Growth failure occurs through a decrease in insulin-like growth factor 1 which is independent of undernutrition in a rat model of colitis

BACKGROUND Linear growth retardation is a frequent complication of inflammatory bowel disease in children. The precise mechanisms causing growth failure are not known. AIMS To determine the relative contribution of reduced calorie intake and inflammation to linear growth delay and to determine the effect of inflammation on the hypothalamic-pituitary-growth axis. METHODS Linear growth was assessed in prepubertal rats with trinitrobenzenesulphonic acid (TNBS) induced colitis, in healthy free feeding controls, and in a pair-fed group (i.e. healthy animals whose daily food intake was matched to the colitic group thereby distinguishing between the effects of undernutrition and inflammation). RESULTS Changes in length over five days in the TNBS colitis and pair-fed groups were 30% and 56%, respectively, of healthy free feeding controls. Linear growth was significantly reduced in the colitic group compared with the pair-fed group. Nutritional supplementation in the colitic group increased weight gain to control values but did not completely reverse the growth deficit. Plasma interleukin 6 (IL-6) concentrations were sixfold higher in the colitic group compared with controls. Plasma concentrations of insulin-like growth factor 1 (IGF-1) but not growth hormone (GH) were significantly lower in the colitic compared with the pair-fed group. Administration of IGF-1 to the colitic group increased plasma IGF-1 concentrations and linear growth by approximately 44–60%. CONCLUSIONS It seems likely that approximately 30–40% of linear growth impairment in experimental colitis occurs as a direct result of the inflammatory process which is independent of undernutrition. Inflammation acts principally at the hepatocyte/IGF-1 level to impair linear growth. Optimal growth in intestinal inflammation may only be achieved by a combination of nutritional intervention and anticytokine treatment.