Postnatal Development of the Effects of Alcohol and of the Induced Tolerance to Alcohol in Mice

The effects of single and repeated intraperitoneally injected doses of ethyl alcohol on selected reflex responses and open field behaviour of mice aged from 2 to 46 days were studied. The effect of alcohol came on very rapidly in the youngest age groups, the maximum effect occurring already 3 minutes after the alcohol injection. The effect was smaller in 20 days old animals than in 8, 14, or 46 days old mice. Significant growth reductions were found in 14 days old mice which had received alcohol daily for 6 days, and in 46 days old mice which had received alcohol daily for 8 or 18 days. Increased tolerance to alcohol was found in 28 days old and in 46 days old animals after 8 daily injections, but not in 20 days old animals after 6 injections or in the younger age groups. The earliest age at which the induced tolerance to alcohol was found to develop corresponds to the age of maturation of the noradrenergic brain mechanisms, as reflected in the attainment of the adult noradrenaline level in the brain.