Acute Ethanol Counteracts the Acquisition of an Aversive Olfactory Learning in Infant Rats.

PAUTASSI RM; MELLONI C; PONCE LF; MOLINA J.C.,

ALCOHOL

Elsevier

Año: 2005 vol. 36 p. 99 - 105

0741-8329

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; mso-layout-grid-align:none; punctuation-wrap:simple; text-autospace:none; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-fareast-language:ES-MX;} @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;} --> Rodents are particularly prone to acquire associative memories during early stages of life. Yet, very little is known about how ethanol interacts with simultaneous associative learning acquired during postabsorptive periods. We have recently observed that preweanling rats avoid a lemon odor previously paired with the intraoral infusion of a sapid sweet solution, a result likely to be caused by aversive consequences inherent to this procedure. Two experiments were conducted to analyze the effects of acute ethanol upon the acquisition of this avoidance response. Fourteen-day old Wistar rats were intragastrically administered with ethanol (0.0, 0.25, 0.5 or 1.25 g/kg) and then exposed 5 min to a lemon-scented chamber while intraorally infused with sucrose (12% v/v). Four of such pairings were conducted immediately after ethanol administration. Control pups experienced these stimuli in an unrelated fashion. On postnatal day 15 animals were tested in a 5 min, two-way odor preference test. Pups administered with vehicle during the acquisition phase exhibited a strong aversion to the lemon odor relative to control subjects. This avoidance response was reduced in those pups that received the 0.5 and 1.25 g/kg doses while completely vanished in those administered with 0.25 g/kg. In a second experiment it was observed that, ten minutes after the administration, blood ethanol concentrations attained with the 0.25, 0.5 and 1.25 g/kg doses were 11, 39 and 83 mg%, respectively. These data indicate that a very low dose of ethanol is able to counteract early aversive associative learning, a result likely to be mediated by anxiolytic properties of ethanol.