THE INFLUENCE OF DIET AND THE ANTERIOR PITUITARY GROWTH HORMONE ON THE GROWTH RATE OF ADOLESCENT RATS

Abstract

The no. of days required by young rats to grow from 60 to 200 gm. was determined in 67 animals fed on Mendel''s special growth diet (diet B) and in 49 animals fed on a poorer control diet (diet C) ; approximately half the animals in each lot were injected with anterior pituitary growth hormone. Those receiving diet B with and without the hormone required an average of 28 and 38 days respectively; those receiving diet C 37 and 50 days, respectively. Injection of anterior pituitary growth hormone enhanced the more rapid and uniform growth which Mendel''s special diet achieves. The body length of selected numbers of all 4 groups, regardless of how long it took them to grow from 60 to 200 gm., was 195 mm. within a reasonable error. At least 3 factors appeared to influence growth rate: the individual growth potential of the particular rat; the quality of the diet; and the injection of the growth hormone. The rapidity of growth in the injected animals was limited in most cases by the diet, and to a lesser degree by the growth potential of the individual rat. The injected animals on diet B approached the maximum average daily increase in weight of which an adolescent [male] rat is capable, namely, 6-7 gm.