DNA and DNases in normal and undernourished rat brain

Earlier studies from our laboratory [Shrivastaw and Subba Rao, 1975; Subba Rao and Shrivastaw, 1976] have indicated a positive correlation between cell proliferation, as indicated by DNA synthesis, and the levels of DNases in developing chick brain. Since undernutrition is known to affect cell proliferation in developing brain, those studies are now extended to see the effect of early undernutrition on the levels of DNA and DNases along with RNA and protein in developing rat brain. Early nutritional deprivation resulted in lesser amounts of DNA, but the concentration of DNA per gram of brain did not alter. DNA, RNA, and protein values in brains of those rats undernourished from birth to 14 days but subsequently rehabilitated up to 130 days, exhibited complete recovery, while rehabilitation up to 50 days did not show full recovery in the case of DNA. Both the specific activity and total activity of acid and alkaline DNases showed significant reduction in 14-day-old undernourished brain. However, with continued nutritional restriction up to 24 days, the specific activity of these enzymes returned to normal, although the total activity was still in deficit. These results, coupled with those on DNA levels, indicate that a compensatory mechanism may come into play when developing brain is exposed to caloric restriction.