Correlation Between Mammary Nucleic Acids of Rats During Immaturity and Lactation1,2

Abstract

Mammary deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) were measured in three abdominal-inguinal glands, surgically removed from rats aged 21, 35, or 49 days, and compared with similar measurements of the contralateral glands at Day 16 (peak) of lactation. At Day 16 the rats were divided into subgroups, depending upon whether (successful) or not (unsuccessful) each had reared six pups of her original litter without adding foster pups between Days 3 and 16 lactation. At Days 35 and 49, but not at Day 21, the mammary tissues of successful rats contained 19 to 69% more DNA and RNA than unsuccessful rats. In general, the measurements at Days 21 or 49 in predicting each criterion measured during the peak of lactation. Measurements were usually more highly correlated in successful rats the correlation coefficients between the various nucleic acid measurements at Day 35 with measurements at the peak of lactation ranged from 0.98 to 0.34. We conclude that with refinements in technique, measurements in pubertal rats may be useful estimators of future mammary development and lactational performance.