Circumstantial evidence for a role of the secretory pattern of growth hormone in control of body growth

Abstract

The effect of frequency of growth hormone (GH) administration on longitudinal bone growth and body weight was studied in hypophysectomized rats which were given replacement therapy with corticosteroids [cortisone acetate], thyroxine and GH with start of therapy on the day of surgery. Longitudinal bone growth, as determined by the tetracycline method, was measured during the last 5 days of the 9 day long period with replacement therapy. The daily replacement dose of GH was 200 .mu.g and was given on 1, 2, 4 or 8 occasions. Longitudinal bone growth was enhanced in the groups of animals receiving the hormone on 2 or more occasions per day. The most pronounced response was seen with an administration frequency of 4 times per day. Changes in body weight during the injection period showed similar changes. The administration frequency of GH is important for the growth rate in hypophysectomized rats which have been given replacement therapy. The findings suggest that the secretory pattern of GH is an important factor for optimum growth.