Elevation of blood NAD level after moderate exercise in young women and mice

We previously reported that the blood NAD levels are decreased by severe ex ercise, and administration of nicotinamide, a precursor of NAD, improves th e endurance capacity of mice, In the present study, we determined whether m oderate exercise changes the blood NAD levels in humans and mice. College f emale students exercised moderately with bike-ergometers, The blood NAD lev els elevated after moderate exercise, Mice were forced to swim in a running water pool for 5 min as a moderate exercise, 15 min as a strong exercise, and until exhaustion as a severe exercise (average swimming time was 28.7 m in). A 5 min swim gave a result similar to that of moderate exercise by hum an subjects. However the blood NAD levels decreased after all-out exercise. The changes in whole blood tryptophan (a precursor of pyridine nucleotides ) levels were similar to that in NAD. The glucose levels in whole blood and the non-esterified fatty acid levels in serum decreased according to exerc ising time. These data are the first demonstration of moderate exercise rai sing the blood NAD levels in human and mice. Elevation of the blood NAD lev els may reflect changes in niacin metabolism that occur in response to exer cise.