Fertility and offspring survival in mice selected for different sensitivities to alcohol

The LS (long-sleep) and SS (short-sleep) selected lines of mice exhibit relatively high and low sensitivity to alcohol, respectively, because of their previous history of selective breeding. The present study identifies other differences between the two lines. SS animals are almost twice as fertile as LS animals. Analysis of vaginal plug formation suggested that higher sexual activity of SS mice is an important component of their greater fertility. Forced maternal drinking of a 10% ethanol solution during gestation, and especially during lactation, caused a decrease in survival of LS but not of SS offspring. Increased cannibalism of pups by LS mothers was probably an important component of this decrease in progeny survival. Maternal consumption of liquid in both lines was decreased during gestation, and especially during lactation, when 10% ethanol was the only available liquid in each case. The physiological basis for decreased survival of LS progeny may involve either direct effects of alcohol on progeny or indirect effects caused by water, nutritional, or hormonal imbalance in LS mothers when they are exposed to alcohol stress. The relationship of fertility and progeny survival differences in the two lines to their differences in alcohol sensitivity produced by selective breeding is discussed.