m-RNA translatability in the liver,brain and kidney of rats: Effect of protein calorie malnutrition in early life

The m-RNA level and its translational capacity were determined in the liver, brain and kidney of rats which had been exposed to under nutrition early in life. To achieve this objective, lactating females were divided into 2 groups 1 week after they gave birth to offspring. These control and experimental groups were made to suckle 8–11 and 13–16 pups, respectively, for a period of 2 weeks. The young of both groups were then killed and their livers, brains and kidneys were isolated. Polyadenylated RNA (poly A⁺ RNA) was fractionated by affinity chromatography on an oligo-dT-cellulose column. Poly A⁺ RNA content as well as the percentage of poly A⁺ RNA in relation to total RNA were both lower in the malnourished pups in comparison to the controls. Analysis of the in vitro translation product primed by poly A⁺ RNA of the liver, brain and kidney revealed a decrease of ³⁵S-methionine-incorporation in the liver and brain of the dietary-insulted offspring, the reduction being greater in the liver than in the brain. No significant variation was noted in the kidney of the control and PCM groups. Sodium dodecyl sulfatepolyacrylamide gel electrophoresis, autoradiography and densitometric autoradiographic tracings confirmed these findings and demonstrated that proteins were synthesized at a lower rate in the livers and brains of the malnourished rats than in the controls. These data indicate that malnutrition early in life modulates the metabolism of m-RNA and, consequently, protein synthesis in the liver, brain and kidney of rats.