High affinity for ethanol ingestión during the course of early ontogeny in genetically heterogenous rats.

MYERS, M.L.; MILLER, S.S.; MOLINA, J.C.; SPEAR, N.E.

Chicago , ILL, USA.

Congreso; 2007 Annual Meeting of the Research Society on Alcoholism.; 2007

Research Society on Alcoholism

Rat neonates and infants exhibit high affi nity for ethanol ingestion. An early ontogenetic course of this phenomenon has been diffi cult to establish since ethanol intake in newborns has been evaluated through the use of an artifi cial nipple (AN) while older infants have been tested in terms consumption off the fl oor (COF). The goal of the present study was to compare affinity for ethanol ingestion using an intake test suitable for both neonates and infants. The intake procedure was developed trying to minimize socio-environmental disruptions (e.g. maternal deprivation) inherent to the AN and COF techniques. Consumption of water, milk or different ethanol solutions (2.5, 5.0 or 10.0% v/v) was tested while pups had access to an anesthetized dam. Fluids were intraorally infused mimicking the rate of milk ejection during a nursing bout. In Experiment 1, fl uid intake was evaluated in 2, 4, 8 and 12 day-old pups. The following day pups were tested while separated from the dam. Body weight gain and absolute ethanol ingestion (g/kg) served as dependent variables. Fluid consumption was signifi cantly higher when the mother was present. Water intake was low and stable across ages. Milk and absolute ethanol intake signifi cantly increased as a function of age. At 8 and 12 days of age ethanol intake scores attained with 10% v/v ethanol were equivalent to 1.5 g/kg. Experiment 2 was conducted  with 8-day-old pups. Water, 5 or 10% v/v ethanol were intraorally infused while pups were in contact with or separated from the mother. One day later these fl uids were infused while systematically varying maternal contact. Maternal presence promoted heightened fl uid intake. Pups ingested signifi cantly more ethanol than water particularly when in contact with the dam. Maximum ethanol intake scores were equivalent to 1.5 g/kg while maximum blood ethanol levels averaged 160 mg%. These results validate prior studies suggesting a progressive affinity for ethanol ingestion during the course of early ontogeny. During the second week of life, under relatively naturalistic conditions, pups ingest pharmacologically relevant amounts of ethanol within a brief period of time and without prior experience with the drug.