By Suzanne Rostler

      NEW YORK, May 12 (Reuters Health) - Newborn rats who are nursed by an intoxicated mother appear to shy away from alcohol later on, suggesting that the smell of ethanol and the mother's altered behavior toward her pup while nursing can shape future memories, a recent study reports.

      According to the authors, these results suggest that very young rats can acquire alcohol-related memories in the context of nursing and these associations affect their reaction to alcohol later on.

      "Maternal ethanol can alter the nursing experience sufficiently by subtle alteration in maternal behavior as well as by the odor and taste of ethanol," one of the study's authors, Dr. Norman E. Spear of Binghamton University in Binghamton, New York, told Reuters Health.

      He added that the study speaks to the power of smell in forming memories at a very young age. In the current study, young rats acquired alcohol-related memories through the smell and taste of alcohol and the mother's aberrant behavior.

      But Spear and colleagues remain cautious about generalizing the results of the study to humans.

      "The most important contribution about our study is simply to indicate that breastfeeding potentially represents a source of generating alcohol-related memories," co-author Dr. Juan Carlos Molina of the University of Cordoba in Argentina, commented in a statement.

      To investigate the effect of alcohol exposure during nursing, the team of researchers observed differences in how very young rats interacted with intoxicated mothers and sober mothers. After interacting, the young rats were isolated and tested for ultrasonic vocalizations or "distress calls," and motor activity when placed on sandpaper and on a soft fabric. Some of the rats were also exposed to an alcohol odor.

      The study results, published in the April issue of Alcoholism: Clinical & Experimental Research, show that rats who were nursed by intoxicated mothers showed significantly higher vocalizations and overall activity 3 days after birth.

      Further, rats nursed by intoxicated mothers who were exposed to both sandpaper and the odor of ethanol avoided the sandpaper later on. They also consumed less of an alcohol solution 2 weeks after birth. Rats nursed by alcohol-free mothers did not avoid the sandpaper.

      "The bottom line is that we still don't know what the long-term detrimental effects of drinking while nursing may be," Spear noted in a statement.

           SOURCE: Alcoholism: Clinical & Experimental Research 2000;24:428-437.