Mouse as a model of growth retardation in cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive disease that results in lung failure and premature death. A long recognized symptom of CF is growth failure, which is clinically relevant because it correlates with the severity of lung disease. We describe growth retardation in a mouse model of CF and discuss its potential for modeling certain aspects of human growth retardation. Mice with a null mutation in Cftr (cystic fibrosis transmembrance conductance regulator) were compared with wild-type (WT) mice at 31, 45, and 84 d of age. CF mice were severely growth retarded in weight and length compared with wild-type controls. Serum insulin like growth factor I (Igf-1) was lower in CF mice by 31-55% (depending on age and sex) and it significantly correlated with the size of mice after controlling for gender, age, and Cftr genotype. There was a marginally significant deficiency of serum growth hormone (Gh) in CF females, but not males. Our findings were consistent with models of an energy deficit in rodents. We, therefore, assessed food intake and found no difference between CF and WT mice, suggesting that CF mice had a malabsorption-mediated energy deficit. We argue that CF mice are suited to study the effects of intestinal disease on growth as well as other proposed growth-modulating processes.