Figure 2: Impact of IGF-1 injection on plasma IGF-1 levels in SECAR mice A: SENCAR mice were exercised with iso-caloric diet for 12 weeks. IGF-I was injected at 10 μg/g B.W. twice per week in the last two weeks. Plasma IGF-1 levels were significantly lower in PE and PE+IGF-1 mice 24 hrs after the last IGF-1 injection (means with different letters differ significantly, P < 0.05, n = 5-8. B: A pharmacokinetic study of plasma IGF-1 levels after injection of IGF-1 at 10 μg/g B.W. once showed the concentration of plasma IGF-1 increased, reaching a maximal concentration near 1 hr after injection and then gradually declining to the basal level around 24 hrs with a half-life of 3.4 hrs. Results are means ± SE, n = 2-7.