Locomotive And Thermal Effects Of Ethanol Underlying The Acquisition Of Ethanol-Mediated Second-Order Conditioning.

MOLINA J.C.,; PAUTASSI RM; TRUXELL E; SPEAR, N.E.

Atlant6a, GA, USA

Congreso; 39th Annual Meeting International Society for Developmental Psychobiology; 2006

International Society for Developmental Psychobiology

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; 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:ES; mso-fareast-language:ES;} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> It has been shown that infant rats encode differential hedonic effects of ethanol (EtOH) as a function of dose and postadministration time (PT). Specifically, intraoral conditional stimuli (CSs) paired with either early (PT 5-20’) or late effects (PT 30-45’) of ethanol (0.5 g/kg) became effective positive second-order reinforcers. Appetitive effects were also exhibited by pups exposed to the CS during commencement of the toxic episode induced by a 2.0-g/kg EtOH dose, whereas aversions were evident when CS presentation was delayed until the late PT (Truxell et al, 2006). This study analyzed several effects of ethanol likely to be underlying this phenomena. On postnatal day 14 (PD 14, first-order conditioning) preweanling rats intoxicated with ethanol (0.0, 0.5 or 2.0 g/kg) were intraorally stimulated with water (CS, 15 5-s pulses) during PT 5-20 or 30-45’. Regardless PT, the 2.0 g/kg dose induced strong hypothermic and locomotor depressant effects. Blood ethanol concentrations attained with the 0,5 and 2.0 g/kg doses were 40, 157 (PT 12.5’); 40 and 200 mg% (PT 37.5’), respectively. Twenty-four hours later, pups were exposed to the water CS while placed over a distinctive texture (second-order phase). No differential locomotion nor corticosterone levels were found at this time. Interestingly, those pups that had originally experienced the CS under the effects of EtOH exhibited significant increases in temperature. It is suggested that the ethanol-induced thermoregulatory response help counteract aversive hedonic contents associated with the drug, so allowing the establishment of EtOH-induced appetitive second-order conditioning.