Ethanol Acceptance Is High During Early Infancy and Becomes Still Higher After Previous Ethanol Ingestion

Abstract

Intake on P12 was increased by prior exposure to ethanol intragastrically as well as by the conventional oral route, suggesting pharmacological effects of prior ethanol exposure. Yet, the apparently greater influence of prior exposure by the oral route and the influence of prior ethanol concentration also implicate the importance of ethanol's chemosensory attributes for effects of prior ethanol exposure. The equivalent g/kg intake of ethanol in 15 or 25% solutions during the early part of the second postnatal week suggests that regulation of ethanol intake at P8 and P10 is similar to that observed previously in adults. Change in aspects of ethanol ingestion at about P6 may reflect the shift in function of the GABA system at about this age.

Acute sensitivity and acute tolerance to ethanol in preweanling rats with or without prenatal experience with the drug

“…It has been recently reported that Sprague-Dawley infants similar to those in the present study consume, without the need of initiation procedures, high amounts of ethanol (Sanders & Spear, 2007;Truxell & Spear, 2004). These animals have also been observed to readily manifest biphasic motivational properties of ethanol.…”

“…In genetically heterogenous rats ethanol's activating effects have been rarely reported, and what seems to predominate is motor suppression Erickson & Kochhar, 1985;Salamone et al, 2006). When focusing on the ontogeny of genetically heterogenous rats, recent studies consistently indicate heightened affinity for ethanol ingestion and marked sensitivity to ethanol's reinforcing properties during early stages in development (Chotro et al, 2007;Spear and Molina, 2005).It has been recently reported that Sprague-Dawley infants similar to those in the present study consume, without the need of initiation procedures, high amounts of ethanol (Sanders & Spear, 2007;Truxell & Spear, 2004). These animals have also been observed to readily manifest biphasic motivational properties of ethanol.…”

“…In rat strains selectively bred for ethanol ingestion the activating effect of ethanol has been consistently observed when employing ethanol doses below 1.0 g/kg (Agabio et al, 2001;Krimmer, 1991;Paivarinta & Korpi, 1993;Quintanilla, 1999;Rodd et al, 2004;Waller, Murphy, McBride, Lumeng, & Li, 1986). As mentioned, preweanling rats show a marked sensitivity to the biphasic reinforcing effects of ethanol during the course of an acute intoxication , and also, they seem to be more predisposed to display heightened ethanol intake patterns than in later stages of development (Sanders and Spear, 2007). If sensitivity to ethanol's effects upon locomotor activity is associated with the sensitivity to the reinforcing properties of the drug, it is plausible that ethanol exerts biphasic locomotor effects in preweanling rats.…”

Naloxone attenuation of ethanol-reinforced operant responding in infant rats in a re-exposure paradigm

“…Studies conducted to analyze ethanol ingestion or sensitivity to the drug's motivational effects during early ontogeny suggest that rapid accumulation of ethanol in blood or brain is conducive to high levels of ethanol ingestion or preference for stimuli that predict ethanol's postabsorptive effects (e.g., see Molina et al 2007Molina et al , 2006Nizhnikov et al 2006a;Pautassi et al 2008a;Sanders and Spear 2007). In other words, and in accordance with recent studies conducted in adult rats (Fidler et al 2006;Kiefer et al 2005;Samson and Czachowski 2003), it appears that acceptance of ethanol requires a balance between the sensory and postabsorptive effects of the drug.…”

“…Infant rats from heterogeneous strains readily consume ethanol at rates comparable to adults genetically selected for high intake of ethanol, without the need for initiation procedures. During their second postnatal week, infant rats consume enough 25% v/v ethanol to increase their blood alcohol levels to approximately 300 mg% within 20 min (Sanders and Spear 2007;Truxell and Spear 2004). Appetitive responses for ethanol can be observed even earlier in development.…”