- One of the consequences of chronic resistive airway loading in rats is malfunction in body weight gain post-surgery. The lower body weight of the obstructed animals was not related to lower caloric intake or to the oxygen consumption/food intake ratio. In the current study, we determined whether the retardation in body weight gain was related to impairment of serum insulin-like growth factor-1 (IGF-1) level or due to activation of inflammatory factors 21 weeks post-surgery. During the observation period, the airway-loaded animals (n = 8) gained 44% less body weight (P < 0.001) compared with controls (n = 8) with no apparent effect on skeletal growth, i.e., body, tail and tibia length. Chronic airway-loaded animals had 32.5% lower serum IGF-1 levels (P < 0.001) compared to the controls. Interleukin-6 and tumor necrosis factor-alpha levels were below 30 pg/ml in both groups. These data suggest that the weight loss in the chronic airway-loading rats is associated with a decreased IGF-1 level and not to activation of the inflammatory response.