Differential effects of early undernutrition in white and grey matter regions of rat brain.

The effect of early postnatal undernutrition and subsequent rehabilitation on wet weight, DNA, RNA, protein, and the activities of acid and alkaline DNases in white and grey matter region of rat brain was studied. In respect to the various parameters studied, white matter was found to be markedly vulnerable to undernutrition, but the grey matter region was unaffected. It has also been observed that the earlier the initiation of nutritional rehabilitation (10th postnatal day) the better was the recovery of the white matter to a normal condition, and in some cases early nutritional rehabilitation resulted in better than normal biochemical composition of the region. The specific activity of acid DNase was unaffected by weaning undernutrition in both white and grey matter. The total activity of this enzyme, which was significantly reduced in white matter of undernourished animals, exhibited a remarkable recovery following rehabilitation, to more than normal levels at 150 days of age. Total activity of alkaline DNase was reduced only in 15-day-old white matter of deprived animals, and here also rehabilitation brought back this enzyme to significantly more than normal levels. It is concluded that the two DNases, whatever their actual physiological role might be, are synthesized in a preferential manner during the rehabilitation.