The impact of tobacco smoking on physical activity and metabolism in mice.

Cigarette smoking can increase the risk of many respiratory and chronic systemic diseases. Particularly, cigarette smoke produces toxic particulate matter (PM), which is harmful to the smokers. Although previous studies have demonstrated the toxicity of cigarette smoke PM and its relationship with disease pathogenesis, systematic data for the impact of cigarette smoke PM on physical activity and metabolism in animals are still lacking. In this report, the C57/B6 mice were exposed to cigarette smoke PM in a smoking chamber coupled with the analysis of metabolic changes and physical activity in metabolic cages at indicated time, for a period up to 12-month-old of age. The mice became excited following short period (e.g., 3 months) but listless after long-term cigarette smoke PM exposures (e.g., 9 or 10 months), as manifested by the changes of drink/food intake and daily activities along with increased oxygen consumption and CO₂ accumulation. Our data suggest that particulate matter originated from cigarette smoke impairs metabolism and physical activities.