Alterations in Protein-Bound Carbohydrate Levels of Rat Serum During Food Restriction and Refeeding. ∗

Summary

The effects of food restriction and refeeding on total protein-bound hexose (HE), hexosamine (HA), sialic acid (SA), and the carbohydrate-rich seromucoid fraction (SM) were investigated. Groups of rats, fed 50% of the food required for weight maintenance were bled following weight losses of 12, 26, and 33%. Other groups were fed ad lib following depletion and serum samples were obtained when their initial weight was regained. HE and SA were significantly decreased following a 12% weight loss and declined further as depletion progressed. Re-feeding caused a marked increase in the 33% depleted group, but the final level was subnormal. HA was more resistant to moderate depletion and a highly significant decline did not occur until a 26% weight loss was attained. HA levels were normal in the 12 and 33% depleted groups following weight repletion. SM values fluctuated during depletion, first decreasing then returning to normal. SM values were significantly elevated in all repleted groups. It was concluded that the protein-bound carbohydrates of rat serum do not respond in a uniform manner to food restriction and refeeding.