Alterations in rat serum proteins in relation to dietary proteins and B vitamins. II. Studies during protein depletion and repletion

Abstract

Protein-fasting for two weeks of rats on the laboratory stock diet results in a decrease in serum level of albumin, and of α₁-, α₂- and β-globulins. The albumin-globulin ratio remains unaltered. Repletion on a 10 per cent. casein diet with minimal as compared to optimal intake of the B vitamins - thiamine, riboflavin, nicotinic acid, pyridoxine, pantothenic acid, folic acid and vitamin B₁₂ - causes a faster restoration of total serum protein but growth is retarded. With minimal intake of the vitamins there is an incomplete restoration of albumin and α₁-globulin; an abnormal initial increase in β- and γ -globulins is followed, upon prolonged regeneration up to two weeks, by a drop in all fractions and in total serum protein. With optimal intake of B vitamins, the fractions attain normal levels at or before two weeks of regeneration. An initial abnormal increase in serum β-globulin resembles that observed at minimal intake of the vitamins. Following prolonged regeneration there is a drop in albumin and in total serum protein to subnormal levels, which effects are attributable to low level of protein in the diet. Rats on a basal, vitamin B₁₂ deficient, Bengal gram diet show reductions in blood hemoglobin, serum albumin and in serum α₁-, α₂-, and β-globulins upon protein-fasting for one week. The effects are moderated with supplements of vitamin B₁₂ and folic acid to the basal diet. Incidental observations also point to growth-promoting and serum protein-generating effects of the vitamins in the growing rat.