Experimental Protein-Calorie Malnutrition: Rapid Induction of Protein Depletion Signs in Early-weaned Rats

Abstract

Young rats, weaned as soon as physiologically possible (25 to 30 g) and fed a low protein diet, rapidly developed signs of protein depletion. Within 4 days plasma albumin concentration had decreased significantly below the starting concentration, and continued to drop for a further 10 days. Plasma globulins in depleted animals were maintained at levels comparable with suckling rats for the initial 10 days, after which they decreased significantly until day 14 and subsequently increased again slowly. By contrast animals fed a 20% casein diet maintained high albumin levels while globulins decreased strikingly within the first 10 days, and thereafter rose rapidly to final levels which were in excess of globulins in depleted animals. Liver glyceride concentrations in suckling, control and low protein groups were not significantly different 4 days after weaning. Six days later, however, liver glycerides in protein-depleted rats had increased fourfold, and the increase continued, albeit at a slower rate, for the remaining 36 days of the experiment. Lipid accumulation was more pronounced when sucrose, as opposed to dextrin, dextrose or starch, constituted the dietary carbohydrate source, but no change was observed in either the level of hepatic lipids, or plasma protein concentration, when dietary protein was further reduced from 4% to 2.5%. Since in addition calorie intake of low protein groups was within the range reported elsewhere for maintenance, these results indicate that early-weaned rats, which rapidly show signs of protein depletion under ad libitum feeding conditions, may provide a convenient model of protein depletion which bears some resemblance to human protein-calorie malnutrition.