Active vs. sedentary lifestyle from weaning to adulthood and susceptibility to ozone in rats

Abstract

The prevalence of a sedentary (SED) life style combined with calorically rich diets has spurred the rise in childhood obesity, which, in turn, translates to adverse health effects in adulthood. Obesity and lack of active (ACT) lifestyle may increase susceptibility to air pollutants. We housed 22-day-old female Long-Evans rats in a cage without (SED) or with a running wheel (ACT). After 10 wk the rats ran 310 ± 16.3 km. Responses of SED and ACT rats to whole-body O3 (0, 0.25, 0.5, or 1.0 ppm; 5 h/day for 2 days) was assessed. Glucose tolerance testing (GTT) was performed following the first day of O3. ACT rats had less body fat and an improved glucose GTT. Ventilatory function (plethysmography) of SED and ACT groups was similarly impaired by O3. Bronchoalveolar lavage fluid (BALF) was collected after the second O3 exposure. SED and ACT rats were hyperglycemic following 1.0 ppm O3. GTT was impaired by O3 in both groups; however, ACT rats exhibited improved recovery to 0.25 and 1.0 ppm O3. BALF cell neutrophils and total cells were similarly increased in ACT and SED groups exposed to 1.0 ppm O3. O3-induced increase in eosinophils was exacerbated in SED rats. Chronic exercise from postweaning to adulthood improved some of the metabolic and pulmonary responses to O3 (GTT and eosinophils) but several other parameters were unaffected. The reduction in O3-induced rise in BALF eosinophils in ACT rats suggests a possible link between a SED lifestyle and incidence of asthma-related symptoms from O3.