Acute effects of ethanol and the first suckling episode in the newborn rat

In humans, early postnatal experience with alcohol is far from rare and includes exposure to alcohol through breast milk or through the bottle to attain sedative effects (Croce, 1987). Exposure to alcohol though mother's milk alters the infant's suckling behavior. However, acute effects of alcohol on suckling behavior using animal models remain to be investigated.

The present study was designed to examine the effects of neonatal alcohol exposure on attachment to a surrogate nipple and ingestion of milk in rat pups, naive both to suckling and to maternal care. Cesarean-delivered rat pups were pre-exposed to four dosages of ethanol (0, 1, 2, and 3 g/kg intragastrically) and tested 30 min after ethanol administration.

Suckling behavior was impaired only in pups exposed to a dosage of 3 g/kg of ethanol. Pups in this group demonstrated longer latency to attach followed by less efficient suckling--the pups maintained contact with the nipple but showed decreased ingestion of milk from it. Pups treated with 1 g/kg of ethanol showed the greatest suckling efficiency, ingesting far more milk per minute attached to the surrogate nipple than pups in all other groups. At the same time, nonevoked motor activity was significantly suppressed by all three dosages of ethanol. Blood alcohol levels showed a linear relationship with dose at 30 min postintubation.

These findings suggest a dissociation between acute ethanol effects on suckling and overall motor activity, with suckling apparently less sensitive to suppressive and more sensitive to activating effects of ethanol.