Conditioned breathing depression during neonatal life as a function of associating ethanol odor and the drug's intoxicating effects.

Fetal and neonatal ethanol-related alterations upon the respiratory system have been described in different mammals. Studies also indicate that perinates learn about the sensory attributes of ethanol and associate them with diverse physiological effects of the state of intoxication. The present study was conducted in rat neonates during a developmental stage equivalent to the third human gestational trimester. The major goal was to analyze the consequences of ethanol odor exposure, the state of intoxication, or the temporal contiguity between these factors upon breathing patterns. The main findings were as follows: (a) a conditioned breathing depression was observed following few trials defined by the association between ethanol odor and the state of intoxication and (b) sequential exposure to ethanol sensitizes the organism to the drug's respiratory depressant effects without affecting ethanol metabolism. These results indicate that early breathing disruptions caused by ethanol can be determined or modulated via learning processes.