THE EFFECTS OF DIETARY DEFICIENCIES ON THE GROWTH OF CERTAIN BODY SYSTEMS AND ORGANS

Abstract

Four groups of 25 young [male] albino ratswere kept at stationary body weight for 40 days by diets representing 4 types of deficiencies: inadequate energy (low calorie diet), inadequate protein, insufficient lysine (gliadin diet), and inadequate salt intake. At the end of the stunting period the rats were dissected and data concerning the skeletal growth, growth of the brain and of some other important organs obtained. Persistent skeletal growth occurred on all diets used, as manifested by an increase in body and tail length and an increase in length of leg bones and skull. The gain in body length amounted to 3-8% of estimated body length at beginning of the experiment, or 8.7-19.5%, of the normal gain. Increase in body length was greatest on gliadin diet and least on the low salt one. Weight of leg bones of rats stunted on low calorie, low protein, and gliadin rations was 50-60% above that of bones of normal animals of same body weight, due partly to increase in length, as shown by the measurements of the bones, but also to other factors. Weight of leg bones of rats stunted on low salt diets was 30-40 % below that of animals stunted in other ways, although increase in length was the same. This applies also to weight of crania and mandibles, and shows that the bones continued to grow even while being depleted of minerals. The persistent skeletal growth apparently did not take place at the expense of any of the organs studied, as in no case was a decrease observed in organ weight. The data show the possibility of a slight increase in brain weight on all diets; no variation was apparent. The most significant change in organs was a marked and consistent increase in kidney weight as a result of food low in salts. This increase amounted to 55% of the estimated weight at beginning of the experiment and to 63 of the normal gain. Effects of ration low in salts on organ weight were similar to those found by Jackson in rats with incipient rickets. Other significant changes were an increase in liver weight, on low salt and low protein diets, an increase in testes on gliadin ration, and in heart on low protein food. Animals on gliadin diet increased in body and tail length more than those on low protein food. There was an increase in kidney and testes weights on gliadin diet which was not paralleled on low protein diet, and an increase in liver and heart weights on low protein diet which was not observed with gliadin. There was in no case during the stunting period an increase in any part of the body comparable with normal increase during a like period of time.