Induction of Glucose-6-Phosphate Dehydrogenase by a 90% Carbohydrate Diet and 8-Azaguanine Insensitive Induction of Glucose-6-Phosphate Dehydrogenase Following a Transfer from the 90% Carbohydrate Diet to a 90% Protein Diet

Abstract

A protein-free 90% sucrose diet was refed for several days to rats starved for 7 days. 8-Azaguanine was then injected intraperitoneally concomitant with a change to a 90% protein diet to determine if glucose-6-phosphate dehydrogenase (G6PD) mRNA was synthesized during the refeeding of an inadequate protein diet. The refeeding of the 90% sucrose diet alone resulted in an induction of G6PD to 2-3 times the prestarvation level. Glucose could be substituted for sucrose with equal effect on the induction of G6PD. After the change to the 90% protein diet a further increase in G6PD activity occurred which was insensitive to 8-azaguanine and thus presumably was independent of mRNA synthesis. This 8-azaguanine insensitive increase in G6PD was greater after a 4-day refeeding of the 90% sucrose diet than after only a 2-day refeeding of the 90% sucrose diet. This indicates that synthesis of G6PD mRNA occurred while refeeding the 90% sucrose diet. Reducing the starvation period to only 2 days resulted in no induction of G6PD by the 90% sucrose diet and the absence of an 8-azaguanine insensitive induction upon changing to the 90% protein diet. J. Nutr. 104; 12-17,