Figure 1. Increase in the levels of D-ribose and related enzymes in type 1 diabetic rats. Male SD rats (6–8 weeks) were intraperitoneally injected with STZ (70 mg/kg bw, n=30) and maintained for 10 weeks. Rats injected with saline were used as controls (n=10). Levels of D-ribose in urine were measured at different time intervals (panel A). D-ribose levels in serum (panel B) and the brain (panel C) were determined within 3 days after dissection. The expression and activity levels of ribokinase, transketolase (TKT), 5-phosphoribosyl 1-pyrophosphate (PRPP) and glucose-6 phosphate dehydrogenase (G6PD) in the brain were measured with ELISA kits (panel D and E). All values are expressed as the mean ± S.E.M. *, P < 0.05; **, P < 0.01; ***, P < 0.001.