Starvation in the rat. II. Effect of age and obesity on protein sparing and fuel metabolism.

摘要: Sixteen-week-old control and obese rats survive longer than 8-wk-old rats. In addition, unlike the group, they conserve tissue RNA protein. To evaluate basis for this, effects of starvation on circulating fuels hormones urinary excretion nitrogen 3-methylhistidine (3MH) were compared in three groups. Urinary 3MH diminished during prolonged 16-wk-old rats, suggesting that both groups are able to protein curtail muscle proteolysis. contrast, urine did not decrease Protein conservation older was associated with blood levels alanine increased lipid fuels, ketone bodies, free fatty acids. Although bodies acids also first few days there no evidence sparing. all groups, as fat stores became exhausted terminally, decreased catabolism increased. Starvation caused insulin comparable rats; however, minimal reached later Thyroxine triiodothyronine (T3) fast groups; T3 These findings support contention requires continued availability fuels. The role thyroid hormone modulating these adaptations is unclear.