DEOXYRIBONUCLEIC ACID OF NEONATAL RAT CEREBRUM INCREASED BY OPERATIVE RESTRICTION OF LITTER SIZE

Unilateral ligation of one uterine horn of mature rats was performed to increase nutrient supply to the other horn. One week postoperative, the animals were mated. They gave birth to offspring half the normal number, which were at that time heavier, having higher cerebral weight, higher total cerebral protein and higher total amount of cerebral DNA (an index of number of cells) than the sham-operated controls. All increases were statistically significant. No such differences were observed when comparing newborn rats from litters naturally small in number with those from large litters. We suggest that the animals operated on had a potential for nourishing twice the number of fetuses that they actually produced so that each of the latter received more nutrient, with a concomitant increase in the cerebral DNA (brain cell number). Part of this increase may have been due to an increase in the number of neurons; such a neuron increment would persist throughout the life of the animal. © 1969.