Effect of malnutrition on regional growth of the developing rat brain

Abstract

Newborn Sprague-Dawley rats were restricted in food intake by increasing the litter size to 18 pups per mother. The rats were killed at 6, 8, 10, 14, 17, and 21 days and the weight, DNA, and protein content of cerebrum, cerebellum, hippocampus, and brain stem were determined and compared with values from control rats of similar age. In the cerebellum, where there is a rapid increase in DNA content (cell number), malnutrition markedly curtailed this increase resulting in an early sustained reduction in DNA content. In brain stem, where the increase in cell number is modest, malnutrition did not affect DNA content. However, the normal increase in protein content and protein/DNA ratio which occurs at 10 days was markedly curtailed. In the cerebrum, cell number increases more slowly than in cerebellum, and malnutrition had no effect until 14 days. Hippocampal cell number remains constant between 6 and 14 days and then rises between 14 and 17 days; only at 17 days was a reduction in cell number apparent in the malnourished animals. These data demonstrate that the effect of malnutrition is proportional to the rate and type of growth in the region studied. Cell division was curtailed earliest and most severely in those parts where cells were rapidly dividing. Regions in which cell division was complete showed a reduction in protein/DNA ratio but cell number (DNA content) was unaffected.