Effect of Acute Amino Acid Deficiencies on Carcass Composition and Pancreatic Function in the Force-fed Rat

Abstract
Groups of rats were force-fed diets free of either histidine, methionine, phenylalanine or threonine for 10 days. Following a single feeding of their respective diets, with or without the pancreatic stimulant, soybean trypsin inhibitor, the animals were killed two hours or 23 hours later. Pancreases and intestinal contents were analyzed for lipase, protease and amylase activities. Stomach contents were weighed as an indication of digestion. The carcasses were analyzed for water, fat and protein. Although the deficient animals lost weight when fed the same amount of diet that allowed the controls to gain, the relative proportions of water, fat and protein in the carcasses of the deficient groups did not differ from those of the control animals. The amount of solids removed from the stomach two hours after feeding was not affected by the acute deficiencies. Analyses of pancreatic and intestinal enzyme activities two and 23 hours after feeding indicated that acute deficiencies of any one of the essential amino acids reduced the level of enzyme activity in the secreting pancreas and impaired the ability of that organ to restore normal activities after a fast. Omission of histidine from the diet caused the greatest decrease in the enzyme activities of the secreting pancreas. A lack of methionine also depressed pancreatic lipase and protease activities, but had much less effect on amylase activity. Threonine-deficient rats appeared to be more able to support a higher level of pancreatic and intestinal protease activity than did animals fed diets devoid of the other amino acids.

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