Rats stunted by high-dose glucocorticoid treatment are capable of undergoing catch-up growth after fasting

Abstract

Experiments were carried out to test the hypothesis that permanent growth retardation after glu-cocorticoid-induced growth suppression is due to an alteration of a central set point for target size rather than an inability of peripheral tissues to carry out catch-up growth. Rats were injected subcutaneously with saline, as controls, or with cortisone acetate, 1 mg/25 g body wt/d, for 4 d, beginning at 37 d of age. The treated animals were submitted to acute fasting for 48 h, beginning at 47 d of age, after which they were allowed to feed ad libitum. Cortisone treatment significantly stunted body wt, tail length, and tibia length. During recovery after fasting, both the cortisone-treated and the saline-injected rats exhibited catchup growth in body wt and tibial length. In other rats killed at different time intervals during recovery after cortisone treatment, only, there was no pattern of catch-up growth in tibia length. There was no difference in tibial epiphyseal width between fasted and nonfasted rats within the saline-or cortisone-treated group. The findings demonstrate that rats that are permanently stunted by high-dose glucocorticoid treatment retain the capability for catch-up growth in both soft and skeletal tissues. The data support the hypothesis that catch-up growth is regulated by a central control with a mechanism (set point) for setting target size of the body. Stunting resulting from glucocorticoid treatment may be the result of a reset of the putative set point. Copyright © 1989 International Pediatric Research Foundation, Inc.