Heterochronic parabiosis model. A: One parabiosed partner was injected with BrdU and the joined pair was killed after 3 h. Both the injected mouse and attached
mouse were stained for DNA (green) and BrdU (red). B: Parabiosed mice demonstrated a significant decline in body weight (*P < 0.05 for Student t test and ANOVA) in all three groups, after which their weight stabilized. C: Fed blood glucose levels of connected mice (all three groups) decreased significantly after 1 week (*P < 0.05 ANOVA) and remained lower throughout the experiment (N = 5). Het, heterochronic; Iso, isochronic.