rats express ethanol-mediated appetitive learning (Pautassi, Myers, et al., 2008). Taken together, these studies should provide a strong theoretical and methodological basis for researchers interested in analyzing the neurobiology of ethanol conditioned reinforcement.